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