Astronomers discover a star that has been torn apart by a giant black hole

It all started on February 11, 2022, at 11:42:40 am (Paris time). It was still dark in California on Mount Palomar, where many telescopes were installed. One is equipped with a camera that scans the sky with a fairly wide field of view, looking for what astronomers call transient events (comets, asteroids, as well as star explosions, etc.). And on this winter’s day, this facility called the Zwicky Transit Facility (ZTF) sees a light in the sky that hasn’t been there before. As announced on Wednesday, November 30, two international studies — one published in nature and the other in nature astronomy –This light is an indication of an event as distant as it is rare: a star being torn apart by a supermassive black hole that was too close to pass.

Written like this, everything seems simple, but before reaching this conclusion, astrophysicists had to follow a long journey undertaken by Susana Ferjani, research director of the National Center for Scientific Research at the Paris Observatory and co-signatory of the study. nature : “When the ZTF scans the sky, it compares it to the previous one to discover the fleeting sources. Many more are found each night and all the game is to understand the cause of each difference. Because we have developed automated tools for this, this initial analysis is done very quickly and then the information is disseminated into an international network.” of the researchers.”

When the behavior of a light source seems particularly interesting, the astronomical community moves to carry out a set of complementary observations at different wavelengths. In the case of the February 11 event, called AT 2022cmc, a total of 21 telescopes were pointed at the source. “The idea then is to put all the notes together and try to understand what they are.”And the Susanna Ferjani confirms. The first hypothesis involved a gamma ray burst, which is the transformation of a dying star into a black hole or neutron star, a cataclysmic event that sends a great deal of energy into space. But this scenario does not fit the notes.

accumulator disc

The best explanation involves a phenomenon known as the tidal rupture event.And the Tidal disturbance has occurred (TDE) in EnglishAnd the Susana Ferjani explains. A star being ripped apart by the gravity of an approaching supermassive black hole. » The black hole’s gravitational pull rips matter from the star, just as a shirt sleeve rips when you pull on it too hard. This matter then begins to spin around the black hole in what specialists call an accretion disk.

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