Astronomers have recorded one of the heaviest neutron stars ever known. This object is providing an unprecedented opportunity to conduct particle physics research from a distance.
Neutron stars are very fascinating objects, heavier than two suns put together. They are super-dense and round, packing an enormous amount of material into a small space. A typical neutron star packs around 500,000 times our planet’s total mass into a sphere measuring 12 miles across. Neutron stars form from the decayed shells of stars between 10 to 30 solar masses, where one solar mass equals the mass of our Sun.
Scientists describe this massive neutron stars as an object containing 2.3 solar masses. Only one known neutron star tops it - a behemoth discovered about seven years ago which weighed in at 2.4 solar masses. About 2,000 neutron stars are known to astronomers, only four are over two solar masses.
The newly described neutron star is called PSR J2215+5135 - a “redback” pulsar. Redback pulsars are binary systems in which a spinning neutron star is closely orbited by a low-mass main sequence star. These stars are bombarded with the radiation coming out of the pulsar, making it difficult for scientists to differentiate the two objects, which in turn makes it difficult to determine the mass of either object.
Researchers have recently developed a new method of measuring the mass of a neutron star in a compact binary. To pull this off, a group of telescopes was used to hone in on the pair: the Gran Telescopio Canarias, the Isaac Newton Telescope, the William Herschel Telescope, and the IAC-80 telescope. The astronomers also used computer models to simulate the objects and study the radiation patterns endured by the pulsar’s stellar companion.
This method allowed the researchers to determine the speed at which the companion star moves in its orbit. The temperature differences between the dimmer and brighter sides of the companion star allowed the researchers to infer both the mass of the neutron star and its velocity. The temperature of the bright side, which faces the pulsar, was measured at 8,080 K and the dimmer side at 5,660 K. Both objects rotate around each other’s center of mass at 412 kilometers per second. With this information, the researchers established the neutron star’s mass at 2.3 solar masses.
The discovery of PSR J2215+5135 and other massive neutron stars has helped scientists understand how extreme these objects can get. They can also learn more about the interactions and behaviours of these particles within their environments. It would be wrong for scientists to replicate the gravitational strength of neutron stars on Earth but they can treat these objects as distant, space-based laboratories.
As pointed out by these scientists, this new technique could also be used to determine the masses of white dwarfs and black holes, both of which are very dense. The researchers hope to discover more objects stranger than PSR J2215+5135. This shows the extent to which the laws of the universe can twist and contort matter.