Lithium-rich giants in the Galactic thick disk

L. Monaco, S. Villanova, C. Moni Bidin, G. Carraro, D. Geisler, P. Bonifacio, O. A. Gonzalez, M. Zoccali, L. Jilkova

Resultado de la investigación: Article

45 Citas (Scopus)

Resumen

Context. Lithium is a fragile element, which is easily destroyed in the stellar interior. The existence of lithium-rich giants still represents a challenge for stellar evolution models. Aims. We have collected a large database of high-resolution stellar spectra of 824 candidate thick-disk giants having 2 MASS photometry and proper motions measured by the Southern Proper-Motion Program (SPM). In order to investigate the nature of Li-rich giants, we searched this database for giants presenting a strong Li I resonance line. Methods. We performed a chemical abundance analysis on the selected stars with the MOOG code along with proper ATLAS-9 model atmospheres. The iron content and atmospheric parameters were fixed by using the equivalent width of a sample of Fe lines. We also derive abundances for C, N, and O and measure or derive lower limits on the 12C/13C isotopic ratios, which is a sensible diagnostic of the stars evolutionary status. Results. We detected five stars with a lithium abundance higher than 1.5, i.e. Li-rich according to the current definition. One of them (SPM-313132) has A(Li) > 3.3 and, because of this, belongs to the group of the rare super Li-rich giants. Its kinematics makes it a likely thin-disk member and its atmospheric parameters are compatible with it being a 4 Ṁ star either on the red giant branch (RGB) or the early asymptotic giant branch. This object is the first super Li-rich giant detected at this phase. The other four are likely low-mass thick-disk stars evolved past the RGB luminosity bump, as determined from their metallicities and atmospheric parameters. The most evolved of them lies close to the RGB-tip. It has A(Li) > 2.7 and a low 12C/13C isotopic ratio, close to the cool bottom processing predictions.

Idioma originalEnglish
Número de artículoA90
PublicaciónAstronomy and Astrophysics
Volumen529
DOI
EstadoPublished - 2011

Huella dactilar

lithium
proper motion
isotopic ratio
stars
stellar interiors
stellar spectra
M stars
stellar evolution
kinematics
resonance lines
metallicity
photometry
iron
atmosphere
luminosity
prediction
atmospheres
parameter
high resolution
predictions

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Citar esto

Monaco, L., Villanova, S., Moni Bidin, C., Carraro, G., Geisler, D., Bonifacio, P., ... Jilkova, L. (2011). Lithium-rich giants in the Galactic thick disk. Astronomy and Astrophysics, 529, [A90]. https://doi.org/10.1051/0004-6361/201016285
Monaco, L. ; Villanova, S. ; Moni Bidin, C. ; Carraro, G. ; Geisler, D. ; Bonifacio, P. ; Gonzalez, O. A. ; Zoccali, M. ; Jilkova, L. / Lithium-rich giants in the Galactic thick disk. En: Astronomy and Astrophysics. 2011 ; Vol. 529.
@article{4e8cc76853534a779581449872979467,
title = "Lithium-rich giants in the Galactic thick disk",
abstract = "Context. Lithium is a fragile element, which is easily destroyed in the stellar interior. The existence of lithium-rich giants still represents a challenge for stellar evolution models. Aims. We have collected a large database of high-resolution stellar spectra of 824 candidate thick-disk giants having 2 MASS photometry and proper motions measured by the Southern Proper-Motion Program (SPM). In order to investigate the nature of Li-rich giants, we searched this database for giants presenting a strong Li I resonance line. Methods. We performed a chemical abundance analysis on the selected stars with the MOOG code along with proper ATLAS-9 model atmospheres. The iron content and atmospheric parameters were fixed by using the equivalent width of a sample of Fe lines. We also derive abundances for C, N, and O and measure or derive lower limits on the 12C/13C isotopic ratios, which is a sensible diagnostic of the stars evolutionary status. Results. We detected five stars with a lithium abundance higher than 1.5, i.e. Li-rich according to the current definition. One of them (SPM-313132) has A(Li) > 3.3 and, because of this, belongs to the group of the rare super Li-rich giants. Its kinematics makes it a likely thin-disk member and its atmospheric parameters are compatible with it being a 4 Ṁ star either on the red giant branch (RGB) or the early asymptotic giant branch. This object is the first super Li-rich giant detected at this phase. The other four are likely low-mass thick-disk stars evolved past the RGB luminosity bump, as determined from their metallicities and atmospheric parameters. The most evolved of them lies close to the RGB-tip. It has A(Li) > 2.7 and a low 12C/13C isotopic ratio, close to the cool bottom processing predictions.",
keywords = "Galaxy: disk, Stars: abundances, Stars: atmospheres, Stars: chemically peculiar",
author = "L. Monaco and S. Villanova and {Moni Bidin}, C. and G. Carraro and D. Geisler and P. Bonifacio and Gonzalez, {O. A.} and M. Zoccali and L. Jilkova",
year = "2011",
doi = "10.1051/0004-6361/201016285",
language = "English",
volume = "529",
journal = "Astronomy and Astrophysics",
issn = "0004-6361",
publisher = "EDP Sciences",

}

Monaco, L, Villanova, S, Moni Bidin, C, Carraro, G, Geisler, D, Bonifacio, P, Gonzalez, OA, Zoccali, M & Jilkova, L 2011, 'Lithium-rich giants in the Galactic thick disk', Astronomy and Astrophysics, vol. 529, A90. https://doi.org/10.1051/0004-6361/201016285

Lithium-rich giants in the Galactic thick disk. / Monaco, L.; Villanova, S.; Moni Bidin, C.; Carraro, G.; Geisler, D.; Bonifacio, P.; Gonzalez, O. A.; Zoccali, M.; Jilkova, L.

