BLACK HOLE SUN: optical photosphere from tidal disruption of a star by a supermassive black hole

Figure 4 in Price et al. (2024): arxiv.org/abs/2404.09381 "Eddington envelopes: The fate of stars on parabolic orbits tidally disrupted by supermassive black holes".
In this movie a one solar mass star approaches a black hole on a marginally bound (parabolic) orbit. Half the star becomes bound to the black hole while the other half continues on its merry journey. This is not a good situation for the star, which stretches into a long thin line that feeds the black hole. The result of this feeding is a growing, optically thick ball of material that surrounds the black hole,
Here the visualisation shows an "observers view" of the expanding bubble, showing the density and temperature at the last scattering surface. This is more or less what is observed as a TDE transient by optical telescopes: A 10-100 au expanding optically thick ball of material with a photospheric temperature of ~10,000 K expanding at velocities of ~10,000 km/s/ Hence the simulation helps to explain some of the key mysteries of why tidal disruption events are observed mostly at optical wavelengths.