On the pulsation modes and masses of RGB OSARGs

OSARG (OGLE Small Amplitude Red Giants) variables are RGB or AGB stars that show multi-periodic light variations with periods of about 10-100 days. Comparing linear nonadiabatic pulsation periods and period ratios with observed ones, we determined pulsation modes and masses of the RGB OSARG variables in the LMC. We found that pulsations of OSARGs involve radial 1st to 3rd overtones, p₄ of l = 1, and p₂ of l = 2 modes. The range of mass isfound to be 0.9-1.4M_⊙ for RGB OSARGs and their mass-luminosity relation is logL/L_⊙ = 0.79 M/M_⊙ + 2.2.