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A group of researchers recently observed a mysterious infrared emission from a device located near a pulsar in NASA's Hubble Space Telescope data. This animation represents a possible source of the emission: a "spare disk" or a disc formed from parent star materials falling into the neutron star after a supernova.
Credit: ESA / N. Tr. Ehnl (Pennsylvania State University) / NASA
The space is filled with weird signals that we try to make sense of – and now the researchers have detected another mysterious signal. This one emanated from a near neutron star, and for the first time, it is infrared.
So, what is nearby that could have created the strange signal? Scientists have some ideas.
When a star arrives at the end of life, it usually undergoes a supernova explosion – the star will collapse and if it has enough mass, it will form a black hole. But if the star is not massive enough, it will form a neutron star. [Supernova Photos: Great Images of Star Explosions]
Neutron stars are very dense and, as their name indicates, they are mainly composed of tight neutrons. According to Space.com, neutron stars can also be called "pulsars" if they are highly magnetized and rotate quickly enough to emit electromagnetic waves.
According to a statement issued yesterday (17 September) by NASA, neutron stars generally emit radio waves or higher energy waves, such as X-rays. But an international group of researchers from Penn State, University of Arizona and Sabanci University in Turkey observed something of interest in NASA's Hubble Space Telescope data: a long infrared signal emitted near a neutron star.
This signal, they discovered, was about 800 light-years away and was "extended", which meant it was spread over a wide space, unlike the "spot" signals typical of neutron stars emitting X-rays. Specifically, the signal spanned 200 astronomical units (AU) of space, or 2.5 times the orbit of Pluto around the sun, according to a Penn State statement. (An AU is the average distance from Earth to the Sun – about 93 million miles or 150 million kilometers.)
Such extended signals have been observed before, but never in the infrared, said Live Science's lead author, Bettina Posselt, associate professor of astronomy and astrophysics research at Penn State.
This illustration shows a "pulsar wind nebula" another source that could have produced this infrared signature.
Credit: ESA / N. Tr'Ehnl (Pennsylvania State University) / NASA
On the basis of the above data, the amount of infrared radiation is much larger than that which the neutron star should emit, said Posselt. Thus, "all the emissions in the infrared we are seeing probably do not come from the neutron star itself," Posselt said. "There is something more."
The neutron star in question, RX J0806.4-4123, is one of the nearby X-ray pulsars known as the Magnificent Seven. These are weird characters: they spin much slower than conventional neutron stars (it takes 11 seconds for a rotation of the RX J0806.4-4123, while the rotations are done in a fraction of a second), and they are much hotter than they are. should be based on when they formed.
In their study, the researchers proposed two possibilities for what could have snuggled close to RX J0806.4-4123 and made these mysterious signals: a dust disk that surrounds the pulsar or a "pulsar wind nebula".
A "spare drive" – which could extend over 18 billion kilometers – could have formed from the remains of a resident star following a supernova explosion, Posselt said. Such discs, which have been searched for for a long time, but not found, would probably be composed mainly of dust particles, she added.
The internal part of such a disc would probably have enough energy to produce infrared light, Posselt said. This could also help explain why RX J0806.4-4123 is so hot and running so slowly. "The records in the past could have provided additional heating," Posselt said.
The second explanation is that the infrared signal may be coming from a nebula near the pulsar wind.
According to NASA's statement, a pulsar wind can form when the electrons of a neutron star are accelerated in an electric field produced by the fast rotation of the neutron star and the powerful magnetic field. As the neutron star moves in space, usually faster than the speed of sound, it enters the interstellar medium – the tiny particles of gas and dust that reside between the great celestial objects. . The interaction between the interstellar medium and the pulsar wind can produce what is called a pulsar wind nebula, which could emit infrared radiation, Posselt said.
Pulsar wind nebulae are usually emitted by X-rays, so a pulsar nebula that radiates only in the infrared is "certainly interesting," Posselt said.
Originally published on Live Science.
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