Oxygen abundances in low- and high-alpha field halo stars and the discovery of two field stars born in globular clusters

作者: I. Ramírez , J. Meléndez , J. Chanamé

DOI: 10.1088/0004-637X/757/2/164

关键词: PopulationAstrophysicsGlobular clusterStarsOxygenHaloMetallicityPhysicsAbundance (ecology)Local fieldAstronomy

摘要: Oxygen abundances of 67 dwarf stars in the metallicity range -1.6<[Fe/H]<-0.4 are derived from a non-LTE analysis 777 nm O I triplet lines. These have precise atmospheric parameters measured by Nissen and Schuster, who find that they separate into three groups based on their kinematics alpha-element (Mg, Si, Ca, Ti) abundances: thick-disk, high-alpha halo, low-alpha halo. We oxygen abundance trends thick-disk halo very similar. The show larger star-to-star scatter [O/Fe] at given [Fe/H] systematically lower compared to other two groups. Thus, we behavior these similar alpha elements. use previously published data disk metal-poor present an overall view (-2.3<[Fe/H]<+0.3) solar neighborhood. Two field stand out Na abundances. Both G53-41 G150-40 low high sodium abundances, which key signatures anomalies observed globular cluster (GC) stars. Therefore, likely born GCs. If true, estimate least 3+/-2% local star population was

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