Wray 15-906 low mass Luminous Blue Variable in a pre-supernova stage

The evolutionary link between Red Supergiants and Luminous Blue variables is interesting, but still poorly understood. We present the results of a study of the Galactic candidate luminous blue variable Wray 15-906, revealed via the detection of its infrared circumstellar shell (of ≍2 pc in diameter) with the Wide-field Infrared Survey Explorer (WISE) and the Herschel Space Observatory. Using the stellar atmosphere code CMFGEN and the Gaia parallax, we found that Wray 15-906 is a relatively low-luminosity, log(L/L _ȯ ) ≍ 5.4, star with a temperature of 25±2 kK. In the framework of single star evolution, the obtained results suggest that Wray 15-906 is a post-red supergiant star with an initial mass of ≍ 25M _ȯ and that before exploding as a supernova it could transform for a short time into a WN11h star. The presence of a shell with a mass 2.9±0.5M _e indicates that Wray 15-906 has suffered substantial mass loss in the recent past.