De Jager et al. 2001
De Jager, C., A. Lobel, H. Nieuwenhuijzen, and R. Stothers, 2001: Instability regions in the upper HR diagram. M. Not. Royal Astron. Soc., 327, 452-458, doi:10.1046/j.1365-8711.2001.04791.x.
The following instability regions for the blueward evolving supergiants are utilized and compared: (1) Areas in the Hertzsprung-Russell (HR) diagram where stars are dynamically unstable. (2) Area where the effective acceleration in the upper part of the photosphere is negative, hence directed outward. (3) Areas where the sonic points of the stellar wind (where vwind = vsound) are situated inside the photospheres, at a level deeper than τRoss = 0.01. We compare the results with the positions of actual stars in the HR diagram and we find evidence that the recent strong contraction of the yellow hypergiant HR8752 was initiated in a period during which <geff> < 0, whereupon the star became dynamically unstable. The instability and extreme shells around IRC+10420 are suggested to be related to three factors: <geff> < 0; the sonic point is situated inside the photosphere; and the star is dynamically unstable.
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De Jager, C., Lobel, A., Nieuwenhuijzen, H., and Stothers, R.: Instability regions in the upper HR diagram, M. Not. Royal Astron. Soc., 327, 452-458, doi:10.1046/j.1365-8711.2001.04791.x, 2001.
De Jager, C., A. Lobel, H. Nieuwenhuijzen, and R. Stothers (2001), Instability regions in the upper HR diagram, M. Not. Royal Astron. Soc., 327, 452-458, doi:10.1046/j.1365-8711.2001.04791.x.
De Jager, C., A. Lobel, H. Nieuwenhuijzen, and R. Stothers, 2001: Instability regions in the upper HR diagram. M. Not. Royal Astron. Soc., 327, 452-458, doi:10.1046/j.1365-8711.2001.04791.x.
De Jager, C., Lobel, A., Nieuwenhuijzen, H., & Stothers, R. 2001, M. Not. Royal Astron. Soc., 327, 452, doi:10.1046/j.1365-8711.2001.04791.x.
De Jager C, Lobel A, Nieuwenhuijzen H, Stothers R. Instability regions in the upper HR diagram, M Not Royal Astron Soc 2001;327:452-458. doi:10.1046/j.1365-8711.2001.04791.x.
C. de Jager, A. Lobel, H. Nieuwenhuijzen, R. Stothers, M. Not. Royal Astron. Soc. 327, 452-458, doi:10.1046/j.1365-8711.2001.04791.x (2001).
