For the first time, astronomers have managed to obtain images of gas bubbles on the surface of a star other than our Sun.
The images of the star R Doradus were taken with the Atacama Large Millimeter/submillimeter Array (ALMA), a network of telescopes managed in part by the European Southern Observatory (ESO), in July and August 2023. Thus, astronomers observed in unprecedented detail huge, hot bubbles of gas, up to 75 times the size of the Sun, on the star’s surface.
“This is the first time that bubbles on the surface of a star can be seen in this way. We would not have expected the data to be of such high quality that we could see many details of the convection on the stellar surface,” explained Wouter Vlemmings, professor at Chalmers University of Technology in Sweden and lead author of the study published in the journal Nature.
What are the giant hot bubbles on the surface of stars?
Bubble convection has been observed in detail on the surface of stars before, including with the PIONIER instrument on ESO’s Very Large Telescope, but the new ALMA images follow the movement of the bubbles better than ever and in a way that has never been possible before, according to one press release remis DISCOPE.ro
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Stars produce energy in their cores through nuclear fusion. This energy can be sent to the star’s surface in huge, hot bubbles, which then cool and sink (like a lava lamp). All this movement, called convection, distributes the heavy elements formed inside the star, such as carbon and hydrogen, all over the star. This process is also believed to be responsible for the stellar winds that transport these elements into outer space and help form new stars and planets.
Convection movements have never been observed in such detail before
Convection movements have never been observed in such detail before except on our Sun. Using ALMA’s array of telescopes, astronomers have obtained high-resolution images of the surface of the star R Doradus.
This is a red giant star, 350 times the diameter of the Sun, located 180 light-years from Earth in the constellation Dorado. Moreover, the star’s mass is similar to that of the Sun, meaning that R Doradus is likely similar to what our Sun will look like in 5 billion years, when it will become a red giant.
“We can see details on the surface of stars so far away”
The grains on R Doradus appear to move on a one-month cycle, which is faster than scientists would have expected. Convection changes appear to occur as the star ages, but astronomers don’t yet fully understand what’s happening.
“It is spectacular that we can now directly observe the details on the surface of such distant stars, and that we can observe physics that until now was largely observable only in our Sun,” concluded Behzad Bojnodi Arbab, a Chalmers PhD student involved in the May study mentioned above.
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Source: www.descopera.ro
