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| Paper: |
Strange-Mode Instability for Micro-Variations in Luminous Blue Variables |
| Volume: |
479, Progress in Physics of the Sun and Stars |
| Page: |
47 |
| Authors: |
Saio, H.; Georgy, C.; Meynet, G. |
| Abstract: |
If a massive star has lost significant mass during its red-supergiant (RSG) stage, it would return to the blue region in the Hertzsprung-Russell (HR) diagram and spend a part of the core-He burning stage as a blue supergiant having a luminosity to mass ratio (L/M) considerably larger than about 104 (in solar units); the duration depends on the degree of internal mixing and on the metallicity. Then, various stellar pulsations are excited by an enhanced κ-mechanism and strange-mode instability. Assuming these pulsations to be responsible for (at least some of) the quasi-periodic light and radial velocity variations in α Cygni variables, including luminous blue variables (LBVs; or S Dor variables), we can predict masses and surface compositions for these variables, and compare them with observation to constrain evolutionary models. We discuss radial pulsations excited in evolutionary models of an initial mass of 40 M☉ with solar metallicity of Z = 0.014, and compare them to micro-variations in the two Galactic LBVs, HR Car and HD 160529. We have found that these stars should have lost more than half of the initial mass and their surface CNO abundances should be significantly modified from the original ones showing partial H-burning products. |
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