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Meynet, Georges; Arnould, M.; Paulus, G.; Maeder, A.

doi:10.1023/a:1013876527660

Cited by 24 publications

(34 citation statements)

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“…In principle, SiC can condense during the WN-WC transition and WC phase (Prantzos et al 1986;Maeder 1987), which is when the products of core He burning are exposed at the surface. In particular, 22 Ne gets enriched in He burning by -capture on 14 N. This leads to 20 Ne/ 22 Ne ratios of between 0.03 and 10 (compared to 20 Ne/ 22 Ne ¼ 0:08 of the G-component; Lewis et al 1994) and the mean 22 Ne abundance increases by a factor of >100 relative to the initial abundance ( Meynet et al 2001 Maeder (1983) proposed W-R stars as a source for Ne-E because of their low 20 Ne/ 22 Ne ratio in their stellar winds. The mean 4 He/ 22 Ne ratio ($165) is comparable to the value expected from an AGB star He shell.…”

Section: Wolf-rayet Starsmentioning

confidence: 99%

Presolar He and Ne Isotopes in Single Circumstellar SiC Grains

Heck

Marhas

Hoppe

et al. 2007

ApJ

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Noble gas isotopes in presolar silicon carbide (SiC) dust grains from primitive meteorites provide, together with major element isotopic compositions, insight into the nucleosynthetic output of different types of evolved stars >4.5 Gyr ago. We report here new results from helium and neon isotopic analyses of single presolar SiC grains with sizes between 0.6 and 6.3 m using an ultrahigh sensitivity mass spectrometer. These noble gas studies were complemented by an ion microprobe study (NanoSIMS) of Si, C, and N isotopic compositions of the same grains. About 40%, or 46 of the 110 grains analyzed, contain nucleosynthetic 22 Ne and/or 4 He from their parent stars above our mass spectrometer's detection limit. We discuss the possible stellar sources using isotopic ratios as constraints combined with new model predictions for low-to intermediate-mass (1.5, 2, 3, and 5 M ) asymptotic giant branch (AGB) stars of different metallicities (1, 1/2, 1/3, and 1/6 Z ). Most SiC grains are of the mainstream type and originated in low-mass AGB stars. We find a higher-than-expected percentage of A/B type grains, with some containing 22 Ne and/or 4 He. In addition, we find one noble gasYrich nova grain candidate, one supernova grain ( X-type grain), and one 22 Ne-rich X-or Z-type grain candidate.

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Section: Wolf-rayet Starsmentioning

confidence: 99%

Presolar He and Ne Isotopes in Single Circumstellar SiC Grains

Heck

Marhas

Hoppe

et al. 2007

ApJ

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“…Results from Arnett (1978) were used to relate the helium core mass to the star's initial main-sequence mass. The massive-star models of Meynet et al (2001) were used by S. Goriely (2005, private communication) to calculate abundances in the W-R winds ejected between the star's birth and the end of the W-R phase for initial stellar masses 40 M , 60 M , and 85 M (see also Binns et al 2005;Arnould et al 2006). Type Ia supernovae were assumed to occur at a rate of 0.3 per century uniformly in the galaxy (van den Bergh & McClure 1994;Hatano et al 1997).…”

Section: Superbubble Compositionmentioning

confidence: 99%

The Phosphorus, Sulfur, Argon, and Calcium Isotopic Composition of the Galactic Cosmic Ray Source

Ogliore

Stone

Leske

et al. 2009

ApJ

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Galactic cosmic ray (GCR) measurements of the phosphorus, sulfur, argon, and calcium isotopes made by the Cosmic Ray Isotope Spectrometer aboard the Advanced Composition Explorer are reported over the energy range from ∼100 to ∼400 MeV nucleon −1 . The propagation of cosmic rays through the Galaxy and heliosphere is modeled with constraints imposed by measurements. Isotopic source abundance ratios 31 P/ 32 S, 34 S/ 32 S, 38 Ar/ 36 Ar, and 44 Ca/ 40 Ca are deduced. The derived 31 P/ 32 S ratio is 2.34 ± 0.34 times larger than the solar system value, lending further credence to the suggestion that refractory elements are enriched in the GCRs due to the sputtering of ions off grains in the cores of superbubbles. By determining the GCR source abundances of argon (a noble gas) and calcium (a refractory), it is determined that material in grains is accelerated to GCR energies a factor of 6.4 ± 0.3 more efficiently than gas-phase material in this charge range. With this information, the dust fraction of phosphorus and sulfur in the interstellar material that is mixed with stellar ejecta to form the GCR seed material is found to be consistent with astronomical observations.

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“…The WC star winds are also rich in 22 Ne, which explains the high 22 Ne/ 20 Ne isotopic ratio observed in the galactic cosmic ray source material (see e.g. Meynet et al 2001). WR stars are also the progenitors of type Ib/Ic supernovae (see the review by Hamuy 2003).…”

Section: Introductionmentioning

confidence: 96%

Stellar evolution with rotation

Meynet

Maeder

2004

A&A

508

553

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Abstract. Grids of models of massive stars (M ≥ 20 M ) with rotation are computed for metallicities Z ranging from that of the Small Magellanic Cloud (SMC) to that of the Galactic Centre. The hydrostatic effects of rotation, the rotational mixing and the enhancements of the mass loss rates by rotation are included. The evolution of the surface rotational velocities of the most massive O-stars mainly depends on the mass loss rates and thus on the initial Z value. The minimum initial mass for a star for entering the Wolf-Rayet (WR) phase is lowered by rotation. For all metallicities, rotating stars enter the WR phase at an earlier stage of evolution and the WR lifetimes are increased, mainly as a result of the increased duration of the eWNL phase. Models of WR stars predict in general rather low rotation velocities (<50 km s −1 ) with a few possible exceptions, particularly at metallicities lower than solar where WR star models have in general faster rotation and more chance to reach the break-up limit. The properties of the WR populations as predicted by the rotating models are in general in much better agreement with the observations in nearby galaxies. Some possible remaining difficulties in these comparisons are mentioned. The evolution of the chemical abundances is largely influenced by rotation in all phases from the MS phase to the WN and WC phases. We also show that the interval of initial masses going through the LBV stage is changing with Z and Ω. The observed variation with metallicity of the fractions of type Ib/Ic supernovae with respect to type II supernovae as found by Prantzos & Boissier (2003) is very well reproduced by the rotating models, while non-rotating models predict much too low ratios. This indicates that the minimum initial masses of single stars going through a WR phase are consistently predicted. At Z = 0.040, stars with initial masses above 50 M reach a final mass at the time of supernova explosion between 5 and 7.5 M , while at Z = 0.004, like in the SMC, the final masses of stars are in the range of 17-29 M . On the whole, rotation appears to be an essential parameter even for the WR properties. Detailed tables describing the evolutionary tracks are available on the web.

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Cited by 24 publications

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Presolar He and Ne Isotopes in Single Circumstellar SiC Grains

Presolar He and Ne Isotopes in Single Circumstellar SiC Grains

The Phosphorus, Sulfur, Argon, and Calcium Isotopic Composition of the Galactic Cosmic Ray Source

Stellar evolution with rotation

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