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BEGIN:VEVENT
DTSTART;TZID=Atlantic/Canary:20180621T103000
DTEND;TZID=Atlantic/Canary:20180621T113000
UID:iactalks-1141
X-WR-CALNAME: IAC Talks: Open Astronomy Seminars
X-ORIGINAL-URL: /iactalks/Talks/view/1141
CREATED:2018-06-21T10:30:00+01:00
X-WR-CALDESC: IAC Talks upcomming talks
SUMMARY:The Chemistry of the First Stars-Carbon in the Early Universe
DESCRIPTION:The Chemistry of the First Stars-Carbon in the Early Universe\n
 Prof. Timothy Beers\n\nThe very metal-poor (VMP; [Fe/H] < –2.0) a
 nd extremely metal-poor (EMP; [Fe/H] < –3.0) stars provide a dire
 ct view of Galactic chemical and dynamical evolution; detailed spectroscop
 ic studies of these objects are the best way to identify and distinguish b
 etween various scenarios for the enrichment of early star-forming gas clou
 ds soon after the Big Bang. It has been recognized that a large fraction o
 f VMP (15-20%) and EMP stars (30-40%) possess significant over-abundances 
 of carbon relative to iron, [C/Fe] > +0.7. This fraction rises to at le
 ast 80% for stars with [Fe/H] < –4.0.  Recent studies show that t
 he majority of CEMP stars with [Fe/H] < –3.0 belong to the CEMP-n
 o sub-class, characterized by the lack of strong enhancements in the neutr
 on-capture elements (e.g., [Ba/Fe] < 0.0). The brightest EMP star in th
 e sky, BD+44:493, with [Fe/H] = –3.8 and V = 9.1, is a CEMP-no star.
  It shares a common elemental-abundance signature with the recently discov
 ered CEMP-no star having [Fe/H] < –7.8. The distinctive CEMP-no p
 attern has also been identified in high-z damped Lyman-alpha systems, and 
 is common among stars in the ultra-faint dwarf spheroidal galaxies, such a
 s SEGUE-1. These observations suggest that CEMP-no stars exhibit the nucle
 osynthesis products of the VERY first generation of stars. We discuss the 
 multiple lines of evidence that support this hypothesis, and describe curr
 ent efforts to identify the nature of the massive stellar progenitors that
  produced these signatures.
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