ND: 2nd-Gen Stars Give Clues about Predecessors

[bystander]

Second-Generation Stars Identified, Giving Clues about Their Predecessors
University of Notre Dame | 2016 Dec 06

[img3="The figure shows a sub-population of ancient stars, called carbon-enhanced metal-poor stars. The unusual chemical compositions of these stars provides clues to their birth environments. A(C) is the absolute amount of carbon, while the horizontal axis represents the ratio of iron, relative to hydrogen, compared with the same ratio in the Sun. (Credit: T.C. Beers (ND, JINA-CEE)"]http://news.nd.edu/assets/220202/origin ... l_size.jpg[/img3][hr][/hr]

University of Notre Dame astronomers have identified what they believe to be the second generation of stars, shedding light on the nature of the universe’s first stars.

A subclass of carbon-enhanced metal-poor (CEMP) stars, the so-called CEMP-no stars, are ancient stars that have large amounts of carbon but little of the heavy metals (such as iron) common to later-generation stars. Massive first-generation stars made up of pure hydrogen and helium produced and ejected heavier elements by stellar winds during their lifetimes or when they exploded as supernovae. Those metals — anything heavier than helium, in astronomical parlance — polluted the nearby gas clouds from which new stars formed.

Jinmi Yoon, Timothy Beers, and Vinicius Placco, a research professor at Notre Dame, along with their collaborators, show that the lowest metallicity stars, the most chemically primitive, include large fractions of CEMP stars. The CEMP-no stars, which are also rich in nitrogen and oxygen, are likely the stars born out of hydrogen and helium gas clouds that were polluted by the elements produced by the universe’s first stars. ...

Observational Constraints on First-Star Nucleosynthesis.

• I. Evidence for Multiple Progenitors of CEMP-no Stars - Jinmi Yoon et al
  • Astrophysical Journal 833(1):20 (10 Dec 2016) DOI: 10.3847/0004-637X/833/1/20
    arXiv.org > astro-ph > arXiv:1607.06336 > 21 Jul 2016 (v1), 27 Sep 2016 (v3)
  II. Spectroscopy of an Ultra Metal-Poor CEMP-no Star - Vinicius M. Placco et al
  • Astrophysical Journal 833(1):21 (10 Dec 2016) DOI: 10.3847/0004-637X/833/1/21
    arXiv.org > astro-ph > arXiv:1609.02134 > 07 Sep 2016