A Model of the Circumstellar Envelope of Luminous Blue Variables

Jian-Heng Guo, Yan Li, Hong-Guang Shan

Abstract


The continuum energy distributions of the luminous blue variables R127 and R110 in the outburst phase are fitted with a circumstellar envelope model. Both stars show two peaks in their continuum, one near 1250Å and the other in the optical band. We suggest that their UV and optical fluxes may have different origins: the UV flux comes from the central star while the optical flux comes from an expanding circumstellar envelope. We construct a model for LBVs consisting of two LTE atmosphere models with different temperatures, and find it to be in agreement with the observed spectral energy distributions of R127 and R110. According to our numerical experiments, R127's continuum is composed of fluxes from a circumstellar envelope of Teff = 8000 K, R = 485R, and log g = 1, and from a central star of Teff = 17 000 K, R = 135R, and log g = 2.5 with a permeating factor f = 0.5; while R110's continuum can be fitted by a circumstellar envelope of Teff = 7000 K, R = 350R, and log g = 0.5, and a central star of Teff = 25 000 K, R = 27R, and log g = 3.0 with a permeating factor f = 0.65. Both models show that the non-spherically symmetric, optically thick regions are formed surrounding the central star in the outburst phase. The light of the central star is shielded by the circumstellar envelope so that the visual brightness increases with the decrease/increase of the temperature/radius of the optically thick regions.

Keywords


sun: filament --- sun: flares --- sun: CMEs

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DOI: http://dx.doi.org/10.1088/1009-9271%2F5%2F3%2F004

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Print ISSN: 1674-4527

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