2013A&A...560A...6G


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.16CEST19:42:34

2013A&A...560A...6G - Astronomy and Astrophysics, volume 560A, 6-6 (2013/12-1)

Stellar mass-loss near the Eddington limit. Tracing the sub-photospheric layers of classical Wolf-Rayet stars.

GRAEFENER G. and VINK J.S.

Abstract (from CDS):

Towards the end of their evolution, hot massive stars develop strong stellar winds and appear as emission line stars, such as Wolf-Rayet (WR) stars or luminous blue variables (LBVs). The quantitative description of the mass loss in these important pre-supernova phases is hampered by unknowns, such as clumping and porosity due to an inhomogeneous wind structure and by an incomplete theoretical understanding of optically thick stellar winds. Even the stellar radii in these phases are badly understood since they are often variable (LBVs) or deviate from theoretical expectations (WR stars). In this work we investigate the conditions in deep atmospheric layers of WR stars to find out whether they comply with the theory of optically thick winds and whether we find indications of clumping in these layers. We used a new semi-empirical method to determine sonic-point optical depths, densities, and temperatures for a large sample of WR stars of the carbon (WC) and oxygen (WO) sequence. Based on an artificial model sequence we investigated the reliability of our method and its sensitivity to uncertainties in stellar parameters. We find that the WR stars in our sample obey an approximate relation with Prad/Pgas≃80 at the sonic point. This ``wind condition'' is ubiquitous for radiatively driven, optically thick winds, and it sets constraints on possible wind/envelope solutions affecting radii, mass-loss rates, and clumping properties. Our results suggest that the presence of an optically thick wind may force many stars near the Eddington limit to develop clumped, radially extended sub-surface zones. The clumping in these zones is most likely sustained by the non-linear strange-mode instability and may be the origin of the observed wind clumping. The properties of typical late-type WC stars comply with this model. Solutions without sub-surface clumping and inflation are also possible but require compact stars with comparatively low mass-loss rates. These objects may resemble the small group of WO stars with their exceptionally hot stellar temperatures and highly ionized winds.

Abstract Copyright:

Journal keyword(s): stars: Wolf-Rayet - stars: early-type - stars: atmospheres - stars: mass-loss - stars: variables: S Doradus - stars: interiors

