A Combined [ITAL]Hipparcos[/ITAL] and Multichannel Astrometric Photometer Study of the Proposed Planetary System of ρ Coronae Borealis

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Abstract
Hipparcos and Multichannel Astrometric Photometer (MAP) observations of ρ Coronae Borealis independently display astrometric motion at the period of the proposed "extrasolar planetary" companion to the star. Individual least-squares fits to each astrometric data set yield independent estimates of the semimajor axis, inclination, and node angle that are in excellent agreement. A combined solution of the Hipparcos and MAP data yields an inclination of 05, a node at 30.5 ± 12.4, and a semimajor axis of 1.66 ± 0.35 mas, indicating a companion mass of 0.14 ± 0.05 M☉, over 2 orders of magnitude greater than the minimum mass for the companion as determined by radial velocity studies. This mass is approximately that of an M dwarf star; the companion cannot be a planetary object.