2011A&A...527A..66G


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.12CEST14:54:44

2011A&A...527A..66G - Astronomy and Astrophysics, volume 527A, 66-66 (2011/3-1)

XMM-Newton observation of the enigmatic object WR 46.

GOSSET E., DE BECKER M., NAZE Y., CARPANO S., RAUW G., ANTOKHIN I.I., VREUX J.-M. and POLLOCK A.M.T.

Abstract (from CDS):

To further investigate the nature of the enigmatic object WR 46 and better understand the X-ray emission in massive stars and in their evolved descendants, we observed this variable object for more than two of its supposed cycles. The X-ray emission characteristics are appropriate indicators of the difference between a genuine Wolf-Rayet star and a specimen of a super soft source as sometimes suggested in the literature. The X-ray emission analysis might contribute to understanding the origin of the emitting plasma (intrinsically shocked wind, magnetically confined wind, colliding winds, and accretion onto a white dwarf or a more compact object) and to substantiating the decision about the exact nature of the star. The X-ray observations of WR 46 were performed with the XMM-Newton facility over an effective exposure time of about 70ks. Both the X-ray luminosity of WR 46, typical of a Wolf-Rayet star, and the existence of a relatively hard component (including the Fe-K line) rule out the possibility that WR 46 could be classified as a super soft source, and instead favour the Wolf-Rayet hypothesis. The X-ray emission of the star turns out to be variable below 0.5keV but constant at higher energies. The soft variability is associated to the Wolf-Rayet wind, but revealing its deep origin necessitates additional investigations. It is the first time that such a variability is reported for a Wolf-Rayet star. Indeed, the X-ray emission exhibits a single-wave variation with a typical timescale of 7.9h which could be related to the period observed in the visible domain both in radial velocities (single-wave) and in photometry (double-wave). The global X-ray emission seems to be dominated by lines and is closely reproduced by a three-temperature, optically thin, thermal plasma model. The derived values are 0.1-0.2keV, 0.6keV, and ∼4keV, which indicates that a wide range of temperatures is actually present. The soft emission part could be related to a shocked-wind phenomenon. The hard tail of the spectrum cannot presently be explained by such an intrinsic phenomenon as a shocked wind and instead suggests there is a wind-wind collision zone, as does the relatively high LX/Lbol ratio. We argue that this scenario implies the existence of an object farther away from the WN3 object than any possible companion in an orbit related to the short periodicity.

Abstract Copyright:

Journal keyword(s): stars: individual: WR 46 - stars: Wolf-Rayet - X-rays: stars

Simbad objects: 16

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Number of rows : 16

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 * gam Cas Be* 00 56 42.5317 +60 43 00.265 1.18 2.29 2.39 2.32 2.40 B0.5IVpe 1137 2
2 HD 9974 WR* 01 38 55.6271504593 +58 09 22.671823428 9.85 10.71 10.69     WN3h-w 156 0
3 OGLE LMC-SC20 113500 EB* 05 46 46.54 -71 08 53.9     19.163   18.886 ~ 241 0
4 HD 50896 WR* 06 54 13.0440847499 -23 55 42.020318514 5.74 6.63 6.91 7.74   WN4b 736 0
5 * gam02 Vel WR* 08 09 31.95013 -47 20 11.7108 0.64 1.58 1.83 1.85 2.00 WC8+O7.5III-V 840 0
6 HD 86161 WR* 09 54 52.9034376427 -57 43 38.273623332 7.94 8.65 8.36 8.93   WN8h 202 0
7 HD 92740 WR* 10 41 17.5154230335 -59 40 36.897706569 5.68 6.50 6.42 7.38   WN7h+O9III-V 381 0
8 HD 93162 WR* 10 44 10.3888220947 -59 43 11.105959983 7.90 8.55 8.80 8.66   O2.5If*/WN6+OB 334 1
9 HD 96548 WR* 11 06 17.2033098417 -65 30 35.237611013 7.10 7.80 7.70 8.49   WN8h 388 0
10 HD 104994 WR* 12 05 18.7203813373 -62 03 10.139083749 9.95 10.94 10.93 11.03   WN3p-w 153 0
11 HD 151932 WR* 16 52 19.2478420644 -41 51 16.269632432 6.06 6.79 6.51 7.64   WN7h 292 0
12 WR 109 WR* 18 07 50.8974693468 -35 10 25.119230585           WN3 51 0
13 HD 165688 WR* 18 07 56.9612003141 -19 23 56.866361615 10.46 10.31 9.87 9.85   WN5-6b 144 0
14 HD 193576 WR* 20 19 32.4230196684 +38 43 53.958209968 8.15 8.53 8.00     WN5+O6II-V 684 0
15 HD 193793 WR* 20 20 27.9763345925 +43 51 16.289775091 6.90 7.25 6.85 4.58   WC7p+O5 649 1
16 EM* AS 431 WR* 20 36 43.6345223872 +40 21 07.453291511       12.51   WN8(h)+B0.5V 209 0

    Equat.    Gal    SGal    Ecl

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2020.07.12-14:54:44

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