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WorkshoponGalacticStudieswiththeLAMOSTSurveys

Chemistry,dynamicsand

structureof theMilkyWay

The Kavli Institute for

Astronomy and Astrophysics

Book of Abstracts

July 19-23, 2010

Beijing - China

Workshop on Galactic Studies with the LAMOST Surverys

Chemistry, dynamics and structureof the Milky Way

The Kavli Institute forAstronomy and Astrophysics

July 19-23, 2010

Beijing, China

Chemistry, dynamics and structure of the Milky WayChemistry, dynamics and structure of the Milky Way

Contents

1 Committees 5

2 Program 9

3 Oral Contributions 17

4 Posters 63

5 Participants List 77

Co

mm

ittees

Committees

Scientific Organizing Committee

Timothy Beers (MSU)Yaoquan Chu (USTC)

Licai Deng (NAOC; co-chair)Zhanwen Han (YAO)Jinliang Hou (ShAO)Biwei Jiang (BNU)

Xiaowei Liu (KIAA-PKU; co-chair)Heidi Newberg (RPI)

Eric Peng (KIAA-PKU)Martin C. Smith (KIAA-PKU)

Nic Walton (IoA)Ji Yang (PMO)

Gang Zhao (NAOC)Yongheng Zhao (NAOC)

Local OrganizingCommittee

RubenGarcıa-Benito

Zhang Ning

Zhiying Huo

HuaweiZhang

Jie Yao

Haibo Yuan

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S AT U R D AY, 1 7 J U LY 2 0 1 0

P U B L I C L E C T U R EP U B L I C L E C T U R EP U B L I C L E C T U R E

1600 - 1700 Ken Freeman Dark matter in galaxies

Location: Beijing Planetarium

Abstract: About 90 percent of the mass in galaxies is invisible. We know it is there from its gravitational field, but we do not yet know what it is. Numerical simulations of galaxy formation make definite predictions about the properties of dark matter in galaxies, but many of these predictions appear to disagree with what we actually observe. I will talk about what we know about dark matter in galaxies, and describe some of the observational and conceptual problems.





S U N D AY, 1 8 J U LY 2 0 1 0

R E G I S T R AT I O N & R E C E P T I O NR E G I S T R AT I O N & R E C E P T I O N

1600 - 2000 --- REGISTRATION & RECEPTION ---

This will be held in the KIAA building (see campus map for location). Drinks and snacks will be provided.

Note that for this workshop we are allowing a significant amount of time for discussions. Talks listed as 45 mins should include 15 mins for questions, while 30 mins talks should include 10 mins for

questions. Please bear this in mind when preparing your presentation.

(R) - this denotes a review talk.

Chemistry, dynamics and structure of the Milky Way http://kiaa.pku.edu.cn/Activities/sw2010/index.php

C H E M I S T RY, D Y N A M I C S A N D S T R U C T U R E O F T H E M I L K Y WAY

K AV L I I N S T I T U T E F O R A S T R O N O M Y A N D A S T R O P H Y S I C S , P E K I N G U N I V E R S I T Y,

B E I J I N G

J U LY 1 9 T H T O J U LY 2 3 R D 2 0 1 0

10

MORNING SESSION CHAIR: Xiaowei Liu

I N T R O D U C T I O N S & O P E N I N G R E M A R K SI N T R O D U C T I O N S & O P E N I N G R E M A R K SI N T R O D U C T I O N S & O P E N I N G R E M A R K S

0800 - 0900 - - - R E G I S T R AT I O N & C O F F E E - - -- - - R E G I S T R AT I O N & C O F F E E - - -

0900 - 0930Doug Lin (KIAA), Jianguo Han (NSFC), Gang Zhao (NAOC)

Welcome and opening remarks

L A M O S T O V E RV I E WL A M O S T O V E RV I E WL A M O S T O V E RV I E W

0930 - 1015 Xiangqun Cui The optical performance of LAMOST telescope

1015 - 1100 - - - CONFERENCE PHOTO & COFFEE ---- - - CONFERENCE PHOTO & COFFEE ---

1100 - 1145 Yongheng Zhao Commissioning and current status of LAMOST

1145 - 1215 Ali Luo Data products from LAMOST pipeline and current problems

1215 - 1245 Further LAMOST discussion

- - - LUNCH ---

Lunch for each day will be provided on the 3rd floor of the Changchunyuan restaurant (outside the west gate of campus). This is included in the registration fee, but participants must bring their

conference badge as identification.

AFTERNOON SESSION CHAIR: Joss Bland-Hawthorn

O U R N E I G H B O U R SO U R N E I G H B O U R SO U R N E I G H B O U R S

1400 - 1430 Roelof de JongGhosts: Bulges, Halos, And The Stellar Outskirts Of Massive Disk Galaxies

1430 - 1515 Alan McConnachie (R) The Pan-Andromeda Archaeological Survey (PAndAS)

1515 - 1545 Dougal MackeyThe Newly-Discovered Remote Globular Cluster System of Andromeda

1545 - 1630 - - - COFFEE ---- - - COFFEE ---

1630 - 1715 Matthew Walker (R) Measuring Dark Mass in the Smallest Galaxies

1715 - 1745 Francesca PrimasThe power of multi-object spectrographs: follow-up studies at high-resolution

Page 2


M O N D AY, 1 9 J U LY

11

MORNING SESSION CHAIR: Eric Peng

D WA R F G A L A X Y & H A L O F O R M AT I O ND WA R F G A L A X Y & H A L O F O R M AT I O ND WA R F G A L A X Y & H A L O F O R M AT I O N

0900 - 0930 Yang-Shyang Li Satellites of simulated Milky Way-like galaxies

0930 - 1000 Noam Libeskind The preferential infall of satellite galaxies

1000 - 1030 Andrew Cooper Modelling Galactic Stellar Haloes

1030 - 1100 - - - COFFEE ---- - - COFFEE ---

S T R E A M M O D E L L I N G & O B S E RVAT I O N SS T R E A M M O D E L L I N G & O B S E RVAT I O N SS T R E A M M O D E L L I N G & O B S E RVAT I O N S

1100 - 1130 Jorge Penarrubia The galactic metamorphosis of the Sagittarius dwarf

1130 - 1200 Ling Zhu Sagittarius debris in SDSS Stripe 82

1200 - 1230 Shoko Jin Dynamics of stellar streams in the Milky Way halo

- - - LUNCH ---

AFTERNOON SESSION CHAIR: Heather Morrison

S T R E A M S M O D E L L I N G & O B S E RVAT I O N S (C O N T I N U E D )S T R E A M S M O D E L L I N G & O B S E RVAT I O N S (C O N T I N U E D )S T R E A M S M O D E L L I N G & O B S E RVAT I O N S (C O N T I N U E D )

1400 - 1445 Amina Helmi (R)Galactic archaeology: characterisation of the dynamical signatures of mergers

1445 - 1515 Heidi Newberg Tidal Debris in the Milky Way Halo

1515 - 1545 Haotong Zhang New stellar stream found in SDSS data

1545 - 1630 - - - COFFEE ---- - - COFFEE ---

H A L O O B S E RVAT I O N S & M O D E L L I N GH A L O O B S E RVAT I O N S & M O D E L L I N GH A L O O B S E RVAT I O N S & M O D E L L I N G

1630 - 1715 Connie Rockosi (R) Recent Results from the SEGUE Survey

1715 - 1745 Licai Deng LAMOST survey for the Milky Way Galaxy

1745 - 1815 Haining Li The LAMOST survey for metal-poor stars

- - - B A N Q U E T - - -

For the conference banquet we will enjoy Peking Duck at Quan Ju De restaurant, located in the Qinghuayuan area east of campus. Buses will leave from the north bank of Weiming Lake (i.e. the

large lake on the centre of campus) at 1845.

Page 3


T U E S D AY, 2 0 J U LY

12

MORNING SESSION CHAIR: Licai Deng

H A L O O B S E RVAT I O N S & M O D E L L I N G (C O N T I N U E D )H A L O O B S E RVAT I O N S & M O D E L L I N G (C O N T I N U E D )H A L O O B S E RVAT I O N S & M O D E L L I N G (C O N T I N U E D )

0900 - 0930 Heather Morrison The Outer Halo of the Milky Way

0930 - 1000 Alis Deason Evidence for Rotating Milky Way Halo Stellar Populations

1000 - 1030 Zhou Fan South Galactic Cap U-band Sky Survey (SCUSS)

1030 - 1100 - - - COFFEE ---- - - COFFEE ---

1100 - 1130 Eric Peng Galactic Structure in the Next Generation Virgo Survey

1130 - 1200 Nicolas Martin Viewing the Milky Way with Pan-STARRS

1200 - 1230 Stefan Keller SkyMapper's Southern Sky Survey

- - - LUNCH ---

- - - F R E E A F T E R N O O N - - -

There is the opportunity for workshop participants to attend a tour of the Great Wall (at Badaling)on Wednesday afternoon. If people wish to join the tour they should sign-up at registration.

In order to finalise numbers, those who would like to attend must let us know before 5pm on Monday.

Page 4


W E D N E S D AY, 2 1 J U LY

13

MORNING SESSION CHAIR: Nicholas Walton

B R I D G I N G T H E H A L O & D I S CB R I D G I N G T H E H A L O & D I S CB R I D G I N G T H E H A L O & D I S C

0900-0945 Kim Venn (R)Chemical and Dynamical properties of the Stars in Low Mass Galaxies

0945-1015 Dan Zucker HERMES: Deciphering the Milky Way's History

1015 - 1045 Laurent Eyer The Gaia mission

1045 - 1115 - - - COFFEE ---- - - COFFEE ---

1115 - 1200 Alyson Brooks Modelling Realistic Dwarf Galaxies (and Stellar Halos)

1200 - 1230 Daisuke Kawatta Metal mixing of disk gas and stars

- - - LUNCH ---

AFTERNOON SESSION CHAIR: Amina Helmi

D I S C S I M U L AT I O N SD I S C S I M U L AT I O N SD I S C S I M U L AT I O N S

1400 - 1430 Ralph Schoenrich Modelling the Galactic disc(s)

1430 - 1500 Ivan MinchevA New Mechanism for Galactic Disc Mixing: Implications to the Milky Way

1500 - 1530 Victor Debattista Stellar Migration In Disk Galaxies and Disk Outskirts

1545 - 1630 - - - COFFEE ---- - - COFFEE ---

D I S C O B S E RVAT I O N S & M O D E L L I N GD I S C O B S E RVAT I O N S & M O D E L L I N GD I S C O B S E RVAT I O N S & M O D E L L I N G

1630 - 1700 Jinliang Hou The Milky Way disk and the LAMOST survey

1700 - 1730 Xiaowei LiuThe Xuyi Schmidt Telescope and LAMOST Digital Sky Survey of the Galactic Anti-center (XLDSS-GAC)

Page 5


T H U R S D AY, 2 2 J U LY

14

MORNING SESSION CHAIR: Jinliang Hou

D I S C O B S E RVAT I O N S & M O D E L L I N G (C O N T I N U E D )D I S C O B S E RVAT I O N S & M O D E L L I N G (C O N T I N U E D )D I S C O B S E RVAT I O N S & M O D E L L I N G (C O N T I N U E D )

0900 - 0945 Arnaud Siebert (R) Science with RAVE

0945 - 1015 Martin C. Smith Kinematics of the MW disc in SDSS

1015 - 1045 Chao Liu Stellar populations in the Galactic thick disk

1045 - 1115 - - - COFFEE ---- - - COFFEE ---

1115 - 1145 Melanie GuittetStudy of the stellar populations of the Milky Way in CFHTLS fields

D I S C O B S E RVAT I O N S & S T A R F O R M AT I O ND I S C O B S E RVAT I O N S & S T A R F O R M AT I O ND I S C O B S E RVAT I O N S & S T A R F O R M AT I O N

1145 - 1215 Martin Asplund Galactic archeology and planet formation

- - - LUNCH ---

AFTERNOON SESSION CHAIR: Martin C. Smith

D I S C O B S E RVAT I O N S & S T A R F O R M AT I O N (C O N T I N U E D )D I S C O B S E RVAT I O N S & S T A R F O R M AT I O N (C O N T I N U E D )D I S C O B S E RVAT I O N S & S T A R F O R M AT I O N (C O N T I N U E D )

1400 - 1430 Li Chen Galactic open cluster survey with LAMOST

1430 - 1500 Nicholas Walton The IPHAS Galactic Plane Survey

1500 - 1530 Hongchi Wang Molecular Clouds and Star Formation in the Milky Way

1530 - 1600 - - - COFFEE ---- - - COFFEE ---

S U M M A RYS U M M A RYS U M M A RY

1600 - 1645 Joss Bland-Hawthorn Conference Summary

1645 - 1700 - - - CONCLUDING REMARKS ---- - - CONCLUDING REMARKS ---

Page 6


F R I D AY, 2 3 J U LY

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Lamost OverviewLamost Overview Monday 19 09:30-10:15

The optical performance of LAMOST telescopeXiangqun Cui

National Astronomical Observatories

China

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) projecthas completed its engineering work, and is going to finish commissioning in 2011.The LAMOST telescope is with both large aperture and wide field of view to achievethe large scale spectroscopic survey observation. It is an innovative meridian activereflecting Schmidt configuration achieved by an active deformable Schmidt plate,which could not be realized by the traditional optical system. Its primary mirrorand active Schmidt plate both are segmented. The active deformable segments(sub-mirrors) are hexagonal. This paper presents the optical performance of thetelescope of LAMOST. It is shown that LAMOST project successfully resolving thebig technical challenges, and developed special active optics. It makes the progressin active optics.

