Observational constraints on first-star nucleosynthesis. II. Spectroscopy of an ultra metal-poor CEMP-no star

Vinicius M Placco, Anna Frebel, Timothy C. Beers, Jinmi Yoon, Anirudh Chiti, Alexander Heger, Conrad Chan, Andrew Casey, Norbert Christlieb

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41 Citations (Scopus)

Abstract

We report on the first high-resolution spectroscopic analysis of HE 0020-1741, a bright (V = 12.9), ultra metal-poor ([Fe/H] = -4.1), carbon-enhanced ([C/Fe] = +1.7) star selected from the Hamburg/ESO Survey. This star exhibits low abundances of neutron-capture elements ([Ba/Fe] = -1.1) and an absolute carbon abundance A(C) = 6.1; based on either criterion, HE 0020-1741 is subclassified as a carbon-enhanced metal-poor star without enhancements in neutron-capture elements (CEMP-no). We show that the light-element abundance pattern of HE 0020-1741 is consistent with predicted yields from a massive (M = 21.5 M), primordial-composition, supernova (SN) progenitor. We also compare the abundance patterns of other ultra metal-poor stars from the literature with available measures of C, N, Na, Mg, and Fe abundances with an extensive grid of SN models (covering the mass range 10-100 M), in order to probe the nature of their likely stellar progenitors. Our results suggest that at least two classes of progenitors are required at [Fe/H]< -4.0, as the abundance patterns for more than half of the sample studied in this work (7 out of 12 stars) cannot be easily reproduced by the predicted yields.

Original languageEnglish
Article number21
Number of pages13
JournalThe Astrophysical Journal
Volume833
Issue number1
DOIs
Publication statusPublished - 10 Dec 2016

Keywords

  • Galaxy: halo
  • stars: abundances
  • stars: atmospheres
  • stars: individual (HE 0020 1741)
  • stars: Population II
  • techniques: spectroscopic

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