An international team of astronomers working with the Atacama Large Millimeter-Wave Array (ALMA), the largest complex of radio telescopes, has obtained the most detailed image of the surface of a distant star ever produced with radio telescopes.
The above photo shows Betelgeuse, the famous red supergiant in the constellation Orion. Thanks to this photograph, scientists have found that the temperature of the inner layers of the star's atmosphere is far from uniform. The discovery may help explain how the atmosphere of such stars is heated and how their stellar matter enters interstellar space.
“ALMA has the ability to show us images of the surface features of nearby stars, as well as direct temperature measurements of these features,” explains Dr. Eamon O'Gorman, an astronomer at the Dublin Institute for Advanced Study and lead author of the study under discussion.
“We suspected for years that the visible surface of Betelgeuse was not uniform in terms of temperature, but ALMA allowed us to look at this feature in amazing detail. It turns out that the lower layers of the star's atmosphere are also not uniform. Most likely, these temperature changes are caused by magnetic fields, as is the case in our own star, the Sun."
The astronomers' observations were recently published in the journal Astronomy & Astrophysics.
Speaking of the size of Betelgeuse, the star is huge. It is about 1400 larger than our Sun, and its mass is more than 1 billion times that of our star. As part of their evolution, stars like Betelgeuse eject a huge volume of their material into interstellar space using the stellar wind. These winds contain heavy elements produced by stars and are important ingredients for the formation of new stars and planets.
Betelgeuse's size compared to the orbits of the planets in our solar system
"Located about 650 light-years away, Betelgeuse is not the closest star to the Solar System, but its size makes it an ideal target for ALMA exploration," said Dr Pierre Kervella, an astronomer at the Paris Observatory who also participated in the study.
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Betelgeuse against the background of the constellation Orion (left). Single image (center). The right image is the previous best image of the star from the Very Large Telescope.
“When we look at the night sky with the naked eye, we see many bright stars all over the place. But since these stars are very far from us, even the most powerful telescopes in the world cannot cope with capturing the surface of these stars. The latest results from ALMA show that the radio telescope is capable of coping with this task when it comes to the surface of very large stars.
ALMA consists of 66 giant 12-meter and 7-meter antennas and is the most powerful radio telescope complex in the world. The distance between individual telescopes can be up to 16 kilometers, giving ALMA outstanding magnification capabilities.
The complex is an international astronomical instrument and is located 5,000 meters above sea level on the Chahnantor plateau in northern Chile, one of the driest places in the world. Many astronomers and observatories from Europe, North America and East Asia work with ALMA.
NIKOLAY KHIZHNYAK