2016MNRAS.458..491M

Query : 2016MNRAS.458..491M

2016MNRAS.458..491M - Mon. Not. R. Astron. Soc., 458, 491-507 (2016/May-1)

On the nature of high reddening of Cygnus OB2 #12 hypergiant.

MARYEVA O.V., CHENTSOV E.L., GORANSKIJ V.P., DYACHENKO V.V., KARPOV S.V., MALOGOLOVETS E.V. and RASTEGAEV D.A.

Abstract (from CDS):

To explain the nature of the high reddening (AV ≃ 10 mag) towards one of the most luminous stars in the Galaxy - Cyg OB2 #12 (B5 Ia-0), also known as MT304, we carried out spectrophotometric observations of 24 stars located in its vicinity. We included five new B-stars among the members of Cygnus OB2, and for five more photometrically selected stars we spectroscopically confirmed their membership. We constructed the map of interstellar extinction within 2.5 arcmin radius and found that interstellar extinction increases towards MT304. According to our results the most reddened OB-stars in the association after MT304 are J203240.35+411420.1 and J203239.90+411436.2, located about 15 arcsec away from it. Interstellar extinction towards these stars is about 9 mag. The increase of reddening towards MT304 suggests that the reddening excess may be caused by the circumstellar shell ejected by the star during its evolution. This shell absorbs 1 mag, but its chemical composition and temperature are unclear. We also report the detection of a second component of MT304, and discovery of an even fainter third component, based on data of speckle interferometric observations taken with the Russian 6-m telescope.

Abstract Copyright: © 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): instrumentation: high angular resolution - binaries: visual - stars: early-type - stars: massive - dust, extinction - open clusters and associations: individual: Cygnus OB2

