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W. D. Heacox (University of Hawaii at Hilo)
Statistical characteristics for recently discovered low-mass companions (``extrasolar planets") to solar-like stars, considered as a group, have been compared to those of stellar companions to solar-like stars in an unbiased survey. Nonparametric statistical models have been used to derive distributions of characteristics not individually observable in all systems, and to correct for observational selection of low-mass companions. The semi-major axis distributions of the two populations are of the same smooth, monotonically decreasing, scale-free form, strongly suggestive of dissipative orbital evolution by transfer of energy and angular momentum to dispersed material in young systems. The mass distribution of low-mass companions, corrected for observational selection due to limited radial velocity precision, is probably a power law with a relatively large negative index; this may be an extension of the stellar companion mass distribution if the latter's roll-over near 0.2 solar masses is an observational selection effect, as seems possible. There is no statistically significant evidence for the existence of two distinct populations (e.g., planets and brown dwarfs) of low-mass companions, and no statistically significant difference between the orbital characteristics of low-mass and stellar companions to solar-like primaries.