1999/09/16 by Inese I. Ivans, Ivans, Inese I.
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9909297
6 pages, 2 figures, To appear in Proceedings of the 35th Liege Astrophysics Colloquium: "The Galactic Halo: From Globular Clusters to Field Stars"
arxiv created 1999/09/16 · openalex publication_date 1999/09/16 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a chemical composition analysis of three dozen giant stars in the nearby ``CN-bimodal'' mildly metal-poor ( = -1.18) globular cluster M4. The analysis combined traditional spectroscopic abundance methods with modifications to the line-depth ratio technique pioneered by Gray (1994). Silicon and aluminum are found to be primordially overabundant by factors exceeding the mild overabundances usually seen in alpha- and light odd elements among halo field and globular cluster giants of comparable metallicity. In addition, barium is found to be overabundant by a factor of about four. Superimposed on the primordial abundance distribution in M4, there is evidence for the existence of proton-capture synthesis of C, O, Ne, and Mg.