Stellar stability and hydrodynamics

Possible Sources of Instability in Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900018799 ◽

1957 ◽

Vol 3 ◽

pp. 186-199

Author(s):

P. Ledoux

Keyword(s):

Stellar Stability

The most immediate purpose of the study of stellar stability is to discover the sources of incipient instability which must be responsible for the observed variability of a great number of stars.

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Ray Trapping in Stellar Envelopes, Pulsational Instabilities and Heating of External Layers

Symposium - International Astronomical Union ◽

10.1017/s0074180900069175 ◽

1974 ◽

Vol 56 ◽

pp. 293-293

Author(s):

Pierre Souffrin

Keyword(s):

Preliminary Report ◽

Classical Problem ◽

Small Scale ◽

Hydrodynamic Instabilities ◽

Stellar Envelope ◽

Stellar Pulsation ◽

Recent Developments ◽

Stellar Stability ◽

Stellar Envelopes

The relation between local criteria for hydrodynamic instabilities and stellar stability is reconsidered. This leads to a discussion of the classical problem of stellar pulsation with a special emphasis on the pressure modes of high order spherical harmonics. It is shown that within the frame of the geometrical approximation, acoustic rays exist which are trapped inside any specified slab of a stellar envelope. The pressure modes associated with such rays are conjectured to give rise to small scale instabilities whenever a region exists in an envelope where any local criterium indicates pulsational instability. The model is expected to support and somewhat extend the recent developments concerning the role of pressure non-radial modes on the dynamics of the solar atmosphere and the heating of external layers.Preliminary report available from Observatoire de Nice.

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