2003A&A...412..185C


Query : 2003A&A...412..185C

2003A&A...412..185C - Astronomy and Astrophysics, volume 412, 185-198 (2003/12-2)

Dusty ring nebulae around new candidate. Luminous Blue Variables.

CLARK J.S., EGAN M.P., CROWTHER P.A., MIZUNO D.R., LARIONOV V.M. and ARKHAROV A.

Abstract (from CDS):

We report on the discovery of a further two ring nebulae in the Midcourse Space Experiment (MSX) Galactic Plane Survey; G24.73+0.69 and G26.47+0.02. Morphologically, both appear similar to the nebulae found around the Luminous Blue Variable (LBV) candidates G79.29+0.46 and Wra 17-96. A central, unresolved point source was identified in both cases - positional coincidence with the star StRS 237 was found for G26.47+0.02, while no optical counterpart could be identified for G24.73+0.69. However, subsequent near IR broadband imaging of the G24.73+0.69 field identified a very red - (J-K)∼2mag - stellar counterpart to the central object. Near-IR spectroscopy of both objects reveal rich emission line spectra dominated by HI, HeI and low excitation metals, suggesting classification as luminous B supergiants and revealing a striking superficial similarity to the other MSX ring sources and known LBVs. We utilised a NLTE model atomsphere code to model the K band spectra and near-IR spectral energy distributions of the central stars in order to determine their physical parameters. Adopting a distance, d=5.2kpc to G24.73+0.69 yields a temperature, T=12kK, luminosity, log(L/L)=5.6 and mass loss rate, {dot}(M)=1x10–5M/yr. G26.47+0.02 appears to be a more extreme object; adopting d=6.5kpc results in T=17kK, log(L/L)=6.0 and {dot}(M)=9x10–5M/yr, placing it at the Humphreys-Davidson limit for massive stellar objects. Analysis of the spatially resolved mid-IR fluxes of both objects reveal extended periods of enhanced mass loss, resulting in comparatively low mass nebulae, with chemistries dominated by O-rich dust (with a population of small Fe grains existing co-spatially with the silicate dust). Comparison to the other MSX ring nebulae sources reveals a homogeneous group of objects, with both stellar and nebular properties consistent with known LBVs. With both spectroscopic and/or photometric variability observed for those sources with multiepoch observations, we propose a close affinity between both classes of object and suggest that long term monitoring of the MSX sources will reveal them to be bona fide LBVs.

Abstract Copyright:

Journal keyword(s): stars: emission line, Be - stars: circumstellar matter - stars: winds, outflows

CDS comments: GAL 79.49+0.26 is a misprint for GAL 79.29+0.46.

Simbad objects: 25

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Number of rows : 25
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 269006 s*b 05 02 07.3944119328 -71 20 13.118657760 9.93 10.60 10.55 10.43 10.38 LBV 237 0
2 LHA 120-S 18 Em* 05 05 53.9807776877 -68 10 50.539871441   12.06 11.903 12.01 11.821 B3Ie 19 0
3 HD 269687 WR* 05 31 25.5247019885 -69 05 38.555025424 10.86 11.78 11.87 12.05   WN11h 100 0
4 HD 269858 s*b 05 36 43.6942807271 -69 29 47.449383685   10.24 10.15 9.95 9.05 LBV 271 2
5 LHA 120-S 61 WR* 05 45 51.9393679113 -67 14 25.939050679 10.870 11.86 11.95 12.09 11.931 WN11h 78 0
6 HD 72754 Be* 08 32 23.3807350291 -49 36 04.768103183 6.38 9.09 8.88 7.77   B2(Ia)pe(_sh) 103 0
7 HD 90177 s*b 10 22 53.8426931454 -59 37 28.361118869 9.16 9.66 8 8.15   LBV 311 0
8 * eta Car Em* 10 45 03.545808 -59 41 03.95124 6.37 7.03 6.48 4.90 4.41 OBepec 2286 0
9 WRAY 15-682 WR* 10 53 59.5776214569 -60 26 44.358376205   11.64 10.85 10.56   WN11h 140 3
10 V* AG Car WR* 10 56 11.5779283438 -60 27 12.809532379 7.00 7.57 6.96 7.73   WN11h 602 0
11 MR 35 s*b 11 08 40.0633818066 -60 42 51.718989987   12.33 10.20 11.66   LBV 119 0
12 [B61] 2 s*b 17 41 35.4374195439 -30 06 38.782935913   18.0 15.00 14.23 10.30 LBV_B[e]: 43 0
13 NAME Quintuplet Cluster OpC 17 46 13.9 -28 49 48           ~ 478 0
14 [FMM95] 3 s*b 17 46 15.240 -28 50 03.58           LBV 142 1
15 [GMC99] D6 s*b 17 46 17.982 -28 49 03.46           LBV 59 0
16 HD 316285 s*b 17 48 14.0369781568 -28 00 53.124817157 11.88 11.27 9.60 9.28   B0Ieq 181 2
17 HD 168625 s*b 18 21 19.5486475779 -16 22 26.077308888 10.15 9.78 8.37 8.76   B6Iap 258 2
18 V* V481 Sct s*b 18 33 55.2778598542 -06 58 38.634278867           LBV_B[e]: 46 0
19 IRAS 18344-0632 PN? 18 37 05.20632 -06 29 37.9752           ~ 56 0
20 IRAS 18368-0546 * 18 39 29.3 -05 43 56           ~ 5 1
21 GPSR5 26.470+0.025 Rad 18 39 31.49 -05 44 13.0           ~ 4 0
22 MSX6C G026.4700+00.0207 s*b 18 39 32.2479397055 -05 44 20.194778342           LBV_B 37 1
23 IRAS 18576+0341 s*b 19 00 10.89456 +03 45 47.1096           B8I 83 1
24 * P Cyg s*b 20 17 47.2020844 +38 01 58.552724 4.66 5.24 4.82 4.28 4.02 B1-2Ia-0ep 1142 1
25 IRAS 20298+4011 Em* 20 31 42.2841507943 +40 21 59.061205285     15.1     B:I[e] 89 0

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2021.09.28-09:31:24

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