S-process deficiencies in low-mass supergiant variables

Abstract

view Abstract Citations (58) References (78) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS S-Process Deficiencies in Low-Mass Supergiant Variables Luck, R. Earle ; Bond, Howard E. Abstract Abundance analyses of four low-mass supergiant variable stars and two Population I Cepheids have been carried out. The Population I Cepheids show normal, solar element ratios, and the low-mass variables show metallicities ranging from solar down to (Fe/H) values typical of thick-disk and, in a few cases, of halo stars. Most low-mass variables show a systematic underabundance of the heavy s- and r-process elements. The heavy-element underabundances correlate with second ionization potential in a manner suggesting that they are a non-LTE phenomenon arising from overionization by Lyman-continuum photons. Several low-mass variables, including RU Cen and V553 Cen, show carbon enhancements and solar s-process abundances. Relative to the majority of the type II variables, these stars are s-process enhanced, and it is argued that they are related to the Ba II and CH stars. Publication: The Astrophysical Journal Pub Date: July 1989 DOI: 10.1086/167607 Bibcode: 1989ApJ...342..476L Keywords: Abundance; Cepheid Variables; Stellar Composition; Supergiant Stars; Variable Stars; Echelle Gratings; Heavy Elements; Mass Ratios; Metallicity; Stellar Atmospheres; Astrophysics; STARS: ABUNDANCES; STARS: RV TAURI; STARS: SUPERGIANTS; STARS: WEAK-LINE full text sources ADS | data products SIMBAD (26)