2009A&A...493..119R


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.12CET08:25:39

2009A&A...493..119R - Astronomy and Astrophysics, volume 493, 119-125 (2009/1-1)

Mid-infrared VISIR and Spitzer observations of the surroundings of the magnetar SGR 1806-20.

RAHOUI F., CHATY S. and LAGAGE P.-O.

Abstract (from CDS):

SGR 1806-20 is the soft gamma-ray repeater that has exhibited the highest activity since its discovery, including a giant flare in 2004 December 27. Previous studies of this source - probably a magnetar - have shown that it was associated with a massive star cluster embedded in a gas and dust cloud. Moreover, several stars in the cluster are peculiar hypergiants - luminous blue variable (LBV) and Wolf-Rayet stars - exhibiting strong and likely dusty stellar winds. We aimed at studying the mid-infrared emission of the stars associated with the same cluster as SGR 1806-20, to detect variations that could be due to the high-energy activity of the magnetar through interaction with the dust. We also studied the morphology of the cloud close to the centre of the cluster. We carried out mid-infrared observations of SGR 1806-20 and its environment, with the highest spatial resolution in this domain to date, using ESO/VISIR in 2005 and 2006, and we retrieved Spitzer/IRAC-MIPS archival data of the same field. We performed broadband photometry of three stars - LBV 1806-20, a WC9 and an O/B supergiant - on our VISIR images, as well as on the IRAC data. We then built and fitted their broadband spectral energy distributions with a combination of two absorbed black bodies, representing their stellar components, as well as a possible mid-infrared excess, to derive their physical parameters. We show that LBV 1806-20 and the WC9 star exhibit a mid-infrared excess, likely because of the presence of circumstellar dust related to their winds. We also show that only LBV 1806-20 has had a variable flux over a period of two years, variability that is due to its LBV nature rather than to a heating of the gas and dust cloud by the high-energy emission of SGR 1806-20. Finally, differences in the intrinsic absorptions of the three stars show an inhomogeneous structure of the density of the gas and dust cloud in the massive star cluster.

Abstract Copyright:

Journal keyword(s): stars: neutron - infrared: stars - dust, extinction - open clusters and associations: general - stars: early-type - supergiants

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 PSR J0146+6145 Psr 01 46 22.21 +61 45 03.8   28.100 25.620     ~ 501 0
2 W 3 MoC 02 27 04.10 +61 52 27.1           ~ 942 3
3 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14338 1
4 PSR B0525-66 Psr 05 26 00.7 -66 04 35           ~ 510 1
5 * eta Car Em* 10 45 03.5455050 -59 41 03.951060 6.37 7.034 6.21 4.90 4.41 OBepec 2150 0
6 V* AG Car WR* 10 56 11.5779283438 -60 27 12.809532379 7.00 7.57 6.96 7.73   WN11h 580 0
7 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11032 0
8 2MASS J18083812-2024347 * 18 08 38.13 -20 24 34.8           ~ 2 0
9 WR 111b WR* 18 08 39.24 -20 24 31.9           WC9d 5 0
10 PSR J1808-2024 Psr 18 08 39.32 -20 24 40.1           ~ 1071 2
11 [EML2004] Star C sg? 18 08 39.51 -20 24 30.0           OBI 5 0
12 [KMN95] Star A s*b 18 08 40.312 -20 24 41.14           LBV 39 3
13 GAL 010.30-00.15 HII 18 08 58.315 -20 05 15.27           ~ 77 0
14 W 31 SFR 18 10 28.6 -19 55 51           ~ 240 0
15 HD 168625 s*b 18 21 19.5486475779 -16 22 26.077308888 10.15 9.78 8.37 8.76   B6Iap 246 2
16 GBS 1900+14 gB 19 07 13 +09 19.6           ~ 768 0

    Equat.    Gal    SGal    Ecl

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2019.11.12-08:25:39

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