The Sun’s surface is speckled with roughly two million convective cells (imagine boiling water), each about 1,000 miles (1,609 kilometers) across. Though the Sun’s pockmarks – more scientifically known as granulation patterns – have been well-studied over the years, never before have astronomers observed the convective cells of another star.
You guessed it: until now.
For the first time, astronomers using the PIONIER instrument on the European Southern Observatory’s (ESO’s) Very Large Telescope have directly observed the surface activity of another star. Unsurprisingly, the star is giant; a cool red giant to be precise.
Located about 530 light-years away in the constellation Grus (the Crane), the red giant in question, π
1 Gruis, is about the same mass as the Sun, yet its radius is 700 times as large. It also shines several thousand times brighter than the Sun.
In the
study, published December 20 in the journal
Nature, an international team of astronomers led by Claudia Paladini of the ESO described how the surface of π
1 Gruis contains only a few convective cells. However, these cells are enormous, with each one spanning around 74.5 million miles (120 million km). That works out to be about a quarter of the red giant’s diameter.