This is Robotelescope MASTER II, created by a joint force of the Lomonosow Moscow State University, Sternberg Astronomical Institute (GAISh) scientists, and Moscow Union “Optica”. Credit: Lomonosow Moscow State University
3 years ago a team of Russian scientists working with the global MASTER network of robotic telescopes spotted that the giant star in Leo minor with a catalogue number TYC 2505-672-1, which was considered to be extinct, in fact just faded – its brightness decreased nearly 100 times.
The MASTER network of telescopes was constructed by MSU scientists for a purpose of detecting and researching Gamma-ray bursts and also thermonuclear flashes on white dwarfs, galactic center flares and quasars. MASTER telescopes already detected >1000 flashes in a distance from several hundred to a billion light years away, and spotted a number of potentially dangerous asteroids.
Though, the later photometric measurements by MASTER-Amur and spectral measurements by the 6-metre BTA-6 telescope showed that the star did not turn red, as, for example, the Sun does before sunset (this happens because it takes longer for the sun rays to pierce the atmosphere). For that reason the star was tracked attentively, and soon it started to restore its luminosity. In October 2014 it recovered its normal shine level completely.
At approximately the same time Rolf Yansen, Dutch astronomer (revised that data of Harvard observatory picture library, and suddenly detected that in 1942-1945 TYC 2505-672-1 underwent the same decrease in luminosity. According to the scientist’s calculations, the star has an unprecedented variation period of 25245 days, which is about 69 years.
This fact means that a common star became a record-breaker in a length of variation period, absolutely out of a reach. According to Denis Denisenko, one of the discovery’s authors, the longest known variation period used to belong to Epsilon Aurigae. Its eclipses repeat in 9890 days, which is a bit more than 27 years. Only 5 stars are known to have a period of >10 years. In other words, the new variable star exceeds the existing record >2.5X.
Scientists assume, that the star is actually a double system, though the nature of its companion by now allows only various guesses. ‘The scale of the new object is already impressive,’ tells Denis Denisenko. ‘Giant stars of such spectral class are about three and a half times heavier than the Sun. Taking into account the second component, the mass of the system should be around at least four solar masses. Orbital radius of such star should be about 33 astronomical units, the orbital length should then exceed two hundred astronomical units.’
‘The system is more than mysterious,’ Vladimir Lipunov agrees. ‘We actually see a total eclipse. That means that something totally occults the giant star. Hence the disc around the second, unseen companion, should be absolutely opaque. But what shines with the same spectrum during the eclipse then? That does not seem to be a stardust disc, though, it can not be another star. If the luminosity of the companion is one hundred times lower, then, the companion is a low-mass star. But a low-mass star can not have the size exceeding the size of a more massive companion in that double system, and would it be smaller, the eclipse would not take place at all, as you can not hide a larger object behind a smaller one.’
http://www.eurekalert.org/pub_releases/2016-03/lmsu-afa031816.php
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