Neutron star might be changing into another starFebruary 21st, 2008 - 4:33 pm ICT by admin
Washington, Feb 21 (ANI): Observations from NASA’s Rossi X-ray Timing Explorer (RXTE) have revealed that the youngest known pulsing neutron star in the Universe occasionally unleashes powerful bursts of X-rays, thus astronomers to think that it might be changing into another star.
A neutron star forms when a massive star explodes as a supernova, leaving behind an ultradense core. Most known neutron stars emit regular pulsations that are powered by rapid spins.
Astronomers have found nearly 1,800 of these so-called pulsars in our galaxy. Pulsars have incredibly strong magnetic fields by Earthly standards, but a dozen of them - slow rotators known as magnetars - actually derive their energy from incredibly powerful magnetic fields, the strongest known in the universe.
These fields can stress the neutron star’s solid crust past the breaking point, triggering starquakes that snap magnetic-field lines, producing violent and sporadic X-ray bursts.
“We are watching one type of neutron star literally change into another right before our very eyes. This is a long-sought missing link between different types of pulsars,” said Fotis Gavriil of NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
Astronomers would like to know if magnetars represent a rare class of pulsars, or if some or all pulsars go through a magnetar phase during their life cycles.
“Never before has a regular pulsar been observed to produce magnetar bursts,” said Gavriil.
According to coauthor Marjorie Gonzalez, Young, fast-spinning pulsars were not thought to have enough magnetic energy to generate such powerful bursts.”
“Here’s a normal pulsar that’s acting like a magnetar,” he added.
Observations from NASA’s Chandra X-ray Observatory also provided key information.
Chandra observed the neutron star, referred to as PSR J1846, in October 2000 and again in June 2006, around the time of the bursts. Chandra showed the object had brightened in X-rays, confirming that the bursts were from the pulsar, and that its spectrum had changed to become more magnetar-like.
According to Victoria Kaspi of McGill University, “PSR J1846’s actual magnetic field could be much stronger than the measured amount, suggesting that many young neutron stars classified as pulsars might actually be magnetars in disguise, and that the true strength of their magnetic field only reveals itself over thousands of years as they ramp up in activity.” (ANI)
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