En: Astronomy and Astrophysics, Vol. 529, A90, 2011.

Resultado de la investigación: Article

TY - JOUR

T1 - Lithium-rich giants in the Galactic thick disk

AU - Monaco, L.

AU - Villanova, S.

AU - Moni Bidin, C.

AU - Carraro, G.

AU - Geisler, D.

AU - Bonifacio, P.

AU - Gonzalez, O. A.

AU - Zoccali, M.

AU - Jilkova, L.

PY - 2011

Y1 - 2011

N2 - Context. Lithium is a fragile element, which is easily destroyed in the stellar interior. The existence of lithium-rich giants still represents a challenge for stellar evolution models. Aims. We have collected a large database of high-resolution stellar spectra of 824 candidate thick-disk giants having 2 MASS photometry and proper motions measured by the Southern Proper-Motion Program (SPM). In order to investigate the nature of Li-rich giants, we searched this database for giants presenting a strong Li I resonance line. Methods. We performed a chemical abundance analysis on the selected stars with the MOOG code along with proper ATLAS-9 model atmospheres. The iron content and atmospheric parameters were fixed by using the equivalent width of a sample of Fe lines. We also derive abundances for C, N, and O and measure or derive lower limits on the 12C/13C isotopic ratios, which is a sensible diagnostic of the stars evolutionary status. Results. We detected five stars with a lithium abundance higher than 1.5, i.e. Li-rich according to the current definition. One of them (SPM-313132) has A(Li) > 3.3 and, because of this, belongs to the group of the rare super Li-rich giants. Its kinematics makes it a likely thin-disk member and its atmospheric parameters are compatible with it being a 4 Ṁ star either on the red giant branch (RGB) or the early asymptotic giant branch. This object is the first super Li-rich giant detected at this phase. The other four are likely low-mass thick-disk stars evolved past the RGB luminosity bump, as determined from their metallicities and atmospheric parameters. The most evolved of them lies close to the RGB-tip. It has A(Li) > 2.7 and a low 12C/13C isotopic ratio, close to the cool bottom processing predictions.

AB - Context. Lithium is a fragile element, which is easily destroyed in the stellar interior. The existence of lithium-rich giants still represents a challenge for stellar evolution models. Aims. We have collected a large database of high-resolution stellar spectra of 824 candidate thick-disk giants having 2 MASS photometry and proper motions measured by the Southern Proper-Motion Program (SPM). In order to investigate the nature of Li-rich giants, we searched this database for giants presenting a strong Li I resonance line. Methods. We performed a chemical abundance analysis on the selected stars with the MOOG code along with proper ATLAS-9 model atmospheres. The iron content and atmospheric parameters were fixed by using the equivalent width of a sample of Fe lines. We also derive abundances for C, N, and O and measure or derive lower limits on the 12C/13C isotopic ratios, which is a sensible diagnostic of the stars evolutionary status. Results. We detected five stars with a lithium abundance higher than 1.5, i.e. Li-rich according to the current definition. One of them (SPM-313132) has A(Li) > 3.3 and, because of this, belongs to the group of the rare super Li-rich giants. Its kinematics makes it a likely thin-disk member and its atmospheric parameters are compatible with it being a 4 Ṁ star either on the red giant branch (RGB) or the early asymptotic giant branch. This object is the first super Li-rich giant detected at this phase. The other four are likely low-mass thick-disk stars evolved past the RGB luminosity bump, as determined from their metallicities and atmospheric parameters. The most evolved of them lies close to the RGB-tip. It has A(Li) > 2.7 and a low 12C/13C isotopic ratio, close to the cool bottom processing predictions.

KW - Galaxy: disk

KW - Stars: abundances

KW - Stars: atmospheres

KW - Stars: chemically peculiar

UR - http://www.scopus.com/inward/record.url?scp=79953856368&partnerID=8YFLogxK

U2 - 10.1051/0004-6361/201016285

DO - 10.1051/0004-6361/201016285

M3 - Article

AN - SCOPUS:79953856368

VL - 529

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A90

ER -

Monaco L, Villanova S, Moni Bidin C, Carraro G, Geisler D, Bonifacio P y otros. Lithium-rich giants in the Galactic thick disk. Astronomy and Astrophysics. 2011;529. A90. https://doi.org/10.1051/0004-6361/201016285