Astronomy and Astrophysics, volume 419, 191-201 (2004/5-3)
The connection between W31, SGR 1806-20, and LBV 1806-20: Distance, extinction, and structure.
CORBEL S. and EIKENBERRY S.S.
Abstract (from CDS):
We present new millimeter and infrared spectroscopic observations towards the radio nebula G10.0-0.3, which is powered by the wind of the Luminous Blue Variable star LBV 1806-20 also closely associated with the soft gamma-ray repeater SGR 1806-20, and believed to be located in the giant Galactic HII complex W31. Based on observations of CO emission lines and NH3
absorption features from molecular clouds along the line of sight to G10.0-0.3, as well as the radial velocity and optical extinction of the star powering the nebula, we determine its distance to be 15.1+1.8–1.3
kpc in agreement with Corbel et al. (1997ApJ...478..624C
). In addition, this strengthens the association of SGR 1806-20 with a massive molecular cloud at the same distance. All soft gamma-ray repeaters with precise location are now found to be associated with a site of massive star formation or molecular cloud. We also show that W31 consists of at least two distinct components along the line of sight. We suggest that G10.2-0.3 and G10.6-0.4 are located on the -30km/s spiral arm at a distance from the Sun of 4.5±0.6kpc and that G10.3-0.1 may be associated with a massive molecular cloud at the same distance as the LBV star, i.e. 15.1+1.8–1.3
kpc, implying that W31 could be decomposed into two components along the line of sight.
stars: neutron - stars: individual: SGR 1806-20 - stars: individual: LBV 1806-20 - ISM: individual: W31 - Galaxy: structure - Galaxy: kinematics and dynamics
Table 1: [CWD97] MC+VVA N=3+2 added.
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