Scientists find entirely new kind of supernova

The remnants of a massive cosmic explosion in a galaxy hundreds of millions of light-years away are no ordinary supernova. A new analysis of this distant event shows that it was caused by the merger of two objects, one of which is a compact black hole or neutron star. The evidence for this event, called VT J121001+495647, is the first supernova to be observed.

“Theorists predicted that this could happen,” said Dillon Dong, an astronomer at Caltech.” But this is the first time we’ve seen such an occasion.”

The supernova was located during a 2017 radio survey called the Very Large Array Sky Survey (VLASS). During that sweep, the VLA picked up a bright, glowing radio source that had not appeared in previous surveys conducted with the same telescope.

Subsequent observations by the VLA and the W.M. Keck Observatory, which observes the sky in optical and infrared light, revealed that this radio source exists and is a supernova remnant expanding as it interacts with dust and gas.

When fast-moving supernova material expands into it, it generates shocks and heat that produce electromagnetic waves bright enough to be detected by other galaxies. Dong and his team tracked VT J121001+4959647 to a dwarf galaxy 480 million light-years away.

They also examined observational data in that region to determine when VT J121001+4959647 began brightening. As a result, they found a burst of soft X-rays captured by the International Space Station’s Monitor of All-sky X-ray Image (MAXI) in 2014.

These observations have allowed researchers to reconstruct the history of the supernova. At least some of the dust and gas heated by the supernova had to have come from somewhere. Most likely, they thought, it was the dying star itself.

As one half of a binary system, the star could have been stripped by its massive companion and lost some of its gas over time.

This early significant mass loss is more consistent with a binary star than a single star since binary systems tend to transfer mass from one star to the other as they reach the end of their lives. This is because the orbits of binary systems decay as the binary stars gradually approach each other.