2010A&A...516A..78N


Query : 2010A&A...516A..78N

2010A&A...516A..78N - Astronomy and Astrophysics, volume 516, A78-78 (2010/6-2)

The population of OB supergiants in the starburst cluster Westerlund 1.

NEGUERUELA I., CLARK J.S. and RITCHIE B.W.

Abstract (from CDS):

After leaving the main sequence, massive stars undergo complex evolution, a process that is still poorly understood. With a population of hundreds of OB stars, the starburst cluster Westerlund 1 offers an unparallelled environment to study their evolutionary tracks. We characterise a large sample of evolved OB stars in the cluster, with the aim of determining cluster parameters and place stars in an evolutionary sequence. We used the FORS2 instrument on the VLT to obtain intermediate-resolution spectroscopy over the range 5800-9000Å of about a hundred stars selected as likely members of the cluster based on their photometry. We developed criteria for their spectral classification using only spectral features in the range observed. We discuss these criteria, useful for spectral classification of early-type stars in the GAIA spectral region, in the appendix. Using these criteria, we obtain spectral classifications, probably accurate to one subtype, for 57 objects, most of which had no previous classification or a generic classification. We identify more than 50 objects as OB supergiants. We find almost 30 luminous early-B supergiants and a number of less luminous late-O supergiants. In addition, we find a few mid B supergiants with very high luminosity, some of them displaying signs of heavy mass loss. All these stars form a sequence compatible with theoretical evolutionary tracks. In addition, two early B supergiants also show indication of heavy mass loss and may represent the evolutionary phase immediately prior to the Wolf-Rayet stage. We investigate cluster properties using the spectral types and existing photometry. We find that the reddening law to the cluster does not deviate strongly from standard, even though extinction is quite variable, with an average value AV=10.8. Though evolutionary tracks for high-mass stars are subject to large uncertainties, our data support an age of >5Myr and a distance d≃5kpc for Westerlund 1. The spectral types observed are compatible with a single burst of star formation (the age range is very unlikely to be >1Myr). Westerlund 1 shows its potentiality as a laboratory for massive star evolution, which can be fulfilled by detailed study of the population presented here.

Abstract Copyright:

Journal keyword(s): stars: early-type - stars: evolution - open clusters and associations: individual: Westerlund 1

