Volume 589, May 2016
|Number of page(s)||6|
|Section||Atomic, molecular, and nuclear data|
|Published online||07 April 2016|
K–H2 line shapes for the spectra of cool brown dwarfs⋆
GEPI, Observatoire de Paris, UMR 8111, CNRS, Université Paris VII, 61
avenue de l’Observatoire,
2 Institut d’Astrophysique de Paris, UMR 7095, CNRS, Université Paris VI, 75014 Paris, France
3 Laboratoire de Chimie et Physique Quantique, UMR 5626, CNRS, Université Paul Sabatier, 118 route de Narbonne, 31400 Toulouse, France
4 Department of Physics and Astronomy, University of Louisville, Louisville, Kentucky 40292, USA
Received: 8 February 2016
Accepted: 24 February 2016
Observations of cooler and cooler brown dwarfs show that the contribution from broadening at many bars pressure is becoming important. The opacity in the red optical to near-IR region under these conditions is dominated by the extremely pressure-broadened wings of the alkali resonance lines, in particular, the K I resonance doublet at 0.77 μm. Collisions with H2 are preponderant in brown dwarf atmospheres at an effective temperature of about 1000 K; the H2 perturber densities reach several 1019 even in Jupiter-mass planets and exceed 1020 for super-Jupiters and older Y dwarfs. As a consequence, it appears that when the far wing absorption due to alkali atoms in a dense H2 atmosphere is significant, accurate pressure broadened profiles that are valid at high densities of H2 should be incorporated into spectral models.
Key words: line: profiles / brown dwarfs
The opacity tables are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (188.8.131.52) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/589/A21
© ESO, 2016
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