A Kepler misszió és az első KASC meeting

tanulságai

Szabó RóbertMTA KTM CsKI

2007. november 13.

Általános adatok

• LAUNCH: 2009 február• NASA Discovery Program• 105 sq. degr. FoV• 0.95 m Schmidt távcső + 42 db CCD-kamera• 3.5 (+2) évig folyamatosan figyel egy területet

Team:PIs and Co-Is

(+SWG)

William Borucki,Principal InvestigatorNASA Ames Research Center

Gibor Basri,Co-InvestigatorUniversity of California-Berkele

David Koch, Deputy Principal InvestigatorNASA Ames Research

Timothy Brown, Co-InvestigatorLas Cumbres Observatory Global Telescope(LCOGT)

William Cochran, Co-InvestigatorMcDonald ObservatoryUniversity of Texas

Jørgen Christensen-DalsgaardCo-investigatorAarhus UniversityDenmark

Edna DeVore, Co-InvestigatorSETI Institute

Jon Jenkins, Co-InvestigatorSETI Institute

Edward (Ted) Dunham, Co-InvestigatorLowell ObservatoryFlagstaff, Arizona

Yoji Kondo, Co-InvestigatorNASA GSFCGreenbelt, MD 20771

Nick Gautier Co-InvestigatorJet Propulsion Lab

John Geary, Co-InvestigatorHarvard Smithsonian CfA

Ronald Gilliland, Co-InvestigatorSpace Telescope Science Institute

Alan Gould, Co-InvestigatorUniversity of CaliforniaBerkeley, CA 94720

Dave MonetCo-Investigator US Naval ObservatoryFlagstaff, AZ 86001-8521

Yoji Kondo, Co-InvestigatorNASA GSFCGreenbelt, MD 20771

David Latham, Co-InvestigatorHarvard Smithsonian CfA

Jack Lissauer, Co-InvestigatorNASA Ames Research CenterMoffett Field, CA 94035

Célja• Determine the percentage of terrestrial and larger planets there are in or near

the habitable zone of a wide variety of stars; • Determine the distribution of sizes and shapes of the orbits of these planets; • Estimate how many planets there are in multiple-star systems; • Determine the variety of orbit sizes and planet reflectivities, sizes, masses

and densities of short-period giant planets; • Identify additional members of each discovered planetary system using

other techniques; and • Determine the properties of those stars that harbor planetary systems

The Kepler Mission also supports the objectives of future NASA Origins theme missions Space Interferometry Mission (SIM) and Terrestrial Planet Finder (TPF),

• By identifying the common stellar characteristics of host stars for future planet searches,

• By defining the volume of space needed for the search and • By allowing SIM to target systems already known to have terrestrial planets.

Célja

• Extending the mission beyond three and one half years provides for:

• Improving the signal to noise by combining more transits to permit detection of smaller planets

• Finding planets in orbits with larger periods

• Finding planets around stars that are noisier either due to being fainter or having more variability

Várható eredmények• Expected Results:

– Based on the mission described above, including conservative assumptions about detection criteria, stellar variability, taking into account only orbits with 4 transits in 3.5 years, etc., and assuming that planets are common around other stars like our Sun, then we expect to detect:

• From transits of terrestrial planets in one year orbits:– About 50 planets if most are the same size as Earth (R~1.0 Re)

and none larger, – About 185 planets if most have a size of R~1.3 Re, – About 640 planets if most have a size of R~2.2 Re, – About 12% with two or more planets per system. – These numbers come out substantially higher, when one takes

into consideration all orbits from a few days to more than one year.

Várható eredmények• From modulation of the reflected light from giant inner planets:

– About 870 planets with periods less than one week. • From transits of giant planets:

– About 135 inner-orbit planet detections, – Densities for 35 inner-orbit planets, and – About 30 outer-orbit planet detections. – Detection of the short-period giant planets should occur within the first

several months of the mission.

• Kepler looks at 100,000 stars so that if Earths are rare, a null or near null result would still be significant.

