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H. A. Abt (KPNO)
We determined the luminosity function for the secondaries of solar-type stars, based on observations of the 170 F7-G8 IV or V stars with Hipparcos parallax distances within 25 pc and declinations of -30 to +75 deg. Like the Van Rhijn function, it shows an increase in numbers of secondaries down to 0.4 solar masses and then a decline to the 10 extrasolar planets in this sample. It is shown that the eccentricities and orbital periods of the extrasolar planets found to date fit those in this sample and not those of the solar system. We conclude that the extrasolar planets found to date were formed in approximately spherical multiple star systems, not in disk systems like the solar system.
We appreciate funding from the Research Corp.
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Bulletin of the American Astronomical Society, 36 5
© 2004. The American Astronomical Society.