Spectral Types of M Dwarf Stars
Abstract
Spectral types on a uniform system based on primarily TiO band strengths are given for 426 M dwarf stars. It is found that the frequency of emission-line stars increases steadily from 5 percent among the early M's through 50 percent at M4.5 to 100 percent for M5.5 and later. The absolute magnitudes of emission-line (dMe) and normal (dM) dwarfs average the same within 0.07 mag at a given spectral type. A new calibration of absolute magnitudes, based on trigonometric parallaxes, is given. The measured width of the main-sequence band can be accounted for mostly in terms of the errors in classification, parallaxes, and photometry and to some duplicity; the cosmic dispersion is less than 0.3 mag. The R - 1 colors of dMe stars are larger by 0.08 1 0.02(p.e.) mag than for dM stars, although the B - V colors do not show this effect. Subject headings: late-type stars - luminosities - spectral classification
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- November 1974
- DOI:
- 10.1086/190307
- Bibcode:
- 1974ApJS...28....1J