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An unusual infrared light emission from a nearby neutron star detected by NASA's Hubble Space Telescope could point to new features never seen before. One possibility is that there is a dusty disc surrounding the neutron star; another is that there is an energetic wind coming out of the object and slamming in the gas in the interstellar space through which the neutron star passes.
Although neutron stars are generally studied in radio and high energy emissions, such as X-rays, this study demonstrates that new and interesting information about neutron stars can also be obtained by studying infrared light.
The observation, by a team of researchers from the Pennsylvania State University, University Park, Pennsylvania; Sabanci University, Istanbul, Turkey; and the University of Arizona, in Tucson, Arizona, could help astronomers better understand the evolution of neutron stars – the incredibly dense remains after the explosion of one. massive star in supernova. Neutron stars are also called pulsars, because their very fast rotation (typically a fraction of a second, in this case of 11 seconds) causes a variable emission of time from light-emitting regions.
An article describing the research and two possible explanations for the unusual discovery appears on September 17, 2018 in the Astrophysical Journal.
"This neutron star belongs to a group of seven nearby X-ray pulsars – nicknamed the" Magnificent Seven "- which are warmer than they should be given their age and the reservoir of 39 available energy provided by the loss of rotational energy. " said Bettina Posselt, associate professor of astronomy and astrophysics research at Pennsylvania State and lead author of the paper. "We observed an extended infrared emission zone around this neutron star – called RX J0806.4-4123 – whose total size translates to about 200 astronomical units (about 18 billion miles) at the assumed distance pulsar. "
It is the first neutron star in which an extended signal has been observed only in infrared light. The researchers suggest two possibilities that could explain the extended infrared signal seen by Hubble. The first is that there is a disc of matter – perhaps mostly dust – surrounding the pulsar.
"One theory is that there could be a so-called" fallback disc "of the material that fused around the neutron star after the supernova," said Posselt. Such a disc would be composed of material from the massive precursor star.Its subsequent interaction with the neutron star could have warmed the pulsar and slowed its rotation.If confirmed as a supernova retreat record, this result could change our general understanding of the neutron star evolution. "
The second possible explanation for the extended infrared emission of this neutron star is a "pulsar wind nebula".
"A pulsating wind nebula would require the neutron star to have a pulsar wind," said Posselt. "A pulsar wind can be produced when the particles are accelerated in the electric field produced by the rapid rotation of a high magnetic field neutron star, when the neutron star passes through the interstellar medium at a speed greater than that of the sound. , a star the shock can form where the interstellar medium and the pulsar wind interact The shocked particles would then emit a synchrotron radiation, provoking the extended infrared signal that we see. As a rule, the nebulae of the pulsar wind are observed in the rays. X and the only infrared pulsar nebula would be very unusual and exciting. "
By using NASA 's next James Webb space telescope, astronomers will be able to further explore this newly opened discovery space in the infrared to better understand the evolution of the neutron star.
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