This Carinae, the largest and most restless star in the Galaxy, constantly generates a huge amount of cosmic rays, accelerating particles of matter to near-light speeds, according to an article published in the journal Nature Astronomy.
“We have known for a long time that shock waves arising after a supernova explosion can accelerate particles of matter to the speed of light,“charging”them with a large amount of energy. It turns out that similar processes can take place in other extreme environments, for example, in the vicinity of stars like Eta Kiel,”notes Kenji Hamaguchi of NASA's Goddard Space Flight Center in Greenbelt, USA.
Cosmic rays - elementary particles and nuclei of atoms of different elements, accelerated to near-light speeds, have long been one of the main mysteries for science and sources of danger to the health of astronauts and astronauts.
To date, there is no consensus among scientists about their origin - some astronomers believe that these particles are accelerated in the hot remnants of exploding stars inside the Milky Way, while others suggest that their source is the nuclei and clouds of gas in distant galaxies. Even more interesting, the third group of researchers believes that they are generated by the decays of dark matter particles in the center of the Galaxy.
Hamaguchi and his colleagues have discovered another source of cosmic rays by observing the largest and potentially most dangerous star in the Milky Way, the supergiant Eta in the constellation Carina, using the NuSTAR X-ray telescope.
This was first marked on a sky map by the English astronomer Edmund Halley in 1677, and since then it has constantly attracted the attention of astronomers by the fact that its brightness periodically increased and decreased. For example, in 1843 it became so bright that it eclipsed Sirius, the brightest star in the vicinity of the Sun, despite the tenfold difference in distance between them and the Earth.
Observations of this star in the current century and in the 20th century have shown that it is an extremely exotic binary system, consisting of the largest star in the Galaxy with a mass of 170-250 Suns and its "small" companion, whose mass is only 30-80 times higher than at our luminary.
The pressure of light inside the interior of a larger star is so great that bursts of activity inside Eta Carina literally "tear off" the outer covers of the star, throwing them into open space. Scientists currently estimate that the larger "half" of the system has already lost about 30 solar masses during such flares, the traces of which formed the beautiful Homunculus nebula surrounding Eta Carinae.
Promotional video:
Scientists, says Hamaguchi, have long been interested in what happens at the moment when the "fresh" ejection of Eta Carina or its satellite collides with the remains of previous emissions. As a rule, such "cosmic accidents" lead to a sharp heating and acceleration of matter particles, but their accurate assessment was impossible before the launch of NuSTAR due to the lack of telescopes capable of operating at ultrahigh energies.
The observations that Hamaguchi and his colleagues carried out in 2014-2016 unexpectedly showed that the gas "mantle" of Eta Kiel produces a huge amount of hard X-rays, the strength of which could not be explained in this way - it was several orders of magnitude higher than theory predicts.
Having received such an unexpected result, the scientists compared the data from NuSTAR with the photographs of Eta Carinae in the gamma range obtained by the XMM-Newton and Fermi telescopes. This comparison showed that hard X-ray beams were generated not by their gas shells, but by "swarms" of electrons, which were accelerated to near-light speeds at the boundary between the colliding puffs of hot gas.
Some of these electrons, as scientists suggest, "escape" from these clouds into the interstellar medium and reach the Earth and other worlds of the Milky Way. In other words, large stars can also act as a source of galactic cosmic rays, Hamaguchi and his colleagues conclude.