The hybrid spectrum of the LMC hypergiant R 126.

Abstract

An extensive spectroscopic (1150 - 6700 Å) and photometric (UBVRIJHKLMN) study of the peculiar LMC hypergiant R126 has been carried out. The authors derive stellar parameters T_eff = 22,500K, R = 72 R_sun; and M_bol = -10.5. The corresponding spectral type is B0.5 Ia⁺. An estimate of the initial and present mass leads to 70 - 80 M_sun; and ≡40 M_sun;, respectively. Thermal radiation of a cool dust component with T_bb = 900K is observed in the infrared. The hybrid character of the line spectrum, i.e., broad UV resonance absorption lines contrasting sharp emission lines, leads to the conclusion that R126 has a two component stellar wind leading to a disk-like outer configuration. The disk is supposed to be formed by a slow (≡40 km s^-1), cool, dense wind. A stellar rotation close to the break-up velocity is regarded as the reason for this two-component structure.