Early-type Stars: Most Favorable Targets for Astrometrically Detectable Planets in the Habitable Zone

Abstract

Early-type stars appear to be a difficult place to look for planets astrometrically. First, they are relatively heavy, and for fixed planetary mass the astrometric signal falls inversely as the stellar mass. Second, they are relatively rare (and so tend to be more distant), and for fixed orbital separation the astrometric signal falls inversely as the distance. Nevertheless, because early-type stars are relatively more luminous, their habitable zones are at larger semi-major axis. Since astrometric signal scales directly as orbital size, this gives early-type stars a strong advantage, which more than compensates for the other two factors. Using the Hipparcos catalog, we show that early-type stars constitute the majority of viable targets for astrometric searches for planets in the habitable zone. We contrast this characteristic to transit searches, which are primarily sensitive to habitable planets around late-type stars.

Submitted to ApJ Letters, 8 pages including 2 figures

References in corpus (4)

• Target Selection for SETI: 1. A Catalog of Nearby Habitable Stellar Systems
• On the Double Planet System Around HD 83443
• Planet finding prospects for the Space Interferometry Mission
• Sensitivity of Transit Searches to Habitable Planets

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