Scientists of the Moscow State University named after M. V. Lomonosov for the first time were able to observe the process of "rejuvenation" of the unique ultra-slow pulsar XB091D. It is called super-slow because it rotates very slowly - one revolution in a few seconds.
A. Polyanina / ria.ru
Pulsars form after massive young stars perish in bright supernovae. In this case, their outer shells are thrown away, and the core is compressed, usually turning into a compact and superdense highly magnetized neutron star (its diameter is about 20 km, while it weighs 1.4 times more than the Sun). A young pulsar rapidly rotates at a speed of several hundred revolutions per second, emitting directed streams of energy, and therefore on Earth it is recorded by astronomers as a pulsating source of X-rays with a frequency of 100-1000 pulses per second. As it ages, the pulsar loses its rotational energy and gradually slows down.
A slowed-down pulsar can “rejuvenate” and start spinning if it approaches an ordinary star - which is much larger than a pulsar (with a diameter of about 3 million kilometers) but less dense. When a stable pair is formed, the neutron star begins to pull the matter of an ordinary star, receiving an additional impulse, accelerating the rotation. In just a hundred thousand years - which by cosmic standards is almost instantaneous - the old pulsar, which has already slowed down to one revolution in a few seconds, can spin up again thousands of times faster. This very rare moment was observed by the team of astrophysicists of the State Astronomical Institute named after PC. Sternberg (GAISH MSU) together with colleagues from Italy and France. The XB091D X-ray pulsar they studied was discovered in the earliest stages of "rejuvenation" and turned out to be the slowest spinning pulsar known to date. This neutron star completes a full revolution in 1.2 seconds - ten times slower than the previous record holder. According to scientists, the "acceleration" of the pulsar began less than a million years ago. Scientists predict that the star will accelerate again and become an ordinary millisecond pulsar in 50 thousand years.
Unique pulsar in the Andromeda galaxy / A. Zolotova / Lomonosov Moscow State University
The work was carried out on the basis of data obtained from the XMM-Newton space telescope between 2000 and 2013. and combined by astronomers of Moscow State University and their colleagues in an open online database of registration of 50 billion photons. Ivan Zolotukhin, a researcher at the Department of Relativistic Astrophysics at the Moscow State University, compares the search for pulsars among the data of the XMM-Newton telescope with the search for a needle in a haystack, since the amount of data received from the pulsar is very small, only a photon every five seconds: “In fact, this required create completely new mathematical tools that allowed us to predict and isolate the periodic signal we need. Theoretically, this method has many applications, including outside astronomy."
However, not only the time that astronomers managed to observe, but also the place in which XB091D is located, was unusual. After carefully assessing its position, Ivan Zolotukhin and his colleagues showed that XB091D is located in the neighboring Andromeda galaxy, 2.5 million light years from us, among the stars of the extremely dense globular cluster B091D, where more than a million are packed in a volume of 45 light years old and dim stars. The age of the cluster itself is estimated at 12 billion years, so all processes associated with supernova explosions and the appearance of pulsars should have ended long ago in it.
The results of the study, scientists of the Moscow State University named after M. V. Lomonosov was published in the prestigious The Astrophysical Journal.
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