AAS 201st Meeting, January, 2003
Session 115. Cool Star Atmospheres and Envelopes
Poster, Thursday, January 9, 2003, 9:20am-4:00pm, Exhibit Hall AB

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[115.05] Preliminary results on photometric and spectroscopic followup of Space Interferometry Mission Grid Giant Star Candidates

J. Arenas (CTIO), D. Geisler (Univ. de Concepcion), S. Majewski (UVa), V. Smith, D. Bisyaev (UTEP), N. Suntzeff, J. Seguel (CTIO)

We have been awarded a NASA grant to obtain followup photometry and spectroscopy of the Grid Giant Star Survey (GGSS) candidates we are establishing in our Space Interferometry Mission (SIM) Preparatory Science program. The GGSS will yield ~4000 metal-poor G-K giants as SIM Astrometric Grid candidates, based on single-epoch photometry and low resolution spectroscopy. Multi-epoch photometric followup observations of these candidates are essential for verifying their photometric stability and thus guaranteeing their utility as SIM Grid stars. These data are not only critical for the SIM project but will also allow us to improve our very limited knowledge of binary and planetary frequency in metal-poor giants. Because the kinematic properties of these stars will eventually be determined to unprecedented accuracy, a detailed understanding of their characteristics will not only be important for the SIM project, but also crucial for future studies of the GGSS database. The survey has already turned up hundreds of halo giants which appear very metal-poor, as well as a number of objects with very anomalous spectral characteristics. Our goal is to obtain high resolution spectra of both classes of these fascinating objects in order to determine their detailed abundances and astrophysical properties. This will allow us to explore chemical evolution in the Galactic halo during its earliest epoch of formation, and to determine the properties of very unusual stars. In addition, our data will be used to supplement radial velocity data. This combined dataset will also allow us to search for planets and binaries among metal-poor giants. In this Meeting, we show both preliminary photometric and spectroscopic results of the GGSS.

We acknowledge funding of this research from NASA/JPL through grant number NRA-99-04-OSS-058.

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