https://www.cnet.com/news/nasa-mysterious-space-cow-explosion-could-be-birth-of-black-hole/

Then, in November 2018, two teams suggested that it may be the birth of a neutron star or a black hole. A second group suggested the event was caused by a huge black hole obliterating a dying star known as a "white dwarf".  On Thursday, astronomers from those teams put forth their theories on the Cow's origins during a panel discussion at the 233rd American Astronomical Society.

"We've never seen anything exactly like the Cow, which is very exciting," said Amy Lien, assistant research scientist at the University of Maryland and NASA's Goddard Space Flight Center.