Abstract

18 KIAA - July 2010 - BeijingKIAA - July 2010 - Beijing


Commissioning and current status of LAMOSTYongheng Zhao

NAOC

China


19


Data products from LAMOST pipeline and currentproblems

Ali LuoLAMOST team, NAOC

China

The talk will present data products that the LAMOST will produce, and then, howprecision of the data reduction will be given. The talk will also introduce currentproblems with the pipeline that need to be solved. At last, some useful informationwill be mentioned regarding to commissioning data acquirement.

Abstract


Our NeighboursOur Neighbours Monday 19 14:00-14:30

Ghosts: Bulges, Halos, And The Stellar Outskirts OfMassive Disk Galaxies

Roelof de JongAstrophysikalisches Institut Potsdam (AIP)

Germany

In recent years we have started to appreciate that the outskirts of galaxies containvaluable information about the formation process of galaxies. In hierarchical galaxyformation the stellar halos and thick disks of galaxies are thought to be the result ofaccretion of minor satellites, predominantly in the earlier assembly phases. The size,metallicity, and amount of substructure in current day halos are therefore directlyrelated to issues like the small scale properties of the primordial power spectrumof density fluctuations and the suppression of star formation in small dark matterhalos.To put observations of the Milky Way halo in a more general context I have startedthe GHOSTS HST survey of the resolved stellar populations of 18 nearby, massivedisk galaxies. I will show that the smaller galaxies (Vrot 100 km/s) have very smallhalos, but that most massive disk galaxies (Vrot 200 km/s) have very extendedstellar envelopes. Structurally these envelopes are smoothly connected to the innerbulges and both components can be fitted by one Sersic profile. The envelopeproperties correlate with Hubble type and bulge-to-disk ratio. The color changes inthe RGB star populations indicate that there are small radial metallicity gradients inthese halos, but at 30 kpc above the disk the envelopes are still much more metalrich than the Milky Way halo. Given the structural and metallicity properties ofthe detected envelopes we may call into question whether we detect very extendedbulge populations or inner halo populations.

Abstract


21


The Pan-Andromeda Archaeological Survey(PAndAS)

Alan McConnachieNRC Herzberg Institute of Astrophysics

Canada

I will present the latest results from the Pan-Andromeda Archaeological Survey(PAndAS) that is contiguously surveying > 300 square degrees surrounding M31and M33, reaching to a maximum projected radius of 150kpc and 50kpc from thecenters of these galaxies. After a few years of data, the main body of the surveyis now complete and the northern and southern hemispheres have been mappedto comparable depth over comparable areas. I will discuss the nature of a largescale structure surrounding M33 and show how this implies an interaction betweenM33 and M31 approximately 2 - 3 Gyrs ago and helps constrain M31’s transversemotion. I will discuss the overall properties of the dSph satellite system (now up toAndXXVII), and review new discoveries of numerous large stellar streams, some ofwhich have identifiable progenitors (such as AndI and some of the dwarf ellipticalcompanions), and some with no clear progenitor. Finally, I will show how this uniquepanoramic view of an L* galaxy system is being quantified from a global perspective,specifically relating to measurement of the 2D shape of the stellar halo out to verylarge radius, and an analysis of the statistics of the substructure distribution forcomparison to galaxy formation models.

Abstract



The Newly-Discovered Remote Globular ClusterSystem of Andromeda

Dougal MackeyThe Australian National University

Australia

Globular clusters are important fossil tracers for deciphering the archaeologicalrecord of star formation and mass assembly in galaxies, with strong implicationsfor cosmological models. However, even in the Milky Way the extent to which theobserved properties of globular cluster sub-groups reflect the assembly history ofthe Galactic halo remains a largely unresolved question. In this talk I will report onrecent results from the Pan-Andromeda Archaeological Survey (PAndAS), which isshedding new light on the outer halo of M31. We have discovered a large sampleof remote globular clusters in this galaxy, reaching up to ∼ 200 kpc from its centre.At projected radii beyond ≈ 30 kpc, where large coherent stellar streams are readilydistinguished in the field, there is a remarkable correlation between these featuresand the positions of the globular clusters. The probability that this could be dueto the chance alignment of clusters that are smoothly distributed within the M31halo is very low, indicating that the observed spatial coincidence reflects a genuinephysical association between the globular clusters and multiple debris streams. Inturn, this implies that the majority of the remote globular cluster system of M31has been assembled as a consequence of the accretion of cluster-bearing satellitegalaxies. This work provides a striking direct illustration of the classical Searle &Zinn type paradigm, and constitutes the strongest evidence to date that the outerhalo globular cluster populations in some galaxies are largely accreted.

Abstract


23


Measuring Dark Mass in the Smallest GalaxiesMatthew Walker

Institute of Astronomy, University of Cambridge

United Kingdom

Dwarf spheroidal galaxies represent the extreme lower limit of galaxy formationas well as the smallest stellar systems with kinematics suggestive of an internaldark matter component. Their properties provide boundary conditions on models ofgalaxy formation, and their large dark matter contents make dSphs attractive targetsfor indirect detection of dark matter self-annihilation and/or decay. Anything dSphsmight teach us about the particle nature of dark matter depends on our ability tomap the dark matter distributions in these systems. I will review efforts to measuredSph masses from stellar kinematics.

Abstract



The power of multi-object spectrographs:follow-up studies at high-resolution

Francesca PrimasEuropean Southern Observatory

Germany

The last decade has clearly demonstrated that surveys, when properly supportedand organized, are a very powerful tool to simultaneously address multiple keyastrophysical questions and to combine all the information in a coherent ”big”picture.A revolution of similar importance has happened also on smaller scales, with theadvent of high resolution multi-object spectrographs on 8-10m class telescopes,which has made possible to reach new frontiers by obtaining detailed informationon the chemical and dynamical evolution of environments outside our own Galaxy.During this presentation, I will show some recent results we have obtained withFLAMES at the VLT, on both Galactic metal-poor globular clusters and the Mag-ellanic Clouds.

Abstract


25

Dwarf Galaxy & Halo FormationDwarf Galaxy & Halo Formation Tuesday 20 09:00-09:30

Satellites of simulated Milky Way-like galaxiesYang-Shyang Li

Kapteyn Astronomical Institute

The Netherlands

We combine a series of high-resolution simulations with semi-analytical galaxy for-mation models to follow the evolution of a system resembling the Milky Way and itssatellites. The semi-analytical model is based on that developed for the MillenniumSimulation, and successfully reproduces the properties of galaxies on large scales aswell as those of the Milky Way. In this model, we are able to reproduce the luminos-ity function of the satellites around the Milky Way by preventing cooling in haloeswith Vvir < 16.7km s−1 (i.e. the atomic hydrogen cooling limit) and including theimpact of the reionization of the Universe. The physical properties of our modelsatellites (e.g. mean metallicities, ages, half-light radii and mass-to-light ratios) arein good agreement with the latest observational measurements. We do not find astrong dependence upon the particular implementation of supernova feedback, buta scheme which is more efficient in galaxies embedded in smaller haloes, i.e. shal-lower potential wells, gives better agreement with the properties of the ultrafaintsatellites.

Abstract



The preferential infall of satellite galaxiesNoam Libeskind

Astrophysikalisches Institut Potsdam (AIP)

Germany

Using a high resolution dark matter (DM) simulation of the Local Group, con-ducted within the framework of the Constrained Local UniversE Simulation (CLUES)project, we investigate the nature of how satellites of the Milky Way (MW) and M31are accreted. Satellites of these two galaxies are accreted anisotropically onto themain halos, entering the virial radius of their hosts, from specific “spots” with re-spect to the large scale structure. Furthermore, the material which is tidally strippedfrom these accreted satellites is also, at z = 0, distributed anisotropically and is char-acterized by an ellipsoidal sub-volume embedded in the halo. The angular patterncreated by the locus of satellite infall points and the projected z = 0 stripped darkmatter stripped is investigated within a coordinate system determined by the loca-tion of the Local Group companion and the simulated Virgo cluster across concentricshells ranging from 0.1 to 5rvir. Remarkably, the principal axis of the ellipsoidal sub-volume shows a coherent alignment extending from well within the halo to a fewrvir. A spherical harmonics transform applied to the angular distributions confirmsthe visual impression: namely, the angular distributions of both the satellites entrypoints and stripped DM for both halos is dominated by the l = 2 quadrupole term,whose major principal axis is approximately aligned across the shells considered. Itfollows that the outer (r > 0.5rvir) structure of the main halos of the Local Groupcomposed of stripped material is closely related to the cosmic web, within which itis embedded. Given the very plausible hypothesis that an important fraction of thestellar halo of the Milky Way has been accreted from satellite galaxies, the presentresults can be directly applied to the stellar halo of the MW and M31. We predictthat the remnants of tidally stripped satellites should be embedded in streams ofmaterial composed of dark matter and stars. The present results can therefore shedlight on the existence of satellites embedded within larger streams of matter, suchas the Segue 2 satellite.

Abstract


27


Modelling Galactic Stellar HaloesAndrew Cooper

University of Durham

United Kingdom

I will describe a combination of semi-analytic and N-body simulations of galacticstellar haloes in the full generality of the CDM model. I will discuss how the struc-ture, kinematics and chemistry of simulated haloes can be related to the assemblyhistory of the galaxy, and compare the models with observational data.

Abstract


Stream Modelling & ObservationsStream Modelling & Observations Tuesday 20 11:00-11:30

The galactic metamorphosis of the Sagittariusdwarf

Jorge PenarrubiaInstitute of Astronomy

UK

The Sagittarius (Sgr) dwarf galaxy and its associated tidal stream are a prototypicalexample of hierarchical galaxy formation in action. Furthermore, the fact that Sgr’sorbit is close to polar and that its orbital plane vector is nearly perpendicular to theaxis formed by the Sun and the Galactic centre provides an ideal configuration toexplore the shape of the Milky Way (MW) potential.However, the Sgr stream is proving very hard to reproduce: (i) first, no model todate has been able to explain why the leading arm is bifurcated, (ii) secondly, andmore worrisome, in order to explain the distances and radial velocities measuredalong the stream, the MW dark matter halo must be triaxial in shape, with theminor axis aligned with the spin vector of the MW disc. Alas, it is well known thatno circular orbits exist in such a configuration, which casts doubts on validity ofthese models. In this talk I will show how the Sgr stream constrains the Milky Wayhalo shape, as well as a possible solution for the existence of a bifurcated leadingarm that also remedies the implausible orientation of the MW halo with respect tothe disc.

Abstract


29


Sagittarius debris in SDSS stripe 82Ling Zhu

Tsinghua University

China

The SDSS equatorial stripe (Stripe 82) contains spectroscopic data for over twentyfive thousand stars. We have identified and analysed Sagittarius debris through theradial velocity of the stars. The stars in the stream have a global radial velocitydifferent from the stars in the halo, and they also have their own velocity disper-sion. This dispersion gives an important constraint on simulations of the Sagittariusstream, which can determine the mass of the progenitor and also diagnose the grav-itational potential of the Milky Way. Combined with photometry, a clean sampleof Sagittarius debris stars has been obtained. Using the wide variety of informationavailable for these stars (metallicity, radial velocity, gravity, photometry), we areable to gain deep insights into the nature of the Sagittarius system.

