14 DAY TRIAL // The PSR J0108-1431 object, located just 770 light-years away from the Earth, is one of the closest pulsars ever observed, but its light is faint, as evidenced by previous optical surveys. It's a pulsar, a collapsed star that spins around its axis very fast, giving away light trails resembling those of a lighthouse. Recently, while looking at it with the Chandra X-ray Observatory telescope, astronomers have noticed that the levels of activity exhibited by the star are far higher than one would expect from a body its age.
According to estimates, it's over 200 million years old, meaning that it has twice the age of any other known pulsar in the Universe. These bodies form relatively simply, when a massive star, much larger than our own Sun, depletes its fuel and bursts into a supernova. When this happens, what's left behind is a very bright and extremely dense core, which is known among astronomers as a neutron star. When they are first formed, these stellar remnants spin with an amazing speed, completing as much as 100 revolutions around their axis each second.
As they rotate, the radiation they emit closely resembles the appearance of a lighthouse to distant observers. This has prompted scientists to call them pulsars, on account of how the light coming from them looks like. Over time, their speed decreases, as evidenced by the fact that J0108 spins a little more than 1 time per second. Accordingly, its levels of radiation should have decreased once speed dropped, but Chandra showed that the old relic still emitted much more radiation than scientists would have expected from a pulsar that was 200 million years old.
“This pulsar is pumping out high-energy radiation much more efficiently than its younger cousins. So, although it's clearly fading as it ages, it is still more than holding its own with the younger generations,” Penn State University researcher George Pavlov, who has led the team of astronomers that has made the find, says. He adds that the energy the pulsar is losing as it slows down gets very effectively converted into X-rays, in amounts so high that it exceeds some of the younger similar stars.
“We can now explore the properties of this pulsar in a regime where no other pulsar has been detected outside the radio range. To understand the properties of 'dying pulsars,' it is important to study their radiation in X-rays. Our finding that a very old pulsar can be such an efficient X-ray emitter gives us hope to discover new nearby pulsars of this class via their X-ray emission,” University of Florida scientist Oleg Kargaltsev, a co-author of the new study, concludes.