2004A&A...417..217T


C.D.S. - SIMBAD4 rel 1.7 - 2020.08.04CEST21:42:22

2004A&A...417..217T - Astronomy and Astrophysics, volume 417, 217-234 (2004/4-1)

Understanding B-type supergiants in the low metallicity environment of the SMC.

TRUNDLE C., LENNON D.J., PULS J. and DUFTON P.L.

Abstract (from CDS):

Spectroscopic analyses of 7 SMC B-type supergiants and 1 giant have been undertaken using high resolution optical data obtained on the vlt with uves. fastwind, a non-LTE, spherical, line-blanketed model atmosphere code was used to derive atmospheric and wind parameters of these stars as well as their absolute abundances. Mass-loss rates, derived from Hα profiles, are in poor agreement with metallicity dependent theoretical predictions. Indeed the wind-momenta of the SMC stars appear to be in good agreement with the wind-momentum luminosity relationship (WLR) of Galactic B-type stars, a puzzling result given that line-driven wind theory predicts a metallicity dependence. However the galactic stars were analysed using unblanketed model atmospheres which may mask any dependence on metallicity. A mean nitrogen enhancement of a factor of 14 is observed in the supergiants whilst only an enrichment of a factor of 4 is present in the giant, AV 216. Similar excesses in nitrogen are observed in O-type dwarfs and supergiants in the same mass range, suggesting that the additional nitrogen is produced while the stars are still on the main-sequence. These nitrogen enrichments can be reproduced by current stellar evolution models, which include rotationally induced mixing, only if large initial rotational velocities of 300km/s are invoked. Such large rotational velocities appear to be inconsistent with observed vsini distributions for O-type stars and B-type supergiants. Hence it is suggested that the currently available stellar evolution models require more efficient mixing for lower rotational velocities.

Abstract Copyright:

Journal keyword(s): stars: atmospheres - stars: early-type - stars: supergiants - stars: mass-loss - stars: abundances - stars: evolution

Simbad objects: 10

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Number of rows : 10

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 SK 13 s*b 00 47 12.2161275650 -73 06 33.114896034   12.52 12.48     B2.5Ia 66 0
2 BBB SMC 259 s*b 00 47 38.7402682564 -73 07 48.852687037   12.17 12.24     B5Ia 31 0
3 AzV 104 s*b 00 51 38.4280173584 -72 48 06.081256145 12.053 13.064 13.226   13.57 B0.5Ia 28 0
4 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9475 1
5 SK 73 s*b 00 58 35.7845024129 -72 16 25.021114826 11.73 12.63 12.66   12.69 B2Ia 26 0
6 SK 76 s*b 00 58 55.6261672908 -72 32 08.470311732 11.64 12.65 12.75   12.84 BN0Ia 39 0
7 AzV 216 Al* 00 58 59.1377106891 -72 44 34.096505158 13.11 14.15 14.32 14.49 14.56 B0IIw 34 0
8 RMC 36 s*b 01 04 49.3496844150 -72 06 21.744673104 10.57 11.34 11.36     B3Ia 49 0
9 WDG 1 s*b 01 41 42.0688016266 -73 50 38.187131393   11.86 11.84     B1.5Ia 55 0
10 NAME NGC 1705 CL* A Cl* 04 54 13.24 -53 21 36.1           ~ 40 0

    Equat.    Gal    SGal    Ecl

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2020.08.04-21:42:22

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