A Mass Function Constraint on Extrasolar Giant Planet Evaporation Rates
Abstract
The observed mass function for all known extrasolar giant planets (EGPs) varies approximately as M-1 for mass M between ~0.2 Jupiter masses (MJ) and ~5 MJ. In order to study evaporation effects for highly irradiated EGPs in this mass range, we have constructed an observational mass function for a subset of EGPs in the same mass range but with orbital radii <0.07 AU. Surprisingly, the mass function for such highly irradiated EGPs agrees quantitatively with the M-1 law, implying that the mass function for EGPs is preserved despite migration to small orbital radii. Unless there is a remarkable compensation of mass-dependent orbital migration for mass-dependent evaporation, this result places a constraint on orbital migration models and rules out the most extreme mass-loss rates in the literature. A theory that predicts more moderate mass loss gives a mass function that is closer to observed statistics but still disagrees for M<1 MJ.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2007
- DOI:
- 10.1086/513422
- arXiv:
- arXiv:astro-ph/0702276
- Bibcode:
- 2007ApJ...658L..59H
- Keywords:
-
- Molecular Processes;
- Stars: Planetary Systems;
- Astrophysics
- E-Print:
- accepted by Astrophys. J. Letters on 1 February 2007