The Nature of the Exoplanets
Abstract
We wonder whether the exoplanets discovered to date were formed in disk systems, like the Solar System, or like stellar and brown-dwarf companions to stars. We show for large samples that the stellar companions, brown-dwarf companions, and exoplanets have large eccentricities (greater than 0.1 in half of the cases) but in only one of the eight planets in the Solar System. Also the stellar, brown-dwarf, and exoplanets usually are close to the primaries, unlike in the Solar System. These suggest that the exoplanets discovered to date were formed like stellar and brown dwarf companions, probably by captures in three-body encounters, and not in disk systems. This is confirmed in that binaries among metal-poor stars have a peak period of 900 days, unlike the 20 days for metal-rich stars, so that explains why few of the exoplanets discovered in the past few years occur around metal-poor stars.
- Publication:
-
International Workshop on Double and Multiple Stars: Dynamics, Physics, and Instrumentation
- Pub Date:
- July 2011
- DOI:
- 10.1063/1.3597582
- Bibcode:
- 2011AIPC.1346...14A
- Keywords:
-
- galaxies;
- brown dwarfs;
- stellar dynamics;
- stellar mass;
- spectroscopy;
- 98.52.Nr;
- 97.20.Vs;
- 97.82.Fs;
- 97.10.Nf;
- 95.75.Fg;
- Spiral galaxies;
- Low luminosity stars subdwarfs and brown dwarfs;
- Substellar companions;
- planets;
- Masses;
- Spectroscopy and spectrophotometry