M Dwarf Luminosity, Radius, and α-enrichment from I-band Spectral Features
Abstract
Despite the ubiquity of M dwarfs and their growing importance to studies of exoplanets, Galactic evolution, and stellar structure, methods for precisely measuring their fundamental stellar properties remain elusive. Existing techniques for measuring M dwarf luminosity, mass, radius, or composition are calibrated over a limited range of stellar parameters or require expensive observations. We find a strong correlation between the KS-band luminosity (MK), the observed strength of the I-band sodium doublet absorption feature, and [Fe/H] in M dwarfs without strong Hα emission. We show that the strength of this feature, coupled with [Fe/H] and spectral type, can be used to derive M dwarf MK and radius without requiring parallax. Additionally, we find promising evidence that the strengths of the I-band sodium doublet and the nearby I-band calcium triplet may jointly indicate α-element enrichment. The use of these I-band features requires only moderate-resolution near-infrared spectroscopy to provide valuable information about the potential habitability of exoplanets around M dwarfs, and surface gravity and distance for M dwarfs throughout the Galaxy. This technique has immediate applicability for both target selection and candidate planet-host system characterization for exoplanet missions such as TESS and K2.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 2015
- DOI:
- 10.1088/2041-8205/802/1/L10
- arXiv:
- arXiv:1503.01776
- Bibcode:
- 2015ApJ...802L..10T
- Keywords:
-
- planets and satellites: fundamental parameters;
- stars: abundances;
- stars: activity;
- stars: fundamental parameters;
- stars: low-mass;
- techniques: spectroscopic;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- Accepted to ApJ Letters