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J.H. Catanzarite, M. Shao, D. Ciardi (Caltech), SIM project science office Team, Michelson Science Center Team
The Space Interferometry Mission (SIM) will determine a global astronomical reference frame based on precise astrometric measurements on a grid comprised of 1302 stars distributed quasi-uniformly on the celestial sphere.
Candidates for the SIM grid will be chosen from two catalogs of K-giant stars: the University of Virginia GGSS catalog (S. Majewski, et. al. 18,617 stars) and the Tycho catalog sample (D. Ciardi 176,728 stars). 7,812 SIM grid candidates (six per eventual SIM grid star) will be selected from these catalogs. Radial velocities for these candidates will be determined during ground based surveys conducted by observing teams in three observatories from August 2004 to July 2008.
The RV surveys will effectively filter out candidates with short-period stellar companions. The SIM grid will be selected from the best 1302 candidates surviving the radial-velocity surveys.
In order to be stable reference points in the grid, SIM grid candidates should have minimal expected (unmodeled) astrometric jitter. Expected astrometric jitter involves complex inter-relationships among brightness, distance, J-Ks color, and [Fe/H] metallicity.
We present a rank-ordering metric that provides a quantitative measure of expected astrometric jitter for a star, and therefore of the fitness of the star for the SIM grid. Application of this metric to the Ciardi and Majewski K-giant catalogs will facilitate selection of the most suitable candidates for the SIM grid.
We acknowledge the significant contribution to this work from Ricky Patterson and Steve Majewski, who provided us with K-giant data tables based on their stellar evolution models.
This work was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.
If you would like more information about this abstract, please follow the link to sim.jpl.nasa.gov. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.
The author(s) of this abstract have provided an email address for comments about the abstract: jcat@s383.jpl.nasa.gov
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.