According to the latest observations, astronomers have confirmed the heaviest known neutron star to date, PSR J0952-0607, about 2.35 times the mass of the sun, because it has almost wiped out the entire mass of its companion star. The discovery will help scientists better determine the mass boundary between large neutron stars and the smallest black holes.
PSR J0952-0607 is located in the southern constellation Sextant and was first discovered by the Low-Frequency Array (LOFAR) in 2016. The neutron star is also classified as a black widow pulsar because it emits a pulse of radio waves in the direction of Earth every time it rotates, and it is cannibalizing another companion star in the binary system.
The pulsar rotates every 1.41 milliseconds, or 707 times per second, faster than any other pulsar, prompting the UC Berkeley team to suspect that PSR J0952-0607 might be unusually heavy and decide to further utilize Keck The observatory observed the system and found that the companion star of PSR J0952-0607 was rapidly revolving around the former at a speed of 380 kilometers per second, with an orbital period of only 6.5 hours.
The calculation results show that the mass of the pulsar PSR J0952-0607 is 2.35 times that of the sun, which is indeed much heavier than that of a typical neutron star, which is about 1.4 times the mass of the sun.
“Ordinary” pulsars usually rotate about once per second, but how does an unusual pulsar like PSR J0952-0607 achieve nearly a thousand rotations per second? One idea is that it devoured the companion star, which contributed a lot of mass and angular momentum to make PSR J0952-0607 the heaviest neutron star known to date in the Milky Way.
The researchers explained that if the mass of PSR J0952-0607 is close to the upper limit of the mass of a neutron star, then the interior of the neutron star is likely to be composed of neutron soup rather than exotic particles. Astronomers will continue to look for more massive neutron stars. If they are not found, they will strengthen the argument that “the upper limit of the mass of a neutron star is 2.3 times the mass of the sun”, and if it exceeds it, it will become a black hole.
The new paper is published in Astrophysical Journal Letters.
(First image source: University of California, Berkeley)
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