Astronomers have witnessed one of the heaviest and largest neutron stars known to science. It is twice as massive as the sun.

Researchers from the Astronomy and Astrophysics Group of the UPC and the Canary Islands Institute of Astrophysics (IAC) have made the discovery. They used a pioneering method to find a neutron star of about 2.3 solar masses. It’s called PSR J2215+5135 and is the most massive one ever detected.

Researchers published the study on the 23rd of May in the Astrophysical Journal.

Neutron stars are super-dense stellar remnants that have reached the end of their evolutionary life. These objects pack a huge amount of material into a small space.

Measurement Method

Researchers used data obtained from the Gran Telescopio Canarias (GTC), the largest optical and infrared telescope in the world, the William Herschel Telescope (WHT), the Isaac Newton Telescope Group (ING) and the IAC-80 telescope, in combination with dynamical models of binary stars with irradiation.

So, PSR J2215+5135 is a “redback” pulsar. Redback pulsars are compact binary systems in which a low-mass main sequence star closely orbits a spinning neutron star. They spin around each other every four hours. One is a “normal” star, just like the sun. The other is a neutron star which strongly radiates its companion.

Manuel Linares a UPC physicist led a team of astronomers which also used computer models to simulate the objects. Thus, studying the radiation patterns endured by the pulsar’s stellar companion.

This approach allowed the researchers to measure the speed at which the companion star moves in its orbit. Also, including the speeds observed at the star’s brighter and slightly dimmer sides.

They also measured the drastic temperature differences between the cooler/dimmer and hotter/brighter sides of the companion star. Therefore, concluding both the velocity of the neutron star and its mass. The bright side, which faces the pulsar, was measured at 8,080 Kelvin (7,807 degrees Celsius), and the dimmer side at 5,660 Kelvin (5,387 degrees Celsius). The objects are rotating around each other’s center of mass at 412 kilometers per second or 921,618 miles per hour.

Previously, scientists thought neutron stars couldn’t get any larger than about one and a half times the size of the sun. But the new discovery debunked that theory. PSR J2215+5135 may even be the very largest pulsar known to date, although the uncertainty around measuring these masses makes that difficult to say for sure.

However, scientists still want to confirm their size estimates using a technique called stellar inclination.

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Thumbnail image. Artist’s impression of a spinning neutron star. Credit: Kevin Gill/Flickr (CC BY-SA 2.0)