2013AJ....145...46L

Query : 2013AJ....145...46L

2013AJ....145...46L - Astron. J., 145, 46 (2013/February-0)

The starburst cluster Westerlund 1: the initial mass function and mass segregation.

LIM B., CHUN M.-Y., SUNG H., PARK B.-G., LEE J.-J., SOHN S.T., HUR H. and BESSELL M.S.

Abstract (from CDS):

Westerlund 1 is the most important starburst cluster in the Galaxy due to its massive star content. We have performed BVIC and JKSphotometry to investigate the initial mass function (IMF). By comparing the observed color with the spectral-type-intrinsic-color relation, we obtain the mean interstellar reddening of < E(B - V) > = 4.19±0.23 and < E(J - KS ) > = 1.70±0.21. Due to the heavy extinction toward the cluster, the zero-age main sequence fitting method based on optical photometry proved to be inappropriate for the distance determination, while the near-infrared photometry gave a reliable distance to the cluster–3.8 kpc from the empirical relation. Using the recent theoretical stellar evolution models with rotation, the age of the cluster is estimated to be 5.0±1.0 Myr. We derived the IMF in the massive part and obtained a fairly shallow slope of Γ = -0.8 ±0.1. The integration of the IMF gave a total mass for the cluster in excess of 5.0x104 M☉. The IMF shows a clear radial variation indicating the presence of mass segregation. We also discuss the possible star formation history of Westerlund 1 from the presence of red supergiants and relatively low luminosity yellow hypergiants.

Abstract Copyright: ∼

Journal keyword(s): open clusters and associations: individual: Westerlund 1 - stars: luminosity function, mass function

VizieR on-line data: <Available at CDS (J/AJ/145/46): table4.dat>

Nomenclature: Table 4: [LCS2013] NNNNN (Nos 1-27521).

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

CDS comments: the radio source A2 is not in Simbad. WR stars B, N, T, X and S = "Cl* Westerlund 1 CN A" in Simbad.

