A Black Hole Triggers a Premature Supernova

this illustration shows a massive star that is about to explode. the explosion was triggered after its dead-star companion (a black hole or neutron star) plunged into the star's core. scientists say that the black hole or neutron star rammed into the massive star, and then, as it traveled inward over the course of centuries, ejected a spiral of material from the star's atmosphere (pictured surrounding the star). when it reached the star's core, material from the core rapidly fell onto the stellar corpse and this led to the launching of a pair of jets at nearly the speed of light. in this artist's depiction, the jets are shown tunneling through the star, and will soon set off the supernova explosion. after a few years, the supernova will crash through the bulk of the ejected spiral, which extends to about 10,000 times the size of the star. this will create the luminous transient radio source observed by the very large array.
Credit: Chuck Carter

The first observation of a brand-new kind of supernova had been predicted by theorists but never before confirmed

Maunakea, Hawaiʻi – In 2017, a particularly luminous and unusual source of radio waves was discovered in data taken by the Very Large Array (VLA) Sky Survey, a project that scans the night sky in radio wavelengths. Now, led by Caltech graduate student Dillon Dong, a team of astronomers has established that the bright radio flare was caused by a black hole or neutron star crashing into its companion star in a never-before-seen process.

“Massive stars usually explode as supernovae when they run out of nuclear fuel,” says Gregg Hallinan, professor of astronomy at Caltech. “But in this case, an invading black hole or neutron star has prematurely triggered its companion star to explode.” This is the first time a merger-triggered supernova has ever been confirmed.

A paper about the findings, which includes data from W. M. Keck Observatory on Maunakea in Hawaiʻi, appears in the journal Science on September 3.