Carbon, nitrogen, and oxygen abundances in early B-type stars

TLDR

Early B‑type stars are studied for their C, N, and O surface abundances to test whether CN‑cycled material is mixed to their surfaces during core hydrogen burning. The study measured weak spectral lines in 39 early B‑type stars with high‑signal‑to‑noise Reticon spectra, derived stellar parameters and rotational velocities, and calculated C, N, and O abundances using LTE and non‑LTE methods. The measured abundances largely match Orion Nebula values, with only a few stars showing nitrogen enrichment, and no systematic rise of nitrogen with age was observed, refuting Liubimkov’s claim of widespread mixing. Published in The Astrophysical Journal, March 1992 (DOI 10.1086/171116).

Abstract

view Abstract Citations (450) References (107) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Carbon, Nitrogen, and Oxygen Abundances in Early B-Type Stars Gies, Douglas R. ; Lambert, David L. Abstract A survey of the C, N, and O abundances in a sample of early B-type stars which was undertaken to test the hypothesis of Liubimkov (1984) that CN-cycled material is mixed to the surfaces of these stars during their core hydrogen-burning phase. Equivalent widths of generally weak lines are obtained using high-signal-to-noise Reticon spectra of 39 stars in four spectral regions. Effective temperatures and gravities for these stars are derived. Projected rotational velocities are measured using a cross-correlation technique. Abundances are derived using LTE methods and non-LTE equivalent width calculations. He, C, N, and O abundances of the nonsupergiant stars in the sample are found to be very close to the values found for the Orion Nebula, with the notable exception of a few stars which show enhanced N, a signature of CN-cycled material. No compelling evidence for a systematic increase in N abundance with evolutonary age was found; thus Liubimkov's claim that mixing occurs generally in main-sequence B stars cannot be confirmed. Publication: The Astrophysical Journal Pub Date: March 1992 DOI: 10.1086/171116 Bibcode: 1992ApJ...387..673G Keywords: Abundance; B Stars; Early Stars; Stellar Composition; Stellar Interiors; Stellar Rotation; Supergiant Stars; Carbon; Line Spectra; Nitrogen; Oxygen; Spectral Line Width; Stellar Spectra; Astrophysics; STARS: ABUNDANCES; STARS: EARLY-TYPE; STARS: INTERIORS; STARS: ROTATION; STARS: SUPERGIANTS full text sources ADS | data products SIMBAD (39)