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High Resolution Spectra of L Type Stars and Brown Dwarfs

from II - Spectroscopic Properties, Fundamental Parameters and Modelling

Published online by Cambridge University Press:  04 August 2010

G. Basri
Affiliation:
Astronomy Dept., Univ. of California, Berkeley, CA 94720, USA
F. Allard
Affiliation:
Centre de Recherche Astronomique de Lyon (UMR 142 CNRS), Ecole Normale Superieure, 69364 Lyon Cedex 07, France
P. Hauschildt
Affiliation:
Dept. of Physics and Astronomy & Center for Simulational Physics, University of Georgia, Athens, GA 30602-2451, USA
S. Mohanty
Affiliation:
Astronomy Dept., Univ. of California, Berkeley, CA 94720, USA
Rafael Rebolo
Affiliation:
Instituto de Astrofísica de Canarias, Tenerife
Maria Rosa Zapatero-Osorio
Affiliation:
Instituto de Astrofísica de Canarias, Tenerife
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Summary

The first brown dwarfs were confirmed only three years ago. Already, however, a library of echelle spectra of objects of a variety of temperatures has been accumulated. This process has been greatly aided by the discovery of relatively nearby free-floating brown dwarfs and companions to M dwarfs. Their spectra show the rapidly increasing importance of dust formation in the atmosphere, and its concomitant decrease of the TiO molecular features which define the M spectral class. This has lead to the proposal of a new spectral class, L, for cooler objects. The primary atomic features visible in red spectra of L and late M stars are resonance lines of alkali metals (Na, K, Rb, Cs, and sometimes Li). Here we present a sample of line profiles from mid-M to mid-L objects, which include both very low mass stars and confirmed brown dwarfs. We compare the line profiles in the alkali lines to very recent models which include effects of dust formation. We show that the models can already make a reasonable representation of the observations, and begin to set a temperature scale for these new very cool objects. There are certainly issues remaining to be addressed, however.

Introduction

Since the announcement of the first brown dwarfs in 1995, the field has been moving very quickly. The number of known brown dwarfs has increased rapidly, along with a growing collection of stars at the bottom of the main sequence.

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Publisher: Cambridge University Press
Print publication year: 2000

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  • High Resolution Spectra of L Type Stars and Brown Dwarfs
    • By G. Basri, Astronomy Dept., Univ. of California, Berkeley, CA 94720, USA, F. Allard, Centre de Recherche Astronomique de Lyon (UMR 142 CNRS), Ecole Normale Superieure, 69364 Lyon Cedex 07, France, P. Hauschildt, Dept. of Physics and Astronomy & Center for Simulational Physics, University of Georgia, Athens, GA 30602-2451, USA, S. Mohanty, Astronomy Dept., Univ. of California, Berkeley, CA 94720, USA
  • Edited by Rafael Rebolo, Instituto de Astrofísica de Canarias, Tenerife, Maria Rosa Zapatero-Osorio, Instituto de Astrofísica de Canarias, Tenerife
  • Book: Very Low-Mass Stars and Brown Dwarfs
  • Online publication: 04 August 2010
  • Chapter DOI: https://doi.org/10.1017/CBO9780511564758.014
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  • High Resolution Spectra of L Type Stars and Brown Dwarfs
    • By G. Basri, Astronomy Dept., Univ. of California, Berkeley, CA 94720, USA, F. Allard, Centre de Recherche Astronomique de Lyon (UMR 142 CNRS), Ecole Normale Superieure, 69364 Lyon Cedex 07, France, P. Hauschildt, Dept. of Physics and Astronomy & Center for Simulational Physics, University of Georgia, Athens, GA 30602-2451, USA, S. Mohanty, Astronomy Dept., Univ. of California, Berkeley, CA 94720, USA
  • Edited by Rafael Rebolo, Instituto de Astrofísica de Canarias, Tenerife, Maria Rosa Zapatero-Osorio, Instituto de Astrofísica de Canarias, Tenerife
  • Book: Very Low-Mass Stars and Brown Dwarfs
  • Online publication: 04 August 2010
  • Chapter DOI: https://doi.org/10.1017/CBO9780511564758.014
Available formats
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Save book to Google Drive

To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.

  • High Resolution Spectra of L Type Stars and Brown Dwarfs
    • By G. Basri, Astronomy Dept., Univ. of California, Berkeley, CA 94720, USA, F. Allard, Centre de Recherche Astronomique de Lyon (UMR 142 CNRS), Ecole Normale Superieure, 69364 Lyon Cedex 07, France, P. Hauschildt, Dept. of Physics and Astronomy & Center for Simulational Physics, University of Georgia, Athens, GA 30602-2451, USA, S. Mohanty, Astronomy Dept., Univ. of California, Berkeley, CA 94720, USA
  • Edited by Rafael Rebolo, Instituto de Astrofísica de Canarias, Tenerife, Maria Rosa Zapatero-Osorio, Instituto de Astrofísica de Canarias, Tenerife
  • Book: Very Low-Mass Stars and Brown Dwarfs
  • Online publication: 04 August 2010
  • Chapter DOI: https://doi.org/10.1017/CBO9780511564758.014
Available formats
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