The Sun is the biggest fish in our small pond of a solar system, but it’s a mere minnow compared to the whales that dwell out in the cosmos. New telescope images show a gigantic star casually blowing bubbles 75 times bigger than our Sun.
The matter in our neighborhood is distributed pretty unevenly – the Sun hogs some 99.8% of all mass in the solar system, making our planets look like little pebbles and gas balls. Put another way, you could cram 1.3 million Earths into the space the Sun takes up.
But if our local star ever wanted a humility check, it need only cast a glance out into the rest of the universe. Other stars at more advanced stages of their life cycles could eat the Sun for breakfast, spit it back up, and eat it again – which is basically what one red giant has been seen doing now.
Astronomers have used the ALMA telescope in Chile to image the surface of a star called R Doradus, located about 180 light-years away. As a red giant, it’s about 350 times wider than the Sun but has roughly the same mass. That’s because some stars go through a phase later in life after burning through their fuel supply when they swell up and essentially start to die. Our Sun is predicted to enter this stage in about 5 billion years’ time.
Thanks to the size and proximity of R Doradus, astronomers have been able to image its surface in unprecedented detail. Clearly visible is a process called convection, where big hot bubbles of gas carry energy from the core to the surface, then cool down and sink again. This cycle kind of looks like a lava lamp in action, and is likely responsible for ejecting vital elements like carbon and nitrogen out into the cosmos.
“This is the first time the bubbling surface of a real star can be shown in such a way,” said Wouter Vlemmings, lead author of the study. “We had never expected the data to be of such high quality that we could see so many details of the convection on the stellar surface.”
Convection has been tracked in the Sun of course, but never in this much detail or in motion in other stars. Some of these bubbles, or convective granules, were up to 75 times the width of the Sun. They also seemed to move in a cycle lasting one month, which is faster than expected.
“We don’t yet know what is the reason for the difference. It seems that convection changes as a star gets older in ways that we don't yet understand,” said Vlemmings.
Studying these kinds of processes on other stars can help us understand how average our own Sun is in the grand scheme of things.
The research was published in the journal Nature (PDF). Check out the motion of these gigantic bubbles in the video below.
Source: ESO