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 - 2026 		#notes
1 NAME Magellanic Clouds GrG 03 00 -71.0           ~ 7988 0
2 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 19090 0
3 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2514 0
4 RMC 136 Cl* 05 38 42.396 -69 06 03.36   5.81 5.40     ~ 2236 2
5 NGC 2264 OpC 06 40 53.7 +09 52 32           ~ 1876 0
6 NGC 2362 OpC 07 18 41.9 -24 57 08           ~ 428 0
7 Cl Westerlund 2 OpC 10 23 58.1 -57 45 49           ~ 400 0
8 Cl Trumpler 14 OpC 10 43 56.0 -59 33 07   5.70 5.5     ~ 547 0
9 Cl Trumpler 16 OpC 10 45 01.9 -59 42 00           ~ 510 0
10 NGC 3372 HII 10 45 02.23 -59 41 59.8           ~ 1071 2
11 NGC 3603 OpC 11 14 57.9 -61 14 32           ~ 1136 1
12 Cl Hogg 15 OpC 12 43 36.8 -63 06 01           ~ 61 0
13 NAME Car-Sgr Arm PoG 15 00 -40.0           ~ 581 1
14 NAME Nor Arm PoG 16 00 -50.0           ~ 485 0
15 WR 77aa WR* 16 46 46.2846745152 -45 47 58.260872472       15.516 13.063 WC9d 16 0
16 Cl* Westerlund 1 W 373 s*b 16 46 57.7255119168 -45 53 20.035273668       14.741 12.318 B0Iab 13 0
17 Cl* Westerlund 1 W 228b * 16 46 58.0541909424 -45 53 00.932401356           O9Ib 12 0
18 Cl* Westerlund 1 CN N WR* 16 46 59.9151721464 -45 55 25.670942256       16.9 13.0 WC9d 17 0
19 Cl* Westerlund 1 W 57 s*b 16 47 01.3600091808 -45 51 45.804003408   20.7 16.877 13.83 11.13 B4Ia 22 0
20 Cl* Westerlund 1 BKS H s*y 16 47 01.4269856784 -45 50 37.248841536   18.781 14.47 11.80 9.15 F3Ia+ 31 0
21 Cl* Westerlund 1 W 12 s*y 16 47 02.2214295629 -45 50 58.987616665   22.0 17.575 13.611 10.42 A5Ia+ 27 0
22 Cl Westerlund 1 OpC 16 47 02.4 -45 51 07           ~ 655 1
23 WR 77f WR* 16 47 02.9772955944 -45 50 19.713734556   21.552 17.792 15.035 12.508 WNL/BIa+ 38 0
24 Cl* Westerlund 1 W 237 s*r 16 47 03.1097130192 -45 52 18.960733164   22.8 19.008 13.634 9.19 M3I 32 0
25 Cl* Westerlund 1 W 7 s*b 16 47 03.6281794392 -45 50 14.365482036   20.0 15.972 12.73 9.99 B5Ia+ 31 0
26 Cl* Westerlund 1 BKS F s*y 16 47 03.6850109472 -45 50 43.536110712     15.05     F5Ia+ 23 0
27 Cl* Westerlund 1 W 43c * 16 47 03.7585229164 -45 50 58.441368189   20.4 18.35 16.18 13.66 O9Ib 12 0
28 Cl* Westerlund 1 W 33 s*b 16 47 04.1256274968 -45 50 48.488202564   20.090 15.61 12.803 10.04 B5Ia+ 26 0
29 Cl* Westerlund 1 W 9 WR* 16 47 04.1419806984 -45 50 31.311670632   21.8 17.47 14.47 11.74 sgB[e] 56 0
30 Cl* Westerlund 1 W 20 s*r 16 47 04.6967287296 -45 51 23.953706496       15.660   M6I 28 0
31 Cl* Westerlund 1 W 8 s*y 16 47 04.7959778348 -45 50 25.013789709   19.9 15.913 12.64 9.89 F8Ia+ 23 0
32 Cl* Westerlund 1 CN B WR* 16 47 05.3717585660 -45 51 04.811705369     20.99 17.50 14.37 WN7o 32 0
33 2MASS J16470540-4550367 s*r 16 47 05.4076906176 -45 50 36.617071668   22.1 16.79 12.63 9.19 M2-5Ia 40 0
34 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+ 27 0
35 Cl* Westerlund 1 W 13 WR* 16 47 06.4540771320 -45 50 26.072579796   21.1 17.19 14.63 12.06 WNL/BIa+ 40 0
36 Cl* Westerlund 1 W 16 sg* 16 47 06.6158603112 -45 50 42.186706944   20.5 16.248 12.82 9.90 A5Ia+ 29 0
37 Cl* Westerlund 1 W 243 s*b 16 47 07.5040736160 -45 52 29.123491188   19.873 15.730     LBV 67 0
38 2MASS J16470892-4549585 s*r 16 47 08.9198319768 -45 49 58.452357324     16.70     M4Ia 29 0
39 PSR J1647-4552 Psr 16 47 10.18 -45 52 16.7           ~ 217 1
40 WR 77sd WR* 16 47 14.1461547746 -45 48 31.963132544           WN5o 13 0
41 NGC 6231 OpC 16 54 14.4 -41 48 53           ~ 562 0
42 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 16269 0
43 NAME Arches Cluster Cl* 17 45 50.5 -28 49 28           ~ 792 0
44 NAME Quintuplet Cluster OpC 17 46 13.9 -28 49 48           ~ 561 0
45 NGC 6530 OpC 18 04 31 -24 21.5           ~ 443 0
46 V* VX Sgr s*r 18 08 04.0442790744 -22 13 26.600899044 11.72 9.41 6.52 3.90 2.11 M8.5Ia 622 0
47 NAME Sgr Arm PoG 19 00 -30.0           ~ 710 1
48 NGC 6823 OpC 19 43 11.3 +23 18 32   7.71 7.1     ~ 279 2
49 V* V509 Cas LP* 23 00 05.1012218544 +56 56 43.350876312 8.01 6.68 5.13 3.96 3.11 G4_0 339 0
50 * rho Cas LP* 23 54 23.0325302520 +57 29 57.774737400 7.00 5.85 4.59 3.63 2.89 G2_0 401 0
51 NAME Sct-Cen PoG ~ ~           ~ 286 0

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