The mass distribution of extrasolar planet candidates and low-mass secondaries

This paper considers the mass distribution of the known nine unseen companions with planetary masses orbiting solar-type stars. The paper compares the mass distribution of these nine extrasolar planet candidates with the distribution of low-mass secondaries in spectroscopic binaries. Although we still have only a very small number of systems, the combined distribution suggests two distinctive populations. The transition region between the two populations might be at the range of 10-30 Jupiter masses. This transition might reflect the borderline between planets and brown dwarf secondaries. (C) 1999 Elsevier Science B.V. All rights reserved.