Extrasolar Planets and the Dry Brown Dwarf Desert

 

Charles H. Lineweaver 1 , Daniel Grether 2

1 Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia
2 Department of Astrophysics, University of New South Wales, Sydney, NSW, Australia

 

Sun-like stars have stellar, brown dwarf and planetary companions. Relatively few brown dwarfs (compared to the number of planets and stellar companions) have been found in close orbits around sun-like stars. Why this should be so is unknown. With PhD student Grether, Lineweaver compiled, analysed and interpreted the world's data on exoplanet, brown dwarf and stellar companions. Our analysis i) confirmed that the brown dwarf desert was not a selection effect and ii) located the position of the driest part of the brown dwarf desert (the mass at which the fewest number of companions exist) at M = 31 +25 -18 M_Jupiter. We found that approximately 16% of Sun-like stars have close companions more massive than Jupiter: 11% +/- 3% are stellar, <1% are brown dwarf and 5% +/- 2% are giant planets. Our results are published in the paper,

References: Grether, D., Lineweaver, C.H. (2006) How Dry is the Brown Dwarf Desert?: Quantifying the Relative Number of Planets, Brown Dwarfs and Stellar Companions around Nearby Sun-like Stars, Astrophysical Journal 640, 1051, astro-ph/0412356.