Publication Abstracts

Stothers and Chin 1995

Stothers, R.B., and C.-W. Chin, 1995: Tests of two convection theories for red giant and red supergiant envelopes. Astrophys. J., 440, 297-302, doi:10.1086/175270.

Two theories of stellar envelope convection are considered in the context of red giants and red supergiants of intermediate to high mass: Böhm-Vitense's standard mixing-length theory (MLT) and Canuto & Mazzitelli's new theory incorporating the full spectrum of turbulence (FST). Both theories assume incompressible convection. Two formulations of the convective mixing length theory are also evaluated: l proportional to local pressure scale height (HP) and l proportional to the distance from the upper boundary of the convection zone (z). Applications to test both theories are made by calculating stellar evolutionary sequences into the red phase of core helium burning. Since the theoretically predicted effective temperatures for cool stars are known to be sensitive to the assigned value of the mixing length, this quantity has been individually calibrated for each evolutionary sequence. The calibration is done in a composite Hertzsprung-Russell diagram for the red giant and red supergiant members of well-observed Galactic open clusters. The MLT model requires the constant of proportionality for the convective mixing length to vary by a small but statistically significant amount with stellar mass, whereas the FST model succeeds in all cases with the mixing length simply set equal to z (as Canuto & Mazzitelli have also found for the Sun and low-mass red giants). The structure of the deep stellar interior, however, remains very nearly unaffected by the choices of convection theory and mising length. Inside the convective envelope itself, a density inversion always occurs, but is somewhat smaller for the convectively more efficient MLT model. On physical grounds the FST model is prferable, and seems to alleviate the problem of finding the proper mixing length.

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BibTeX Citation

  author={Stothers, R. B. and Chin, C.-W.},
  title={Tests of two convection theories for red giant and red supergiant envelopes},
  journal={Astrophysical Journal},

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RIS Citation

ID  - st08000d
AU  - Stothers, R. B.
AU  - Chin, C.-W.
PY  - 1995
TI  - Tests of two convection theories for red giant and red supergiant envelopes
JA  - Astrophys. J.
JO  - Astrophysical Journal
VL  - 440
SP  - 297
EP  - 302
DO  - 10.1086/175270
ER  -

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