Abstract



Dynamics of stellar streams in the Milky Way haloShoko Jin

ARI/ZAH University of Heidelberg

Germany

The numerous stellar streams recently discovered around the Milky Way hold vitalclues to the assembly history and mass distribution of our Galaxy, provided one isable to fully understand their 6D phase-space properties. I will present two analytictechniques that can be used to reconstruct the motion of these streams from thelimited 3 or 4-dimensional information provided by the current and upcoming bestphotometric and/or spectroscopic surveys, such as LAMOST. Using gradients inradial velocity and distance (either independently or in combination), I will showthat one can infer the orbits of stream-like structures in the Galactic halo, a crucialstep in shedding light on their origins and for their use in understanding the MilkyWay’s structure and formation.

Abstract


31


Galactic archaeology: characterization of thedynamical signatures of mergers

Amina HelmiKapteyn Institute, Univ. of Groningen

Netherlands

I will review our current understanding of the dynamical imprints of accretion events,especially in the Galactic halo. I will also discuss new models and methods to retrievesuch events from future surveys.

Abstract



Tidal Debris in the Milky Way HaloHeidi Newberg

Rensselaer Polytechnic Institute

USA

The number of known tidal debris streams in the Milky Way’s halo has recentlygrown every year, particularly from analysis of SDSS/SEGUE data. In time weexpect these streams will elucidate the merger history of the galaxy and allow usto determine the shape of the Milky Way’s dark matter halo. Sometimes poorunderstanding of the observational data have led to misconceptions, controversies,or ambiguities in determining halo substructure. I will show examples of how tidaldebris streams are beginning to constrain the Galactic potential. We are currentlyusing over 1 petaflop of volunteer computing (MilkyWay@home) to fit the densitydistribution of tidal debris in the Sagittarius dwarf galaxy, and we are implementingsemi-analytic N-body modeling of tidal debris streams on this platform.

Abstract


33


New stellar stream found in SDSS dataHaotong Zhang

NAOC

China

We report detection of several faint stellar stream candidates in SDSS DR7 pho-tometric data. The distances of these stream candidates ranging from 8 to 15Kpcand spanning more than 10 degree on the sky. Available kinematic data such asproper motion and radial velocity data was checked to improve their reliability.

Abstract


Halo Observations & ModellingHalo Observations & Modelling Tuesday 20 16:30-17:15

Recent Results from the SEGUE SurveyConnie Rockosi

University of California, Santa Cruz

USA

I will review recent results from the SEGUE survey on the assembly history of theMilky Way halo and old stellar populations.

Abstract


35


LAMOST survey for the Milky Way GalaxyLicai Deng

NAOC

China

The Chinese key scientific project, LAMOST, has concluded its construction phase,and is now under going technical commissioning. This is a dedicated survey facilitywhich will carry out a full sky spectral survey of stellar and galactic source. Scientificprogram of LAMOST will be started in 1 year or 2 from now. LAMOST is a reflectingtelescope with a horizontal layout, aperture diameter 3.6-4.8 m, field of view of 20square degrees and 4000 fibers evenly distributed on the focal plane of 1.75m, witheach fiber driven by 2 independent motors. In this talk, I will cover instrumentspecifications, site conditions, scientific potential in Galactic structure studies, aswell as the latest status of the project.

Abstract



The LAMOST survey for metal-poor starsHaining Li

NAOC

China

Metal-deficient stars are regarded as fossils of the early generation of stars. Theyprovide fundamental information and insights on properties of the very early stageof the chemical history of the Galaxy and have been investigated for decades.The unique design of LAMOST such as the large field, and multi-object observation,prepares it to be an excellent tool for searching for these metal-poor stars in the MilkyWay. We give a brief report on the result of test observation on searching for metal-poor stars with LAMOST, during which 9 candidate metal-poor stars with [Fe/H] <-1.0 were newly detected based on the low-resolution spectroscopic observation ofLAMOST commissioning period. The test sample provides support to the efficiencyof selection for the input catalogue, as well as to the ability of LAMOST in enlargingthe sample of metal-poor stars in the Milky Way. Furthermore, the sample starscould be used for future calibration of LAMOST stellar parameter pipeline.

Abstract


37

Halo Observations & ModellingHalo Observations & Modelling Wednesday 21 09:00-09:30

The Outer Halo of the Milky WayHeather Morrison

Case Western Reserve University

USA

I will present recent results from SEGUE on the kinematics and abundance distribu-tion of a large sample of outer halo stars, identified in situ, and contrast this withextrapolations using orbits of halos in the solar neighborhood. The outer halo isthe best place to study the accretion history of the Milky Way, and SEGUE’s largesample sizes have allowed us to revolutionize this field.

Abstract



Evidence for Rotating Milky Way Halo StellarPopulations

Alis DeasonInstitute of Astronomy, University of Cambridge

United Kingdom

Rotational properties of halo populations can provide clues as to their origin andevolution, and may allow us to identify associations sharing a common formationhistory. Simple and flexible distribution functions are used to model rotating stellarpopulations in dark halos. I apply such methods to model the outer stellar halotraced by Blue horizontal branch (BHB) stars. An apparent dichotomy betweenrelatively metal-rich and metal-poor stars is discussed. I argue that a signal ofretrograde rotation in the metal-poor stars is due to an underestimate of the LocalStandard of Rest. An independent estimate of this important Galactic parameteris given, in agreement with recent estimates based on masers in high star formingregions of the Galaxy.

Abstract


39


South Galactic Cap U-band Sky Survey (SCUSS)Zhou Fan

NAOC

China

The South Galactic Cap U-band Sky Survey is an international cooperative projectbetween National Astronomical Observatories, Chinese Academy of Sciences andSteward Observatory, University of Arizona, USA. We plan to perform a sky surveyof about 3700 square degree field of the south Galactic cap in U-band (3550 A)with the 90 inch (2.3 m) Bok telescope , which belongs to the Steward Observatory,University of Arizona and it is located on the Kitt Peak. The telescope equippedwith four 4K × 4K CCD mosaic (64-magapixel) and it will image over 1 deg ×1 deg of the sky at one time. The exposure time is 5 minutes and the limitingmagnitude will reach about 23 mag (signal-to-noise = 5).

Abstract



Galactic Structure in the Next Generation VirgoSurveyEric Peng

Peking University

China

The Next Generation Virgo Survey is an ongoing Large Program withCFHT/Megacam to create a deep map of the nearby Virgo cluster of galaxies,covering 104 square degrees in u*g’r’i’z’, and going nearly 3 magnitudes deeperthan the SDSS. Although the main science goal is to study the member galaxiesand environment of the Virgo cluster, this region of sky also includes two impor-tant substructures in the Galactic halo - the Virgo Overdensity and the SagittariusStream. Combined with follow-up spectroscopy from MMT/Hectospec, these datagive us a unique view on two of the largest substructures in the halo. I will presentearly Galactic science results from the NGVS, itself a precursor to the era of LAM-OST, Pan-STARRS, and LSST.

Abstract


41


Viewing the Milky Way with Pan-STARRSNicolas Martin

Max Planck Institute for Astronomy

Germany

The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) is asystematic survey of three quarters of the sky. Starting in 2010, it will map a largefraction of the Local Group in five filters (grizy) and provide an unprecedented mapof the Milky Way and its satellite system, probing a volume 30 times larger thanthat probed by the Sloan Digital Sky Survey. I will review the Local Group sciencethat will be performed with the survey data and present preliminary data analysisfrom commissioning observations.

Abstract



SkyMapper’s Southern Sky SurveyStefan Keller

RSAA, Australian National University

Australia

The SkyMapper telescope will perform the Southern Sky Survey encompassing the2π steradians south of the celestial equator to a limiting magnitude of g < 23. Thesurvey will be a multi-colour and multi-epoch survey that utilises a filter set opti-mised for stellar astrophysics. Namely, SkyMapper’s filter set provides unparalleledresolution of stellar temperature, surface gravity and metallicity within the stellarpopulations of the Milky Way and the Magellanic Clouds.In my talk I will discuss the survey design, science goals (which include a searchfor metal-poor stars and tracing galactic structure), and timeline. I will discuss thesynergies between GAIA, the multi-object echelle spectrograph for the AAT calledHERMES and SkyMapper.

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Bridging the Halo & DiscBridging the Halo & Disc Thursday 22 09:00-09:45

Chemical and Dynamical properties of the Starsin Low Mass Galaxies

Kim VennUniversity of Victoria

Canada

The chemical abundances and dynamical properties of stars can be used to tracethe origins and evolution of a stellar population. Chemical abundances are the keyto unlocking the effects of star formation history, with stellar mass and metallicity,due to variations in nucleosynthetic yields. Dynamical properties can be used tostudy the effects of stellar feedback, tidal interactions, and the merging history ofthese low mass systems. The chemical abundances of stars in the Galaxy and nearbydwarf spheroidals now show that the most metal-poor stars have surprisingly similarproperties, however subsequent chemical evolution has been unique to each stellarpopulation. The chemical-dynamical analysis of the more isolated dwarf galaxies isalso now possible, and first results for one system (WLM) show that the stars havelower rotational velocities and higher velocity dispersions than the HI gas, whichcan be used to examine effects of stellar feedback, internal dynamics, and merging.

Abstract



HERMES: Deciphering the Milky Way’s HistoryDaniel Zucker

AAO / Macquarie University

Australia

HERMES is a multi-fibre spectrograph being built for the AAT 3.9m telescopeat Siding Spring, Australia. Designed to work with the 2dF robotic positioner,HERMES will simultaneously obtain high resolution (R ∼ 30,000) spectra for ∼ 400stars over a 2 degree field of view. The spectra will cover four passbands selectedto include elements from all major independently-varying element groups, allowingdirect determination of detailed abundances for each star. HERMES will be used tosurvey a million stars down to V ∼ 14 (at a S/N of ∼ 100 per resolution element),with the goal of using chemical tagging to decipher the formation history of theMilky Way. The survey will be directly complementary to wide-area photometricsurveys like Skymapper, spectroscopic surveys such as LAMOST/LEGUE, and themultidimensional dataset which will come from Gaia.

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45


The Gaia missionLaurent Eyer

Observatoire de Geneve, Universite de Geneve

Switzerland

The Gaia mission is a cornerstone mission of the European Space Agency (ESA)with a target launch date of 2012. It is a whole sky survey mission, and aimsat measuring repeatedly a mean of 70 times over 5 years 1 billion sources up tomagnitude V ∼ 20. The measurements consists of positions, apparent magnitude,spectrophotometry in the blue and red, and near infra-red spectroscopy (for starsbrighter than magnitude 17). These measurements will lead to the 3-D position ofthe sources, the 3 components of their space velocity and some of their intrinsicproperties such as their surface temperature, their surface gravity and their metal-licity; the interstellar extinction along the line of sight may also be derived. Gaiawill impact not only the understanding of the Galactic structure and evolution, butalso a wide range of scientific topics such as the studies of solar system minorbodies, stellar astrophysics, exo-planets, distance scale, etc... Gaia data will alsobenefit from and contribute to other surveys either spectroscopic such as LAMOSTor photometric such as LSST.

Abstract



Modeling Realistic Dwarf Galaxies (and StellarHalos)

Alyson BrooksCaltech

USA

A realistic model for the formation of galaxies depends on a proper treatment ofthe gas in galaxies. Recent computational progress has allowed for unprecedentedresolution in cosmological disk galaxy simulations, which in turn allows for a morerealistic treatment of feedback. In this talk, I will discuss the first simulation of abulgeless dwarf disk galaxy, and the ingredients necessary to create it. I will alsohighlight predictions on chemical abundance trends for the inner stellar halo basedon fully cosmological simulations.

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47


Metal mixing of disk gas and starsDaisuke Kawata

Mullard Space Science Laboraroty, UCL

UK

Using chemodynamical simulations of disk galaxies, we study star formation andenergy and chemical feedback in disks. Our improved chemodynamical simulationcode includes modelling of powerful supernovae feedback and metal diffusion ofthe gas. High-resolution simulations with the improved code allow us to follow themixing of chemical properties of disk gas and stars due to supernovae feedback andradial migration. We present how the radial mixing affect the final metal distributionin disk stars, and discuss how the current and future observations provide constraintson the radial mixing.

