The Mass Dependence of Planet Formation: A Search for Extrasolar Planets Around A-F-type Stars

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This project will start the first extensive search for extrasolar planets around A-F type main sequence stars using precise stellar radial velocities (RV). These stars have largely been ignored by all current survey. As a result we only have knowledge about extrasolar planets around stars covering the narrow spectral (and thus mass) range of stars F8-K1. Consequently, we have little understanding of how planet formation varies with the most fundamental parameter of a star - its mass. Several programs are searching for planets around late type M-dwarfs, but no systematic search has been made for planets around early- type stars. By finding planets around the more massive earlier type stars we can probe how the process of planet formation depends on the mass of the host star which is of fundamental importantance for planet formation theories. This program will search for extrasolar planets around a special class of A stars, the chemically peculiar Ap stars. These objects are more suitable for RV searches over normal A-stars because they rotate less rapidly and they have peculiar abundances which translates into a high density of spectral absorption lines. Preliminary measurements indicate that a radial velocity precision of about 7 m/s is possible for these stars. Such measurements will be able to detect extrasolar giant planets in orbit around these stars. We propose to search for extrasolar planets around a significantly large sample (at least 100 stars) of A-type stars and thus probe the dependence of planet formation on stellar mass.