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Title: Hubble space telescope near-ultraviolet spectroscopy of the bright cemp-no star BD+44°493

We present an elemental-abundance analysis, in the near-ultraviolet (NUV) spectral range, for the extremely metal-poor star BD+44°493 a ninth magnitude subgiant with [Fe/H] =–3.8 and enhanced carbon, based on data acquired with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. This star is the brightest example of a class of objects that, unlike the great majority of carbon-enhanced metal-poor (CEMP) stars, does not exhibit over-abundances of heavy neutron-capture elements (CEMP-no). In this paper, we validate the abundance determinations for a number of species that were previously studied in the optical region, and obtain strong upper limits for beryllium and boron, as well as for neutron-capture elements from zirconium to platinum, many of which are not accessible from ground-based spectra. The boron upper limit we obtain for BD+44°493, log ε (B) <–0.70, the first such measurement for a CEMP star, is the lowest yet found for very and extremely metal-poor stars. In addition, we obtain even lower upper limits on the abundances of beryllium, log ε (Be) <–2.3, and lead, log ε (Pb) <–0.23 ([Pb/Fe] <+1.90), than those reported by previous analyses in the optical range. Taken together with the previously measured low abundance of lithium, the very lowmore » upper limits on Be and B suggest that BD+44°493 was formed at a very early time, and that it could well be a bona-fide second-generation star. Finally, the Pb upper limit strengthens the argument for non-s-process production of the heavy-element abundance patterns in CEMP-no stars.« less
Authors:
 [1] ; ;  [2] ;  [3] ;  [4] ;  [5] ; ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [11]
  1. Gemini Observatory, Hilo, HI 96720 (United States)
  2. National Optical Astronomy Observatory, Tucson, AZ 85719 (United States)
  3. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)
  4. Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)
  5. Kavli Institute for Astrophysics and Space Research and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)
  6. Department of Physics and Astronomy, The University of Utah, Salt Lake City, UT 84112 (United States)
  7. Department of Physics, University of Wisconsin, Madison, WI 53706 (United States)
  8. JINA—Joint Institute for Nuclear Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556-5670 (United States)
  9. Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States)
  10. Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States)
  11. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan)
Publication Date:
OSTI Identifier:
22365607
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 790; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATMOSPHERES; BERYLLIUM; BORON; CARBON; ELEMENT ABUNDANCE; GALAXIES; LITHIUM; NEAR ULTRAVIOLET RADIATION; NEUTRON REACTIONS; PLATINUM; S PROCESS; SPACE; SPECTRA; SPECTROSCOPY; STARS; TELESCOPES; TRITIUM; ULTRAVIOLET RADIATION; ZIRCONIUM