Giant black holes sometimes like to snack on nearby stars.
This process is quite dramatic. As a star falls towards the black hole, it's stretched out into a long, thin shape before it's spaghettified and ripped apart in what's known as a tidal disruption event.
A new study, published in The Astrophysical Journal Letters, shows detailed simulations of how this process unfolds over the course of a year.
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In the 1970s and 80s, American astronomer Jack G. Hills and British astronomer Martin Rees first theorised about tidal disruption events.
Rees predicted that when a star gets torn apart, half of its debris will end up forming a hot, glowing disc around the black hole, which should emit a lot of X-rays.
Surprisingly however, most of the more than 100 tidal disruption events observed so far glow mostly in visible light, not X-rays.
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What's more, the glowing material around the black hole appears to be several times larger than our Solar System and is continuously expanding.
Scientists have guessed that the black hole might be covered by material during these events which would have blocked X-ray emissions, but no one had demonstrated how this happens - until now.
PhD student David Liptai created a new simulation method that lets scientists track the entire process. Turns out, only 1% of the shredded star is swallowed. The rest is blown away from the hole in a final cosmic 'burp,' triggering a powerful, nearly spherical outflow.
'These simulations, seen in the videos here, are the first to show tidal disruption events all the way from the slurp to the burp,' Daniel Price, professor of Astrophysics, Monash University, wrote for The Conversation.
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'They follow the spaghettification of the star through to when the debris falls back on the black hole, then a close approach that turns the stream into something like a wriggling garden hose. The simulation lasts for more than a year after the initial plunge.'
The black hole simply can't swallow all that much, so what it can't swallow smothers the central engine and gets steadily flung away.
Despite taking over a year to run, the simulations show a whole new side of black holes.
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'The new simulations reveal why tidal disruption events really do look like a solar-system-sized star expanding at a few percent of the speed of light, powered by a black hole inside,' Price added. 'In fact, one could even call it a "black hole sun".'