Simbad objects: 64

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Number of rows : 64
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 HD 39866 * 05 56 33.7678235616 +28 56 32.156125080   6.617 6.336     A2II 46 0
2 BD+75 325 HS* 08 10 49.4903003712 +74 57 57.931973676 8.002 9.23 9.50 9.698 9.884 sdO5 253 0
3 NAME Homunculus Nebula ISM 10 45 03.5 -59 41 04           ~ 369 1
4 * eta Car Em* 10 45 03.545808 -59 41 03.95124 6.37 7.03 6.48 6.123 4.41 LBV 2440 0
5 * eps Vir PM* 13 02 10.5970152536 +10 57 32.935398266 4.45 3.71 2.79 2.16 1.71 G8III-IIIb 553 0
6 HZ 44 HS* 13 23 35.2629445608 +36 07 59.544140304 10.186 11.42 11.65 12.00 11.995 sdBN0VIIHe28 418 0
7 BD+33 2642 pA* 15 51 59.8854348048 +32 56 54.329485272 9.806 10.61 10.73 10.884 10.961 O7p 429 0
8 * ups Her PM* 16 02 47.8978183032 +46 02 12.133917132 4.33 4.616 4.709     B9III 236 0
9 * tau Her Pu* 16 19 44.4367980146 +46 18 48.102135319 3.190 3.73 3.87 4.00 4.16 B5IV 403 0
10 HD 157881 PM* 17 25 45.2324302566 +02 06 41.123732402 10.126 8.865 7.56 6.649 5.89 K7V 336 0
11 [FMM95] 3 s*b 17 46 15.240 -28 50 03.58           LBV 148 1
12 HD 168625 s*b 18 21 19.5484021368 -16 22 26.075142156 10.15 9.78 8.37 8.76   B8Ia+ 279 2
13 V* V1827 Cyg s*b 20 30 27.3018237840 +41 13 25.130220744     13.053     O6Iaf+O9Ia 36 0
14 [CPR2002] A23 s*b 20 30 39.6999117024 +41 08 48.792195024   12.41 11.296     B0.7Ib 17 0
15 GSC 03161-01224 * 20 30 51.1144819416 +41 20 21.764885280 17.28 16.66 14.48     B0V 16 0
16 [CPR2002] A15 * 20 31 36.9100232904 +40 59 09.036657888           O7Ib(f) 15 0
17 RLP 887 SB* 20 32 31.5335925286 +41 14 08.189588225   15.44 13.00 12.15   O7.5III-I+O/B 20 0
18 [CPR2002] A11 SB* 20 32 31.5336715464 +41 14 08.190216276           O7Ib(f) 27 0
19 SDSS J203233.07+411359.6 * 20 32 33.0763458120 +41 13 59.639304720           ~ 2 0
20 SDSS J203233.44+411406.0 * 20 32 33.5030122968 +41 14 05.600953896           ~ 3 0
21 RLP 886 * 20 32 35.3380727112 +41 14 45.394646460   16.5 15.23     ~ 9 0
22 CXOCyg J203235.65+411509.5 * 20 32 35.6386648920 +41 15 09.680989464     15.48     ~ 5 0
23 SDSS J203236.58+411644.7 * 20 32 36.5805552696 +41 16 44.695876692           ~ 2 0
24 2MASS J20323790+4115098 * 20 32 37.9014693096 +41 15 09.780449328   16.51 15.42     ~ 5 0
25 SDSS J203238.09+411441.8 * 20 32 38.1072057840 +41 14 41.762871672           ~ 2 0
26 2MASS J20323851+4115412 * 20 32 38.5138187280 +41 15 41.149855656   17.2 16.09     ~ 5 0
27 KMJ 1718 * 20 32 39.5067307512 +40 52 47.457723828   15.2   13.1   B0:V: 11 0
28 SDSS J203239.90+411436.2 * 20 32 39.9463927200 +41 14 35.963822724           ~ 3 1
29 2MASS J20324040+4114205 * 20 32 40.3617222192 +41 14 19.945150548           ~ 3 1
30 Schulte 12 s*b 20 32 40.9572199728 +41 14 29.279036940 16.1 14.45 11.702     B3-4Ia+ 424 0
31 SDSS J203241.80+411439.2 * 20 32 41.8096724568 +41 14 39.295452084           ~ 2 0
32 RLP 885 * 20 32 41.8366536600 +41 14 22.441062984   16.03 15.02     ~ 5 0
33 SDSS J203243.01+411529.9 * 20 32 43.0113820272 +41 15 29.973774132           ~ 2 0
34 CXOCyg J203243.34+411514.1 * 20 32 43.340 +41 15 14.19           ~ 2 0
35 SDSS J203243.49+411445.1 * 20 32 43.5141897480 +41 14 45.013095132           ~ 2 0
36 SDSS J203243.61+411513.9 * 20 32 43.6118492520 +41 15 13.917161700           ~ 3 0
37 SDSS J203243.84+411446.5 * 20 32 43.8460636440 +41 14 46.562939376           ~ 2 0
38 2MASS J20324431+4114453 * 20 32 44.3129885496 +41 14 45.310877700           ~ 2 0
39 CXOCyg J203244.85+411419.1 * 20 32 44.850 +41 14 19.17           ~ 2 0
40 SDSS J203245.07+411416.5 * 20 32 45.0716269080 +41 14 16.591038468           ~ 3 0
41 SDSS J203247.17+411501.0 * 20 32 47.1735332304 +41 15 01.023681852           ~ 2 0
42 SDSS J203247.28+411339.0 * 20 32 47.2855053552 +41 13 39.044428932           ~ 2 0
43 Schulte 32 * 20 32 48.6269320440 +41 14 29.870941128   17.92 15.61     ~ 8 0
44 SDSS J203250.25+411448.4 * 20 32 50.2543635168 +41 14 48.442662780   13.37 12.57     ~ 4 0
45 ALS 15170 * 20 32 50.7471146328 +41 15 02.183388768 17.2 16.42 14.44     B1V 16 0
46 USNO-B1.0 1312-00389914 * 20 32 56.7113073744 +41 15 41.276868660   18.9   16.0   ~ 3 0
47 [CPR2002] A20 * 20 33 02.9279638392 +40 47 25.319304852           O8II((f)) 20 0
48 Schulte 22 SB* 20 33 08.799 +41 13 18.21 14.33 13.59 11.55     O3If*+O6V((f)) 72 0
49 Schulte 9 s*b 20 33 10.7362926720 +41 15 08.222370372 13.38 12.77 10.96     O5I+O4III 232 0
50 ALS 15181 * 20 33 11.0607015672 +41 10 32.027017008 17.82 16.97 14.78     B0V 17 0
51 Ass Cyg OB 2 As* 20 33.2 +41 19           ~ 943 0
52 RLP 853 SB* 20 33 13.2612575376 +41 13 28.656230412 16.63 15.76 13.61     O6.5V((f)) 36 0
53 Schulte 7 * 20 33 14.1095938872 +41 20 21.904113804 12.24 12.00 10.55     O3If* 145 0
54 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) 246 0
55 Schulte 8C * 20 33 17.9820761856 +41 18 31.194812988 12.2 11.43 10.19     O4.5III(fc) 83 0
56 Schulte 64 Be* 20 33 18.5309527200 +41 15 35.149489128 18.17 17.24 14.88     B1Ve-B3Ve 27 0
57 RLP 841 ** 20 33 23.472072 +41 09 12.90312 14.97 14.23 11.83 10.98   O6IV((f)) 41 0
58 BD+41 3807 SB* 20 34 08.5147948176 +41 36 59.408503092 11.74 11.52 10.03     O5.5Ifc 128 0
59 [CPR2002] A24 * 20 34 44.1106226280 +40 51 58.699418040           O6.5III(f) 14 0
60 [CPR2002] A27 * 20 34 44.7167065392 +40 51 46.731492072   13.61 11.08     B0Ia 16 0
61 MR 112 WR* 20 35 47.0859278605 +41 22 44.703520146     12.64 12.16   WC6+O8I-IIf 155 1
62 BD+28 4211 HS* 21 51 11.0221915656 +28 51 50.367627468 8.922 10.25 10.58 10.656 10.831 sdO2VIIIHe5 798 0
63 [SCC2002b] Core A MoC ~ ~           ~ 5 0
64 [SCC2002b] Core B glb ~ ~           ~ 5 0

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