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D. A. Golimowski (JHU), T. J. Henry (Harvard-Smithsonian CfA), J. E. Krist, C. J. Burrows (STScI), H. C. Ford (JHU), D. W. McCarthy (U. Arizona), D. J. Schroeder (Beloit College)
We continue a near-IR search for very-low-mass (VLM) companions to stars within 10~pc of the Sun, via a SNAP survey using NICMOS Camera~2. With a 10~\sigma detection limit of MJ ~22 at 10~pc, we can detect companions at separations of 0\farcs5 to 10\arcsec that are at least 11~mag fainter than the empirical end of the main sequence and at least 6.5~mag fainter than brown dwarf Gl~229B. By directly imaging in four bandpasses (F110W, F180M, F207M, F222M), we may readily distinguish VLM stars and cool brown dwarfs from white dwarfs and more distant main-sequence stars, thereby identifying companion candidates for follow-up observation.
By the end of NICMOS's useful lifetime in November, about 45 Completion of the entire 10 pc survey will depend on the successful refurbishment of NICMOS in 2000 and the renewal of HST observing time. If completed, this survey will be the largest, most sensitive, volume-limited search for VLM companions ever undertaken. Together with existing IR speckle and wide-field surveys, our program will firmly establish the luminosity function and multiplicity fraction for stars within 10~pc.
We present here the first scientific results of our survey.