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G. Schneider (Univ. of Az.), E.E. Becklin (UCLA), B.A. Smith (Univ. of Hawaii), R.J. Terrile (JPL), P.J. Lowrance, A.J. Weinberger (UCLA), C. Dumas (JPL), D.W. Koerner (Univ. of Penn.), D. C. Hines (Univ. of Az.), R. Meier (Univ. Hawaii), D. Kirkpatrick (IPAC), R.I. Thompson, M.J. Rieke, F.J. Low (Univ. of Az.)
The NICMOS Instrument Definition Team is conducting a systematic coronagraphic survey of nearby low-mass and young stars searching for very low-mass (VLM) and substellar companions, and circumstellar dust disks primarily around main-sequence stars. The NICMOS camera 2 coronagraph is particularly well-suited to this task. Depending upon the nature of the candidate, we employ the F160W (1.4-1.8 micron) and/or F110W (0.8-1.4 micron) filters, as appropriate. We were able to achieve statistically significant detections of unresolved objects with a \DeltaH\approx10 at separations as close 0.5", or \DeltaH\approx13 at 1", and significantly better stray-light rejection at 1.1 microns for imaging close-in circumstellar disk material. For the observed targets in our sample this corresponds to physical separations in the range of 1.5 to 200 AU at the inner spatial detection limit). The lower mass detection limit for substellar companions depends on their age, distance, and angular separation from their primaries, but can extend below 10 Jupiter masses for a significant number of our candidates.
The observational "detection" phase of this program was completed in mid-November, 1998. We now report on the overall status and statistics of the VLM, brown dwarf, giant planet, and dust disk search programs. We discuss the results of these searches for a sub-set of our candidates including the discovery of at least one companion brown dwarf and the first NIR imaging of several circumstellar dust disks. The implications for imaging high-mass planets around the younger stars in our sample are also discussed. This work is supported by NASA grant NAG 5-3042. This paper is based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS5-26555.