A possible dividing line between massive planets and brown-dwarf companions

TL;DR

This study investigates the mass distribution of brown-dwarf companions to Sun-like stars, suggesting a potential dividing line between massive planets and brown dwarfs based on combined spectroscopic and astrometric data.

Contribution

It introduces a method combining radial-velocity and astrometric measurements to identify a mass gap between 25 and 45 Jupiter masses, indicating a possible boundary between planets and brown dwarfs.

Findings

Identified a mass gap between 25 and 45 Jupiter masses.

Discovered new brown-dwarf companions using CORALIE and Hipparcos data.

Suggested a dividing line between planets and brown dwarfs.

Abstract

Brown dwarfs are intermediate objects between planets and stars. The lower end of the brown-dwarf mass range overlaps with the one of massive planets and therefore the distinction between planets and brown-dwarf companions may require to trace the individual formation process. We present results on new potential brown-dwarf companions of Sun-like stars, which were discovered using CORALIE radial-velocity measurements. By combining the spectroscopic orbits and Hipparcos astrometric measurements, we have determined the orbit inclinations and therefore the companion masses for many of these systems. This has revealed a mass range between 25 and 45 Jupiter masses almost void of objects, suggesting a possible dividing line between massive planets and sub-stellar companions.