Eddington envelopes require fine tuning of the luminosity in order to produce extended envelopes. It appears unlikely that the luminosity is held within such a tight region. More reasonably, either the average luminosity will be sub-critical at the base, and the envelope will collapse, or the luminosity will be super-critical at the base, and the envelope will grow (and thereby radiate at lower temperatures between 80,000 K and 20,000 K as shown in Fig. 2) and eventually reach the most extended hydrostatic model or the wind solutions, as described in Sect. 2. This scenario may be valid only if convection is efficient. The stellar structure equations are not as tractable if convection is inefficient, and we have not attempted to solve them here.
We reiterate that the remarkable feature of extended envelopes is that they could reprocess much of the hard radiation produced by a tidal disruption event into the optical band. Bolometric corrections would drop from magnitudes to 1-2. The color temperatures of the objects may be slightly higher than the effective temperatures due to suppression of absorption processes at such low densities, but such changes are expected to be about a factor of two (see the work on neutron stars by Babul & Paczynski (1987)). Even scattering-dominated envelopes retain their important property of producing optically bright flares.
© European Southern Observatory (ESO) 1998
Online publication: April 15, 1998