Stability boundaries for massive stars in the sHR diagram

Saio, Hideyuki ; Georgy, Cyril ; Meynet, Georges

In: Proceedings of the International Astronomical Union, 2014, vol. 9, no. S307, p. 230-231

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    Stability boundaries of radial pulsations in massive stars are compared with positions of variable and non-variable blue-supergiants in the spectroscopic HR (sHR) diagram (Langer & Kudritzki 2014), whose vertical axis is 4 log T eff - log g(= log L/M). Observational data indicate that variables tend to have higher L/M than non-variables in agreement with the theoretical prediction. However, many variable blue-supergiants are found to have values of L/M below the theoretical stability boundary; i.e., surface gravities seem to be too high by around 0.2-0.3 dex