Mega bubbles filmed on the star’s surface

The images of the star called R Doradus were taken in July and August 2023 with the Atacama Large Millimeter/submillimeter Array (ALMA), a telescope of the European Southern Observatory (ESO).

It shows huge, hot bubbles of gas 75 times larger than our sun, emerging from the surface and sinking back into the star’s interior faster than astronomers expected.

“This is the first time that the bubbling surface of a real star can be imaged in this way,” says Wouter Vlemmings of Chalmers University of Technology in Sweden in the journal Nature. “We never expected the data to be of such high quality that we would be able to see so many details of the convection on the surface of the star,” the scientist says.

Energy rises to the surface in gas bubbles
Stars gain energy in their centers through nuclear fusion. This energy can be transported to the surface of the star in huge, hot bubbles of gas, which then cool and sink – like a lava lamp. This mixing, known as convection, distributes the heavy elements formed in the core, such as carbon and nitrogen, throughout the star.

It is also thought that so-called convection is responsible for the stellar winds that carry these elements out into the cosmos to form new stars and planets. Until now, convective motions have never been observed in detail in stars other than the Sun.

180 light years from our Earth
R Doradus is a so-called red giant with a diameter about 350 times larger than that of our Sun and is located about 180 light-years from Earth in the constellation Dorado.

R Doradus’ size and proximity to Earth make it an ideal target for detailed observations. It also has a similar mass to the Sun, meaning it will likely look something like our Sun will look in five billion years as it expands into a red giant.