A second luminous blue variable in the quintuplet cluster

Abstract

H- and K-band moderate-resolution and 4 μm high-resolution spectra have been obtained for FMM 362, a bright star in the Quintuplet Cluster near the Galactic center. The spectral features in these bands closely match those of the Pistol Star, a luminous blue variable and one of the most luminous stars known. The new spectra and previously obtained photometry imply a very high luminosity for FMM 362, L ≥ 106 L⊙, and a temperature of 10,000-13,000 K. Based on its luminosity, temperature, photometric variability, and similarities to the Pistol Star, we conclude that FMM 362 is a luminous blue variable.