A Black Hole's Lunch Provides a Treat for Astronomers

Scientists have discovered the heaviest known neutron star, or maybe the lightest known black hole: “Either way it breaks a record.”

Astronomers announced today that they had discovered something new out in the dark: a stellar corpse too heavy to be a neutron star — the remnant of a supernova explosion — but not heavy enough to be a black hole.

Whatever it once was, it is long gone. About 780 million years ago — and 780 million light-years away — it was eaten by a black hole 23 times more massive than the sun. That feast left behind an even heavier black hole — a vast, hungry nothing with the mass of 25 suns.

News of that event only recently reached Earth, in the form of space-time ripples known as gravitational waves. These evanescent vibrations were felt on Aug. 14, 2019, by an array of antennas in Italy and the United States called the International LIGO-Virgo Collaboration, and the results were published on Tuesday in Astrophysical Journal Letters.

According to a theory that has been the backbone of decades of astrophysical excitement, a star can wind up in one of three final states, depending on its mass: a perpetually cooling cinder known as a white dwarf; a dense star, with the mass of a couple of suns compressed into a ball only 12 or so miles wide, known as a neutron star; or a black hole, a beast reluctantly predicted by Albert Einstein to be so dense that nothing, not even light, can escape its gravity.

https://www.nytimes.com/2020/06/24/science/black-hole-ligo-gravitational.html