Abstract


Disc SimulationsDisc Simulations Thursday 22 14:00-14:30

Modelling the Galactic disc(s)Ralph Schonrich

MPA

Germany

Combining chemical evolution with kinematics and dynamics the model of Schonrich& Binney gives new insights into the structure of the Galactic disc and its origin. Iwill give an outline of the model and its implications and discuss what we can learnfrom data provided by the large Galactic surveys.

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49


A New Mechanism for Galactic Disc Mixing:Implications to the Milky Way

Ivan MinchevStrasbourg Observatory

France

We have identified a previously unknown radial migration mechanism resulting fromthe overlap of spiral and bar resonances in galactic discs. We have confirmed theseresults in fully self-consistent, tree Sph simulations, as well as high-resolution N-bodysimulations. I will show that, depending on the spiral and bar amplitudes, metallicitygradients in galactic discs can flatten in less than 1 Gyr, rendering mixing in barredgalaxies up to an order of magnitude more efficient than previously thought. Inaddition, migration caused by resonance overlap can extend disc profiles to morethan 10 scale-lengths in both massive and low-mass galaxies, such as NGC 300.I will show that mixing in the Milky Way disc may be much more efficient thanexpected from previous studies not considering the effect of the Galactic bar. Thisnew mechanism can account for both the observed age-velocity relation and theabsence of age-metallicity relation in the solar neighborhood.

Abstract



Stellar Migration In Disk Galaxies and Disk OutskirtsVictor Debattista

Jeremiah Horrocks Institute

UK

I review the simulation picture of spiral induced stellar migration in disk galaxies forvarious galaxy properties and present observational support for its occurance. I alsoconsider the outer disks, where migration can be most easily discerned and comparevarious models of outer disk formation.

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51

Disc Observations & ModellingDisc Observations & Modelling Thursday 22 16:30-17:00

The Milky Way disk and the LAMOST surveyJinliang Hou

Shanghai Astronomical Observatory

China

I will talk about some observed properties of the Milky Way disk and what LAMOSTcan contribute to our understanding of the Milky Way disk. I will also talk aboutthe survey plan of LAMOST.

Abstract


Disc Observations & ModellingDisc Observations & Modelling Thursday 22 17:00-17:30

The Xuyi Schmidt Telescope and LAMOST DigitalSky Surevy of the Galactic Anti-center

(XLDSS-GAC)Xiaowei Liu

KIAA

China

As an integral component of the planned LAMOST Experiment for Galactic Under-standing and Evolution (LEQUE), the LAMOST Galactic anti-center spectroscopicsurvey will survey over four thousand square degree sky area centered on the Galac-tic anti-center (|b| ≤ 30 deg, 150 ≤ l ≤ 210 deg) and obtain medium resolutionoptical spectra for a statistically complete sample of several million stars distributedin a spatially contiguous area. Sample stars of the LAMOST survey of the Galac-tic anti-center will derive from an ongoing CCD imaging survey utilizing the newlybuilt 1.0/1.2m Schmidt Telescope at the Xuyi Station of the Purple Mountain Ob-servatory. The Xuyi imaging survey will deliver high quality photometry (∼ 1–2per cent) in the SDSS g, r and i bands and astrometry (∼ 0.1 arcsec) for about ahundred million stars down to limiting magnitude of fainter than 19 (10σ) in a skyarea of over six thousand square degree (3 ≤ RA ≤ 9 hr, −10 ≤ Dec ≤ +60 deg)that envelopes the sky area of the LAMOST spectroscopic survey of the Galacticanti-center, with an extension to the M 31/M 33 region.This Xuyi Schmidt Telescope and LAMOST Digital Sky Survey of the Galactic Anti-center (XLDSS-GAC) will yield for the first time optical photometry and spectra formillions of stars in the Galactic disk, the defining component of disk galaxies thatcontains most of the baryonic material and angular momentum. XLDSS-GAC willdeliver spectral and luminosity classification, radial velocity and stellar parameters(Teff , Log g, [Fe/H], and probably also α/Fe and C/Fe elemental abundance ratios),for each sample star. Together with the accurate proper motions and distances to beobtained with the forthcoming GAIA mission, XLDSS-GAC offers unique prospectsfor major breakthroughs in studies of Galactic structure. In particular, XLDSS-GAC will generate a unique data set to 1) study the stellar populations, chemicalcomposition and kinematics of the thin and thick disks and their interface with thehalo; 2) identify tidal streams and debris of disrupted dwarfs and clusters; 3) probethe gravitational potential and dark matter distribution; 4) map the distribution andextinction of the interstellar medium as a function of distance; 5) search for rareobjects (e.g. stars of peculiar chemical composition, hyper-velocity stars); and 6)ultimately advance our understanding of the formation and evolution of stars andgalaxies.In this short contribution, I will summarize the current status of the project.

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Disc Observations & ModellingDisc Observations & Modelling Friday 23 09:00-09:45

Science with RAVEArnaud Siebert

Observatoire de Strasbourg

France

The RAdial Velocity Experiment (RAVE) is an ambitious survey to measure the radialvelocities, temperatures, surface gravities, metallicities and abundance ratios for upto a million stars using the 1.2-m UK Schmidt Telescope of the Anglo-AustralianObservatory (AAO), over the period 2003-2011. RAVE is now releasing its thirdcatalog containing the measurements obtained during the pilot survey. This catalogcontaing more than 80,000 radial velocities is one of the largest database currentlyavailable to study the Milky Way and will be growing in size with subsequent releases.In this presentation I will review the scientific results obtained using the RAVE datathat help understand our host galaxy and beyond and present the current datarelease.

Abstract



Kinematics of the Milky Way disc in SDSSMartin C. Smith

KIAA, Peking University

China

Spectroscopic surveys like LAMOST and SEGUE offer great opportunities to inves-tigate the disc of the Milky Way, which holds many clues to the formation of ourGalaxy. The disc of the Milky Way is interesting as its present-day state can tell usabout the merging history of our Galaxy. As accretion events build up the Galactichalo they “heat” the disc, increasing the random velocities of the stars. Therefore,by tracing properties such as velocity dispersions as a function of age or metallicity,we can assess how different heating mechanisms contributed during the Milky Way’sformation. We have constructed a high-precision catalogue of disc stars using datafrom the SDSS survey (Smith et al., in prep), with a total of over 10,000 nearbydisc dwarfs. We use these stars to probe the heating history as well as investigatingthe detailed phase-space distribution. This sample is also important for probing theglobal properties of the Milky Way’s disc, for example constraining the local massdensity.

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55


Stellar populations in the Galactic thick diskChao Liu

Max Planck Institute for Astronomy

Germany

The origin of the thick disk is an open issue for years. Metal weak thick disk(MWTD) found more than a decade ago indicates that the thick disk may not bea single population. In this work, we apply SDSS data to detect the populationsin the thick disk. By analysing the spatial variation of the metallicity distributionfunctions (MDFs), we find three populations in the thick disk. The observationaldata are then compared with N-body simulation to study the possible origins of thepopulations. Kinematics are used as well to give more constraint.

Abstract



Study of the stellar populations of the Milky Wayin CFHTLS fields

Melanie GuittetObservatoire de Paris

France

The galactic thick disk has characteristics intermediate between the thin disk andthe halo but no consistent description has been given so far, even though recentstudies with the Sloan Digital Sky Survey (SDSS) has improved our understanding.The Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) has provided ac-curate photometry with the MegaCam camera in four wide and deep fields. Thepresentation will focus on stellar populations of the Milky Way in these fields bystudying metallicity distributions and distances to the Galactic plane. Results willbe then compared to previous work made with the SDSS.

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57

Disc Observations & Star FormationDisc Observations & Star Formation Friday 23 11:45-12:15

Galactic archeology and planet formationMartin Asplund

Max Planck Institute for Astrophysics

Germany

I will review the chemical composition of the Sun and solar-type stars. We haverecently performed a complete re-analysis of the solar abundances and found signifi-cantly lower values of the most abundant metals compared with the canonical valuesfrom a decade ago, especially for C, N, O and Ne. This revision has far-reachingconsequences for astronomy, including having caused a crisis for helioseismology andsolar interior models.I will also present a detailed comparison of the Sun with solar twins and solaranalogs. We find that the Sun is deficient in refractory elements with a very strongcorrelation with dust condensation temperature. We attribute this to the effects ofplanet formation having been more efficient in the solar system compared with mostother solar-type stars. This opens the truly enthralling prospect of identifying starslikely to host planets, arguably even terrestrial planets, purely from a very accuratedetermination of their chemical compositions. This has important ramificationsalso for Galactic archeology – using stellar abundances to infer the formation andevolution of the Milky Way – which will be discussed, especially in the light of newsurveys like LAMOST and HERMES.

Abstract



Galactic open cluster survey with LAMOSTLi Chen

Shanghai Observatory

China

We have proposed a Galactic open cluster survey project, aiming at fully exploringthe unique capability of the newly built LAMOST in studying the open clustersystem in our Milky Way. This talk will briefly introduce some main features ofLAMOST, the background and scientific goals of the project.

Abstract


59


The IPHAS Galactic Plane SurveyNicholas Walton

Institute of Astronomy, University of Cambridge

UK

This presentation will review recent results from the IPHAS survey of the GalacticPlane (see http://www.iphas.org)IPHAS has surveyed the Galactic plane visible from the northern hemisphere in theH-alpha, r and i bands using the Wide Field Camera on the 2.5-m Isaac New-ton Telescope. Observations are now essentially complete, with the release ofthe public catalogues now being prepared. The early data release is available athttp://idr.iphas.org.This presentation will focus on scientific highlights from IPHAS, including recentuse of it in generating a sophisticated extinction map of the Galactic plane.Further, information will be provided on the upcoming extension of the survey tothe southern hemisphere, utilising the ESO VST telescope.

Abstract



Molecular Clouds and Star Formation in the MilkyWay

Hongchi WangPurple Mountain Observatory

China

Molecular clouds are an important ingredient of the Milky Way and they are thesites for the formation of stars. In this talk I will first review our current under-standing of the overall properties of molecular clouds and star formation in theMilky Way. In particular, properties of molecular clouds and star formation at theGalactic center are compared with those in the solar neighborhood to show thevast diversity of molecular clouds and star formation in the Milky Way and thestrong dependence of star formation on the environments. Then I will discuss howLAMOST can help to reveal the properties of star formation in the solar neighbor-hood. Compared with optical techniques, millimeter/sub-millimeter observationsof interstellar molecules have much higher spectral resolutions and are unique indetermining isotope ratios. I will present our recent results about the isotope ratiosof elements C/N/O/S/Si obtained from observations of molecular cloud cores withthe Delingha 13.7 m millimeter-wavelength telescope. Finally, the implications ofour isotope ratio measurements for the evolution of Milky Way are discussed.

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Conference SummaryConference Summary Friday 23 16:00-16:45

Conference SummaryJoss Bland-Hawthorn

University of Sydney

Australia


Po

sters

Posters

Schwarzschild models of dwarf spheroidal galaxies

Maarten Breddels01

We have developed a spherically symmetric dynamical model of a dwarf spheroidal galaxy (dSph) using theSchwarzschild method. This type of modelling yields constraints both on the total mass distribution (e.g.enclosed mass and scale radius) as well as on the orbital structure of the system modelled (e.g. velocityanisotropy). Therefore not only can we derive the dark matter content of these systems, but also explorepossible formation scenarios. We present tests on a mock dSph galaxy and our preliminary results for theSculptor dSph.

The orbital content of merger remnants

Sarah Bryan02

Galaxies are thought to form hierarchically, through the merging and accretion of smaller systems. As such,there should be observational signatures of these merging processes in the remnant galaxy, providing dynamicalinformation about its formation history. The orbital content of a galaxy serves as a probe of the gravitationalpotential and could provide clues as to how the Milky Way and galaxies in general form and evolve. Weinvestigate the orbital content of galaxy, group and cluster sized dark matter haloes in order to explorewhat observational signatures may result. To do this, we have used the OverWhelmingly Large Simulations,a set of state-of-the-art high resolution cosmological hydrodynamical simulations run with different physicalprescriptions for the feedback processes. We quantify the effects of the feedback prescriptions on the dynamicsand orbits of the dark matter, the stellar particles and the subhaloes, by comparing runs with no feedback,with stellar feedback and with feedback from AGN. We compare results of spectral analysis of the orbitalcontent of these simulations and quantify the change in fraction of box orbits as different implementations offeedback are considered, illustrating the influence of feedback processes on the orbital content of the haloes.We also investigate how the orbital content of these haloes depend on several key parameters such as theirmass, redshift and dynamical state.

