A Definition for Giant Planets Based on the Mass-Density Relationship
Abstract
We present the mass-density relationship (log M - log ρ) for objects with masses ranging from planets (M ≈ 0.01 MJup) to stars (M > 0.08 M⊙). This relationship shows three distinct regions separated by a change in slope in the log M - log ρ plane. In particular, objects with masses in the range 0.3 MJup-60 MJup follow a tight linear relationship with no distinguishing feature to separate the low-mass end (giant planets) from the high-mass end (brown dwarfs). We propose a new definition of giant planets simply based on changes in the slope of the log M versus log ρ relationship. By this criterion, objects with masses less than ≈0.3 MJup are low-mass planets, either icy or rocky. Giant planets cover the mass range 0.3 MJup-60 MJup. Analogous to the stellar main sequence, objects on the upper end of the giant planet sequence (brown dwarfs) can simply be referred to as “high-mass giant planets,” while planets with masses near that of Jupiter can be called “low-mass giant planets.”
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2015
- DOI:
- arXiv:
- arXiv:1506.05097
- Bibcode:
- 2015ApJ...810L..25H
- Keywords:
-
- brown dwarfs;
- planets and satellites: fundamental parameters;
- stars: low-mass;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 11 pages, 2 figures, submitted to ApJ Letters
