Moderate-resolution spitzer infrared spectrograph observations of M, L, and T dwarfs

A. K. Mainzer, Thomas L. Roellig, D. Saumon, Mark S. Marley, Michael C. Cushing, G. C. Sloan, J. Davy Kirkpatrick, S. K. Leggett, John C. Wilson

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


We present 10-19 μn moderate-resolution spectra of 10 M dwarfs, one L dwarf, and two T dwarf systems obtained with the Infrared Spectrograph (IRS) on board the Spitzer Space Telescope. The IRS allows us to examine molecular spectroscopic features/lines at moderate spectral resolution in a heretofore untapped wavelength regime. These R = λ/△λ ∼ 600 spectra allow for a more detailed examination of clouds and nonequilibrium chemistry, as well as the molecular features of H2O, NH3, and other trace molecular species that are the hallmarks of these objects. A cloud-free model best fits our mid-infrared spectrum of the T1 dwarf ε Indi Ba, and we find that the NH3 feature in e Indi Bb is best explained by a nonequilibrium abundance due to vertical transport in its atmosphere. We examined a set of objects (mostly M dwarfs) in multiple systems to look for evidence of emission features, which might indicate an atmospheric temperature inversion, as well as trace molecular species; however, we found no evidence of either.

Original languageEnglish (US)
Pages (from-to)1245-1253
Number of pages9
JournalAstrophysical Journal
Issue number2 I
StatePublished - Jun 20 2007
Externally publishedYes


  • Infrared: stars
  • Stars: late-type
  • Stars: low-mass, brown dwarfs

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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