Chromosphere modelling of the star R CrB

  • E.A. Baranovsky Crimean Astrophysical Observatory, Nauchny, 298409
  • A.E. Rozenbush Главная астрономическая обсерватория, Киев, Украина

Abstract

The model chromosphere is calculated for the R CrB star using the observed profiles of H,K CaII, D lines of NaI and H-alpha. The profiles of H,K CaII and H-alpha, calculated with the model, are in good agreement with the observed profiles both for the undisturbed state and for the minimum. The profile calculations for the state of minimum are made by the assumption that minimum is caused by the dust cloud obscuring the photosphere of the star. The model is not hydrostatic in the sense that mass column density at the base of chromosphere is about 2 orders higher as compared to the value corresponding to hydrostatic model. The density is lower at the base of chromosphere and higher at the upper chromosphere and the extension is greater as compared to hydrostatic model. The temperature in the chromosphere is 5000–7000 K and density is 108–1010 atoms in 1 cm3. The extension of the calculated chromosphere is about 3 star radii. To get an agreement of the profiles of D lines of NaI was possible only with the assumption that around the star there exists cold envelope, containing the NaI atoms which expands with the velocity about 30 km/s. This envelope is located beyond the bounds of chromosphere, but nearly enough to be observed as one object with the star. Optical thickness of the envelope in the D2 line is about 1.8. In the undisturbed state of star the envelope contributes to the absorption in D lines, but in the minimum this envelope, illuminated by the star light, creates also the additional emission caused by the resonance scattering in the D lines.

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Published
2009-06-01
How to Cite
Baranovsky E., Rozenbush A., 2009. Izvestiya Krymskoi Astrofizicheskoi Observatorii, vol. 105, no. 1, pp. 97-106. Available at: https://jn.craocrimea.ru/index.php/izvcrao/article/view/885 (Accessed: 5December2020)
Section
Research articles