Query : 2003A&A...404..975M

2003A&A...404..975M - Astronomy and Astrophysics, volume 404, 975-990 (2003/6-4)

Stellar evolution with rotation. X. Wolf-Rayet star populations at solar metallicity.


Abstract (from CDS):

We examine the properties of Wolf-Rayet (WR) stars predicted by models of rotating stars taking account of the new mass loss rates for O-type stars and WR stars (Vink et al., 2000A&A...362..295V, 2001A&A...369..574V; Nugis & Lamers, 2000A&A...360..227N) and of the wind anisotropies induced by rotation. We find that the rotation velocities v of WR stars are modest, i.e. about 50km/s, not very dependent on the initial v and masses. For the most massive stars, the evolution of v is very strongly influenced by the values of the mass loss rates; below ∼12M the evolution of rotation during the MS phase and later phases is dominated by the internal coupling. Massive stars with extreme rotation may skip the LBV phase. Models having a typical v for the O-type stars have WR lifetimes on the average two times longer than for non-rotating models. The increase of the WR lifetimes is mainly due to that of the H-rich eWNL phase. Rotation allows a transition WN/WC phase to be present for initial masses lower than 60M. The durations of the other WR subphases are less affected by rotation. The mass threshold for forming WR stars is lowered from 37 to 22M for typical rotation. The comparisons of the predicted number ratios WR/O, WN/WC and of the number of transition WN/WC stars show very good agreement with models with rotation, while this is not the case for models with the present-day mass loss rates and no rotation. As to the chemical abundances in WR stars, rotation brings only very small changes for WN stars, since they have equilibrium CNO values. However, WC stars with rotation have on average lower C/He and O/He ratios. The luminosity distribution of WC stars is also influenced by rotation.

Abstract Copyright:

Journal keyword(s): stars: evolution - stars: rotation - stars: Wolf-Rayet

Simbad objects: 5

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Number of rows : 5
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 HD 269485 WR* 05 24 24.1935093984 -68 31 35.592471948 13.593 14.40 14.46 14.39 14.574 WN4b/WCE+OB 57 0
2 HD 62910 WR* 07 44 58.2217347768 -31 54 29.554957188 10.08 10.44 10.10 10.17   WN6/WC4 126 0
3 HD 165763 WR* 18 08 28.4692108104 -21 15 11.183076540 7.16 7.54 7.82 8.55   WC6 280 0
4 HD 192163 WR* 20 12 06.5418877464 +38 21 17.784181008 7.12 7.49 7.50     WN6(h)-s 541 0
5 EM* AS 422 WR* 20 32 06.2786571432 +40 48 29.527101576   13.46 11.83     WN7o/CE+O7V(f) 100 0

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