AAS 199th meeting, Washington, DC, January 2002
Session 129. Astrometric Surveys
Display, Thursday, January 10, 2002, 9:20am-4:00pm, Exhibit Hall

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[129.07] An Astrometric Survey of Companions to Nearby Stars

I.J. Kaplan, D.W. Koerner (University of Pennsylvania), T.J. Henry (Georgia State University)

Existing parallax surveys routinely measure changes in apparent stellar positions to within 2 mas by means of CCD imaging against background stars. A dedicated survey using similar techniques could thus expect to detect perturbations due to the gravitational influence of a companion in a regime of importance to our understanding of the substellar companion mass function. This technique could uncover Jupiter-mass (MJ) companions orbiting at 5 AU from late M Dwarfs 8 pc away, or 13-MJ companions (deuterium-burning mass limit) 5 AU from late K dwarfs at a distance of 20 pc. In contrast, previous companion searches with photographic plates did not reliably detect reflex motions of less than 30 mas and produced no conclusive evidence for a single substellar companion. Technological advances in ground-based interferometry promise order-of-magnitude improvements but are not well-suited to large-scale surveys of relatively faint stars. Space-based surveys will do better, but are limited to mission lifetimes that preclude measurement of companions with orbital periods greater than a few years. A survey with small telescopes in each hemisphere can economically probe the substellar companion population in a statistically significant sample for a time period that is not accessible to currently planned space missions. We explore the limits of such a search by calculating detection efficiencies for a variety of observing strategies.

The author(s) of this abstract have provided an email address for comments about the abstract: ijk@brahe.physics.upenn.edu

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