Visiting Committee Catania, 17 dicembre 2007 G. Umana Circumstellar Environments.

Visiting CommitteeCatania, 17 dicembre 2007

G. Umana

Circumstellar Environments


G. Umana

The Team

Historical Group (from IRA-Noto):

G.Umana, C.S. Buemi INAF-OACt

C. Trigilio INAF-OACt and Università di Catania

P. Leto INAF-IRA, Noto

PhD students:L. Cerrigone, CfA-Università di Catania

S. Dolei, P. Manzitto, C. Siringo Università di Catania

Collaborators:F. Leone, Università di CataniaJ. Hora, G. Fazio, M. Marengo SAO-CfAC. Burigana INAF-IASFH. Olofsson OSO, G. Giardino (ESA), R. Paladini (JPL)


G. Umana

The project

The study of circumstellar environments

by means of radio observations Radio techniques very useful in multi-frequency approaches

Unique for some classes of Galactic objects

Circumstellar environments:• Coronae around active stellar systems• Stellar Magnetosphere• Stellar ejecta, late stage of stellar evolution


G. Umana

The project

Funds (since 2004):

Besides normal (small) INAF science funding….

2005-2007 ASI-Planck Science

18 k€

2007-2008 ASI-Planck Science

7.5 k€

2006-2008 INAF/Alma 6.2 k€


G. Umana

Radio Emission from CP stars

• Anomalous abundances

• Strong (>3000 G) dipolar magnetic field

• Variability (continuum, lines, B) - Oblique Rotator Model

Explained in terms of oblique rotator model

Radio emission (also variable ) consistent with Gyrosynchrotron plus a coherent component

radio


G. Umana

Goal Understanding the origin of variable radio emission from CP

Method

By modeling the radio flux density light-curve

VLA and ATCA project (multi-frequency, multi-configuration)

Principal Results:

o Full coverage of radio curve at different frequency for 3 stars

o Development of a 3D code to reconstruct the magnetosphere of CP and modeling of radio light curve

o Discovery of a new component in the radio emission

o Use of coherent emission as a period marker

Radio Emission from CP stars


G. Umana

18 cm, 4 cm, 1 cm

-Gyrosynchrotron from the magnetosphere

The 3D code for radio emission

Trigilio C., Leto, P., Umana, G., Buemi, C., Leone, F., 2004

Leto P., Trigilio, C., Buemi, C. Umana, G., Leone, F. ,2006

Good agreement with observations


G. Umana

Discovery of a new component of radio emission:

CU Vir: the coherent radio component

• occurring only at particular rotational phases • 100% circularly polarized • highly directive• persistent over years

Consistent withCyclotron Maser Emission


G. Umana

Marker of the rotational period

Consistent withCyclotron Maser Emission

• occurring only at particular rotational phases

• persistent over years

CU Virginis is slowing downdP/dt ~ 10-9 s yr-1 Trigilio C., Leto, P., Umana, G., Buemi, C., Leone, F.,

2008

CU Vir: the coherent radio component


G. Umana

Stellar Ejecta

Observed around stellar objects in late evolutionary phases:

-AGB PNe Mass-loss CSE

-LBV

Open questions:o Shaping: mass-loss (asymmetric) or evolution in an asymmetric environment?o Mass and T (gas & dust content)o Multiple components (different mass-loss episodes?)o Chemistry and its evolution with time (photodissociation, shocks)

o Chemical evolution of Galaxy (processed material return to ISM)o Ideal laboratory to study wind/shocks interaction with ISM


G. Umana

O B A F G K M

104 L

102 L

1 L

10-2 L

10-4 L

MMS 1 -8 Mo Stellar Ejecta: AGB PNe

~800~1000

yrs

* VisibleUV

IRIR-farIR

IR-radio


G. Umana

Goal Understanding the shaping of PNe, through observation of YPNe where the shaping mechanism is still active

Method

Select a sample of TO (AGBPNe) objects; Detect radio to find YPNe

VLA and ATCA project (multi-frequency, multi-configuration) 42 objects

Principal Results: o Detected 17 sources; Established their evolutionary status

(YPNe)

o Other 25 objects are genuine hot post-AGB stars.

o Radio spectra consistent with a PN in the early stage of its evolution

o High-resolution mapping Bi-polar morphology

Hunting for Young PNe

far-IR characteristics (excess) Optical characteristics

B spectral type spectral and photometric variability

-The onset of ionization can be marked by the presence of free-free emission…


G. Umana

YPNe: sub-arc observations

VLA-A, 3.6cm

1

Radio morphology: bi-polar shaping is already active!

