Nuclei in the Cosmos - IX

Session

5 Element production and stellar evolution: MP/UMP and Novae

27 Jun 2006, 08:30

CERN, Geneva

Conveners

5 Element production and stellar evolution: MP/UMP and Novae

• André Maeder (Geneva Observatory)

275. r-Process Enhanced Metal-Poor Stars

John Cowan (University of Oklahoma)

27/06/2006, 08:30

Element production, stellar evolution and stellar explosions

Invited

Abundance observations indicate the presence of rapid-neutron capture (i.e., r-process) elements in old Galactic halo and globular cluster stars. These observations provide insight into the nature of the earliest generations of stars in the Galaxy -- the progenitors of the halo stars -- responsible for neutron-capture synthesis of the heavy elements. The large star-to-star...

134. The First Nova Explosions

Jordi Jose (Institut d'Estudis Espacials de Catalunya/UPC)

27/06/2006, 09:00

Element production, stellar evolution and stellar explosions

Oral contribution

Classical nova outbursts are powered by thermonuclear runaways (hereafter, TNRs) that take place in the hydrogen-rich accreted envelopes of white dwarfs in close binary systems. Extensive numerical simulations of nova outbursts have shown that the accreted envelopes attain peak temperatures ranging between 100 and 400 MK for about several hundred seconds, and therefore, their ejecta is...

202. Mass loss at very low metallicity: impacts on nucleosynthesis and GRB progenitors

Georges Meynet (Geneva Observatory)

27/06/2006, 09:20

Element production, stellar evolution and stellar explosions

Oral contribution

Massive stars with no or very little amount of metals are generally considered as having very weak stellar winds. We reconsider here this question through stellar models accounting for the effects of axial rotation and show that rotating models of massive stars might lose a significant fraction of their initial mass through mass loss. The physical mechanisms triggering these mass losses...

240. Chemical Compositions Derived from Near Ultra-Violet Observations of Low-Metallicity Stars: New Insights into the Sites of Neutron-Capture Nucleosynthesis Processes

Inese Ivans (Carnegie Observatories & princeton university)

27/06/2006, 09:40

Invited

Numerous signatures of r- and s-process nucleosynthesis can be observed in the photospheres of stars. To date, however, the stellar abundance determinations of many of the elements have been scarce because a large portion of the dominant atomic transitions reside in the UV. To be reported in the context of other recent results of neutron-capture studies, are the abundances (or upper...

185. The Frequency of Carbon-Enhanced Stars in HERES and SDSS

Timothy Beers (Michigan State University and JINA)

27/06/2006, 10:10

Element production, stellar evolution and stellar explosions

Oral contribution

Recent large surveys of metal-poor stars in the Galaxy have revealed that a surprising fraction of them are enhanced in their carbon-to-iron ratios by factors of from 10-10,000 relative to the solar ratio. Although most of the stars in the metallicity interval -2.7 < [Fe/H] < -2.0 are likely to have arisen from Asymptotic Giant Branch processing (and subsequent dumping via mass transfer...