Publication Abstracts

De Jager et al. 2001

De Jager, C., A. Lobel, H. Nieuwenhuijzen, and R. Stothers, 2001: Instability regions in the upper HR diagram. Mon. Not. Roy. 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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BibTeX Citation

  author={de Jager, C. and Lobel, A. and Nieuwenhuijzen, H. and Stothers, R.},
  title={Instability regions in the upper HR diagram},
  journal={Monthly Notices of the Royal Astronomical Society},

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RIS Citation

ID  - de00100w
AU  - de Jager, C.
AU  - Lobel, A.
AU  - Nieuwenhuijzen, H.
AU  - Stothers, R.
PY  - 2001
TI  - Instability regions in the upper HR diagram
JA  - Mon. Not. Roy. Astron. Soc.
JO  - Monthly Notices of the Royal Astronomical Society
VL  - 327
SP  - 452
EP  - 458
DO  - 10.1046/j.1365-8711.2001.04791.x
ER  -

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