ACES The Binary Fraction of RSGs in the Large Magellanic Cloud and Small Magellanic Cloud - Min Dai
Min Dai
Beijing Normal University, China
Red supergiants (RSGs) are the evolved descendants of OB-type main-sequence stars. The
current study shows that the binary fraction (≈ 15%−40%) of RSGs is significantly lower than
that of its predecessor that is ≈ 50% − 70%. In this work, we investigate the binary fraction of
RSGs in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) with the recently
selected largest samples of 4697 and 2097 RSGs in the LMC and SMC respectively. The binary
system with a hot companion (O-, B- and A-type star) is identified by detecting the UV excess
in the observed spectral energy distribution (SED) ranging from ultraviolet to mid-infrared after
subtracting the model SED of RSG based on the fact that RSGs are very weak in the UV band.
It is found that the lower limit of binarity is 37.6% and 37.3% in the LMC and SMC respectively.
A handful of the binaries identified by the SED fitting method are confirmed by their light curves
and radial velocity dispersions. Furthermore, the stellar parameters of the companions, i.e. Teff ,
R, L and log g, are calculated by model fitting.
