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The Astrophysical Journal / The Astrophysical Journal Letters 751 (2012) 156
Red Supergiant Stars as Cosmic Abundance Probes: NLTE Effects in J-band Iron and Titanium Lines
Maria Bergemann1, Rolf-Peter Kudritzki1, Bertrand PLEZ1, Ben Davies1, Karin Lind1, Zach Gazak1
(02/04/2012)

Detailed non-LTE calculations for red supergiant stars are presented to investigate the influence of NLTE on the formation of atomic iron and titanium lines in the J-band. With their enormous brightness at J-band red supergiant stars are ideal probes of cosmic abundances. Recent LTE studies have found that metallicities accurate to 0.15 dex can be determined from medium resolution spectroscopy of individual red supergiants in galaxies as distant as 10 Mpc. The non-LTE results obtained in this investigation support these findings. Non-LTE abundance corrections for iron are smaller than 0.05 dex for effective temperatures between 3400K to 4200K and 0.1 dex at 4400K. For titanium the non-LTE abundance corrections vary smoothly between -0.4 dex and +0.2 dex as a function of effective temperature. For both elements, the corrections also depend on stellar gravity and metallicity. The physical reasons behind the non-LTE corrections and the consequences for extragalactic J-band abundance studies are discussed.
1 :  LUPM - Laboratoire Univers et Particules de Montpellier
Astrophysique Stellaire
Planète et Univers/Astrophysique/Astrophysique stellaire et solaire

Physique/Astrophysique/Astrophysique stellaire et solaire

Planète et Univers/Astrophysique/Cosmologie et astrophysique extra-galactique

Physique/Astrophysique/Cosmologie et astrophysique extra-galactique
Lien vers le texte intégral : 
http://fr.arXiv.org/abs/1204.0511