2009A&A...499..291K


C.D.S. - SIMBAD4 rel 1.7 - 2020.01.20CET13:11:07

2009A&A...499..291K - Astronomy and Astrophysics, volume 499, 291-299 (2009/5-3)

Parameters of galactic early B supergiants. The influence of the wind on the interstellar extinction determination.

KRAUS M., BORGES FERNANDES M. and KUBAT J.

Abstract (from CDS):

The interstellar extinction, E(B-V), of OB supergiants is usually derived from the observed color index, (B-V), in comparison with the intrinsic one. This method works properly only if the stellar wind does not influence the optical continuum emission. Over the past years, many OB supergiants have been found to have wind-velocity distributions with rather high β values; i.e., their winds are only slowly accelerating, resulting in relative density enhancements within the wind-continuum forming region. It has been found that these kinds of winds might indeed influence the total continuum emission even at optical wavelengths. We investigate the influence of the wind on the observed color indices of OB supergiants, in order to distinguish between interstellar and circumstellar extinction contributions. We first tested the influence of the wind on the UBV band fluxes of a model O supergiant star with artificial winds of different β values and a fixed interstellar extinction value. From the UBV magnitudes of these systems, the apparent interstellar extinction was then derived by calculating the values of E(B-V), from the (B-V) as well as from the (U-B) color index. Then we turned to a sample of galactic early-type B supergiants for which the stellar and wind parameters are known. All except one of these stars have β values higher than 1.0, which makes this set the most suitable one for our investigation. We calculated each star's wind contribution to the BV band fluxes. The observed magnitudes were corrected for the wind contributions, and the interstellar extinctions were derived and compared with those derived purely from the (B-V) color index. From our model supergiant, we find that with increasing β the wind starts to influence the observable color indices. The wavelength dependence of the wind contribution is thereby different from that of the interstellar extinction contribution. Thus, the interstellar extinction values derived from the two color indices of our reddened star plus wind systems disagree. This effect is stronger for higher β. In addition, E(B-V) derived from the (B-V) color index always overestimates the real interstellar extinction. This trend is also found for the investigated B supergiant sample. Consequently, the luminosities of these stars are systematically overestimated. Our wind model always computes lower limits to the real wind contributions. This means that the real interstellar extinction values, hence the stellar luminosities of the studied B supergiant sample, might well be lower.

Abstract Copyright:

Journal keyword(s): stars: early-type - stars: fundamental parameters - supergiants - stars: winds, outflows

Simbad objects: 26

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Number of rows : 26

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 * kap Cas s*b 00 32 59.9911963 +62 55 54.417374 3.50 4.30 4.16 4.02 3.96 B1Ia 444 0
2 LHA 115-S 23 Em* 00 55 53.8117943063 -72 08 59.510230206 12.82 13.29 13.25   13.04 B8Ib[e] 31 1
3 HD 13854 s*b 02 16 51.7161542593 +57 03 18.880915822 6.10 6.76 6.48 6.14 5.95 B1Iab 203 0
4 HD 14134 s*b 02 19 04.4524770508 +57 08 07.798163786 6.63 7.00 6.5678   6.6876 B3Ia 195 0
5 HD 14143 * 02 19 13.9415940972 +57 10 09.233997883 6.71 7.16 6.7000     B3I 191 0
6 * 10 Per s*b 02 25 16.0286810463 +56 36 35.357178267 5.95 6.56 6.26 5.93 5.74 B2Ia 228 0
7 HD 14956 s*b 02 26 45.6957079560 +57 40 45.045880095 7.63 7.92 7.20 6.56 6.05 B1.5Ia 134 0
8 * alf Cam s*b 04 54 03.0103983 +66 20 33.636467 3.47 4.34 4.29 4.18 4.18 O9Ia 635 1
9 * eps Ori s*b 05 36 12.81335 -01 12 06.9089 0.48 1.51 1.69 1.76 1.93 B0Ia 856 0
10 * kap Ori s*b 05 47 45.3888404 -09 40 10.577707 0.87 1.88 2.06 2.09 2.27 B0.5Ia 545 0
11 * chi02 Ori s*b 06 03 55.1848402263 +20 08 18.441609669 4.24 4.91 4.63 4.32 4.10 B2Ia 427 0
12 * omi02 CMa s*b 07 03 01.4721150 -23 49 59.852308 2.14 2.94 3.02 3.01 3.10 B3Ia 304 0
13 * rho Leo s*b 10 32 48.6716770 +09 18 23.709445 2.780 3.720 3.870 3.90 4.06 B1Iab 509 0
14 HD 91943 Pu* 10 35 42.0070286836 -58 11 34.375764723 5.91 6.74 6.70 7.70   B0.7Ib 95 0
15 HD 91969 * 10 35 49.3175809360 -58 13 27.411203873 5.57 6.41 6.43 7.56   B0Ib 103 0
16 HD 94909 s*b 10 56 24.4659629041 -57 33 04.826803339 7.31 7.82 7.34 8.13   B0Ia 64 0
17 HD 115842 Em* 13 20 48.3389216362 -55 48 02.482627552 5.70 6.39 6.09 5.77 5.52 B0.5Ia/ab 141 0
18 HD 122879 V* 14 06 25.1577457205 -59 42 57.253857893 5.90 6.64 6.50 6.33 6.18 B0Ia 156 1
19 HD 148688 s*b 16 31 41.7695375461 -41 49 01.729591907 5.16 5.78 5.39 5.05 4.70 B1Iaeqp 152 0
20 HD 152235 s*b 16 53 58.8524252928 -41 59 39.573669251 6.47 6.92 6.38 5.84 5.42 B0.5Ia 174 0
21 * zet01 Sco s*b 16 53 59.7270104119 -42 21 43.313745214 4.80 5.31 4.79 4.32 3.86 B1Ia-0ek 345 0
22 HD 152234 s*b 16 54 01.8374467 -41 48 23.007764 4.92 5.64 5.45     B0.5Ia 179 0
23 * k Sco s*b 17 04 49.3525354906 -34 07 22.541655837 4.44 5.13 4.87 4.59 4.42 B2Iab 142 0
24 HD 190603 s*b 20 04 36.1744053423 +32 13 06.952102252 5.73 6.19 5.65 5.13 4.71 B1.5Ia 323 0
25 HD 194279 s*b 20 23 18.1650257662 +40 45 32.596789171 8.01 8.04 7.01 5.98 5.17 B2Ia 174 0
26 * 55 Cyg s*b 20 48 56.2911163453 +46 06 50.883966851 4.83 5.28 4.86 4.41 4.10 B4Ia 470 0

    Equat.    Gal    SGal    Ecl

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2020.01.20-13:11:07

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