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PhobosDown t1_j27b0xy wrote

Reply to comment by LordRobin------RM in Black hole question by Impossible_Pop620

Exactly right - the more massive the black hole the gentler the tidal forces at the event horizon.

For example, stars can be torn apart by a million solar mass black hole, creating tidal disruption events that have been observed in synoptic surveys. At a billion solar masses though, the black hole swallows stars whole because the tidal forces aren’t strong enough to disrupt the star before it enters the event horizon.

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LordRobin------RM t1_j27s8do wrote

Wow, has this been observed?

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PhobosDown t1_j29t44q wrote

Tidal disruptions have been, yes. They are also simulated in supercomputers and they were predicted decades before they were observed!

The direct “swallowing” of a star by a billion solar mass black hole has not been observed. One way to think about it is this event would just involve the center of the galaxy decreasing in brightness by 1 star’s worth, whereas a tidal disruption event is like fireworks - a lot of energy gets released and if we happen to have a telescope checking on that galaxy at least every few weeks, we’ll see it.

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LordRobin------RM t1_j2c1e4h wrote

Right, now that I take the time to think about it, a “swallowing” wouldn’t look exciting at all, even observed from within the galaxy. The doomed star’s light would just red-shift as it approached until the wavelength was unobservable.

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