Astronomers have discovered firm evidence of a rare double cosmic cannibalism — a star consuming a compact object like a black hole or neutron star for the first time. As a result, the object devoured the star’s core, triggering an eruption and leaving behind a black hole in its wake.
The Very Large Array (VLA), a radio telescope comprising of 27 enormous dishes in the New Mexican desert near Socorro, documented the first traces of the event, as reported in Science on September 3.
A flash of radio radiation as intense as the brightest exploding star – a supernova – erupted in a dwarf star–forming galaxy 500 million light-years away during the observatory’s night sky scans in 2017.
Dillon Dong, an astronomer at Caltech, and his colleagues used the VLA and one of the telescopes at the W.M. Keck Observatory, to do follow-up observations of the galaxy. A bright outpouring of material flaring in multiple directions at 3.2 million kilometers per hour from a central position was captured by the Keck telescope indicating that an intense explosion had transpired there in the past.
Researchers hypothesize that a binary pair of stars formed a long time ago was born orbiting each other. One died in a magnificent supernova and materialized into either a neutron star or a black hole. As gravity drove the two objects closer together, the dead star actually pierced the outer layers of its larger stellar sibling.
For hundreds of years, the compact object swirled within the still-living star, subsequently reaching and devouring its partner’s core. The larger star discarded massive amounts of gas and dust at this time, building a material shell around the couple.
Gravitational forces and complex magnetic interactions from the dead star’s consumption caused tremendous streams of energy to be propelled into the living star’s core, as well as causing the larger star to combust, as evidenced in an X-ray burst in 2014. Debris from the explosion blasted into the surrounding shell of material at incredible speeds, generating optical and radio light.
Theorists have already postulated the event, dubbed a merger-triggered core collapse supernova, but this is the first firsthand observation of the phenomena.
In cosmic time, such stages in a star’s life are relatively brief, making them difficult to detect and recreate. Most of the time, the enveloping partner dies before its core is devoured, resulting in two compact objects orbiting each other, such as white dwarfs, neutron stars, or black holes.
