2000/06/13 by S. Moehler, A. V. Sweigart, Moehler, S. +5
Physics and Astronomy · #Astro and Planetary Science #Astronomy and Astrophysical Research #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #FOS: Physical sciences #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0006182
14 pages, 7 figures, uses aa.cls (included), accepted for publication in A&A (revised version corrected for too much bold face, too long footnote, figure placement; no changes in actual contents)
openalex publication_date 2000/06/13 · arxiv created 2000/06/15 · arxiv updated 2009/12/01 · openalex created_date 2020/04/17 · openalex updated_date 2026/07/28
Atmospheric parameters (effective temperature Teff, surface gravity log g),\nmasses and helium abundances are derived for 42 hot horizontal branch (HB)\nstars in the globular cluster NGC 6752. For 19 stars we derive magnesium and\niron abundances as well and find that iron is enriched by a factor of 50 on\naverage with respect to the cluster abundance whereas the magnesium abundances\nare consistent with the cluster abundance. Radiation pressure may levitate\nheavy elements like iron to the surface of the star in a diffusive process.\nTaking into account the enrichment of heavy elements in our spectroscopic\nanalyses we find that high iron abundances can explain part, but not all, of\nthe problem of anomalously low gravities along the blue HB. The blue HB stars\ncooler than about 15,100 K and the sdB stars (Teff > 20,000 K) agree well with\ncanonical theory when analysed with metal-rich ([M/H] = +0.5) model\natmospheres, but the stars in between these two groups remain offset towards\nlower gravities and masses. Deep Mixing in the red giant progenitor phase is\ndiscussed as another mechanism that may influence the position of the blue HB\nstars in the (Teff, log g)-plane but not their masses.\n