Comparisons among different evolutionary population synthesis models

Xiaoyan Chen03

The spectrum of galaxies hold information about age and metallicity distributions of their stellar populationsand star formation histories. So we can analyze stellar populations through the integrated lights of galaxies.We aim to compare six popularly used evolutionary population synthesis (EPS) models through fitting thefull optical spectra of six representative types of galaxies (star-forming, composite, Seyfert 2, LINER, E+A,and early-type galaxies). We also explore the dependence of stellar population synthesis results on the mainingredients of the EPS models. Meanwhile we study whether there is an age sequence among these types ofgalaxies. We find that using different EPS models the resulted numerical values of contributed light fractionschange obviously, even though the dominant populations are consistent. The stellar population synthesis doesdepend on the selections of age and metallicity, while it does not depend on the stellar evolution track much.The importance of young populations decreases from star-forming, composite, Seyfert 2, LINER to early-typegalaxies, and E+A galaxies lie between composite galaxies and Seyfert 2s in most cases. Our conclusion isdifferent EPS models do derive different results of stellar populations, so that it is not reasonable to comparestellar populations estimated from different EPS models directly. To get reliable results, we should use thesame EPS model for the compared samples.

Determination of atmospheric parameters of FGK stars from LAMOST spectra

Mariagrazia Franchini04

A method to derive atmospheric parameter values by minimizing the difference between spectral indices fromLAMOST spectra and synthetic ones is presented. The accuracy of the achievable results is evaluated byusing, as templates, SDSS-DR7 spectra and by means of different minimization codes.


Posters

Ages of young SMC/LMC star clusters and the re-cent star formation history of the Magellanic Clouds

Katharina Glatt05

The interaction of the Milky Way (MW) with the Small and the Large Magellanic Cloud (SMC and LMC)and the interaction between the Clouds affects the star formation history of these galaxies. Possible orbits ofthese three galaxies have been modelled by several authors (e.g., Gardiner & Noguchi 1996, Bekki & Chiba2005) using the latest proper motion measurements (Kallivayalil et al. 2006a/b, Piatek et al. 2008). Thesesimulations have shown that the Clouds are not a bound system and that they are making their first passageclose to the MW. The last close encounter between SMC and LMC occurred about 200 million years ago.Interactions should trigger enhanced star formation, which should also be reflected in the age distribution ofthe star clusters in the Magellanic Clouds.

We used the cluster catalog of Bica et al. (2008) to re-identify these star clusters in the photometriccatalogs of the Magellanic Cloud Photometric Surveys (MCPSs) by Zaritsky et al. (2002/2004). The MCPSsare CCD driftscans of the central 64 deg2 of the LMC and the central 18 deg2 of the SMC and contain resolvedstellar point source photometry obtained in the UBVI bands. The MCPS data were used to determine the agesand luminosities of star clusters in the Magellanic Clouds from their color-magnitude diagrams and isochronemodels of the Padova and Geneva group. Owing to the limited depth of the MCPSs we cannot age-dateclusters older than approximately 1 billion years.

We present the resulting age distributions of the star clusters and investigate the recent spatial andtemporal star formation histories of the Magellanic Clouds covering a period of approximately 10 million yearsto 1 billion years (about four rotation periods). We find clear evidence for episodic star formation in bothgalaxies.

The Milky Way disc dynamics

Oleksiy Golubov06

I present some results of our semi-analytic investigations of the Milky Way stellar disc. I propose an improvedmass model for the rotation curve of the Milky Way and the effect of flattened mass distributions for bulgeand dark matter halo. I also show how RAVE data can be used to constrain the vertical dependence of theMilky Way gravitational potential.

Massive stellar formation in the inner Milky Way

Carlos Gonzalez Fernandez07

The existence of a long, flat bar in the inner Milky Way is a rather established fact, as it affects clearlythe in-plane stellar distribution as far as l=28 (as it has been evinced studying the density of K2III starsalong several lines of sight, Hammersley et al. 1994, Benjamin et al. 2005, Lopez-Corredoira et al. 2007,Cabrera-Lavers et al. 2008). One of the effects expected from such an structure comes in the form of inducedstellar formation in the Galactic ring at Rgc 5kpc (Jackson et al. 2006).

It is in the area where the tip of the bar and this ring touch where a excess of young stars was detected(Garzon et al. 1997) and where various massive, young stellar clusters lie (RSGC3, Davies et al. 2007,Alicante 8, Negueruela et al. 2010). It has yet to be demonstrated if this enhanced formation only occursin this region or if it is extended through all the ring. Large scale spectroscopic programs such as LEGUE orAPOGEE, coupled with deep photometric surveys as GPS-UKIDSS will become the tool of choice for thesekind of studies, as they will provide both chemical and dynamical information for single stars, giving us theinformation that we need to assess cluster and structure membership and to recover the formation history ofour Galaxy, both in small and in large scales.


65

Posters

Detection of a Tidal Stream (Un)Associated with M 13

Carl Grillmair08

Using Sloan Digital Sky Survey data, we detect tidal tails that appear to emanate from the globular clusterM 13 (NGC 6205). Both leading and trailing tails are detected, extending for at least 15 degrees on the sky.The tails agree approximately with the orbit of the cluster, as determined from radial velocity and propermotion measurements. On the other hand, initial estimates of the distance to the stream put it at least 5kpc beyond M 13.

Metallicity distribution function and three dimensional maps of the LMC

Raoul Haschke09

In a series of papers analysing lightcurves, Kovacs et al. (1995,1996) found relations between the Fourierparameter φ31, the period and the metallicity of RR Lyrae stars. The metallicity is used to calculate theabsolute magnitude (Clementini et al. 2003) and to obtain distances to each single RR Lyrae star presentin the OGLE data of the Large Magellanic Cloud (LMC). The metallicities are used to derive a metallicitydistribution function of the old populations of the LMC. For the Cepheids, found by OGLE, the relations bySandage (2004) is used to compute the absolute magnitudes and to estimate the distances. These two verydifferent populations (RR Lyrae are about 10 Gyr old, while Cepheids are only a few 100 Myr in age) are usedto obtain three dimensional maps that show the depth and distribution of each group in this satellite galaxy.The LMC has a depth of a few kpc and both populations are not aligned with each other. The Cepheidsare in general farther away. This offset is probably connected to the unresolved short and long distance scaleproblem.

Insights from the Observed Orbital Eccentric-ity Distribution of the Milky Way Halo Stars

Kohei Hattori10

Theoretical calculations for the differential orbital eccentricity distribution of solar-neighbor halo stars indynamical equilibrium is explored. We adopt two types of potentials (an isochrone and a Navarro-Frenk-Whitepotential) and a distribution function of the form f(E,L) that is more or less consistent with observations inthe solar neighborhood. In order to mimic the observation, we define a (virtual) survey region within which thehalo stars are sampled and obtain the expected eccentricity distribution to be compared with observation, bytaking into account the probability of halo stars to be found in the survey region. We find that the eccentricitydistribution is inevitably biased as far as nearby halo stars are selected and that it has a strong dependencenot only on the size of the survey region but also on the orbital energy. For example, solar-neighbor halostars with orbital energy nearly equal to that of solar-neighbor disk stars are expected to show relatively flateccentricity distribution, while those with higher and lower orbital energy would lack in lower-eccentricitystars. This can be understood by the geometry of the orbits, because halo stars with too small apocenterdistance or too large pericenter distance cannot be observed in the solar neighborhood.

Since reliable orbital eccentricities of halo stars can be obtained only within a limited distance (say, 4kpc) from the sun at present, our calculations for the inherent bias of local sample would be indispensable ininterpreting the observed eccentricity distribution such as that obtained from SDSS/SEGUE data (see Figure5 of Carollo et al. 2009). If we subdivide the local sample of a given stellar component into several subgroupsin terms of energy, we would be able to test whether the stellar component is in dynamical equilibrium, bychecking if the eccentricity distribution of all the subgroups are explainable by our calculations. If prominentdeviation from our prediction should be confirmed for some of the subgroups, it might imply the existence ofother stellar components or contamination by halo stars that are not in dynamical equilibrium. In this way,we might be able to obtain some new insights into the origin of the stellar halo as well as the possible numberof stellar components.


Posters

Triggered clustering of star formation in IC 1396

Yafang Huang11

Historical studies of active star formation (SF) were limited to the densest parts of IC 1396 e.g. regions A &N. Triggered SF was proposed in IC1396A, the “key hole” like elephant trunk in the giant, faint HII region.Here we present studies of triggered formation of star clusters and stellar aggregations in the HII region asa whole. IR excessive emission sources were selected based on color-color diagrams in the NIR (2MASSPSC) and mid- to far-IR (AKARI IRC and FIS PSC). Spatial distribution of the excessive emission sourcesrevealed the existence of new clusters and/or aggregates both around the exciting source, HD206267, of theHII region and in the surrounding areas. SEDs of some of the candidate young stellar objects were fittedto try to discriminate their status of evolution. Optical identification of the NIR excessive emission sourceswith optical counterparts was performed. Spectroscopic observations based on the 2.16m telescope has ledto the discovery of two new Herbig Ae/Be and three new WTTS/CTTS, further observations were neededto complete the sample.

New background quasars in the vicinity of the AndromedaGalaxy discovered with the Guoshoujing Telescope (LAMOST)

Zhiying Huo12

We present preliminary analyses of spectra of quasar candidates in two Guoshoujing Telescope (GSJT, formerlynamed the Large Sky Area Multi-Object Fiber Spectroscopic Telescope - LAMOST) test fields near M 31where one is close to the optical center of the disk and the other is towards the northeastern outskirts ofthe halo, obtained during the early stage of the GSJT commissioning in the last season of 2009. Both fieldscontain background low-redshift quasar candidates selected from the SDSS photometry. In total, 14 newquasars with redshifts up to 2 and i magnitudes between 16.7 and 19.2, are discovered, including 7 withinthe 2.5 deg central region of M 31. We briefly discuss the potential applications of these newly discoveredbright quasars.

Preliminary Spectrum Analysis of the Guoshoujing Telescope (LAM-OST) observations of stellar spectrum of the Galactic-anti Center Field

Zhiying Huo13

Survey on the Galactic-anti center direction will be of great benefit in the understanding of the outer partsof the Miky Way’s stellar component, and the galactic thin/thick disk. During the last observation seasonof 2009, one test field near to the Galactic-anti Center has been observed by the Guoshoujing Telescope(LAMOST). Here, we present our very preliminary analysis of stellar spectrum of this test field.

A chemical abundance study of the carbon-enhancedmetal-poor star BD+44◦493 with Subaru/HDS

Hiroko Ito14

We present a one-dimensional LTE chemical abundance analysis of the very bright (V = 9.1) carbon-enhancedmetal-poor (CEMP) star BD+44◦493, based on high-resolution, high signal-to-noise spectra obtained withSubaru/HDS. The star is shown to be a subgiant with an extremely low iron abundance ([Fe/H]= -3.7), while itis rich in C ([C/Fe] = +1.3) and O ([O/Fe] = +1.6). Although astronomers have been searching for extremelymetal-poor stars for decades, this is the first star found with [Fe/H] < -3.5 and an apparent magnitude V <12. Based on its low abundances of neutron-capture elements (e.g., [Ba/Fe]= -0.6), BD+44◦493 is classifiedas a “CEMP-no” star. Its abundance pattern implies that a first-generation faint supernova is the most likelyorigin of its carbon excess, while scenarios related to mass loss from rapidly rotating massive stars or masstransfer from an asymptotic giant branch companion star are not favored.


67

Posters

Galactic Orbits of Two Old and Metal-rich Open Clusters

Lucie Jilkova15

We present some results and discussion on Galactic orbits of two open clusters — NGC 6253 and NGC 6791.Both clusters have considerably higher metallicity than it would correspond to their age and location in theGlactic disk. We investigate a possible influence of the Galactic bar on cluster’s orbits and their puzzlinglocation.

