One of the Milky Way’s most extreme stars just got an even bigger shock. Scientists have measured the mass of a neutron star called PSR J0952-0607, and found it to be the most massive neutron star ever discovered, at 2.35 times the mass of the Sun.
If correct, this is very close to the theoretical upper mass limit of about 2.3 solar masses for neutron stars, representing an excellent laboratory for studying these very dense stars that we think are on the brink of collapse. But there is, hopefully, the strange quantum state of matter from which they are made.
“We know roughly how matter behaves at atomic densities, such as in the nucleus of a uranium atom,” said astrophysicist Alex Filippenko of the University of California, Berkeley.
“A neutron star resembles a monster core, yet when you have an article with a sunlight based mass and a half, which is around 500,000 Earth cores remained together, it’s not exactly clear the way that they act. Got it.”
Neutron stars are the broken cores of massive stars that were between 8 and 30 times the mass of the Sun, before they went supernova and blasted most of their mass into space.
These cores, about 1.5 times the mass of the Sun, are among the densest objects in the universe. The main thing denser is a dark opening.
Their mass is packed into a circle only 20 km (12 mi) or so across. At this density, protons and electrons can combine to form neutrons. The only thing stopping this ball of neutrons from collapsing into a black hole is the force they would need to occupy the same quantum states, called the degeneracy pressure.
In some ways this means that neutron stars behave like large atomic nuclei. But what happens at that tipping point, where neutrons form exotic structures or fade into a soup of tiny particles, is hard to say.
PSR J0952-0607 was already one of the most interesting neutron stars in the Milky Way. This is what is known as a pulsar – a neutron star spinning very fast with jets of radiation emitted from the poles. As the star rotates, these poles pass by the observer (us) in a cosmic lighthouse fashion so that the star appears to pulsate.
These stars can be extremely fast, with rotation rates on the millisecond scale. PSR J0952-0607 is the second fastest pulsar in the Milky Way, rotating brain 707 times a second. (The quickest is just somewhat quicker, with a revolution pace of 716 times each second.)
This is known as a “dark widow” pulsar. The star is in a close orbit with a binary companion – so close that its enormous gravitational field pulls material away from the companion star. This material forms an accretion disk that rotates and intrudes into the neutron star, a bit of water like a trough swirling around. Angular momentum is transferred from the accretion disk to the star, causing its spin rate to increase.
A group drove by Stanford University astrophysicist Roger Romani needed to more readily grasp how PSR J0952-0607 squeezes into the timetable of this cycle.
The binary companion star is small, less than 10 percent of the mass of the Sun. The research team carefully studied the system and its orbit and used this information to obtain a new, accurate measurement for the pulsar.
Their computations returned a consequence of 2.35 times the mass of the Sun, plus or minus 0.17 sun based masses. Assuming that a standard neutron star has a starting mass of about 1.4 times the mass of the Sun, this means that PSR J0952-0607 has shrunk from its binary companion to the value of the entire Sun. The team says this is very important information about neutron stars.
“This gives probably the most grounded requirements on the properties of issue commonly the thickness seen in nuclear cores. In fact, many popular models of dense matter physics are ruled out by this result,” Romani explained.
“A most extreme mass for neutron stars proposes that it is a combination of cores and their broke up unpredictable quarks.
Binaries also show a mechanism by which isolated pulsars, without binary companions, can have millisecond rotation rates. J0952-0607’s companion is nearly extinct. Once it is completely consumed, the pulsar (if it does not tip over the upper mass limit and collapse further into the black hole) will maintain its super-fast rotation speed for a long time.
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And it will be lonely, just like all the other isolated millisecond pulsars. “As the sidekick star develops and begins to turn into a red monster, material spreads onto the neutron star, and it turns up the neutron star.
By spinning up, it’s now incredibly energetic, and the neutrons A wind of particles begins to escape. The star. That wind then collides with the donor star and begins to strip it of material, and over time, the mass of the donor star becomes equal to that of the planet, and even more so. Over time, it disappears completely,” Filippenko said.
“So, this is how solitary millisecond pulsars can be created. They weren’t quite alone to begin with — they had to be in a binary pair — but they slowly evaporated their companions, and now they’re alone. are.”
