The Russian astronomers have learned how pulsars untwist “propeller”


Astronomers from a number of the Russian institutes and their foreign colleagues have for the first time seen how pulsars turn into peculiar “propellers” when they “steal” too much matter from the next star and begin to scatter it after the district, it is told in article published in the Astronomy & Astrophysics magazine.

“The understanding of how magnetic fields of neutron stars are arranged, is extremely important for studying of processes of their evolution and formation. We have found out how magnetic field at two pulsars is arranged and have found out how it gives rise to the effect of the propeller predicted by the theory” — Alexander Lutovinov from Institute of space researches of RAS in Moscow whose words are transferred by the press service of MIPT tells.

As Lutovinov and his colleagues from Physics and Technology faculty, and also scientists from IKI RAS and Pulkovo Observatory tell, existence of this effect has been predicted at the theoretical level more than forty years ago, however so far nobody observed him “alive” during observations of real pulsars.

Pulsars represent a special type of the neutron stars, the remains which have blown up supernew from which poles narrow bunches of radio waves proceed. Usually “newborn” pulsars rotate very quickly and are gradually slowed down, spending own energy for radiation. But if the pulsar has a neighbor, a usual star of the big or small sizes, he can be untwisted again, having become a peculiar space vampire and “stealing” substance from it. In such cases he turns into a x-ray pulsar, radiating not in radio, and in the x-ray range.

In certain cases, as astrophysicists-theorists in 70 years of the last century have found out, this process of “theft” of matter can proceed unusually when the star which plasma is “drunk” by a pulsar vampire is in itself an unusual object.

For example, if she rotates very quickly or will have very big sizes, then the pulsar – “vampire” will just not manage to absorb all matter which will flow on it from his “victim”, and in literal sense to choke, scattering the lunch remains on surrounding space. Thanks to it the pulsar actually itself loses “lunch” and ceases to absorb new matter because of what its brightness sharply falls.

Scientists called this process “propeller” effect as magnetic field of a pulsar and centrifugal forces will scatter matter of the next star approximately in the same way as the propeller of the fan scatters the water flowing on him.

Lutovinov and his colleagues managed to see how it occurs, watching two x-ray pulsars, 4U 0115+63 and V 0332+53 in Kassiopei and Perseus’s constellations which brightness periodically increases or falls each 3-4 years.

Watching them by means of the orbital x-ray Swift telescope, the Russian astronomers could understand when the pulsar “includes” and “switches off” the propeller and to understand that this process two main physical properties of a pulsar – force of his magnetic field and speed of rotation operate.

It has become clear by an unexpected image that “propeller” at pulsars rejected – brightness of pulsars at turning on of the propeller fell not by 400 times as showed calculations, and by only 200 times. It means that a part of the stolen matter of the next star nevertheless somehow falls on a pulsar or that it is cooled with physical mechanisms, still unclear for scientists, which still should be studied.

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