The local star formation history derived from SDSS star counts

Andreas Just16

We use a self-consistent vertical disc model of the thin and thick disc in the solar vicinity. The model is basedon a series of stellar sub-populations with surface densities and velocity dispersions according to an adoptedstar formation history (SFR) and a dynamical heating function (AVR). The model is optimized to fit thelocal kinematics of main sequence (MS) stars. The disc is in dynamical equilibrium incuding the gravitationalforces of the gas component and the dark matter halo. A simple chemical enrichment model is included toreproduce the metallicity distribution of the G-dwarfs in the solar neighbourhood. An isothermal thick disccomponent is included self-consistently.

For each pair of (SFR,AVR) the local model allows predictions of star counts at high galactic latitude as afunction of colour (along the MS) with no free parameter. The comparison with North Galactic Pole (NGP)data of SDSS/SEGUE leads to significant constraints of the local SFR.

The relations between the metallicity andorbital parameters of Galactic disk stars

Ji Li17

The iron abundance gradient in the Galactic disk provides fundamental constraints on the chemical evolutionof this important component of the Galaxy. However, there are still some arguments about the slope of theiron abundance gradient across the Galactic stellar disk. To provide quantitative constraints on these trends,we constructed an unbiased stellar sample from the common objects of two large observations. The sampleconsists of 4004 disk stars in the solar neighborhood with the range of metallicity [Fe/H] from ∼-1.0 to ∼0.5,including 3855 thin disk stars and 146 thick disk stars. The range of their mean Galactocentric distances Rmis from ∼4 to ∼11 kpc, and the range of their maximum vertical distance from the Galactic Plane Zmaxis from 0 to ∼3.5 kpc. The relations of the stellar metallicity [Fe/H] with the orbital eccentricity e, and[Fe/H] with Rm, as well as [Fe/H] with Zmax are investigated in detail. The results showed that: (1) Theorbital eccentricity of disk stars decreases with increasing metallicity, while this trend becomes flat for starswith [Fe/H]>-0.2. (2) For thin disk, there is a clear radial iron gradient of -0.051±0.005 dex/kpc. However,this metallicity gradient is discontinuous once we split the sample in to the inner (Rm<8kpc) and outer disk(Rm≥8kpc): a slope of about 0 dex/kpc is present in the inner disk and a slope of -0.12dex/kpc is in theouter disk. For thick disk, there is no trend of [Fe/H] with Rm. (3) The vertical gradient of iron abundance is-0.146dex/kpc and -0.251dex/kpc for the thick and thin disks, respectively. Moreover, the vertical abundancegradient shows a steeper trend with the evolution of the Galaxy. Our results confirm the collapse mechanismassociated with the formation and evolution of the Galactic disk.

LASS - LAmost Spectroscopic Survey of the Northern Galactic Plane

Jinzeng Li18

The LASS project, abbreviated for the LAmost Spectroscopic Survey of the Northern Galactic Plane, is oneof the major survey programs for Galactic studies. It will perform a homorgeneous spectroscopic survey of allstars brighter than R=16 mag. across the Northern Galactic Plane with 20<l<230 degree and |b| <5 degree.The average source density of 2000-3000 stars per square degree is highly suitable for such a legacy surveybased on the newly built Lamost telescope. Once completed, LASS will lead to the census of especially all


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kinds of intermediate and low-mass young stellar objects (Herbig Ae/Be, Classical T Tauri stars and weak-lined T Tauri stars), active solar like stars, OB stars, PNe, WRs, interacting binaries and so on. LASS will bethe first magnitude-limited spectroscopic survey of the Galactic Plane and will produce one of the strongestdatabase for many astronomical studies.

Reconsidering the Galactic coordinate system

Jiacheng Liu19

Initially defined by the IAU in 1958, the Galactic coordinate system was thereafter in 1984 transformed fromthe FK4-based B1950.0 system to the FK5-based J2000.0 system. In 1994, the IAU recommended that thedynamical reference system FK5 be replaced by the ICRS, which is a kinematical non-rotating system definedby a set of remote radio sources. However the definition of the Galactic coordinate system was not updated.We consider that the present Galactic coordinates may be problematic due to the unrigorous transformationmethod from FK4 to FK5, and due to the non-inertiality of the FK5 system with respect to the ICRS. Thishas led to some confusions in applications of the Galactic coordinates. We have obtained the transformationmatrix in the framework of the ICRS after carefully investigating the definition of the Galactic coordinatesystem and transformation procedures. To avoid unnecessary misunderstandings, we suggest to re-considerthe definition of the Galactic coordinate system which should be directly connected with the ICRS for highprecise observation at micro-arcsecond level.

Ultra-Faint Dwarfs as Probes of First Light

Ragnhild Lunnan20

The Sloan Digital Sky Survey has revealed a population of ultra-faint systems orbiting the Milky Way. Ob-servations of stars in these systems reveal a metal-poor stellar population with abundance patterns similar tothe low-metallicity tail of the halo of the Milky Way, suggesting that these systems may be relics of earlygalaxy formation and analogs to the early building blocks of the stellar halo. Understanding the formation ofthe smallest structures in the Milky Way and how they relate to the current stellar content of the halo andsatellites is crucial for interpreting any dwarf galaxy observations to learn about the early universe.

We present work in progress on modeling the stellar populations of the subhalos orbiting Milky-Way sizedsystems. We combine the six high-resolution dark matter Aquarius simulations with a semi-analytic starformation prescription and particle-tagging approach. Special attention is given to the impact of reionizationon the surviving satellite population at z=0, calculating and applying patchy reionization models based on theinitial density field. While reionization strongly influences the number of faint satellites that are able to form,the total number expected for a Milky Way-sized halo varies at least a factor of 2-3 between the six Aquariushalos. This suggests that part of the solution to the ”missing satellite problem” lies in cosmic variance, andthat the power of the satellite population to constrain the Milky Way’s reionization epoch would be greatlyimproved with a better understanding of the distribution. In addition, we find that the faintest systems areonly able to form stars for a relatively short period before and during reionization, leading to exclusively oldstellar populations that perhaps are only enriched by a few supernova events. Thus, we expect ultra-faintsatellites to be excellent sites for ”stellar archeology” to learn about conditions in the early universe.

Tracing the Milky Way’s Inner and Outer Halo Using BHB Stars and K Giants

Zhibo Ma21

Comparisons between inner and outer halo in the Galaxy give strong constraints on its formation. However,large ”in situ” samples of both are rare. We use a carefully selected sample of about 5000 BHB stars reachingto 80kpc in galactic radius, with moderate resolution spectra from the SEGUE-II project, to trace changesin kinematics and abundance between inner and outer halo. To avoid the possible bias caused by the use ofBHBs, we have also improved the SEGUE calibrations for halo K giants, using a technique similar to Morrisonet al (2003). Further we will compare the results from our BHB sample using K giants through the inner andouter stellar halo.


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Tracing the Milky Way spiral arms. Now and in the Gaia era

Maria Monguio22

The cartography and dynamics of the spiral structure of the Milky Way is still, nowadays, highly controversial.Different spiral tracers lead to different conclusions about basic geometric parameters such as the strengthand number of arms and, more important, we are far from understanding the mechanisms acting to createthis perturbation on the galactic disk. Two complementary approaches are presented here aiming to shedlight on these issues: 1) a photometric and spectroscopic survey in the anticenter direction is ongoing todetect the overdensity and kinematic perturbation of the Perseus arm, and 2) detailed simulations are beingperformed to evaluate the capabilities that the future Gaia database will have to help us to undertake thisstudy. We show how the preliminary radial distribution of young stars, with distances obtained from thefirst 3sqd photometric survey completed up to now (INT/WFC, La Palma), suggests an overdensity around1.5-2kpc probably associated with the Perseus arm. Complementary, using actual expectations on the Gaiamission accuracy on astrometric and spectroscopic data, we present a first and very preliminary simulationcode to evaluate how Gaia data will help in establishing a definitive cartography and a velocity distributionfunction through the galactic disk.

A synthetic spectral index library for LAMOST spectra analysis

Carlo Morossi23

A library of ad-hoc designed Lick-LAMOST spectral indices is computed starting from 2550 high resolutionsynthetic spectra. Accurate calibration is performed by using Solar neighborhood stars an SDSS-DR7 spectra.

Mapping the Sagittarius Dwarf Tidal Stream: Galac-tic Astronomy Through Volunteer Computing

Matthew Newby24

We use data from the Sloan Digital Sky Survey Data Release 7, and maximum likelihood methods, to accu-rately determine positions of the Sagittarius Dwarf Tidal stream. The Sagittarius Dwarf Stream dominates asignificant portion of the Milky Way Halo, complicating other searches for galactic halo structure. Mappingthis stream will make further investigations of the galactic halo more accurate, and provide information onoverall halo star distribution. The data sets contain upwards of several hundred thousand stars each, while fit-ting up to 20 parameters provides for a computationally expensive problem. We solve this problem through theMilkyWay@Home BOINC (Berkely Open Infrastructure for Network Comuting) volunteer computing network.MilkyWay@home currently has over 25,000 active volunteer hosts in 128 countries, and has the computingpower equivalent to 1.2 petaFLOPS (floating point operations per second).

Dynamical segregation in NGC 3603

Xiaoying Pang25

NGC 3603 is one of the most massive, compact young star clusters of the Milky Way. The cluster has anage of only about 1 Myr and is embedded in a giant molecular cloud with ongoing star formation. We haveanalyzed deep imaging data separated by 10 years from the Wide Field and Planetary Camera 2 on boardof the Hubble Space Telescope, from which we got proper motions and determine cluster membership. Wederive an age 1Myr for main-sequence stars with solar abundance and pre-main-sequence stars, with a possibleage spread of up to 3 Myr. This age spread is possible due to the prolonged star formation history in thisyoung cluster. Despite the young age, the cluster was fairly significantly mass segregated down to 2 solarmasses. Due to the coverage of a large mass range (sub-solar to 87 solar masses), it results in massive starshave already undergone violent relaxation while low mass stars are still far from equilibrium. The age of thecluster is already 30 times of crossing-time which agrees with dense collapse phase. The possible dynamicalorigin of this mass segregation shows that massive stars could form in relative isolation in large cores andmass segregate later.


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Hypervelocity stars: simulations in the con-text of the accreted satellite mechanism

Tilmann Piffl26

Hypervelocity stars (HVSs) are stars with unusually high radial velocities that are thought to originate fromthe gravitational interaction of a stellar binary with the massive black hole (SMBH) in the Galactic center. Inan exchange collision one the binary components is propelled out at speeds exceeding 1000 km/s. Presently atotal of 17 HVSs are reported from observations with a maximum velocity of 717 km/s. The lack of HVSs withthe very extreme velocities predicted from the SMBH-ejection scenario as well as some other inconsistenciesin the properties of the HVS population raised doubts on an SMBH-origin. Abadi et al. (2009) proposed adifferent formation scenario: the accreted satellite mechanism. In this scenario the HVSs are envisaged tooriginate from the debris of an infalling satellite galaxy tidally disrupted by the Milky Way potential. Here wepresent a systematic study of the accreted satellite mechanism via N-body simulations. We model the collisionof a satellite galaxy with its much more massive host. Repeating this simulation for a range initial conditionswe investigated the efficiency of generating HVSs during such an encounter. Comparing the variations of theresult obtained during the analysis of the individual runs we develop an empirical procedure to predict thenumber of HVSs generated from the initial conditions. We conclude that a tidal origin is consistent with theproperties of the observed HVS population and that similar quantities of HVSs are produced via the accretedsatellite mechanism as via the classical SMBH-ejection mechanism.

Proper Motions of Stars Observed in the Direc-tion of the Magellanic Clouds by the OGLE Project

Radoslaw Poleski27

The third phase of the Optical Gravitational Lensing Experiment (OGLE-III) collected photometric dataspanning 8 years with the 1.3 m Warsaw telescope at Las Campanas Observatory, Chile. Some fields wereobserved also during the OGLE-II phase and for them data span 13 years. Altogether more than 40 millionobjects were monitored in the directions of the Small and Large Magellanic Clouds. Typically over 400 imagesof each star were collected at very good seeing. This allows measuring proper motions as small as 1 mas/yearfor around 105 Milky Way objects. Among stars with measured proper motions we will search for nearbydwarfs and hyper velocity objects. Paralaxes will be measured for at least a hundred stars. Here we presentanalysis procedure and give preliminary results.

