2003/07/11 by Bradford B. Behr · 9 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/378352
47 pages, 9 figures, 5 tables, accepted for publication in November 2003 ApJS
arxiv created 2003/07/11 · openalex publication_date 2003/10/24 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
We present measurements of the projected stellar rotation velocities ( v sin i ) of a sample of 45 candidate field horizontal-branch (HB) stars spanning a wide range of effective temperatures, from red HB stars with T eff ≃ 5000 K to blue HB stars with T eff of 17,000 K. Among the cooler blue HB stars ( T eff = 7500-11500 K), we confirm prior studies showing that, although a majority of stars rotate at v sin i < 15 km s -1 , there exists a subset of "fast rotators" with v sin i as high as 30-35 km s -1 . All but one of the red HB stars in our sample have v sin i < 10 km s -1 , and no analogous rotation bimodality is evident. We also identify a narrow-lined hot star ( T eff ≃ 16,000 K) with enhanced photospheric metal abundances and helium depletion, similar to the abundance patterns found among hot BHB stars in globular clusters, and four other stars that may also belong in this category. We discuss details of the spectral line fitting procedure that we use to deduce v sin i and explore how measurements of field HB star rotation may shed light on the issue of HB star rotation in globular clusters.