1997/11/18 by Andrew Ulmer, A. Ulmer, Bohdan Paczynski +4
Engineering · Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Heat Transfer Mechanisms #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9711199
6 pages including 2 figures; latex; submitted to A&A
arxiv created 1997/11/18 · openalex publication_date 1997/11/18 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Optically-thick envelopes may form following the tidal disruption of a star by a massive black hole. Such envelopes would reprocess hard radiation from accretion close to the black hole into the UV and optical bands producing AGN-luminosity flares with duration ~1 year. We show that due to relativistic effects, the envelopes are convective. If convection is efficient, then the structure of the envelopes is similar to that described in previous work; however, the photospheric radius is shown to be very sensitive to the luminosity at the envelope base, suggesting that either the envelope collapses or the envelope expands to a maximum radius at which point a wind may set in. For an envelope without winds, we find a maximum photospheric radius of ~1016 cm (i.e. minimum effective temperature ~6,000 K). The evolution of the envelopes is described based on simple energy arguments.