Simbad objects: 85

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Number of rows : 85
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 HD 32034 s*b 04 55 11.0851969440 -67 10 10.411470552 9.13 9.756 9.715 9.70 9.51 B9Iae 72 0
2 HD 33579 sg* 05 05 55.5114721104 -67 53 10.932988848   9.32 9.13     A2Ia+ 136 0
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16528 1
4 HD 269781 sg* 05 34 22.4676706872 -67 01 23.569790196 9.34 9.94 9.87 9.74 9.67 A0Iae 54 0
5 HD 80077 s*b 09 15 54.7869062472 -49 58 24.575734452 10.50 10.29 9.00 7.89   B2Ia+e 136 0
6 HD 90177 s*b 10 22 53.8430096928 -59 37 28.363616256 9.16 9.66 8 8.15   LBV 321 0
7 * eta UMa PM* 13 47 32.43776 +49 18 47.7602 0.99 1.67 1.86 1.98 2.16 B3V 597 0
8 HD 148688 s*b 16 31 41.7687715992 -41 49 01.732565676 5.16 5.78 5.39 5.05 4.70 B1Iaeqp 156 0
9 Cl* Westerlund 1 W 86 * 16 46 57.1589551488 -45 50 09.938630292   22.9 18.76 16.43 14.00 O9.5Ib 9 0
10 Cl* Westerlund 1 W 373 s*b 16 46 57.7255119168 -45 53 20.035273668       14.741 12.318 B0Iab 10 0
11 Cl* Westerlund 1 W 228b * 16 46 58.0541909424 -45 53 00.932401356           O9Ib 10 0
12 Cl* Westerlund 1 W 55 s*b 16 46 58.4205093840 -45 51 31.294157724   21.6 18.030 15.283 12.758 B0Ia 15 0
13 Cl* Westerlund 1 W 56b * 16 46 58.8667320511 -45 51 45.947165816   22.8 18.88 16.36 13.76 O9.5Ib 10 0
14 Cl* Westerlund 1 W 56a s*b 16 46 58.9489660320 -45 51 48.908566764   21.7 17.46 14.81 12.15 B1.5Ia 12 0
15 Cl* Westerlund 1 W 84 * 16 46 59.0490595608 -45 50 28.293859689   21.3 17.82 15.60 13.63 O9.5Ib 11 0
16 Cl* Westerlund 1 W 2 s*b 16 46 59.7175806088 -45 50 51.190946043   20.4 16.978 14.287 11.771 B2Ia 16 0
17 Cl* Westerlund 1 W 53 s*b 16 47 00.3870731784 -45 51 31.849633872   22.9 18.51 15.80 13.13 OBIa+OBIa 9 0
18 Cl* Westerlund 1 W 21 s*b 16 47 01.1124528826 -45 51 13.583454380   22.5 18.41 15.619 12.861 B0.5Ia 10 0
19 Cl* Westerlund 1 W 50b * 16 47 01.1722949256 -45 50 26.807447580   22.8 19.66 17.21 14.69 O9III 8 0
20 Cl* Westerlund 1 W 57 s*b 16 47 01.3600091808 -45 51 45.804003408   20.7 16.877 13.83 11.13 B4Ia 19 0
21 Cl* Westerlund 1 W 232 s*b 16 47 01.41 -45 52 34.9   21.3 17.53 14.98 12.45 B0Iab 6 0
22 Cl* Westerlund 1 W 78 s*b 16 47 01.5500127120 -45 49 57.922981500   21.0 17.413 14.621 12.04 B1Ia 11 0
23 Cl* Westerlund 1 W 52 s*b 16 47 01.8449474352 -45 51 29.434394880   21.8 17.876 14.745 12.065 B1.5Ia 11 0
24 Cl* Westerlund 1 W 49 s*b 16 47 01.9027544712 -45 50 31.660433592   22.6 18.76 16.392 13.638 B0Iab 12 0
25 Cl* Westerlund 1 W 24 s*b 16 47 02.1561069816 -45 51 12.581922276   23.0 18.71 15.96 13.24 O9Iab 17 0
26 Cl* Westerlund 1 W 11 s*b 16 47 02.2390158456 -45 50 47.186514564   21.2 17.508 14.599 11.898 B2Ia 15 0
27 Cl* Westerlund 1 W 61a s*b 16 47 02.2999985640 -45 51 41.772039336   21.2 17.506 14.633 12.01 B0.5Ia 14 0
28 Cl* Westerlund 1 W 62a * 16 47 02.5204504462 -45 51 38.051924860           B0.5Ib 7 0
