Abundance variations in the globular cluster M71 (NGC 6838)

被引：7

作者：

Alves-Brito, A. ^{[1
]}

Schiavon, R. P. ^{[2
]}

Castilho, B. ^{[3
]}

Barbuy, B. ^{[1
]}

机构：

[1] Univ Sao Paulo, IAG, BR-05508900 Sao Paulo, Brazil

[2] Univ Virginia, Dept Astron, Charlottesville, VA 22903 USA

[3] Lab Nacl Astrofis MCT, BR-37500000 Itajuba, MG, Brazil

来源：

ASTRONOMY & ASTROPHYSICS | 2008年 / 486卷 / 03期

关键词：

globular clusters : individual : M71; stars : abundances; stars : atmospheres; Galaxy : abundances;

D O I：

10.1051/0004-6361:200809405

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

Context. Abundance variations in moderately metal-rich globular clusters can give clues about the formation and chemical enrichment of globular clusters. Aims. CN, CH, Na, Mg and Al indices in spectra of 89 stars of the template metal-rich globular cluster M71 are measured and implications on internal mixing are discussed. Methods. Stars from the turn-off up to the Red Giant Branch (0.87 < log g < 4.65) observed with the GMOS multi-object spectrograph at the Gemini-North telescope are analyzed. Radial velocities, colours, effective temperatures, gravities and spectral indices are determined for the sample. Results. Previous findings related to the CN bimodality and CN-CH anticorrelation in stars of M71 are confirmed. We also find a CN-Na correlation, and Al-Na, as well as an Mg-2-Al anticorrelation. Conclusions. A combination of convective mixing and a primordial pollution by AGB or massive stars in the early stages of globular cluster formation is required to explain the observations.

引用

页码：941 / 950

页数：10

共 59 条

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