• If Earth-size planets are common then Kepler should detect hundreds of them

Hardver• Spacebased Photometer: 0.95-m

aperture• Primary mirror: 1.4 meter diameter,

85% light weighted• Detectors: 95 mega pixels (42 CCDs

with 2200x1024 pixels)• Bandpass: 430-890 nm FWHM• Dynamic range: *9th to 16th

magnitude stars• Fine guidance sensors: 4 CCDs

located on science focal plane• Attitude stability: <9 milli-arcsec, 3

sigma over 15 minutes.• Uplink X-band: 7.8125 bps to 2 kbps• Downlink X-band: 10 bps to 16 kbps• Downlink Ka-band: Up to 4.33125

Mbps• No mechanisms other than a one-time

ejectable cover

up to 7.2 magnitude

Hardver• Mission Characteristics:• Continuously point at a single star field in Cygnus-Lyra

region except during Ka-band downlink.• Roll the spacecraft 90 degrees about the line-of-sight every

3 months to maintain the sun on the solar arrays and the radiator pointed to deep space.

• Monitor 100,000 main-sequence stars for planets• Mission lifetime of 3.5 years extendible to at least 6 years• D2925-10L (Delta II) launch into an Earth-trailing heliocentric

orbit• Scientific Operations Center and Project management

(operations) at Ames Research Center• Project management (development) at Jet Propulsion

Laboratory• Flight segment design and fabrication at Ball Aerospace &

Technologies Corp. • Mission Operations Center at Laboratory for Atmospheric

and Space Physics (LASP)—University of Colorado • Data Management Center at Space Telescope Science

Institute• Deep Space Network for telemetry• Routine contact• X-band contact twice a week for commanding, health and

status• Ka-band contact once a month for science data downlink

Pálya

• Earth-trailing heliocentric orbit with a period of 372.5 d• In this orbit the spacecraft slowly drifts away from the Earth and is at a distance of 0.5 AU (worst case) at the end of four years • it has a very-low disturbing torque on the spacecraft, which leads to a very stable pointing attitude. • not being in Earth orbit means that there are no torques due to gravity gradients, magnetic moments or atmospheric drag. • the "largest" external torque then is that caused by solar pressure.

Schedule• Concept Study Mar 2001 to July 2001 • Discovery selection Dec. 21, 2001• Phase B Feb 2002 to Oct 2004• Phase C/D Nov 2004 to Oct 2008    • Launch February 2009    • Commissioning Launch + 30 days• Phase E    • Flight operations For 3.5 years from end of

commissioning    • Data analysis For 5 years from end of commissioning    • Optional extended mission    Additional 2 yrs of ops and data

analysis

Kepler field

• 21 modul – 42 CCD• kp: RA 19h22m40s

Dec 44°30'00" Cygnus• >100 sq. degr.• 3 havonta 90 fokos

rotáció• CCD pixel calculator -

célpont kiválasztás• Fényes csillagok a

gap-ekben

• 21 modul – 42 CCD• kp: RA 19h22m40s

Dec 44°30'00" Cygnus• >100 sq. degr.• 3 havonta 90 fokos

rotáció• CCD pixel calculator -

célpont kiválasztás• Fényes csillagok a

gap-ekben

Fotometria• The design of the entire system is such that the combined differential photometric precision over

a 6.5 hour integration is less than 20 ppm (one-sigma) for a 12th magnitude solar-like star including an assumed stellar variability of 10 ppm. 8 sigma detection of a Earth-size planet transit on a 1yr orbit (1 AU) around this star.

• Differential spatial photometry: The brightness of each target star is normalized to the average of all nearby stars, providing common-mode rejection in the measuring system.

• Differential temporal photometry: Transit durations are a few hours to less than about half of a day. Brightnesses are compared to data just shortly before and after the test interval, so there is no need for long term stability.

• Decorrelation of image motion: Motion due to the image drifting over time scales long compared to a transit produce highly correlated amplitude variations that are removed.

• Optimal weighting of pixels: The individual pixels that comprise each star image are weighted to maximize the SNR.

• Keeping each star image on the same pixels for three months: Eliminates effects of inter- and intra-pixel quantum-efficiency variations.

