2018A&A...614A.116R


Query : 2018A&A...614A.116R

2018A&A...614A.116R - Astronomy and Astrophysics, volume 614A, 116-116 (2018/6-1)

Identifying two groups of massive stars aligned in the l ∼ 38° Galactic direction.

RAMIREZ ALEGRIA S., HERRERO A., RUBKE K., MARIN-FRANCH A., GARCIA M. and BORISSOVA J.

Abstract (from CDS):


Context. Recent near-infrared data have contributed to unveiling massive and obscured stellar populations in both new and previously known clusters in our Galaxy. These discoveries have lead us to view the Milky Way as an active star-forming machine.
Aims. We look for young massive cluster candidates as over-densities of OB-type stars. The first search, focused on the Galactic direction l = 38°, resulted in the detection of two objects with a remarkable population of OB-type star candidates.
Methods. With a modified version of the friends-of-friends algorithm AUTOPOP and using 2MASS and UKIDSS-GPS near-infrared (J, H, and K) photometry for one of our cluster candidates (named Masgomas-6) we selected 30 stars for multi-object and long-slit H and K band spectroscopy. With the spectral classification and the near-infrared photometric data, we derive individual distance, extinction, and radial velocity.
Results. Of the 30 spectroscopically observed stars, 20 are classified as massive stars, including OB-types (dwarfs, giants and supergiants), two red supergiants, two Wolf-Rayets (WR122-11 and the new WR122-16), and one transitional object (the LBV candidate IRAS 18576+0341). The individual distances and radial velocities do not agree with a single cluster, indicating that we are observing two populations of massive stars in the same line of sight: Masgomas-6a and Masgomas-6b. The first group of massive stars, located at 3.9^{+0.4}_{-0.3}-0.3+0.4 kpc, contains both Wolf-Rayets and most of the OB-dwarfs; the second group, located at 9.6 ± 0.4 kpc, hosts the LBV candidate and an evolved population of supergiants. We are able to identify massive stars at two Galactic arms, but we cannot clearly identify whether these massive stars form clusters or associations.

Abstract Copyright: © ESO 2018

Journal keyword(s): infrared: stars - open clusters and associations: general - stars: early-type - stars: massive - stars: Wolf-Rayet - supergiants

VizieR on-line data: <Available at CDS (J/A+A/614/A116): table3.dat list.dat fits/*>

