Publication Abstracts

Carson and Stothers 1984

Carson, T.R., and R.B. Stothers, 1984: Long-period classical Cepheids - Theory versus observation. Astrophys. J., 276, 593-601, doi:10.1086/161648.

Full-amplitude models of classical Cepheids with periods longer than 13 days have been calculated in order to supplement the models of short-period classical Cepheids reported earlier by Vemury and Stothers. The Carson opacities have again been adopted. With the new models, the complete systematics of the observed light and velocity curves of classical Cepheids can be discussed in detail. Under the assumption that a normal evolutionary mass-luminosity relation is obeyed, the following empirical phenomena are reproduced well by the models (except for a small displacement of the theoretical periods): (1) the full Hertzsprung progression of light and velocity curves; (2) the gradual shift in phase of the Hertzsprung bump, together with the persistence in phase of the postmaximum shoulder on the light curve; (3) the retardation of maximum expansion velocity after maximum light; (4) the correlation between light amplitude and velocity amplitude; and (5) the period-amplitude scatter diagram for both light amplitude and velocity amplitude. The average period that is theoretically predicted for a specific Cepheid light-curve type, however, turns out to be ∼40% longer than the period actually observed, although individual models agree well in many respects with particular observed Cepheids. This period discrepancy definitely exists for periods below 14 days but is less certain above. It can probably be removed by a reduction of the adopted masses by roughly 15 %, which is within the estimated 20% uncertainty of the evolutionary masses.

Use of the Los Alamos opacities leads to a period discrepancy of ∼140% (or a mass discrepancy of roughly 50%) for periods below 24 days and possibly above, as shown by Stobie, Simon and Davis, and others.

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BibTeX Citation

  author={Carson, T. R. and Stothers, R. B.},
  title={Long-period classical Cepheids - Theory versus observation},
  journal={Astrophys. J.},

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RIS Citation

ID  - ca05220c
AU  - Carson, T. R.
AU  - Stothers, R. B.
PY  - 1984
TI  - Long-period classical Cepheids - Theory versus observation
JA  - Astrophys. J.
VL  - 276
SP  - 593
EP  - 601
DO  - 10.1086/161648
ER  -

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