Cerrigone,L., Umana, G., trigilio, C., Buemi, C., Leto, P. ., 2008


G. Umana

H-alpha

IRAS 22568+6141

VLA-C, 3.6cm VLA-A, 3.6cm

Total flux= 32mJyCentral component 1.65 0.05 mJyConsistent with stellar wind? (Mass-loss)

new VLA, high resolution, multi-frequency data already available (AU119), waiting for reduction!

1

Umana, G., Trigilio, C., Cerrigone, L., Buemi, C., Leto, P., 2008


G. Umana

CSE: the dust component

Goal Understanding the dust contribution to the shaping

Method

Inspecting the dust properties of envelope in TO (AGBPNe) objects: -systematic differences between radio detected (YPNe) and post-AGB?

SST project on YPNe, part of the SST-GTO on Stellar ejecta (PI G. Fazio)IRAC + IRS observations of 42 TO (with radio infos)

Principal Results:

o CSE around TO generally very compact (not resolved by IRAC)

o IRS spectra dominated by thermal dust emission plus spectral structures due to dust (crystalline silicates)

o besides recombination lines, no evident differences between radio (YPNe) and not radio detected (hot post-AGB) objects.

o about 50% of the sample shows mixed chemistry

o necessity to introduce big grains to fit SEDs


G. Umana

The dust component: Results

- IRS spectra dominated by thermal dust emission plus spectral

structures due to crystalline silicates - part of the sample shows mixed chemistry: not consistent with evolution theory

Silicates

Cerrigone, L., Hora, J., Umana, G., Trigilio, C., 2007Cerrigone, L., PhD Thesis, 2008

[ArII][NeII]

PAH PAHSilicates

When SED (up to mm) are modeled:- necessity to consider multi-component CSE - big grains (0.05-100 m)

- Consistent with a reservoir of O-rich material, probably an equatorial disk (PPNe Red Rectangle) strong clue for stellar ejecta being collimated by such structures!


G. Umana

Stellar Ejecta: LBV

log L/L ~ 5.0-6.3 strong mass-loss ~ 10-6 ÷10-4 Myr-1

Variability Outbursts ΔV ~ 1-2 mag

MMS > 25 Mo


G. Umana

LBVs: the ionized gas

Goal Understanding the LBV phenomenon through the study of their ejecta (morphology and physics of the nebula)

Method

Determine the properties of the radio emission, tracing the ionized gas component of the ejecta -Symmetric versus Asymmetric morphology

- Mass-loss of the central objects (current-day mass-loss)

VLA Multi-frequency, multi-configuration project

Principal Results:

o Radio morphologies in general asymmetric and structured

o High-resolution allows to resolve the core component

o High-resolution, multi-frequency allows to determine mass-loss

o Radio observations more efficient than usual H (no extinction) essential to probe the ionized component in strongly reddened object


G. Umana

LBVs in Radio

Probing the ionized component in a very dusty environment

Umana, G., Buemi, C.S., Trigilio, C. , Leto, P. et al., 2005

IRAS 18576+0341

Strongly reddened object: no optical counterpart VLA-A, C-band-Multi-frequency, high resolution VLA observations:-a core component (LBV’s wind)-an extended, asymmetric nebula

Current day mass-loss 3.7 10-5 Myr-1

B0-B0.5 I, Teff ~ 2.6 104 K


G. Umana

LBVs: the dust component

Goal Understanding the LBV phenomenon through the study of their ejecta (morphology and physics of the nebula)

Method

Determine the properties of the mid-IR emission, tracing the dust component of the ejecta -Symmetric versus Asymmetric morphology

- Comparison with ionized gas component to derive clues for shaping

VISIR@VLT project multi-frequency sub-arcsec imaging

Principal Results:

o Ejecta morphologies: highly structured

o Thermal dust morphologies DIFFERENT from radio.


G. Umana

Mapping with VISIR@VLT pixel scale 0.075

17.65 m12.27 m

11.26 m

IRS@SST

IRAS 18576+0341


G. Umana

Comparison between ionized gas and dust: sub-arcsec mapping

IRAS 18576+0341

4

-4VLA-A, 5 GHz (6cm) VISIR 12.25

m

Clues on mass-loss and shaping:A) Mass-loss can occur asymmetrically; outflows may be shaped by dusty structures

B) dust distribution not homogeneous dust competes with gas in absorbing UV radiation: holes in dust allow gas to glow!


