Guest
Figure 1 from “Eddington envelopes: The fate of stars on parabolic orbits tidally disrupted by supermassive black holes“, by Price et al. (2024): In this movie a 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. The most bound debris returns to the black hole first, but after passing through pericentre, the apsidal advance of the orbit caused by general relativity causes the stream to self-intersect. This results in a small amount of material that can fall onto the black hole itself, in the process generating a lot of heat. This drives strong outflows of mass, where the loosely bound debris is steadily driven from the black hole. This movie shows the density in the stream on a linear colour scale from 0 to 1500 g/cm^2. See accompanying movie showing the same simulation but with density on a log scale and zoomed out. Key thing is that a lot of the action is buried under an optically thick ball of outflowing material, which is what is observed as an optical transient by telescopes.
