Astronomy and Astrophysics – Astrophysics – Solar and Stellar Astrophysics
Scientific paper
2011-03-05
Astronomy and Astrophysics
Astrophysics
Solar and Stellar Astrophysics
Accepted for publication in the Astronomical Journal; 54 pages, 12 figures
Scientific paper
The globular cluster M15 is unique in its display of star-to-star variations in the neutron-capture elements. Comprehensive abundance surveys have been previously conducted for handfuls of M15 red giant branch (RGB) and red horizontal branch (RHB) stars. No attempt has been made to perform a single, self-consistent analysis of these stars, which exhibit a wide range in atmospheric parameters. In the current effort, a new comparative abundance derivation is presented for three RGB and six RHB members of the cluster. The analysis employs an updated version of the line transfer code MOOG, which now appropriately treats coherent, isotropic scattering. The apparent discrepancy in the previously reported values for the metallicity of M15 RGB and RHB stars is addressed and a resolute disparity of $\Delta(RHB-RGB) \approx 0.1$ dex in the iron abundance was found. The anti-correlative behavior of the light neutron capture elements (Sr, Y, Zr) is clearly demonstrated with both Ba and Eu, standard markers of the {\it s}- and {\it r}-process, respectively. No conclusive detection of Pb was made in the RGB targets. Consequently for the M15 cluster, this suggests that the main component of the {\it s}-process has made a negligible contribution to those elements normally dominated by this process in solar system material. Additionally for the M15 sample, a large Eu abundance spread is confirmed, which is comparable to that of the halo field at the same metallicity. These abundance results are considered in the discussion of the chemical inhomogeneity and nucleosynthetic history of M15.
Burley Greg S.
Cowan John J.
Kraft Ralph Porter
Preston George W.
Shectman Stephen A.
No associations
LandOfFree
The Abundances of Neutron Capture Species in the Very Metal-Poor Globular Cluster M15: An Uniform Analysis of RGB and RHB Stars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The Abundances of Neutron Capture Species in the Very Metal-Poor Globular Cluster M15: An Uniform Analysis of RGB and RHB Stars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The Abundances of Neutron Capture Species in the Very Metal-Poor Globular Cluster M15: An Uniform Analysis of RGB and RHB Stars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-8643