Metallicity gradients of disc stars for a cosmologically simulated galaxy

Awat Rahimi28

We analyse for the first time the radial abundance gradients of the disc stars of a disc galaxy simulatedwith our three dimensional, fully cosmological chemodynamical galaxy evolution code GCD+. We study how[Fe/H], [N/O], [O/Fe], [Mg/Fe] and [Si/Fe] vary with galactocentric radius. For the young stars of thedisc, we found a negative slope for [Fe/H] and [N/O] but a positive [O/Fe], [Mg/Fe] and [Si/Fe] slope withradius. By analysing the SFR at different radii, we found that the simulated disc contains a greater fractionof young stars in the outer regions, while the old stars tend to be concentrated in the inner parts of thedisc. Since massive stars produce more α-elements, this can explain the positive [α/Fe] gradient as well asthe negative [N/O] gradient with radius. This radial trend of star formation history is a natural outcome ofan inside-out formation of the disc, regardless of the size of the disc. Our simulation demonstrates that therecently observed positive [α/Fe] gradients in the Milky Way disc open clusters can be explained if the MilkyWay disc underwent an inside-out formation scenario and has a significant difference in the fraction of youngstars between the inner and outer regions.


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Oxygen and barium abundances in nearby disk stars

Ivan Ramırez29

In Ramırez et al. (2007, A&A, 465, 271) we presented iron and oxygen abundances for about 520 nearby(d < 150 pc) disk stars. We analyzed the O i 777 nm triplet lines taking into account non-LTE effects andshowed that they are crucial for interpreting correctly differences between thin- and thick-disk members. Wehave recently observed about 260 more stars, most of them solar analogs and stars covering the yet unexploredregion of stars with kinematics intermediate between those normally attributed to thin- and thick-disk stars.We are now determining oxygen and barium abundances for our full sample of about 780 stars, adoptingimproved stellar parameters and correcting for non-LTE effects (both O and Ba). Preliminary results fromthis research will be presented.

Hunting for stellar streams in the solar neighbour-hood with the SDSS and GSC-II kinematic survey

Paola Re Fiorentin30

The growing awareness of the importance of the “fossil record” in the Milky Way for constraining galaxyformation theory is reflected by the increasing number of new ground- and space-based surveys designed tounravel the formation history of the Galaxy.

Recently, a new kinematic survey has been produced by means of spectro-photometric data from the SloanDigital Sky Survey (DR7) and high-quality proper motions derived from multiepoch positions from the GuideStar Catalog II. In this framework, we assembled a sample of ∼ 30 000 FGK nearby metal-poor (sub)dwarfs forwhich selection and distance estimates take advantage of accurate stellar atmospheric parameters (effectivetemperature, surface gravity and metallicity) derived from SDSS spectra.

Here, as one of the most interesting applications of this (extremely accurate) catalog, we consider thefeasibility of probing fossil signatures of the formation of the Milky Way by selecting and analysing subsamplesof stars as tracers of the seven-dimensional space distribution (full phase-space coordinates plus chemicalabundance) of the Galactic halo population within a few kiloparsecs from the Sun. Preliminary results exhibitstatistical evidence for discrete overdensities localised in kinematics and in the space of adiabatic invariants(angular momentum and energy). By examination of their intrinsic properties, we suggest that they may bepossible fossil signatures of past mergers or other accretion events.

Testing Radial Migration in Thick Disks

Michael Solway31

Recently, Schonrich and Binney showed that adding radial migration of stars due to churning by transientspiral patterns and flow of gas through the disk to models of the Galaxy’s chemical evolution reproducesvarious important observed properties of the metallicity gradients in both stars and gas. Among them, thedisk naturally separates into a thin disk and an alpha-enhanced thick disk. Sellwood and Binney showedthat spiral waves in a razor-thin 2D Mestel disk cause the angular momenta of individual stars to change onaverage by as much as 50 percent over the disk lifetime while largely preserving the overall angular momentumdistribution. A key assumption in the work by Schonrich and Binney was that radial migration also occurs inthick disks. Here, we test whether this assumption holds by repeating the work of Sellwood and Binney fora thick 3D Mestel disk.

Searching stellar streams in the Galaxy based on the BHB stars

Hao Tian32

In the last decades, hierarchical theory about the evolution of the Galaxy became more and more acceptableand the stellar streams are taken as the evidence of it. We select the blue horizontal branch stars by colorcutting and distance cutting from the Sloan Digital Sky Survey DR7 as the tracer. The stellar streamcandidates are searched in the

√U2 + 2V 2and V space, which are related to the orbit eccentricity and the


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angular momentum. The overdensity in the specific phase space is found out through the wavelet transform.In order to estimate the significance of the candidates, 200 Monte Carlo simulations are performed to obtaina smooth background distribution. As a result, we find 9 candidate stellar streams. 7 of them agree withothers’ work well. Besides, 2 are new, with the velocity V at about 70km/s and 120km/s.

Insight into the Galactic structure using CoRoTsolar-like oscillating red giants: first steps

Marica Valentini33

The detection of solar-like oscillations in red giants with CoRoT allows us to access the properties of so farpoorly-constrained distant stars in the Galactic disk.Among CoRoT Red Giants, a large number of Red Clump stars were identified as those with νmax between25 and 40 micro-Hz (Miglio et al. 2009). The almost costant luminosity of the Red Clump allows us to esti-mate the distance of these stars from their dereddened magnitude. Distances of CoRoT asteroseismologicallyidentified RC stars span from 2 to 12 Kpc, with an height between 30 and 600 pc from the Galatic plane.Coupling this information with a ground-based spectroscopic program, our sample of solar-like pulsating redgiants could provide an unique information on stars belonging to the composite population of the Galactic disk.

The Shape of Dark Matter Halos in the Aquar-ius Simulations: Evolution and Memory

Carlos Vera Ciro34

We analyze in detail the shape of the dark matter halos in five Milky-Way sized objects using the AquariusSimulations. These cosmological high-resolution N-body simulations provide an excellent basis for the studyof the dark matter halos geometry in the Lambda cosmology, allowing a clear comparison among severalmethods previously used in the literature to determine halo’s shapes. The several resolution levels on Aquariusare also vital to evaluate the numerical convergence of our results. In contrast with earlier studies on thissubject, which had mostly focused on a single simulation output, we explore the temporal evolution of thedark matter halo shapes, and its relation with environment and mass accretion history. We find that, whenmeasured at the virial radius, the shape of individual halos changes with time, evolving from a typicallyprolate configuration at early stages to a more triaxial/oblate geometry towards the present day. This virialellipsoid tends to be oriented with its minor axis perpendicular to the local filamentary structure, althoughtransient misalignments are also present during the halo’s history. We successfully correlate these changesin shape and orientation with the dominant mode of accretion at a given time. We perform a multi-poleexpansion analysis of the infalling material and find that prolate shapes are established when continuous,long-standing accretion proceeds through a clear preferred direction, i.e. a filament; whereas halos evolvetowards triaxiality if the mass accretion turns more isotropical. On the other hand, mergers induce temporarychanges in the orientation of the virial ellipsoids, which tend to recover their alignment with the large scalestructure quickly after the accretion episode. Interestingly, at redshift z=0, halos show clear imprints of theirpast history recorded on their shapes at different radius; which also show an evolution from prolate in theinner regions to triaxial/oblate as we move outwards. We conclude that the shape of the dark matter halosis a complex, time-dependent attribute, with each radial shell retaining memory of the local conditions at thetime of collapse.

Using microlensed quasars to probe the structure of the Milky Way

Jian Wang35

We present an investigation into gravitational microlensing of quasars by foreground Milky Way lenses, whichcan be used to probe the structure of our Galaxy. We predict the all-sky microlensing optical depth, thetime-scale distributions and the event rates for future large-area sky surveys. We find that the total event


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rate increases rapidly with the magnitude limit, owing to the fact that the background quasar number densityincreases steeply with magnitude. Finally, we predict that tens of microlensing events will be detected everyyear by Pan-STARRS and LSST. Among them, about one or two events will occur on nearby stars and maybe utilized to obtain a model- independent mass of the lensing star.

Kinematic evidence of merger events of M31 from Planetary Nebulae

Maosheng Xiang36

We have analyzed the spatial distribution and kinematics of planetary nebulae in M 31 published by Merrettet al. We find that there exists two groups of planetary nebulae with obviously different kinematic properties,and thus we speculate that M 31 has experienced a major merger event. The inclination angle of the planeof the merger remnants differs significantly from the generally accepted value of the disk. In addition, wefind a group of retrograde planetary nebulae which show excellent symmetry in both spatial distribution andkinematic properties, we think it is an evidence of debris possibly left by satellites disrupted in a mergerevent. The stream identified previously by Merrett et al. is probably parts of the debris, instead of productsof interaction of M 31 and M 32 originally proposed by Merrett et al. The existence of those remnants anddebris provides a possible mechanism to explain the widely-spread distortions and warps of the disk of M 31as well as its very extended bulge.

Substructures in Milky-Way-sized dark matter halos from numerical simulations

Dandan Xu37

Lensing flux-ratio anomalies have been frequently observed and taken as evidence for the presence of abundantdark matter substructures in lensing galaxies, as predicted by the cold dark matter (CDM) model of cosmogony.We have examined the cusp-caustic relations of the multiple images of background quasars lensed by Milky-Way-sized dark matter haloes, using a suite of high-resolution N-body simulations (the Aquarius simulations),and further extended our calculations to incorporate both the baryonic and diffuse dark components in lensinghaloes (and subhaloes). Taking the dark matter substructure population from the Aquarius project, we haveincluded in each lensing simulation: (1) a satellite galaxy population derived from a semi-analytic modelapplied to the Aquarius haloes, (2) an empirical Milky-Way globular cluster population and (3) satellitestreams (diffuse dark component) identified in the simulations. Accounting for these components, we haveconfirmed that the abundance of intrinsic substructures (dark or bright, bound or diffuse) is still not sufficientto explain the observed frequency of cusp-caustic violations in the CLASS survey. We conclude that theobserved effect could be the result of the small number statistics of CLASS, or intergalactic haloes along theline of sight acting as additional sources of lensing flux anomalies. Another possibility is that this discrepancysignals a failure of the CDM model on the substructure population of Milky-Way-sized haloes.

The star counts of the thick disk in SuperCOSMOS Archive

Yan Xu38

SuperCOSMOS Archive is database of all sky Photography sky survey. Blue turnoff stars are selected tostudy the structure of the thick disk with SuperCOSMOS data whose Bj magnitude is calibrated by GSC2.3.Thick disk warp, overdensities which may have relation with Virgo overdensity, Monoceros stellar stream,overdensity found by larsen (1996) can be detected in distance scale from 2.8 to 7Kpc.

Abundance analysis of barium stars

Guochao Yang39

We analysis the chemical abundances of 45 barium stars based on the high signal-to-noise ratio (S/N ) andhigh resolution Echelle spectra which were obtained with the 2.16 m telescope at National AstronomicalObservatories (Xinglong, China). Through the analysis, we want to study more characters about this class ofgiant stars.


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New Planetary Nebulae in the Outskirts of M 31 Dis-covered with the Guoshoujing Telescope (LAMOST)

Haibo Yuan40

Planetary nebulae (PNe) are good tracers of the stellar populations, chemical composition and dynamics oftheir host galaxies. This paper reports the discovery of new PNe in the outskirts of the Andromeda Galaxy(M 31) with the Guoshoujing Telescope (formerly named Large Sky Area Multi-Object Fiber SpectroscopicTelescope –LAMOST) during its early commissioning phase. In total, 36 candidates selected from SDSSphotometry are confirmed in terms of their PN nature, including 17 new discoveries and another 19 previouslyknown emission line objects. Their positions, spectra, radial velocities and m5007 magnitudes are presented.We discuss the potential for detecting more PNe in M 31 with the Guoshoujing Telescope’s multi-objectspectroscopy and the related applications in studies of the dynamics and chemistry of M 31 and its assemblagehistory.

