M-Subdwarfs: Spectroscopic Classification and the Metallicity Scale

1996/11/26 by John E. Gizis · 7 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #History and Developments in Astronomy #Stellar, planetary, and galactic studies #astro-ph

paper · pdf · doi:10.1086/118302

published as Astron.J.113:806-822,1997 · AASTeX, 43 pages, 11 figures, A.J. accepted

arxiv created 1996/11/26 · openalex publication_date 1997/02/01 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

We present a spectroscopic classification system for M-dwarfs and M-subdwarfs based on quantitative measures of TiO and CaH features in the region lambda lambda 6200 - 7400 Angstroms. Our sample of cool stars covers the range from solar metallicity stars to the most extreme subdwarfs known. Using synthetic spectra computed by Allard and Hauschildt (1995), we derive metallicities for the stars. Stars are classified as dwarfs (M V), subdwarfs (sdM), or extreme subdwarfs (esdM). These classifications correspond to [m/H] ~ 0.0, -1.2, and -2.0 respectively. Our metallicity scale agrees with theoretical HR diagrams and HST globular cluster measurements. We discuss some nearby subdwarfs of particular interest in light of our metallicity scale.

Cited by

• A Cross‐Match of 2MASS and SDSS: Newly Found L and T Dwarfs and an Estimate of the Space Density of T Dwarfs
• Stellar Activity Manifesting at a One-year Alias Explains Barnard b as a False Positive
• A cannonball star candidate in Canis Minor
• K2-111 b − a short period super-Earth transiting a metal poor, evolved old star
• Abundance Measurements of the Metal-poor M subdwarf LHS 174 Using High-resolution Optical Spectroscopy
• The LHS 1678 System: Two Earth-sized Transiting Planets and an Astrometric Companion Orbiting an M Dwarf Near the Convective Boundary at 20 pc
• Barnard's Star [wikipedia]