The stellar object is considered the densest seen from Earth, since neutrons and quarks are deposited inside its core. However, no evidence of exotic matter such as kaons, which are strange quarks, was observed.
A group of researchers from American scientific institutions revealed that a ‘black widow’ type pulsar, designated as PSR J0952-0670set a record for being the most massive neutron star known so far, since its mass is 2.35 times more than that of the Sun (0.17 solar masses), reported this Tuesday the University of California at Berkeley.
According to the study authors, published en The Astrophysical Journal Letters, el PSR J0952-0670, que se localiza a 3,000 light years away from Earth, is part of a binary cosmic system called ‘black widow’, because it absorbs material from its smaller stellar companion, just as its arachnid homonym does. This causes both the mass and the speed of rotation of the neutron star to increase.
PSR J0952-0670 is one of the fastest spinning pulsars in the Milky Way.
Scientists determined that PSR J0952-0670 rotates at a rate of 707 times per second, making it one of the fastest rotating pulsars in the Milky Way. Likewise, they considered that the pulsar is the densest stellar object seen from Earth, since neutrons and quarks are deposited inside its nucleus, which constitute the natural protons and neutrons. However, they reiterated that there is no exotic matter like kaons, which are particles that contain a strange quark.
“A high maximum mass for neutron stars suggests that it is a mixture of cores and its quarks are dissolved up and down to the core,” said Stanford University astronomer Roger Romani, adding that “this rules out many proposed states of matter, especially those with an exotic interior composition”.
To calculate the mass of the neutron star, the researchers made comparisons of the visible light spectrum of its stellar companion through observations with the Low Resolution Imaging Spectrometer. Images obtained with the Keck I telescope at the WM Keck Observatory, located in Hawaii. This evaluation also allowed us to know the orbital speed of the smaller star (6.4 hours), as well as its size (20 times the mass of Jupiter).
In addition, they contemplate the possibility that it will become an isolated millisecond pulsar, once the PSR J0952-0670 has completely devoured its star. This name is due to the fact that the pulsar will have an even faster rotation speed.
“As the companion star evolves and begins to become a red giant, material spills onto the neutron star, causing it to spin.”, noted Alexei Filippenko, who assured that “as it spins, it now becomes incredibly energized, and a wind of particles begins to come out of the neutron star.” “That wind then hits the donor star and starts shedding material, and over time the donor star’s mass decreases to that of a planet. If more time passes, it disappears completely,” Filippenko said.
“So this is how lone millisecond pulsars could form. They weren’t alone to begin with and had to be in a binary pair, but gradually they evaporated their partners, and now they’re lonely,” he said.
The original article can be read here