The connection between W31, SGR 1806-20, and LBV 1806-20: Distance, extinction, and structure
Abstract
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 NH_3 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. (\cite{Corbel1997). 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 -30 km s-1 spiral arm at a distance from the Sun of 4.5 ± 0.6 kpc 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.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- May 2004
- DOI:
- 10.1051/0004-6361:20034054
- arXiv:
- arXiv:astro-ph/0311313
- Bibcode:
- 2004A&A...419..191C
- Keywords:
-
- stars: neutron;
- stars: individual: SGR 1806-20;
- stars: individual: LBV 1806-20;
- ISM: individual: W31;
- Galaxy: structure;
- Galaxy: kinematics and dynamics;
- Astrophysics
- E-Print:
- Accepted for publication in Astronomy &