G2.4+1.4: An Extraordinary Mass-Loss Bubble Driven by an Extreme WO Star

Abstract

The nebula, G2.4+1.4, is shown to be a highly reddened, photoionised, mass-loss bubble of very high excitation powered by WR 102, the most extreme oxygen sequence Wolf-Rayet star known. It lies at a distance of 3±1kpc, and is about 11 pc in diameter. The exciting star, contains neither hydrogen nor helium in its atmosphere, is losing mass at a velocity of 5530 km.s-1, and has the following properties: log (Tion) = 5.20±0.05; log (R/R⊙) = 0.05±0.20; log (L/L⊙) = 5.85±0.20. We conclude that the star is the ~20M⊙ core of a supermassive star (M ≤ 60M⊙) seen near the end of its life.