Testing Hipparcos K giants as grid stars for SIM

Sabine Frink, Andreas Quirrenbach, Siegfried Röser, Elena Schilbach

in: Working on the Fringe, ASP Conference Series,
eds. S.C. Unwin & R.V. Stachnik, Vol.194, p.128-133, 1999


We investigate some astrometric properties of Hipparcos K giants with the aim to explore their suitability as SIM (Space Interferometry Mission) grid stars. After discriminating the K giants from K dwarfs using photometry and parallaxes provided by the Hipparcos Catalogue, we eliminate unwanted variable and double stars from the sample by applying a number of different criteria. These include the various flags given in the Hipparcos Catalogue indicating either photometric variability or problems with the astrometric solution as well as a consistency check between the proper motion given in the Hipparcos Catalogue on one hand and the ACT and TRC proper motion catalogs on the other hand. We end up with a sample of about 12 000 K giants as candidate grid stars, which could serve as a starting point for further investigations aimed at finding the best subsample to represent the SIM astrometric grid.
[ps-file (645 kb)] [gzipped ps-file (61 kb)]