Simbad objects: 58

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Number of rows : 58
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 V* PR Per s*r 02 21 42.4097766240 +57 51 46.144950588 12.84 10.31 8.00 6.13 4.60 M1-Iab-Ib 117 0
2 NAME Per Arm PoG 03 30 +45.0           ~ 1525 0
3 * alf Cam s*b 04 54 03.0113886719 +66 20 33.633625509 3.47 4.34 4.29 4.18 4.18 O9Ia 661 1
4 * bet Ori s*b 05 14 32.27210 -08 12 05.8981 -0.56 0.10 0.13 0.13 0.15 B8Iae 764 0
5 * lam Ori A Em* 05 35 08.2760807112 +09 56 02.991326316 2.17 3.48 3.47     O8III((f)) 509 0
6 * iot Ori SB* 05 35 25.9819073 -05 54 35.643537 1.45 2.53 2.77     O9IIIvar 775 0
7 * eta Leo * 10 07 19.9523915176 +16 45 45.587968398 3.17 3.39 3.41 3.32 3.35 A0Ib 337 0
8 HD 93521 * 10 48 23.5113981120 +37 34 13.083332412 5.67 6.79 7.03     O9.5IIInn 427 1
9 VVV CL009 Cl* 11 56 03 -63 19.0           ~ 6 0
10 [MCM2005b] 30 Cl* 12 14 32.0 -62 58 49           ~ 15 0
11 * eta UMa PM* 13 47 32.43776 +49 18 47.7602 0.99 1.67 1.86 1.98 2.16 B3V 611 0
12 [CRB2015] VVV CL041-8 WR* 14 46 26.3834090003 -59 23 29.107419054       14.889   WN8-9h 5 0
13 [GKF2010] MN76 WR* 18 07 05.1603210192 -20 15 16.705010880           WN9 8 0
14 Cl Alicante 8 OpC 18 34 51.0 -07 14 00           ~ 26 0
15 RSGC 1 OpC 18 37 58 -06 53.0           ~ 108 0
16 Cl Stephenson 2 OpC 18 39 20 -06 01.7           ~ 94 0
17 Cl Alicante 7 OpC 18 44 29.45 -03 30 02.4           ~ 22 0
18 RSGC 3 OpC 18 45 20.0 -03 24 43           ~ 54 0
19 Masgomas-1 Cl* 18 50 15.408 +00 20 58.07           ~ 8 0
20 * 13 Lyr LP* 18 55 20.1023376286 +43 56 45.922489780 7.00 5.59 4.00 1.95 0.04 M4.5III 315 1
21 Masgomas-4 Cl? 18 56 07.0 +07 56 07           ~ 3 0
22 2MASS J18595769+0345153 * 18 59 57.69336 +03 45 15.3072           O9IIIe 1 0
23 2MASS J18595935+0344586 LP? 18 59 59.3503832520 +03 44 58.557111180           M5III 2 0
24 2MASS J18595936+0346036 sg* 18 59 59.36208 +03 46 03.6192           A0I 1 0
25 NAME Sgr Arm PoG 19 00 -30.0           ~ 640 1
26 2MASS J19000240+0346150 * 19 00 02.4114328536 +03 46 14.901432096           B3V 1 0
27 2MASS J19000245+0345025 LP? 19 00 02.4563180688 +03 45 02.468998008           M5III 2 0
28 2MASS J19000306+0348205 * 19 00 03.06816 +03 48 20.5128           O9V 1 0
29 2MASS J19000318+0344351 * 19 00 03.18672 +03 44 35.1816           ~ 1 0
30 2MASS J19000334+0345361 * 19 00 03.34608 +03 45 36.1152           O9I-III 1 0
31 2MASS J19000350+0346186 * 19 00 03.5023589520 +03 46 18.558025932           B3V 1 0
32 2MASS J19000472+0344522 * 19 00 04.7199297432 +03 44 52.171634076           O9I-III 1 0
33 2MASS J19000509+0347270 WR* 19 00 05.09736 +03 47 27.0996           WN6 2 0
34 2MASS J19000519+0345289 LP? 19 00 05.1887329512 +03 45 28.941992604           M5III 2 0
35 2MASS J19000524+0348211 * 19 00 05.24112 +03 48 21.1572           O9V 1 0
36 2MASS J19000709+0347305 * 19 00 07.09776 +03 47 30.5412           K5-M1III 1 0
37 2MASS J19000774+0345057 * 19 00 07.7447656944 +03 45 05.918604624           G5III-V 1 0
38 2MASS J19001023+0346197 * 19 00 10.23744 +03 46 19.7580           O8III 1 0
39 2MASS J19001075+0347512 * 19 00 10.75152 +03 47 51.2988           O9III 1 0
40 IRAS 18576+0341 s*b 19 00 10.89456 +03 45 47.1096           B8I 86 0
41 2MASS J19001102+0346009 * 19 00 11.02536 +03 46 00.9300           O9.5I-III 1 0
42 2MASS J19001104+0347347 WR* 19 00 11.04024 +03 47 34.7892           WN8-9h 2 0
43 Masgomas-6 Cl* 19 00 11 +03 46.6           ~ 3 0
44 2MASS J19001125+0347186 * 19 00 11.2445977200 +03 47 18.534896988           K2III 1 0
45 2MASS J19001138+0345491 * 19 00 11.38704 +03 45 49.1904           G8III-V 1 0
46 UGPS J190011.43+034624.5 s*b 19 00 11.43336 +03 46 24.5892           O5-6I 1 0
47 2MASS J19001226+0344512 s*r 19 00 12.2573375616 +03 44 51.078438924           M5I 1 0
48 2MASS J19001409+0344321 * 19 00 14.09568 +03 44 32.1180           O9.5I-III 1 0
49 2MASS J19001492+0344086 * 19 00 14.9290418688 +03 44 08.925349884           B3V 1 0
50 2MASS J19001578+0345289 * 19 00 15.78072 +03 45 28.9800           K3III 1 0
51 2MASS J19001584+0346153 * 19 00 15.8421466992 +03 46 15.613686984           G5III-V 1 0
52 2MASS J19001775+0345083 * 19 00 17.7537430680 +03 45 08.353728720           O9V 1 0
53 2MASS J19001899+0344235 * 19 00 18.99672 +03 44 23.5860           K2III 1 0
54 Juchert 3 OpC 19 07 32.6 +06 16 44           ~ 17 0
55 HD 191765 WR* 20 10 14.1928045152 +36 10 35.070683376 7.64 8.08 8.08     WN6-s 442 0
56 Schulte 8C * 20 33 17.9820761856 +41 18 31.194812988 12.2 11.43 10.19     O4.5III(fc) 83 0
57 NAME Galactic Bar reg ~ ~           ~ 1234 0
58 NAME Sct-Cen PoG ~ ~           ~ 232 0

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