29 Cl* Westerlund 1 W 61b s*b 16 47 02.5662082776 -45 51 41.864431536   22.7 18.59 16.00 13.31 O9.5Iab 15 0
30 Cl* Westerlund 1 W 23a s*b 16 47 02.5776330614 -45 51 08.902293204   22.1 18.316 14.986 12.081 B2Ia+B:I? 16 0
31 Cl* Westerlund 1 W 40a * 16 47 02.6756695632 -45 50 50.489371572   22.2 18.05 15.38 12.73 ~ 6 0
32 Cl* Westerlund 1 W 41 s*b 16 47 02.7105467198 -45 50 56.972033345   21.3 17.87 15.39 12.78 O9Iab 13 0
33 Cl* Westerlund 1 W 38 s*b 16 47 02.8628531323 -45 50 46.145964246   23.2 19.10 16.47 13.81 O9Iab 10 0
34 Cl* Westerlund 1 W 6b * 16 47 02.9390384334 -45 50 22.480676456   23.6 20.20 17.91 15.25 O9.5III 9 0
35 WR 77f WR* 16 47 02.9772955944 -45 50 19.713734556   21.552 17.792 15.035 12.508 WN10-11h 29 0
36 Cl* Westerlund 1 W 6a s*b 16 47 03.0477797919 -45 50 23.748131606   22.2 18.41 15.80 13.16 B0.5Iab 17 0
37 Cl* Westerlund 1 W 54 s*b 16 47 03.06 -45 51 30.5           B0.5Iab 5 0
38 Cl* Westerlund 1 W 42 s*b 16 47 03.2521856424 -45 50 52.195013052         10.764 B9Ia+ 16 0
39 Cl* Westerlund 1 W 10 s*b 16 47 03.3405625992 -45 50 34.603317456   22.720 18.516 15.257   O9.5/B0.5Iae 16 0
40 Cl* Westerlund 1 W 63a s*b 16 47 03.4010407564 -45 51 57.852956239   22.6 18.56 16.20 13.68 B0Iab 7 0
41 Cl* Westerlund 1 W 43b s*b 16 47 03.5274881368 -45 50 56.525344948           B1Ia 5 0
42 Cl* Westerlund 1 W 43a s*b 16 47 03.5568442836 -45 50 57.728053296   22.8 18.05 15.22 12.26 B0Ia 11 0
43 Cl* Westerlund 1 W 46b * 16 47 03.61 -45 51 20.0           O9.5Ib 5 0
44 Cl* Westerlund 1 W 7 s*b 16 47 03.6281794392 -45 50 14.365482036   20.0 15.972 12.73 9.99 B5Ia+ 26 0
45 Cl* Westerlund 1 BKS F s*y 16 47 03.6850109472 -45 50 43.536110712     15.05     F5Ia+ 20 0
46 Cl* Westerlund 1 W 43c * 16 47 03.7585229164 -45 50 58.441368189   20.4 18.35 16.18 13.66 O9Ib 8 0
47 Cl* Westerlund 1 W 31 s*b 16 47 03.7862784096 -45 50 40.366601376           B0I+OB 9 0
48 Cl* Westerlund 1 W 65 * 16 47 03.8973039959 -45 51 46.495252717   22.9 18.73 16.27 13.68 O9Ib 10 0
49 Cl* Westerlund 1 W 46a s*b 16 47 03.9147803107 -45 51 19.743263385   23.0 18.55 15.537 12.499 B1Ia 15 0
50 Cl Westerlund 1 Cl* 16 47 04.00 -45 51 04.9           ~ 527 0
51 Cl* Westerlund 1 W 30 ** 16 47 04.1126936513 -45 50 39.164057275   22.4 18.45 15.80 13.20 O4-5Ia+ 21 0
52 Cl* Westerlund 1 W 33 s*b 16 47 04.1256274968 -45 50 48.488202564   20.090 15.61 12.803 10.04 B5Ia+ 21 0
53 Cl* Westerlund 1 W 60 s*b 16 47 04.1335644720 -45 51 52.259535324   22.8 18.50 16.041 13.384 B0Iab 17 0
54 Cl* Westerlund 1 W 9 WR* 16 47 04.1419806984 -45 50 31.311670632   21.8 17.47 14.47 11.74 sgB[e] 51 0
55 Cl* Westerlund 1 W 35 s*b 16 47 04.2023052264 -45 50 53.727473868   22.7 18.59 16.00 13.31 O9Iab 12 0
56 WR 77k WR* 16 47 04.2072122904 -45 51 07.177760892   22.6 18.86 15.61 12.52 WN7 24 0
