The Pistol Nebula surrounds one of the most massive stars known, the Pistol Star. Both are located 25,000 light years away from Earth, near the center of the Milky Way galaxy. The nebula contains approximately 10 solar masses worth of ionized gas that was ejected by the star several thousand years ago. The nebula was named in the 1980s for its shape as seen in low resolution images that were available at the time. The Pistol Star, a luminous blue variable is 1.7 million times as bright as the Sun, and 120-200 times as massive.
^ abFiger, D. F., Morris, M., Geballe, T. R., Rich, R. M., Serabyn, E., McLean, I. S., Puetter, R., & Yahil, A. 1999, High-Resolution Infrared Imaging and Spectroscopy of the Pistol Nebula: Evidence for Ejection, Astrophysical Journal, 525, 759
^ abFiger, D. F., Najarro, F., Morris, M., McLean, I. S., Geballe , T. R., Ghez, A. M., & Langer, N. 1998, The Pistol Star, Astrophysical Journal, 506, 384