Progress Report on the Digital Sky Survey ofthe Galactic-anti Center Direction (DSS-GAC)

Haibo Yuan41

We have been carrying out a photometry survey toward the galactic-anti center direction (3h ¡ Ra ¡9h, -10 ¡dec ¡ 60) in g, r and i bands using the Xuyi 1.0/1.2m Schmidt Telescope, motivated by the a) Target selectionfor the LAMOST spectroscopic survey; b) Follow-up analyses of LAMOST spectra will benifit enormouslyfrom high-quality optical photometry, especially in deducing the stellar fundamental parameters, such aseffective temperature, surface gravity and metallicity, as well as interstellar reddening towards the stars; c)Such an imaging photometry survey is in itself scientifically extremely interesting and highly complementaryto the LAMOST spectroscopic survey in the study of the outer parts of the Milky Way’s dominant stellarcomponent, the galactic disk(s), which has already revealed complex structure that is poorly understood.Here I report the progress of the survey and its data reduction, especially on flat fielding, psf photometry,astrometric and photometric calibrations.

Pencil Beam Exploration of the Outer Galactic Halo

Simone Zaggia42

We present the results of an in-situ study of the Outer galactic Halo (up to 100Kpc). We have used theFLAMES facility on the VLT to obtain medium resolution spectra of stars, down to V 20, in 2 deep fields.The spectra have been analyzed with state of the art model atmospheres and spectrum synthesis techniquesto determine chemical abundances, kinematical and physical properties of each star of the sample. We alsoused precise astrometric data to have a full orbit solution for each star. We found a decreasing density ofHalo stars with a lower than expected rate with the Galactic Halo extending up to at least 165 Kpc from theGalactic Centre. Our stars constitute a pure Halo sample with a mean [Fe/H]=-1.4 and a large metallicitydispersion, covering the range -2.4, -0.1. There is a suggestion of a weak metallicity gradient in the Halo.

Helium abundances of OB stars within 9-11 kpc from the Galactic Center

Maria Isela Zevallos Herencia43

The radial distribution of the chemical properties of the Galaxy can be studied analyzing different youngobjects of the Galactic thin disk and the results indicate the existence of a radial gradient of metallicity inthe disk. The structure of such abundance gradient, however, is not completely constrained. Some worksdescribe the abundance gradient as a function of the Galactocentric distance RG by linear fits with a singleslope. However, some analyses of open clusters, cepheids and OB stars suggest that a discontinuity doesexist in the abundance distributions around RG =10 kpc. In this work, we analyze the helium abundance of asample of 32 OB stars members of six open clusters located around RG = 10 kpc in order to better constrainthe chemical distribution in this region of the disk.


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Observational Study of the Magnetic Activ-ity for Active Members of Young Open Clusters

Liyun Zhang44

The solar activities, such as sunspots, plages, flares and other phenomena are caused by the magnetic activityof the Sun. The late-type stars with thick convective zones and rapid rotation also show similar phenomena.However, in many such kinds of stars, the details of the active phenomena caused by the magnetic fields arenot understood well. In order to know the stellar magnetic activities of different physical parameters better,we intend to acquire low and medium resolution spectra for members of different young open clusters (agedin 1-500 Myr) with the LAMOST so as to investigate the property and regularity of the detailed magneticactivity in the chromosphere, and to discuss the relations of the magnetic activity and stellar parameters,especially the relation between magnetic activity and rotational periods.

Planetary Nebulae Detected in the SpitzerSpace Telescope GLIMPSE3D Legacy Survey

Yong Zhang45

We have used the data from the Spitzer GLIMPSE3D survey to investigate the mid-infrared (MIR) prop-erties of planetary nebulae (PNs) in the Galactic plane. By comparing the GLIMPSE3D data with theMacquarie/AAO/Strasbourg (MASH) Ha PN catalog, we find that 90 highly obscurely PNs have visible MIRcounterparts. These PNs are clearly more red than the field stars, and show strong emission from cold dust.We present images and photometry of these PNs at 3.6, 4.5, 5.8, and 8.0 um.

Blue Straggler Stars in Galactic Globular Clusters

Zhengshi Zhao46

Blue straggler stars (BSS) are located above and blue-ward of MS turn-off in a CMD of stellar clusters.Two different mechanisms of them are commonly believed nowadays: mass transfer in binary systems (MT-scenario) and stellar merger occurred through a direct stellar collision (CL-scenario). Globular Clusters (GCs)are ideal objects to study BSSs because both of these two formation mechanisms would occur in them.The MT mechanism is likely to be dominant in outer part of GCs; whereas the CL mechanism might occurmainly in the central part of GCs. Dynamical simulations had been matched well with the observed radialdistribution of BSSs frequency. But the dispute on formation mechanisms has been heated recently. Kniggeet al. have strongly suggested that the most BSSs are the progeny of binary systems, even in a cluster core.On the contrary, Ferraro et al. provided their observational evidences to prove that both of two mechanismswere occurred in GCs. In this respect, the further spectroscopic investigation of BSSs will play an importantrole to confirm and distinguish the different formation mechanisms. Here, we review the main observationalproperties of BSSs in GCs and also introduce our spectroscopic studies of BSSs with Subaru telescope.

The star formation history of red and blue disk LSBGs

Guohu Zhong47

We present a large sample of red and blue low surface brightness disk galaxies to study their star formationhistories, and want to find whether their star formation histories of two kinds of galaxies are different byusing spectral synthesis mode, lick index and D(4000). We found that red LSBGs are more massive, older,and more metal-rich than blue LSBGs. Moreover, blue LSBGs are more likely to form their star continu-ously, while blue LSBGs tend to form their star sporadically. The results of two sub-samples, mass-limiting(9.5<logM/M0<10.5) and surface brightness limiting (µ0(R)>20.7 mag arcsec−2), show nearly no differencesto the total sample.


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Participants List

Participant e-mail Institute

Jin An [email protected] NAOC, CASMartin Asplund [email protected] Max Planck Institute for AstrophysicsJoss Bland-Hawthorn [email protected] University of SydneyMaarten Breddels [email protected] Kapteyn Astronomical InstituteAlyson Brooks [email protected] CaltechSarah Bryan [email protected] University of ManchesterLi Chen [email protected] Shanghai ObservatoryXiaoyan Chen [email protected] NAOCZhaoyu Chen [email protected] Peking UniversityYaoquan Chu [email protected] Center for Astrophysics, USTCAndrew Cooper [email protected] University of DurhamWenyuan Cui [email protected] Hebei Normal UniversityAlis Deason [email protected] Institute of Astronomy, University of CambridgeVictor Debattista [email protected] Jeremiah Horrocks InstituteLicai Deng [email protected] NAOCWei Du [email protected] Peking UniversityLaurent Eyer [email protected] Observatoire de Geneve, Universite de GeneveZhou Fan [email protected] NAOCMariagrazia Franchini [email protected] INAF-Trieste Astronomical ObservatoryShuang Gao [email protected] ARI, University of HeidelbergRuben Garcıa-Benito [email protected] KIAAKatharina Glatt [email protected] Astronomisches Rechen-InstitutOleksiy Golubov [email protected] Astronomisches Rechen-InstitutCarlos Gonzalez Fernandez [email protected] Universidad de AlicanteCarl Grillmair [email protected] Spitzer Science CenterMelanie Guittet [email protected] Observatoire de ParisRaoul Haschke [email protected] Astronomisches Rechen-InstitutKohei Hattori [email protected] University of TokyoAmina Helmi [email protected] Kapteyn Institute, Univ. of GroningenJinliang Hou [email protected] Shanghai Astronomical ObservatoryShuiyao Huang [email protected] Nanjing UniversityYafang Huang [email protected] NAOCZhiying Huo [email protected] NAOCHiroko Ito [email protected] SOKENDAI / NAOJBiwei Jiang [email protected] BNULucie Jilkova [email protected] ESO SantiagoShoko Jin [email protected] ARI/ZAH University of HeidelbergRoelof de Jong [email protected] Astrophysikalisches Institut Potsdam (AIP)Andreas Just [email protected] ARI at ZAH, University of HeidelbergDaisuke Kawata [email protected] Mullard Space Science Laboraroty, UCLStefan Keller [email protected] RSAA, Australian National UniversityHaining Li [email protected] NAOCJi Li [email protected] Hebei Normal UniversityJinzeng Li [email protected] NAOCYang-Shyang Li [email protected] Kapteyn Astronomical InstituteNoam Libeskind [email protected] Astrophysikalisches Institut Potsdam (AIP)Chao Liu [email protected] Max Planck Institute for AstronomyChengze Liu [email protected] Peking UniversityGaochao Liu [email protected] NAOCJiacheng Liu [email protected] Nanjing UniversityXiaowei Liu [email protected] KIAARichard Long [email protected] University of ManchesterRagnhild Lunnan [email protected] Harvard-Smithsonian Center for AstrophysicsAli Luo [email protected] LAMOST team, NAOCZhibo Ma [email protected] Case Western Reserve UniversityDougal Mackey [email protected] The Australian National University


Participants List


Nicolas Martin [email protected] Max Planck Institute for AstronomyAlan McConnachie [email protected] NRC Herzberg Institute of AstrophysicsIvan Minchev [email protected] Strasbourg ObservatoryMaria Monguio [email protected] Universitat de BarcelonaCarlo Morossi [email protected] INAF-Trieste Astronomical ObservatoryHeather Morrison [email protected] Case Western Reserve UniversityHeidi Newberg [email protected] Rensselaer Polytechnic InstituteMatthew Newby [email protected] Rensselaer Polytechnic InstituteXiaoying Pang [email protected] Heidelberg UniversityJorge Penarrubia [email protected] Institute of AstronomyEric Peng [email protected] Peking UniversityTilmann Piffl [email protected] Astrophysikalisches Institut PotsdamRadoslaw Poleski [email protected] University of Warsaw Astronomical ObservatoryHelene Posbic [email protected] Observatoire de Paris - MeudonFrancesca Primas [email protected] European Southern ObservatoryAwat Rahimi [email protected] MSSL, University College LondonIvan Ramırez [email protected] Max Planck Institute for AstrophysicsPaola Re Fiorentin re [email protected] INAF-OAToConnie Rockosi [email protected] University of California, Santa CruzRalph Schonrich [email protected] MPAJianrong Shi [email protected] NAOCArnaud Siebert [email protected] Observatoire de StrasbourgMartin C. Smith [email protected] KIAA, Peking UniversityMichael Solway [email protected] Rutgers, The State University of New JerseyHao Tian [email protected] Beijing Normal UniversityMarica Valentini [email protected] University of LiegeKim Venn [email protected] University of VictoriaCarlos Vera Ciro [email protected] Kapteyn Astronomical InstituteDiah Titari Wahyuningtyas [email protected] Bandung Institute of Technology (ITB)Matthew Walker [email protected] Institute of Astronomy, University of CambridgeNicholas Walton [email protected] Institute of Astronomy, University of CambridgeHongchi Wang [email protected] Purple Mountain ObservatoryJian Wang [email protected] Tsinghua UniversityYougang Wang [email protected] NAOCMaosheng Xiang [email protected] KIAAWeike Xiao [email protected] Harbin Institute of TechnologyDandan Xu [email protected] NAOCMing Xu [email protected] Nanjing UniversityYan Xu [email protected] NAOCGuochao Yang [email protected] NAOCJi Yang [email protected] PMOLei Yang [email protected] Peking UniversityHaibo Yuan [email protected] PKUSimone Zaggia [email protected] INAF - Osservatorio Astronomico di PadovaMaria Isela Zevallos Herencia [email protected] Observatorio NacionalHaotong Zhang [email protected] NAOCHuawei Zhang [email protected] Peking UniversityHuihua Zhang [email protected] KIAALiyun Zhang liy [email protected] Guizhou UniversityNingxiao Zhang [email protected] Nanjing UniversityYanxia Zhang [email protected] NAOCYong Zhang [email protected] The University of Hong KongGang Zhao [email protected] NOACYongheng Zhao [email protected] NAOCZhengshi Zhao [email protected] NAOJGuohu Zhong [email protected] NAOC


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Participants List


Jing Zhong [email protected] SHAOXu Zhou [email protected] NAOCLing Zhu [email protected] Tsinghua UniversityDaniel Zucker [email protected] AAO / Macquarie UniversityWenwen Zuo [email protected] Peking University


Chemistry,dynamicsand...

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