Simbad objects: 51

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Number of rows : 51

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 HD 16523 WR* 02 41 11.6752293070 +56 43 49.735743590 10.03 10.34 9.99     WC6 123 0
2 HD 17638 WR* 02 52 11.6616623898 +56 56 07.129636750 10.99 10.86 10.41     WC6 109 0
3 HD 32257 WR* 04 56 02.8932766544 -69 27 21.547497496 13.441 13.962 14.23 14.31 14.514 WC 45 0
4 HD 32125 WR* 04 56 11.0963828140 -66 17 33.055645578 13.704 14.295 14.33   14.618 WC 49 0
5 HD 32402 WR* 04 57 24.0824729521 -68 23 57.122171327   12.53 12.69 13.24   WC 69 0
6 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14838 1
7 HD 37026 WR* 05 30 12.1637558730 -67 26 08.329160840 12.853 13.16 13.53 13.56 13.856 WC 68 0
8 HD 37680 WR* 05 34 19.2497853756 -69 45 10.298101295 12.807 12.98 13.25 13.21 13.490 WC 67 1
9 HD 269888 WR* 05 37 44.6347648981 -69 14 25.676649551 14.413 14.772 14.628 14.81 14.761 WR 40 0
10 * gam02 Vel WR* 08 09 31.95013 -47 20 11.7108 0.64 1.58 1.83 1.85 2.00 WC8+O7.5III-V 840 0
11 Ve 6-15 WR* 08 49 52.9567193962 -45 10 24.003480427   13.83 12.93 12.72   WC6 35 0
12 HD 76536 WR* 08 54 59.1670924993 -47 35 32.662255423 9.04 9.13 8.80 9.52   WC 113 0
13 HD 79573 WR* 09 13 11.7691173632 -50 06 25.521002105 12.30 11.80 10.69 10.52   WC6 72 0
14 HD 88500 WR* 10 10 31.9111494342 -60 38 42.417239257   10.84 10.65 10.67   WC5 76 0
15 HD 92809 WR* 10 41 38.3243559450 -58 46 18.721755258 8.95 9.28 9.03 9.60   WC6 137 0
16 LSWR 4 WR* 10 44 38.0516299704 -58 48 28.804895283   14.95 13.70 13.39   WC6+OB 34 0
17 HD 95435 WR* 11 00 00.7206077473 -57 48 59.273968690   11.78 11.61 11.67   WC6 54 0
18 WR 38 WR* 11 05 46.43 -61 13 48.8     14.66     WC4 38 2
19 WRAY 16-97 WR* 11 38 05.0965069040 -62 16 01.900568734   14.98 13.92 13.60   WC6 37 2
20 Sand 2 * 12 02 49.7231612280 +28 51 23.162335682   17.25 15.80     M3: 10 0
21 HD 115473 WR* 13 18 27.9938060343 -58 08 13.603603690 9.09 9.68 9.00 9.72   WC5 104 0
22 HD 117297 WR* 13 30 53.2511996037 -62 04 51.856386987 10.81 11.10 10.90 10.70   WC8 87 0
23 WR 56 WR* 13 33 45.3813582944 -64 07 31.275908021   12.75 14.00 13.60   WC6 38 0
24 HD 119078 WR* 13 43 16.3585170935 -67 24 04.971391283 9.11 9.737 9.40 10.08   WC7/8 97 0
25 WRAY 16-136 WR* 13 49 32.5620701404 -61 31 42.271625889 12.09 11.99 11.69 12.72   WC9d 45 1
26 HD 121194 WR* 13 55 48.4480921364 -61 09 48.458279758 14.34 13.65 12.20 12.12 10.31 WC8 37 0
27 WR 64 WR* 14 56 55.1948891854 -55 50 58.552033391   15.11 15.08     WC6.5 23 0
28 WRAY 15-1297 WR* 15 13 41.7098852670 -59 11 44.971320833 16.25 15.58 13.65 13.11   WC9d+OB? 57 0
29 WRAY 16-172 WR* 15 18 20.7582942767 -59 38 17.323706383 14.83 14.52 13.28 12.99   WC7 46 2
30 HD 136488 WR* 15 24 11.3111665819 -62 40 37.575311536 9.15 9.514 9.10 9.71   WC9d+OB? 112 0
31 WRAY 15-1581 WR* 16 59 02.1891502339 -45 43 10.016531285   16.34 14.49 14.31 11.95 WC9 36 0
32 MR 66 WR* 17 02 40.3825863866 -45 59 15.455194984   13.62 12.07 11.77   WC9 59 0
33 CPD-33 4347 WR* 17 18 49.7246525731 -33 57 41.389875461   13.93 12.56 12.21   WN8/WC9 61 0
34 HD 156385 WR* 17 19 29.9012727857 -45 38 23.874796927 6.55 6.97 6.92 8.11   WC7 153 0
35 HD 157451 WR* 17 25 23.2779746024 -43 29 31.469615959 10 10.59 10.20 10.46   WC9 82 0
36 MR 74 WR* 17 36 19.8953384759 -33 26 12.274561705 16.01 14.87 13.18 12.99   WC9 82 1
37 V* V3893 Sgr WR* 17 45 47.5403190596 -26 10 26.777772852   15.13 14.20 14.23   WR 106 1
38 NAME Arches Cluster Cl* 17 45 50.5 -28 49 28           ~ 630 0
39 HD 164270 WR* 18 01 43.1452971756 -32 42 55.161881733 8.52 8.97 8.74 9.51   WC9d+? 212 0
40 HD 313643 WR* 18 04 43.6647304100 -21 09 30.557213987 13.58 13.27 12.02 11.67   WC9d 87 0
41 HD 165763 WR* 18 08 28.4691215895 -21 15 11.182287576 7.16 7.54 7.82 8.55   WC6 266 0
42 HD 169010 WR* 18 23 16.3425134513 -13 43 26.103469647 13.53 12.99 12.02 11.95   WC 75 0
43 MR 88 WR* 18 31 02.5171189240 -06 35 49.629115130   15.34 14.19     WC9 37 0
44 THA 20-1 WR* 18 39 17.9036019736 -10 05 30.898511525   13.07 12.43     WC9d 50 0
45 EM* AS 320 WR* 18 44 13.1527220304 -03 47 57.779718279 13.7 13.340 13.983     WC9d 110 0
46 HD 190002 WR* 20 01 39.7319767776 +32 34 17.995790084 13.83 13.42 12.67     WC7 63 0
47 HD 192103 WR* 20 11 53.5274946554 +36 11 50.523501826 7.77 8.13 8.11     WC8+OB: 317 0
48 WR 142 WR* 20 21 44.3438534563 +37 22 30.543604467   14.39 12.99 12.73 11.04 WO2 120 0
49 MR 110 WR* 20 32 03.0200838781 +41 15 20.497485753   15.99 13.97     WC5 72 0
50 WR 150 WR* 21 50 05.5724802971 +50 42 24.715095369   14.00 13.47     WC5 29 0
51 HD 213049 WR* 22 27 17.8189297929 +56 15 11.768608852   11.71 10.99     WC6 79 0

    Equat.    Gal    SGal    Ecl

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2020.07.16-19:42:34

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