• Operating the CCDs near full well capacity: Read noise and dark current are negligible.

• Selection of an Earth-trailing heliocentric orbit: Stable thermal environment and negligible scattered light background.

Célpontok - pontosság

• The actual number of stars with mv<14 of all spectral types and luminosity classes in the 105 deg2 FOV to be 223,000.

• About 61%, i.e., 136,000, are estimated to be main-sequence stars. Prior to launch high-resolution spectroscopy is performed to identify and eliminate the giant stars in the FOV.

• During the first year of the mission, the 25% most active of the dwarf stars are eliminated reducing the number to 100,000 useful target stars.

mv Prediction (ppm) / 6.5 hr integrations• 9• 10 6.5• 11 10• 12 17• 13 28• 14 50• 15 95• 16 200

Kepler Asteroseismology Science Consortium (KASC)

Kepler - részvételi lehetőségekParticipating Scientist Program (PSP)– The PSP funds investigators whose research program is directlyconcerned with the detection, characterization, or understandingof extrasolar planets. Such research programs complementthose developed by the PI and Co-Is.

Guest Observer Program– The GOP will function similar to facilities instrument such asHST. Approximately 3% of the downlink bandwidth will beavailable for astrophysical investigations by the GO.Observations of up to 3000 stars at the 30 minute cadence canbe requested and/or 25 stars at a 1 minute cadence. Any type ofobject in the Kepler FOV will be observed upon request by asuccessful proposer.

Astrophysics Data Program– This program funds investigators who wish to data mine theKepler observations.

Guest Observer Program• 3000 stars - long cadence• 25 stars – short cadence

• The data will be calibrated. Bias (dark level) and smear (the photometer has no shutter) will be removed and values converted to fluxes.

• The multiple pixels making up a single star's psf will not be combined, permitting users to perform their own photometry or other forms of analysis.

• In addition, light curves for all the stars will be processed on a quarterly basis at NASA Ames Research Center. Ensemble-normalized light curves will be placed in the archive; there may be a quarter year lag for processing.

• The STScI will provide support to the GO users through the Multi-mission Archive Support Tool (MAST).

• Users will be able to search data bases to ascertain what data exists on targets of potential interest, and to determine when specific observations will be available (consistent with proprietary restrictions) for access.

• No transit filtering!

Kepler Input Catalog (KIC)Dave Latham (CfA)

Includes all known stars in Kepler FOV– ~ 20 million stars (USNO-B)

• Photometry– 2MASS JHK + SDSS griz + D51– ~ 2 million stars down to K~14.5 mag

• Astrophysical characteristics– Teff, log(g), [Fe/H], reddening; Mass, Radius– Radial and rotational velocities

• Used to select optimum targets:– Late F through M dwarfs for planet detection– Expect ~ 170,000 through 16th mag– ~ 1/3 will be younger than the Sun & too noisy

Szervezeti felépítés• KASC (Kepler

Asteroseismology Science Consortium)

• KASOC (Kepler Asteroseismic Science Operations Center)

• KAI (Kepler Asteroseismic Investigation)

Szervezeti felépítés• KASC (Kepler

Asteroseismology Science Consortium)

• KASOC (Kepler Asteroseismic Science Operations Center)

• KAI (Kepler Asteroseismic Investigation)

Lehetséges észlelési stratégia

Data policy

• Letter of Direction from William Borucki to Ronald Gilliland and Jørgen C.-D. formally setting up KAI and KASC.

• Data Release and Scientific Publications Policy. KKPO-16001-003, 7 August 2007, NASA Ames Research

Center.

Data release policy - generalThe Kepler Mission data will be made publicly available at specified times:1. data from commissioning and initial, partial quarter within 1 year of end of quarter2. one year later release next 3 months of data3. At t+n years release additional 6 month blocks of data.4. All data within one year of mission end.5. All data for any stars that have been dropped from the planet search program willbe made public within 2 months of their being dropped.6. Full frame images, and general metadata describing observations will be madepublicly available as soon as ingested.

