Astronomers Discover Brightest and Furthest Pulsar Yet

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An international team of scientists has discovered the furthest and brightest pulsar yet. It's an extreme object and they think its properties depend on an incredible magnetic field structure.

According to the research paper, published in Science, this pulsating neutron star is an Ultraluminous X-ray source (ULX) emitting more than 30 million times the luminosity of the Sun. The star is located in NGC 5907, a galaxy 55 million light-years away from us.

“What makes this object unique are its properties. First of all, it’s the most distant pulsar ever detected,” lead author Gian Luca Israel from the Italian National Institute for Astrophysics (INAF) stated in a press briefing. “When the pulsation we detected originated in the neutron star, humans were not yet roaming on Earth. Secondly, this pulsar is also the most luminous we have ever detected.”

The researchers believe that an intense magnetic field has allowed the star to grow so luminous. Material falls onto a star due to gravity but the pulsar light is also propelling it away. When these two are balanced this is the maximum luminosity a star can achieve, known as the Eddington luminosity.

The ULX in NGC 5907 is 1,000 times brighter than its Eddington luminosity and the scientists think that a complex multipolar magnetic field is helping the pulsar increasing its mass. Its magnetic field could be a million billion times stronger that the magnetic field of our planet.

Neutron stars are incredibly dense objects, which sometimes form from supernovae, and pulsars are a special class where the neutron star is rotating very quickly and emitting light pulses. This particular pulsar pulsates every 1.13 seconds.

The pulsation is another indication that the object is acquiring mass. When material falls onto the star it speeds up its rotation, and this pulsar had previously been recorded as pulsating every 1.43 seconds back in 2003, meaning it has acquired a lot of material to speed it up. This is an incredible change in such a short period.

If we were to compare this to Earth’s rotation it would mean a day would have become five hours shorter in just over a decade.

This result is part of a wider project called Exploring X-ray Transient and variable Sky (EXTraS), devoted to the search of hidden sources and their properties in a very large archival database of observations from the European Space Agency's XMM-Newton observatory.

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