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Session 67 - Stars: Evolution, Atmospheres, Intrinsic.
Display session, Thursday, June 11
Atlas Ballroom,
The Space Telescope Imaging Spectrograph (STIS), placed aboard the Hubble Space Telescope (HST) in February 1997, provides a unique opportunity to search for very low mass stars, including brown dwarfs, out to a great distance from the Sun. When STIS is operated in parallel with other cameras on board HST, it takes deep images and slitless spectra of a field a few arcminutes from the primary target. In a 2000 second exposure, good S/N can be achieved for stars as faint as m_V=28 in the imaging mode and m_V=22 in the spectral mode. The spectra have a wavelength range 5200 to 10300Åand a resolution of \sim5Å\ per pixel, well suited for identification of low mass stars using their molecular absorption features, and do not suffer from telluric absorption.
Preliminary investigation and analysis of STIS parallels have yielded many low mass star candidates. Approximately 100 low and 500 high galactic latitude fields have been taken since the start of the STIS parallel survey; it is expected that one extreme low mass star candidate will be found in every five low latitude fields, and one in every 100 high latitude fields. If this is borne out, STIS will provide a great deal of information about the extreme low mass end of the luminosity function and the distribution of such stars in the local galactic disk and halo.
