2013A&A...557A..20V


Query : 2013A&A...557A..20V

2013A&A...557A..20V - Astronomy and Astrophysics, volume 557A, 20-20 (2013/9-1)

Herschel imaging and spectroscopy of the nebula around the luminous blue variable star WRAY 15-751.

VAMVATIRA-NAKOU C., HUTSEMEKERS D., ROYER P., NAZE Y., MAGAIN P., EXTER K., WAELKENS C. and GROENEWEGEN M.A.T.

Abstract (from CDS):

We have obtained far-infrared Herschel-PACS imaging and spectroscopic observations of the nebular environment of the luminous blue variable (LBV) WRAY 15-751. The far-infrared images clearly show that the main, dusty nebula is a shell of radius 0.5 pc and width 0.35 pc extending outside the Hα nebula. Furthermore, these images reveal a second, bigger and fainter dust nebula that is observed for the first time. Both nebulae lie in an empty cavity, very likely the remnant of the O-star wind bubble formed when the star was on the main sequence. The kinematic ages of the nebulae are calculated to be about 2x104 and 8x104-years, and we estimated that each nebula contains ∼0.05M of dust. Modeling of the inner nebula indicates a Fe-rich dust. The far-infrared spectrum of the main nebula revealed forbidden emission lines coming from ionized and neutral gas. Our study shows that the main nebula consists of a shell of ionized gas surrounded by a thin photodissociation region illuminated by an ``average'' early-B star. We derive the abundance ratios N/O=1.0±0.4 and C/O=0.4±0.2, which indicate a mild N/O enrichment. From both the ionized and neutral gas components we estimate that the inner shell contains 1.7±0.6M of gas. Assuming a similar dust-to-gas ratio for the outer nebula, the total mass ejected by WRAY 15-751 amounts to 4±2M. The measured abundances, masses and kinematic ages of the nebulae were used to constrain the evolution of the star and the epoch at which the nebulae were ejected. Our results point to an ejection of the nebulae during the red super-giant (RSG) evolutionary phase of an ∼40M star. The multiple shells around the star suggest that the mass-loss was not a continuous ejection but rather a series of episodes of extreme mass-loss. Our measurements are compatible with the recent evolutionary tracks computed for an ∼40M star with little rotation. They support the O-BSG-RSG-YSG-LBV filiation and the idea that high-luminosity and low-luminosity LBVs follow different evolutionary paths.

Abstract Copyright:

Journal keyword(s): circumstellar matter - stars: massive - stars: mass-loss - stars: variables: S Doradus - stars: individual: WRAY 15-751

Simbad objects: 9

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Number of rows : 9
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 16242 1
2 HD 269858 s*b 05 36 43.6936418088 -69 29 47.451149232   10.24 10.15 9.95 9.05 LBV 277 2
3 NAME HMW1 Cl* 05 36 43.7 -69 29 48           ~ 6 1
4 HD 90177 s*b 10 22 53.8430096928 -59 37 28.363616256 9.16 9.66 8 8.15   LBV 320 0
5 * eta Car Em* 10 45 03.5377808928 -59 41 04.051599720 6.37 7.03 6.48 4.90 4.41 OBepec 2341 0
6 V* AG Car WR* 10 56 11.5781414448 -60 27 12.810673260 7.00 7.57 6.96 7.73   WN11h 614 0
7 MR 35 s*b 11 08 40.0634208096 -60 42 51.721320060   12.33 10.20 11.66   LBV 124 0
8 WRAY 15-1676 pA* 17 19 49.3290860880 -39 10 37.928806356     13.1     ~ 44 1
9 HD 168625 s*b 18 21 19.5484021368 -16 22 26.075142156 10.15 9.78 8.37 8.76   B6Iap 268 2

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2022.09.26-03:33:59

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