MOSCOW, 11 Dec, Tatyana PichuginaEarly in the morning of December 12, a unique event will take place — the eclipse of Betelgeuse, one of the brightest stars in our sky. Asteroid 319 Leona will hide it for about 12 seconds, causing a rare effect — a «ring of fire». This will allow astronomers to better understand what is happening to the red giant and clarify its future fate.
All eyes on Betelgeuse
Betelgeuse is visible in the constellation Orion with the naked eye — it is located on the left “shoulder” of the ancient Greek hero holding a shield and mace, diagonally with Rigel. This star is one of the ten brightest in the sky. Its angular diameter varies widely — from 500 to 800 times the diameter of the Sun. During the observation period, this figure decreased by 15 percent, which has not yet been explained.
Betelgeuse is a red supergiant at a late stage of development, tens of times more massive than the Sun. Such stars eventually explode, turning into supernovae.
Betelgeuse's brightness varies, which gives grounds to classify it as variable. This is due to pulsations: the star either contracts or expands.
At the end of 2019, its brightness weakened five times, which caused an unprecedented commotion among astronomers. It was assumed that the supergiant would soon explode. We discussed how this threatens the Earth. It was later discovered that the «great darkening» was caused by a dust cloud. Now the star is back in the spotlight.
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Prediction of a Russian astronomer
“An Internet search for Leona and Betelgeuse did not produce results, so this unique eclipse was probably discovered by me in April 2004,” astronomer Denis Denisenko, a former employee of the Space Research Institute of the Russian Academy of Sciences, wrote on his page dedicated to rare stellar eclipses , now — SAI.
He predicted that asteroid 319 Leona will cover Alpha Orion on December 12, 2023 at one hour, nine minutes, 27 seconds UTC (four am Moscow time). The eclipse will be visible in Turkey, Greece, Sicily, Tunisia, Algeria, Morocco, and Cuba.
The discovery was made using the WinOccult program, developed by Australian David Harald. Denisenko reported on it in October 2004 at the AstroFest astronomy festival.
“This is an exceptional eclipse not only because of the brightness of the star, but also because of its angular size,” the scientist noted.
According to interferometric measurements, the diameter of the red giant is about 50 milliseconds of arc (this is several hundred Suns at a distance of 400-500 light years). The Leona asteroid has about the same number. This means, the astronomer concluded, the eclipse, unlike ordinary asteroid ones, will be similar to the solar one.
What will the Betelgeuse eclipse be like
Covering stars with asteroids is not uncommon. But this case is unique, notes an international group of scientists from Europe, Turkey and Brazil in an article posted on the preprint portal Arxiv.org. Effects will arise that will make it possible to study the diameter and brightness distribution of the star's photosphere along light curves during observations from different points of the Earth and at different wavelengths.
The eclipse will create a 60-kilometer shadow strip in southern Europe, Transcaucasia, Central Asia and southern Florida in the USA. The shadow will not look into Russia.
Asteroid 319 Leona was discovered in 1891. It belongs to the Cybele family, it is on the outer side of the asteroid belt. The semimajor axis is 3.3 astronomical units, the period of revolution around the Sun is more than six years. It is distinguished by a dark surface, slow, irregular rotation around an axis.
Scientists have been monitoring him since the fall. So, on September 13, 23 observation stations were used to adjust its parameters at the time of occultation of stars. It has been established: the maximum length of the visible disk is almost 80, the width is about 54 kilometers.
Astronomer Artem Novichonok from Petrozavodsk University draws attention to the fact that the exact size of Betelgeuse is unknown. “If it turns out to be greater than current estimates, then at the peak of the eclipse the stellar disk will be divided into two parts by the elongated body of the asteroid,” he indicated in his Telegram channel.
The international network of optical telescopes at the M. V. Keldysh Institute of Applied Mathematics of the Russian Academy of Sciences published a photograph of an asteroid taken a week ago at the ISON-Kitab observatory in Uzbekistan. Due to uncertainty about the sizes of the star and asteroid, the eclipse could be either total or annular, scientists warn.
«An exceptional case. Such a chance comes once in a lifetime,» Business insider quotes astrophysicist Miguel Montagres from the Paris Observatory. Leona is the perfect size to hide the star disk while leaving a “ring of fire” around the edges. This effect will help determine the temperature of the stellar wind generated by the convection of matter. As a result, all this allows us to better understand how our Galaxy was formed.
The online broadcast of the eclipse is organized on the website of the virtual telescope project 2.0.