LiHe spectra from brown dwarfs to helium clusters

Nicole F. Allard (1) , Akira Nakayama (2) , Frank Stienkemeier (3) , John F. Kielkopf (4) , Grégoire Guillon (5) , Alexandra Viel (5)

1 GEPI - Galaxies, Etoiles, Physique, Instrumentation
2 Division of Chemistry, Graduate School of Science
3 Physikalisches Institut [Freiburg]
4 Department of Physics and Astronomy [Louisville]
5 IPR - Institut de Physique de Rennes

The detection of Li I lines is the most decisive spectral indicator of substellarity for young brown dwarfs with masses below about 0.06 solar mass. Due to the weakness of the Li resonance lines, it is important to be able to model precisely both their core widths and their wing profiles. This allows an adequate prediction of the mass at which Li lines reappear in the spectra of brown dwarfs for a given age, or reversely an accurate determination of the age of a cluster. We report improved line profiles and the dependence of line width on temperature suitable for modeling substellar atmospheres that were determined from new LiHe molecular potential energies. Over a limited range of density and temperature, comparison with laboratory measurements was used to validate the potential energies which support the spectral line profile theory.

Mots clés: Helium clusters; Line: profiles; Stars: atmospheres-brown dwarfs; Atomic and molecular clusters; Spectroscopy

Domaines: Physique de l'espace [physics.space-ph]; Chimie théorique et/ou physique; Astrophysique [astro-ph]

Nicole F. Allard, Akira Nakayama, Frank Stienkemeier, John F. Kielkopf, Grégoire Guillon, et al.. LiHe spectra from brown dwarfs to helium clusters. Advances in Space Research, 2014, 54, pp.1290-1296. ⟨10.1016/j.asr.2013.08.032⟩. ⟨hal-00876511⟩