Lessons Learned from an HST Faint Companion Search Program

A.B. Schultz, H.M. Hart, F.C. Hamilton, M. Kochte
Astronomy Programs, Computer Sciences Corporation,
Space Telescope Science Institute, Baltimore, MD

F.C. Bruhweiler
Catholic University, Washington, D.C.

G.F. Benedict
McDonald Observatory, University of Texas, Austin, TX

John Caldwell, C.C. Cunningham
York University, Ontario, Canada

O.G. Franz
Lowell Observatory, Flagstaff,

C.D. Keyes
Space Telescope Science Institute, Baltimore, MD

J.C. Brandt
LASP, University of Colorado, Boulder, CO

We have searched five nearby stars for faint companions using the Faint Object Spectrograph (FOS) on HST as a coronagraph. Each target star was positioned behind the bar (width 0.27 arcsec) of the FOS large barred aperture. This was followed by a long exposure ACQIMAGE, revealing detail in the open regions of the aperture (1.7 arcsec square). Two targets, Wolf 424AB and GJ 1245AC, have known companions and were imaged as calibration targets. For these two stars, the close companions were resolved. Although no bright companions were discovered about the other three target stars, the data do not allow us to exclude definitely the possibilities that a companion could have been behind the bar or be found outside the aperture search area, or be too faint to detect with the FOS. Our search strategy offers insights for future searches for brown dwarfs and possibly giant extra-solar planets about the nearby stars.