Evolution of Massive Stars and the VLT

Charbonnel, C.; Maeder, A.

doi:10.1007/978-3-540-49215-3_21

Cited by 6 publications

(7 citation statements)

References 6 publications

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“…The striking Li-Be depletion correlation discovered in field dwarfs on the cool side of the Li dip (Deliyannis et al 1998;Boesgaard et al 2001) and in open clusters (Boesgaard et al 2004) argues strongly in favor of slow mixing induced by rotation, as in the Yale and other models that produce the specifically observed Li/Be ratio (e.g., Charbonnel et al 1994), and argues strongly against diffusion (where Li and Be are depleted from the surface at a similar rate) and mass loss (where all the Li must disappear before Be depletion can be observed). The Li-Be correlation can even discriminate among models with slow mixing; for example, the wave-driven mixing in the Garcia Lopez & Spruit (1991) models does not penetrate very deeply, and as a result the predicted Li/Be ratio is too large.…”

Section: Li-dip: Structure and Evolutionmentioning

confidence: 89%

Lithium in the Intermediate-Age Open Cluster, NGC 3680

Anthony-Twarog

Deliyannis

Twarog

et al. 2009

The Astronomical Journal

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Section: Li-dip: Structure and Evolutionmentioning

confidence: 89%

Lithium in the Intermediate-Age Open Cluster, NGC 3680

Anthony-Twarog

Deliyannis

Twarog

et al. 2009

The Astronomical Journal

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“…1 on the STARBURST99 web site, http://www.stsci.edu/science/starburst99/). It implements the BaSeL 2.2 library (Lejeune et al 1997(Lejeune et al , 1998, and for stars with strong mass loss it also takes into account extended model atmospheres by Schmutz et al (1992), combined with the Geneva isochrones (Meynet et al 1994;Schaller et al 1992;Schaerer et al 1993a,b;Charbonnel et al 1993). For old populations, the "BC99" spectrum was used, since the Starburst99 data package only contains spectra up to 900 Myr.…”

Section: Synthetic Stellar Populationsmentioning

confidence: 99%

Virgo Cluster Early?Type Dwarf Galaxies with the Sloan Digital Sky Survey. II. Early?Type Dwarfs with Central Star Formation

et al. 2006

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Despite the common picture of an early-type dwarf (dE) as a quiescent galaxy with no star formation and little gas, we identify 23 dEs that have blue central colors caused by recent or ongoing star formation in our sample of 476 Virgo cluster dEs. In addition, 14 objects that were mostly classified as (candidate) BCDs have similar properties. Among the certain cluster members, the dEs with blue centers reach a fraction of more than 15% of the dE population at brighter (m B ≤ 16) magnitudes. A spectral analysis of the centers of 16 galaxies reveals in all cases an underlying old population that dominates the mass, with M old ≥ 90% for all but one object. Therefore the majority of these galaxies will appear like ordinary dEs within ∼ one Gigayear or less after the last episode of star formation. Their overall gas content is less than that of dwarf irregular galaxies, but higher than that of ordinary dEs. Their flattening distribution suggests the shape of a thick disk, similar to what has been found for dEs with disk features in Paper I of this series. Their projected spatial distribution shows no central clustering, and their distribution with projected local density follows that of irregular galaxies, indicative of an unrelaxed population. This is corroborated by their velocity distribution, which displays two side peaks characteristic of recent infall. We discuss possible formation mechanisms (ram-pressure stripping, tidally induced star formation, harassment) that might be able to explain both the disk shape and the central star formation of the dEs with blue centers.

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“…Even worse, the observations of excess 3 He (X 3 of order 10 −3 ) in three planetary nebulae (Rood, Bania & Wilson 1992;RBWB95) appear to confirm that stars around 1.5 M ⊙ are efficient 3 He producers, in conflict with Hogan's proposal. Charbonnel (1995) has recently argued that the deep convective mixing responsible for the 3 He destruction in Hogan's suggestion takes place in stars experiencing the helium flash and gives an upper mass limit of 2 M ⊙ to the phenomenon. This would reconcile the deep mixing 3 He destruction with the high PNe abundances if the initial mass of the PNe progenitor was at least 2 M ⊙ .…”

Section: The Galactic Evolution Of 3 He: Non-standard Modelsmentioning

confidence: 99%