The collision with a black hole triggered the supernova prematurely
Stars can become supernovae only when they have run out of nuclear fuel. But now astronomers have observed how a supposed black hole forced an premature explosion.
In New Mexico is the Very Large Array, a radio telescopic observatory consisting of 27 satellite dishes. In 2017, the VLA Sky Survey project captured radio waves from an unusually strong source. Now a team at Caltech thinks they have an explanation for the outbreak.
According to astronomers, this is a phenomenon that has never been observed before. The remains of an exploded star, in the form of a black hole or a neutron star, have collided with its former sibling star. Caltech’s discovery is published in the scientific journal Science.
– Usually, massive stars explode like supernovae when they run out of nuclear fuel. But in this case, an intrusive black hole or neutron star has triggered its companion star to explode prematurely. This is the first time that it has been possible to confirm that a supernova has been triggered by a merger, says Gregg Hallinan, professor of astronomy at Caltech in a press release.
Strong radio waves occurred
The black hole or neuron star is believed to have been in a dense orbit around its sibling star and over time sucked up its atmosphere, which was finally completely lost a few hundred years ago. The gas has then been ejected into space where it has formed a thick ring – a so-called torus. The process brought the two closer together until the black hole crashed into the star, which then collapsed and exploded in the form of a supernova.
The team was looking for radio transients, short and thus elusive shocks from radio waves. They then found the most powerful example to date that has been linked to a supernova. Awake astronomers noted, however, that the same place, VT 1210 + 4956, several years earlier was the origin of a shock of strong X-rays, and the source was the jet that then shot out of the center of the star when it collapsed.
The strong radio waves only appeared when the exploding star reached the ring of gas that had previously been ejected from the supposed black hole, which took several years.
The scenario of a collision triggering a supernova has previously been described theoretically, but the two events with the jet from the collapsing star and radio waves that occur when an explosion meets a torus of gas have never been linked.
