Model atmospheres of very low mass stars and brown dwarfs

France Allard, Peter H. Hauschildt, David R. Alexander, Sumner Starrfield

Research output: Contribution to journalArticlepeer-review

290 Scopus citations


As progressively cooler stellar and substellar objects are discovered, the presence first of molecules and then of condensed particulates greatly complicates the understanding of their physical properties. Accurate model atmospheres that include these processes are the key to establishing their atmospheric parameters. They play a crucial role in determining structural characteristics by setting the surface conditions of model interiors and providing transformations to the various observational planes. They can reveal the spectroscopic properties of brown dwarfs and help establish their detectability. In this paper, we review the current state-of-the-art theory and modeling of the atmospheres of very low mass stars, including the coolest known M dwarfs, M subdwarfs, and brown dwarfs, i.e. Teff ≤ 4,000 K and -4.0 ≤ [M/H] ≤ +0.0. We discuss ongoing efforts to incorporate molecular and grain opacities in cool stellar spectra, as well as the latest progress in (a) deriving the effective temperature scale of M dwarfs, (b) reproducing the lower main sequences of metal-poor subdwarfs in the halo and globular clusters, and (c) results of the models related to the search for brown dwarfs.

Original languageEnglish (US)
Pages (from-to)137-177
Number of pages41
JournalAnnual Review of Astronomy and Astrophysics
Issue number1
StatePublished - 1997


  • Brown dwarfs
  • Low mass stars
  • Stellar atmospheres
  • Stellar fundamental parameters

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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