Open main menu

1806-20 (originally named the SGR 1806-20 cluster) is a heavily obscured star cluster on the far side of the Milky Way, approximately 50,000 light years distant. It contains the Soft gamma repeater SGR 1806-20 and the luminous blue variable hypergiant LBV 1806-20, a candidate for the most luminous star in the Milky Way. LBV 1806-20 and many of the other massive stars in the cluster are thought likely to end as supernovas in a few million years, leaving only neutron stars or black holes as remnants.

1806-20 cluster
Observation data (2000 epoch)
Right ascension 18h 08m 39.33s[1]
Declination−20° 24′ 40.0″[1]
Distance~50000 ly (~15000 pc)
Physical characteristics
Notable featuresContains SGR 1806-20 and LBV 1806-20.
Other designationsG10.0-0.3, W31
See also: Open cluster, List of open clusters
H-band infrared image of 1806-20 cluster

The cluster is heavily obscured by intervening dust, and mostly visible in the infrared. It is part of the larger W31 H II region and giant molecular cloud. It has a compact core of ~0.2 pc in diameter with a more extended halo of ~2 pc in diameter containing the LBV[1] and at least three Wolf–Rayet stars (of types WC8, WN6, and WN7) and an OB supergiant, plus other young massive stars.[2]

See alsoEdit


  1. ^ a b c SIMBAD/Aladin plot, of r=30 asec region around SGR B18054117-20251165
  2. ^ D. F. Figer et al. Astrophys. J. 622 (2005) L49-L52

External linksEdit

  • The Unusual High-Mass Star Cluster 1806-20 [1]