G. Umana

LBVs: ionized gas and dust comparison

Different situation in HD168625 - The ionized gas appears contained by dust:

- Outflow channeled by a dusty equatorial torus??

kinematical information necessary!

VISIR 12.25 m

VLA-A 3.6cm


G. Umana

LBV: more on the dust component

Goal Determine the characteristics of dust component: yield to ISM Chemistry; mass-loss history

Method

Determine mid-IR spectral and morphological propertiesModeling the SEDs (CLOUDY) Mass-loss history

-SST project on Galactic LBVs, part of the SST-GTO on Stellar ejecta (PI G. Fazio)

IRAC+IRS (low + high res) of nine Galactic LBV

-SAGE Collaboration on LBVs in MCs (IRAC+IRS+MIPS)

First Results:

o Dusty CSE around Galactic LBV can be very extended

o Both regular (spherical) and asymmetric morphology observed.

o IRS spectra: dominated by emission lines and dust spectral features (PAHs)

o [Fe II] mid-IR lines detected: possible diagnostics for shocks


G. Umana

Stellar ejectaWray17-96

SST-IRAC mosaicIRAC LBV GTO program


G. Umana

In the next years new instrumentations will come on-line

ALMA: mm interferometer ( 30-900 GHz)spectral and continuum capabilities (sub-mJy) , sub-arcsec imaging 2011

EVLA: cm interferometer (1.4-50 GHz) :spectral and continuum capabilities (sub-mJy) , sub-arcsec imaging 2009

Stellar ejecta: the future


G. Umana

Stellar ejecta possible foregrounds for CMB:- from a feasibility study ~400 CSE will be detected by PLANCK (Umana, G. Burigana, C., Trigilio, C.- 2006)

- PLANCK will provide flux measurements, between 30 and 900 GHz, for the radio brightest PNe SEDs Umana, Leto, Trigilio, Buemi, Toscano, Manzitto, Dolei, Cerrigone, 2008

(based on 43 GHz single dish INAF-IRA teleacope Obs)

PLANCK mission, full sky coverage (30 to 900 GHz)-end 2008

Stellar ejecta:the future


G. Umana

Stellar ejecta:ALMA

ALMA will provide detailed (sub-arcsec, sub-mJy) maps of: ionized gas continuum (30 GHz…..) morphology molecular gas CO (100 GHz) morphology (Kinematic) dust continuum (100 GHz…) morphologyMorphological and spectral studies of different components

coexisting in the ejecta CLUES on shaping

ALMA (sub-arc, sub-mJy)VISIR@VLT (sub-arc, mJy)HST (sub-arc)EVLA (sub-arc, sub-mJy)

SYNERGIES

ionized gas continuum continuum (1.4-50 GHz) RRLs (1.4-50 GHz) molecular gas CO H2 (near-IR) Dust continuum continuum (mid-IR)


G. Umana

ALMA-2011+…… putting together the pieces

Radio jet that makes its way through the CO cocoon

Dusty disk/torus

Molecular Cocoon


G. Umana

mm and submm observations provide strong constraints for SED modeling

Post-AGB starsmm obs MAMBO@Iram 30m + SEDs modeling (DUSTY): = 0.9-1.6

R =1016 10 17 cm dM/dt~ 10-6-10-5

Stellar ejecta:ALMA

Buemi, C, Umana, G., Leto,P., Trigilio, C 2007

ALMA: Detailed maps of CSE dimension, structure…

VERY strong constraints to the SED Modeling!


G. Umana

The link to the Catania University

Radioastronomy (C. Trigilio) Undergraduate course (Physics)Galactic Radiosources (G. Umana) Lectures for PhD program

PhD students:L. Cerrigone, Infrared and Radio properties of YPNeCfA-Università di Catania Thesis defence next February

P. Manzitto, SEDs modeling of PNeUniversità di Catania, III year

C. Siringo, SiO maser in CSE

Università di Catania, begin III year S. Dolei, Radio modeling of PNeUniversità di Catania, begin II year

All the students trained at INAF-IRA 32m Radiotelescope: acquisition techniques,

data reductions …..

Science for ALMA

Science for ALMAPLANCK, HERSCHEL

Science for ALMA

Science for ALMAPLANCK, HERSCHEL

Visiting Committee Catania, 17 dicembre 2007 G. Umana Circumstellar Environments.

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