Observations over the past a fading Betelgeuse showed that its surface is covered with giant spots. Astronomers believe that they cover from 50 to 70% of the surface of the star. An article describing the study published the scientific journal Astrophysical Journal Letters.
"We were surprised that the brightness of Betelgeuse decreased by 20% even in the submillimeter range. This suggests that the fading of this star is unlikely to have been due to the fact that its light was obscured by a huge cloud of dust. Changed the brightness of the lights", – commented on the results of the work of one of its authors, an astronomer at the East Asian Observatory (USA) Steve Marse.
Betelgeuse is one of the biggest and brightest stars in the sky, it is located in the constellation of Orion. Due to the huge size and mass, which is more solar in 15-25 times, and the fact that it is close to the Ground, Betelgeuse can be easily seen even with the naked eye. If this star was in the center of the Solar system, its outer layers would have reached the orbits of Mars or Jupiter.
Astronomers believe that Betelgeuse is now at the last stage of stellar evolution – the red supergiant stage. So scientists call the elderly stars that have almost out of hydrogen; they dramatically expanded and began to dump the substance of the outer shells into space. This generated a huge amount of dust and formed a bright nebula of gas and dust.
Some of the features of fluctuations in the brightness of Betelgeuse indicate that this star will end its existence in the next few thousand years. It will turn into a supernova, flash which on Earth can be seen even during the day. Because of this, the fate of Betelgeuse are interested in both professional astronomers and ordinary people.
At the end of December last year, scientists started to notice that Betelgeuse began to fade. By the beginning of January the strength of its glow fell by about 63%, reaching a record low over the past 25 years of observations. It will tarnish even more spurred the interest of astronomers.
The first such observation, as noted by Marse and his colleagues, scientists were using optical telescopes. Because of this, they are unable to pinpoint the cause tarnishing. Astronomers have proposed three explanations: real reduction in the brightness of the entire surface of Betelgeuse, the appearance of stains and education between the sun and the star a giant cloud of dust.
Marse and his colleagues tried to find out the real cause of this phenomenon using two microwave Observatory telescope by James Maxwell in the Hawaiian Islands, and also of the telescope APEX, which is installed in a Chilean high mountain Observatory Chajnantor.
In the range that was configured, these telescopes, microwaves.��th particularly active radiation interacts with particles of cosmic dust. If Betelgeuse really was obscured by a cloud of dust, the telescopes had to fix an excess of such radiation. Dimming, in turn, would indicate that the star has faded.
Data showed that closer to the truth was the second theory. Despite the large amount of dust in the vicinity of red supergiants, the brightness of Betelgeuse in the microwave range fell by 20%. According to scientists, something like this was bound to happen, if the surface of this star was colder than 200 Kelvin.
As noted Marse and his colleagues, it is quite possible. However, the more likely it is another option pointed to December’s photo of Betelgeuse. As the researchers suggest, from 50 to 70% of cover giant star spots. Like sunspots, they represent the points at which the magnetic field of the star "breaks" out and slows the circulation of plasma in the interior of stars. As a result, the surface at these points becomes colder.
According to researchers, the fading of Betelgeuse could be due to the fact that this star came low stellar activity, which is similar to the one that recently ended in the Sun. To confirm this theory Marse and his colleagues hope in the next observation, when Betelgeuse "Wake up". Then the brightness of the stars will re-grow.