Monday, September 04, 2006

D. Koch: The Kepler Mission and Binary Stars (S 240 invited talk, Wed, Aug. 23)

The talk started with a detailed description of the Kepler mission concept. It is a photometric mission which will look for habitable planets (0.5 to 10 Earth masses). The instrument is a 1m Schmidt telescope with a very large field of view (FOV; a 42 CCD array larger than 100 square degrees - one would need six Palomar sky survey plates to cover the FOV). Kepler will observe in the Cygnus-Lyra region along the Orion arm of our Galaxy. It will achieve a differential photometric precision of 6.6 ppm for a 6.5 hour integration. A single FOV will be continuously observed for 4-6 years (except for less than 1 day every month). Simultaneous observations of more than 103000 main-sequence stars will be obtained (3000 "guest objects" can be proposed). The time resolution is 30 minutes for most stars, and one minute for a subset of 512 objects. Kepler will observe a single bandpass from 430 to 890 nm, where the cutoffs are set to avoid CaII H&K and fringing. The PSF FWHM will be about six arcsec.

The detection capability was also discussed - it depends on many different parameters.

The selected targets are late dwarf stars (F,G,K,M). A "Stellar Classification Program" is gathering new multi-band photometric data (SDSS griz filters + filter for Mg b lines). The "Kepler Project" is producing a catalog of stars in the target field.

Data processing will partly be performed on board (only pixels of interest are extracted). Ground processing will consist of cosmic ray, bias, smear and common-mode noise removal and the analysis of fluxes for threshold events. All light curves will be archived at STScI.

Other results from the data include results relevant to binary stars - follow-up radial velocity observations to get masses and to differentiate between planetary transits and grazing eclipsing binaries. 1000 to 1500 eclipsing binaries with high precision light curves are expected. Non-eclipsing binaries will be identified using astrometry (distance), effective temperature and luminosity. The data will also be useful for other astrophysical purposes (oscillations, etc.).

Community participation and access will be possible through the guest observer program. Scientists may propose to observe targets in the FOV not being observed as part of Kepler planet search. The objects can be brighter or fainter than the nominal dynamic range. The observation duration can be three months or longer.

The launch of Kepler is scheduled for October 2008.

More information is available on the Kepler website.


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