2010A&A...516A..35H


Query : 2010A&A...516A..35H

2010A&A...516A..35H - Astronomy and Astrophysics, volume 516, A35-35 (2010/6-2)

Obscured clusters. III. Follow-up observations of Mercer 23.

HANSON M.M., KURTEV R., BORISSOVA J., GEORGIEV L., IVANOV V.D., HILLIER D.J. and MINNITI D.

Abstract (from CDS):

New infrared surveys have revealed over 1000 new open cluster candidates in the Milky Way, but these candidates need to be confirmed with follow up observations. Of particular interest are young, massive star clusters because they serve as nearby analogues to the distant super star clusters studied as point sources in other galaxies. We determine the physical parameters and investigate the high-mass stellar content of the infrared star cluster Mercer23, situated near the Galactic plane (l=53.772deg, b=+0.164deg). Our analysis is based on new Baade/PANIC JHKS and ISAAC/VLT imaging of Mercer23 and ISAAC/VLT moderate resolution (R≃4000) spectroscopy of the brightest cluster members in the H- and K-bands. The cluster age is determined from isochrone main-sequence (MS) and pre-MS fitting. We derive stellar parameters for eight of the stellar members, using a full non-LTE modeling of the obtained spectra. Mercer23 is a very young cluster, with age of t=2-4Myr. The cluster suffers reddening of E(J-KS)=1.35, AV=7.2mag. The derived distance is d=6.5±0.3kpc. Our spectral modeling allows us to conclude that the three most luminous member are evolved highly massive stars: a WR star, and two mid-O supergiant stars, based on their derived luminosity. Mercer23 is not a super-massive cluster such as those recently recognized to exist in the Milky Way. However, its mass estimate of 4-6x103M and possibly more, puts it in the class of young Galactic clusters hosting WR stars.

Abstract Copyright:

Journal keyword(s): Galaxy: open clusters and associations: general - stars: Wolf-Rayet - open clusters and associations: individual: [MCM2005b] 23

Nomenclature: Fig. 2, Tables 2-3: [HKB2010b] ObjNN (Nos 1-11).

Simbad objects: 28

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Number of rows : 28
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 NAME SMC G 00 52 38.0 -72 48 01   2.79 2.2     ~ 10540 1
2 HD 5980 WR* 00 59 26.5838833944 -72 09 53.927337312   11.13 11.31   11.029 WN4+O7I: 380 1
3 HD 36166 V* 05 29 54.7742113464 +01 47 21.333288804 4.74 5.562 5.745     B2V 118 0
4 * tet01 Ori C SB* 05 35 16.4662967280 -05 23 22.921811880 4.20 5.15 5.13 4.91 4.73 O7Vp 1368 1
5 NAME Ori Trapezium OpC 05 35 16.5 -05 23 14           ~ 1568 1
6 * sig Ori Y*O 05 38 44.7653828520 -02 36 00.283179888 2.54 3.58 3.79 3.87 4.11 O9.5V+B0.2V(n) 779 0
7 Cl Westerlund 1 Cl* 16 47 04.00 -45 51 04.9           ~ 527 0
8 NAME Arches Cluster Cl* 17 45 50.5 -28 49 28           ~ 701 0
9 WR 102al WR* 17 45 50.58 -28 49 17.2           WN7-8 24 0
10 [BSP2001] 8 Em* 17 45 50.76 -28 49 16.2           O4-6If 20 0
11 HD 167785 * 18 16 22.2040390176 +10 48 53.281752300   7.48 7.57     B2V 22 0
12 HD 171149 * 18 33 22.7083484664 -05 54 42.189219396   6.381 6.354     B9V 49 0
13 HD 174262 * 18 48 53.3862583776 +19 19 43.379146992   5.902 5.880     A1V 47 0
14 [HKB2010b] Obj4 * 19 30 11.4734473210 +18 32 23.843838057           O9/B2 3 0
15 [HKB2010b] Obj10 * 19 30 12.504 +18 31 52.01           O9/B2 1 0
16 2MASS J19301254+1832070 * 19 30 12.5376496704 +18 32 07.128571308           ~ 1 0
17 [HKB2010b] Obj9 * 19 30 12.792 +18 31 56.99           O9/B2 1 0
18 [HKB2010b] Obj3 * 19 30 12.831 +18 32 10.14           O9/B2 1 0
19 [HKB2010b] Obj7 * 19 30 13.061 +18 32 14.52           B 1 0
20 [HKB2010b] Obj11 * 19 30 13.0714002615 +18 32 02.290029085           O9/B2 3 0
21 Teutsch 42 OpC 19 30 13.1 +18 32 09           ~ 17 0
22 [HKB2010b] Obj6 * 19 30 13.3142389608 +18 32 18.519704592       15.59   O6If 4 0
23 2MASS J19301355+1832024 WR* 19 30 13.5631598928 +18 32 02.466071772           WNL7-8 1 0
24 [HKB2010b] Obj5 * 19 30 13.659 +18 32 23.95           B 1 0
25 2E 1928.0+1825 X 19 30 13.8 +18 32 16           ~ 2 0
26 [HKB2010b] Obj1 * 19 30 13.8166134769 +18 32 00.074997177           O5.5I 3 0
27 HD 191639 Be* 20 11 10.0777272648 -08 50 32.440964532 5.42 6.34 6.49     B1IVe 74 0
28 BD+40 4227A SB* 20 33 15.0781182864 +41 18 50.479292556 10.42 10.27 8.98 8.03 6.83 O6Ib(fc)+O4.5:III:(fc) 238 0

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2023.02.07-15:01:54

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