Research Division Seminar
FS CMa stars: overlooked channel of mergers

Abstract

FS CMa stars are a subgroup of the B[e] stars. The forbidden emission lines and infrared excess are present in their spectra. This is a sign of very extended circumstellar region. While the B[e] phenomenon has been explained for other B[e] groups, the nature and evolutionary status of FS CMa stars has not been explained. Recently, we discovered very strong magnetic field in one of FS CMa stars, IRAS 17449+2320. The strength of the magnetic field modulus, about 6.2 kG, is in the order of the strongest Ap stars. The magnetic field together with other properties point to the post-merger origin of IRAS 17449+2320. It is very likely that other post-mergers are hidden among FS CMa stars.

The first results of our new N-body simulations show that more than half of mergers occurs in B-type stars. In other words, we are overlooking the most frequent channel of the mergers. This may have an important consequence for the enrichment of the ISM by heavier elements. Especially important it may be in the early universe.