2015A&A...581A..21H


C.D.S. - SIMBAD4 rel 1.7 - 2019.12.09CET22:51:35

2015A&A...581A..21H - Astronomy and Astrophysics, volume 581A, 21-21 (2015/9-1)

Wolf-Rayet stars in the Small Magellanic Cloud. I. Analysis of the single WN stars.

HAINICH R., PASEMANN D., TODT H., SHENAR T., SANDER A. and HAMANN W.-R.

Abstract (from CDS):

Wolf-Rayet (WR) stars have a severe impact on their environments owing to their strong ionizing radiation fields and powerful stellar winds. Since these winds are considered to be driven by radiation pressure, it is theoretically expected that the degree of the wind mass-loss depends on the initial metallicity of WR stars. Following our comprehensive studies of WR stars in the Milky Way, M31, and the LMC, we derive stellar parameters and mass-loss rates for all seven putatively single WN stars known in the SMC. Based on these data, we discuss the impact of a low-metallicity environment on the mass loss and evolution of WR stars. The quantitative analysis of the WN stars is performed with the Potsdam Wolf-Rayet (PoWR) model atmosphere code. The physical properties of our program stars are obtained from fitting synthetic spectra to multi-band observations. In all SMC WN stars, a considerable surface hydrogen abundance is detectable. The majority of these objects have stellar temperatures exceeding 75kK, while their luminosities range from 105.5 to 106.1L. The WN stars in the SMC exhibit on average lower mass-loss rates and weaker winds than their counterparts in the Milky Way, M31, and the LMC. By comparing the mass-loss rates derived for WN stars in different Local Group galaxies, we conclude that a clear dependence of the wind mass-loss on the initial metallicity is evident, supporting the current paradigm that WR winds are driven by radiation. A metallicity effect on the evolution of massive stars is obvious from the HRD positions of the SMC WN stars at high temperatures and high luminosities. Standard evolution tracks are not able to reproduce these parameters and the observed surface hydrogen abundances. Homogeneous evolution might provide a better explanation for their evolutionary past.

Abstract Copyright:

Journal keyword(s): stars: Wolf-Rayet - Magellanic Clouds - stars: early-type - stars: atmospheres - stars: winds, outflows - stars: mass-loss

Simbad objects: 18

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Number of rows : 18

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 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 10608 1
2 SMC AB 1 WR* 00 43 42.3082179697 -73 28 55.260280231 14.33 15.20 15.24   15.21 WN3+O4: 27 0
3 SMC AB 10 WR* 00 45 28.9080513213 -73 04 45.623440187 14.69 15.81 15.55   15.96 WN3ha 18 0
4 SMC AB 2 WR* 00 48 30.8442971820 -73 15 45.831809104 13.23 14.23 14.43   14.52 WN4.5/O3 45 0
5 LHA 115-N 28 Em* 00 48 34.5 -73 15 40           ~ 12 0
6 LIN 160 WR* 00 50 43.43 -73 27 05.7 12.363 13.304 13.426   13.55 WN6 44 0
7 SMC AB 11 WR* 00 52 07.39 -72 35 38.6   15.593 15.816   16.011 WN4h:a 20 0
8 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 9134 1
9 SMC AB 9 WR* 00 54 32.16 -72 44 35.6 14.31 15.26 15.43   15.69 WN3ha 25 0
10 HD 5980 WR* 00 59 26.5847969465 -72 09 53.927725716   11.13 11.31   11.029 WN4+O7I: 355 1
11 SMC AB 12 WR* 01 02 52.4009598642 -72 06 52.532173554   16 16.08     WN3ha 19 0
12 LIN 547 WR* 01 31 04.1366633984 -73 25 03.786377386   12.75 12.90     WO4+O4V 91 0
13 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 5402 1
14 Brey 19a WR* 05 14 57.2839962735 -71 36 18.314627217   14.87 15.10 15.49   WN4ha 17 0
15 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14380 1
16 Brey 63a WR* 05 35 52.4534325950 -68 55 08.630284898 14.703 15.438 15.584   15.670 WN3(h)a 14 0
17 RMC 136 Cl* 05 38 42.396 -69 06 03.36   9.63 9.50     ~ 1680 2
18 NAME Arches Cluster Cl* 17 45 50.5 -28 49 28           ~ 615 0

    Equat.    Gal    SGal    Ecl

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2019.12.09-22:51:35

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