The MAST (Multimission Archive atSTScI ) will be the source for generalcommunity access to the data.

Data release policy – asteroseismology specific

1. Targets observed at 1-minute cadence for the purposes of asteroseismology.• after processing at Ames for basic time series creation, ingest into MAST, thenRon Gilliland will perform high pass filtering and pass to KASOC (Hans Kjeldsendiscussed filter options yesterday.) for KASC access.• total time ~4 months from last data collected in quarter

2. Targets observed at 1-minute cadence for exoplanet research.• as above upon request from Kepler PI for KASOC analysis -- these data are notmade available to the KASC

3. Long-cadence (30-minute) targets (100s/1000s) of red giants, beta Cephei, pulsatingB stars, delta Scuti, etc.• generally available to KASOC and KASC upon ingest to MAST

Data collected for asteroseismology will enter the public domain as defined for the general case. In addition KASC members (contingent upon having signed “non-disclosure agreement”) will have access to additional data as follows:

KASC members work under a data/publication policy. If a person cannot accept the policy or fails to comply with it, the KAI Steering committee can take the action to cancel the KASC membership.

Data policy / data publication guidelines

– 1. All KASC members have unrestricted access to all data on KASC-selected targets in KASOC. Access is password controlled and data downloads are logged.

– 2. All members that contribute to a given data set (analysis, target selection, ground-based follow-up etc.) shall be on publications related to that given data set.

– 3. Members are supposed to collaborate and specifically the individual subgroups of KASC that will be set up to select targets and ensure analysis for specific targets will also be responsible for publication of those data.

– 4. KASC members that work on data related to a specific target are asked to join a possible subgroup that may be responsible for that target.

– 5. Any publication that will be submitted shall be checked and formally approved by the KAI Steering committee (or by others selected by the steering committee) before submission. The KAI Steering Committee has the right to modify the list of authors to make it conform with the data-policy guidelines. Prior notification to the KAI Steering Committee is also expected for press releases, conference presentation, general talks, etc.

– 6. The KAI Steering Committee will keep the PI/KSC informed of requests for publication and presentation reviews. Early and/or mission-comprehensive papers in asteroseismology may be required to have broader authorship reflecting general contributions of the Kepler Science Team in accordance with NASA policy.

Target selection

• Possible planet hosts

• Solar-like oscillations – asteroseismology

• „classical” variables

• variability surveys:– Clusters– Spectroscopy– Cross correlation with NSVS, etc.

Target selection

• Possible planet hosts

• Solar-like oscillations – asteroseismology

• „classical” variables

• variability surveys:– Clusters– Spectroscopy– Cross correlation with NSVS, etc.

Classical variables• Short cadence (1 min)

– 20 targets / 3.5 yr– 40 targets / 1 yr– 330 targets / 90 days

• Long cadence (30 min)– 15 targets / 3.5 yr– 45 targets / 1 yr– 30 targets / 180 days

• Beta Cep, SPB, Be stars• Delta Sct, gamma Dor• sdB (2)• WD• Cepheids (1), RR Lyrae• No WR star, no roAp• No red giants, M, SR in this panel

Data analysis- transit filtering

Raw data

High-pass filtered

Transit filtering

The phase information is not destroyed by the high-passfilter – we may therefore recover the original time series

Transit filtering

1. Raw data

2. High pass filtered

3. Recovered time series

Transit filtering

• Add false transits• High (band) pass filtering• Power spectrum with no phase information

– Extracted frquencies

Removing the planet transit signals – keeping the stellar oscillations

Power spectrum analysis

0,n0,1n0 )n(

1,n1,1n1 )n(

Large separation:

Small separation:

01,n0,1n0,n01,0 D221

)n(

02,n0,1n2,0 D6)n(

03,n1,1n3,1 D10)n(

0l,n Dl1l2/ln

Szeizmológiai „HR”-diagram

Stellar mass – core hydrogen content (age)

Large separation

1. Select a range of possible values Δν2. Cut selected parts of the spectrum into bins ofΔν/23. Sum the power of each bin4. Find the peak of the summed powerDetermine the large Separation

Data analysis pipeline

The Kepler Asteroseismic analysis pipeline

Data interpretation pipeline

Simulations show that we are able to reach a high precision in the determinations of stellar radii (relative accuracy below 2-3 per cent) and ages (better than 5-10 per cent of the total main sequence lifetime).

