Called neutron stars, the dense, collapsed remnants of a massive star weigh more than twice the mass of our sun, making it the heaviest known neutron star to date. The object spins 707 times per second, which also makes it one of the fastest spinning neutron stars in the Milky Way.
The neutron star is known as the black widow because, like those arachnids known to female spiders that consume much smaller male partners after mating, the star has shredded and devoured almost all of its companion star’s mass.
This stellar feast allowed the Black Widow to become the heaviest neutron star observed so far.
Astronomers were able to weigh the star, called PSR J0952-0607, by using the Sensitive Keck Telescope at the WM Keck Observatory on Maunakea in Hawaii.
The observatory’s low-resolution imaging spectrometer recorded visible light from the jagged companion star, which was glowing due to its elevated heat.
The companion star is now about the size of a large gaseous planet, or 20 times the mass of Jupiter. The side of the companion star that faces the neutron star is heated to 10,700 degrees Fahrenheit (5,927 degrees Celsius) – hot and bright enough to be seen by a telescope.
According to study author Roger W. Romani, professor of physics at Stanford University in California.
This particular neutron star is the densest object in sight of Earth, according to the researchers.
“We roughly know how matter behaves at nuclear densities, such as in the nucleus of a uranium atom,” study co-author Alex Filippenko said in a statement. Filippenko holds the double title of professor of astronomy and eminent professor of physical science at the University of California, Berkeley.
“A neutron star is like a giant nucleus, but when you have a solar mass and a half of that stuff, or about 500,000 Earth masses of nuclei all hooked together, there’s no telling how they’ll behave.”
A neutron star like PSR J0952-0607 is called a pulsar because as it spins, the object acts like a cosmic beacon, steadily emitting light through radio waves, X-rays, or gamma rays.
Normal pulsars spin and blink about once a second, but this one pulsates hundreds of times a second. This is because the neutron star becomes more excited as it removes material from the companion star.
“In a case of cosmic ingratitude, the Black Widow Pulsar, which devoured much of its companion, is now heating up and evaporating the companion to planetary masses and possibly complete annihilation,” Filippenko said. .
Astronomers first discovered the neutron star in 2017, and Filippenko and Romani have studied similar black widow systems for more than a decade. They tried to figure out how big neutron stars can get. If neutron stars get too heavy, they collapse and become black holes.
The star PSR J0952-0607 is 2.35 times the mass of the sun, which is now considered the upper limit for a neutron star, the researchers said.
“We can keep looking for Black Widows and similar neutron stars skating even closer to the edge of the black hole. But if we don’t find any, it strengthens the argument that 2.3 solar masses is the true limit, beyond which they become black holes,” Filippenko said.