57 Cl* Westerlund 1 CN H WR* 16 47 04.2489212873 -45 51 20.211867845           WC9d 13 0
58 Cl* Westerlund 1 W 34 s*b 16 47 04.3941837044 -45 50 47.222852634   22.1 18.15 15.40 12.69 B0Ia 9 0
59 Cl* Westerlund 1 W 29 s*b 16 47 04.4118843432 -45 50 39.933732768   22.6 18.66 16.02 13.38 O9.5/B0.5Ia 10 0
60 Cl* Westerlund 1 W 238 s*b 16 47 04.4263582176 -45 52 27.788277972   21.4 17.820 14.98 12.45 B1Iab 14 0
61 Cl* Westerlund 1 W 28 s*b 16 47 04.6646286552 -45 50 38.503394520   20.9 17.146 14.303 11.64 B2Ia 13 0
62 Cl* Westerlund 1 W 8 s*y 16 47 04.7959778348 -45 50 25.013789709   19.9 15.913 12.64 9.89 F8Ia+ 20 0
63 Cl* Westerlund 1 W 19 s*b 16 47 04.8672458112 -45 50 59.295902136   22.6 18.784 15.366 12.452 B1Ia 15 0
64 Cl* Westerlund 1 W 8b s*b 16 47 04.95 -45 50 26.7           B1.5Ia 8 0
65 Cl* Westerlund 1 W 27 s*b 16 47 05.1550269480 -45 50 41.418677508   21.5 17.94 15.35 12.80 O9I+OI 11 0
66 2MASS J16470540-4550367 s*r 16 47 05.4076906176 -45 50 36.617071668   22.1 16.79 12.63 9.19 M2-5Ia 33 0
67 Cl* Westerlund 1 W 18 s*b 16 47 05.7082494087 -45 50 50.480383849   21.2 17.610 14.898 12.228 B0.5Ia 9 0
68 Cl* Westerlund 1 W 25 s*b 16 47 05.7882476736 -45 50 33.368306136   21.9 17.85 15.22 12.61 O9Iab 9 0
69 Cl* Westerlund 1 W 39a * 16 47.1 -45 51           ~ 3 0
70 Cl* Westerlund 1 W 37 * 16 47 06.01 -45 50 47.4   22.8 19.11 16.40 13.65 O9Ib 6 0
71 Cl* Westerlund 1 W 17 s*b 16 47 06.2490500592 -45 50 49.292687328   22.7 18.87 16.19 13.56 O9Iab 16 0
72 Cl* Westerlund 1 W 265 s*y 16 47 06.2785465416 -45 49 23.774098692   22.0 17.739 13.62 10.54 F1-5Ia+ 23 0
73 Cl* Westerlund 1 W 13 s*b 16 47 06.4540771320 -45 50 26.072579796   21.1 17.19 14.63 12.06 B0.5Ia++OB 32 0
74 Cl* Westerlund 1 W 15 * 16 47 06.6306037464 -45 50 29.723762580   22.8 18.96 16.38 13.75 O9Ib 24 0
75 Cl* Westerlund 1 W 74 s*b 16 47 07.0783996992 -45 50 13.086504168       15.835 13.312 O9.5Iab 13 0
76 Cl* Westerlund 1 W 243 s*b 16 47 07.5040736160 -45 52 29.123491188   19.873 15.730     LBV 57 0
77 Cl* Westerlund 1 W 71 s*b 16 47 08.4584673360 -45 50 49.338181284   21.5 17.531 14.158 11.16 B2.5Ia 20 0
78 Cl* Westerlund 1 W 70 s*b 16 47 09.3836656992 -45 50 49.668960804   21.2 16.88 14.10 11.352 B3Ia 16 0
79 PSR J1647-4552 Psr 16 47 10.18 -45 52 16.7           ~ 193 1
80 * iot Her bC* 17 39 27.8860861 +46 00 22.800110 2.940 3.630 3.800     B3IV 440 1
81 HD 186568 * 19 43 51.4515233208 +34 09 45.809025300 5.72 5.979 6.053     B8III 66 0
82 HD 190603 s*b 20 04 36.1742825304 +32 13 06.953333016 5.73 6.19 5.65 5.13 4.71 B1.5Ia 336 0
83 HD 199478 s*b 20 55 49.8039729168 +47 25 03.564093468 5.79 6.12 5.64 5.16 4.78 B8Ia 221 0
84 * 6 Cas ** 23 48 50.17052 +62 12 52.2577       6.60   A2.5(I)+O9.8II 187 0
85 Cl* Westerlund 1 W 12b ? ~ ~           ~ 2 0

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2023.02.07-15:15:27

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