An official report was published yesterday that shows interpreted data from the Transiting Exoplanet Survey Satellite (TESS) earlier this year. As it turns out, the astronomers reading its data had just witnessed a black hole gobble up an entire star.
The astronomical event is designated as ASASSN-19bt, about 375 million light-years away from Earth. The supermassive black hole that generated the event was measured at about 6 million times heavier than our own Sun. It was actually first observed by TESS as early as January 21, 2019, However, it took several more days, up until January 29, before the event became bright enough for the All-Sky Automated Survey for Supernovae (ASAS-SN) array collect data on it.
This powerful phenomenon is technically called a tidal disruption event. It occurs when a star approaches a black hole close enough that the black hole’s gravitational tidal forces rip the star literally apart. A portion of the star’s mass gets scattered around the black hole in an accretion disk, while matter that gets dragged directly into it causes a massive pulse of electromagnetic radiation.
Usually, this gigantic energy pulse is the one that gets detected by Earth-based instruments, although there are also occasions when the energy around the accretion disk is simply detected by our local astronomical instruments.
Tidal disruption events, as astonishing as they are to imagine or to even witness up close, are incredibly rare as far as human timelines are concerned. In a galaxy like the Milky Way, for example, it only happens around once every 10,000 to 100,000 years. Which is why astronomers working on TESS were more than amazed to witness such a cataclysmic event very early in its observation period.
Oddly enough, while black holes are known to be strong emitters of X-rays, during tidal disruption events, there is actually a much higher concentration of UV rays being emitted. This has baffled scientists, and there is yet to be a complete explanation as to why this occurs.