Data interpretation pipeline

Data interpretation pipeline

• Problémák:– Aktivitás hatása a

frekvenciákra– Felszíni folyamatok

jobb modellezése– Frekvenciafüggő offset

Oscillatory signals

HeII ionization

Houdek & Gough (2007; MNRAS375, 861)

He I

He II

BCZ

Hare & Hound excersiseasteroFLAG:“Sun-as-a-star” community:- solar Fitting at Low Angulardegree Group (solarFLAG)- CoRoT Data Analysis Team (DAT)

- Stellar community (e.g., ground-based observers)- Theoreticians (structure, dynamics,excitation and damping)- Data interpretation

W. J. Chaplin, T. Appourchaux, T. Arentoft,J. Ballot, F. Baudin, M. Bazot, T. R. Bedding,J. Christensen-Dalsgaard,D. O. Gough, A. Jiménez, S. J. Jiménez-Reyes,G. Houdek, B. H. Kjeldsen, J. W. Leibacher, M. J. P. F. G. C. Monteiro, R. New, R. Samadi,T. Sekii, S. G. Sousa, T. Toutain, S. Turck-

Chièze

Hare & Hound excersise

Sun 4 yrs 9 mag

Data analysis, target selection

KASOC pipelineKASC group

ICD

ICD

KASC workpackage

Work packages Interface Control Documents

• WP:– Tasks:– Input:– Deliverable Items and Due dates;– Assumption and Comments:– Detailed Description of Tasks and Deliverables:– Staff related to this WP

• ICD:description of required data (format, etc)descriprion of delivered data (what, how, format, etc)

KASOC timeline

KASOC timeline

•July-December 2007 KASC is set up, Work Packages (WP) will be defined and a first version of the KASOC pipeline will exist. • October 2007 First KASC workshop (October 29-31) • March 2008 KASOC Review #1: Data analysis review (internal) • June 2008 Second KASC workshop in Aarhus: Target Selection Procedure • The preliminary target selection will be based on the preliminary version of the KIC. • KASOC Steering Committee meeting • August 2008 Final Kepler Input Catalogue (KIC) received • September 2008 KASOC Steering Committee meeting: Target Selection • October 1, 2008 First set of asteroseismology targets transferred to Kepler Science Office • November 2008 KASOC Review #2: Final review (internal) • January 2009 Third KASC workshop: Data Analysis • KASOC Steering Committee meeting • February 2009 Kepler Launch

KASOC timeline

• February 2009 Kepler Launch • March 2009 Commissioning (Kepler in space) • April 2009 Flight Operations begins (science phase, phase E) • May 1, 2009 Second set of asteroseismology targets transferred to Kepler Science Office (uplink: July 2009). • Transfer of targets to Science Office for next three years: February 1, May 1, August 1 and November 1. • November 2009 First set of data is ready for KASC analysis through KASOC. • Data release during next three years will be: February, May, August and November • November 2009 KASOC Steering Committee meeting: Data release • March 2010 Fourth KASC workshop: First Results of the KAI KASOC Steering Committee meeting • March 2011 Fifth KASC workshop KASOC Steering Committee meeting • October 2012 End of Flight Operations, Phase E (extended mission?) • April 2014 End of Data Analysis, Phase E

Hasznos linkek

• http://kepler.nasa.gov

• http://astro.phys.au.dk/KASC

DocumentationLetter of direction

KAI draft data and publication policy

The Kepler Asteroseismic analysis pipeline

KASC WP template (Word)

KASC ICD template (Word)

Asteroseismology withthe Kepler mission

(CoAst, 150, 350-356, 2007).

The Kepler Asteroseismic Investigation

(Proc. HELAS II, Göttingen, August 2007;

J. Phys. Conf. Ser., in the press)