Baby sun shows signs of windy weather

Baby sun shows signs of windy weather

Read time: 3 minutes

Astronomers have detected windy weather around a baby star. The star is like a newborn version of our own sun. It is surrounded by a flat, rotating disk of gas and dust.
In the future, the gas and dust in this disk may clump together into planets. Unless it is being blown away by some kind of wind. And that’s just what the astronomers seem to have detected, using the Atacama Large Millimeter/submillimeter Array (ALMA).

On Earth, a strong wind means that air is moving rapidly from one place to another. In space, it’s more or less the same. Normally, the gas around a baby sun sits in a nice, circular disk. But if some of the gas is moving away from this disk, it means something is blowing it into space. So if you find gas where it doesn’t belong, you have discovered windy weather around the star.

Astronomers already thought that some baby stars might show strong winds. Some of the disks glow bright at infrared wavelengths (‘heat’ radiation) – just what you would expect if they were stirred up by strong winds. But no one could be really sure: most baby stars are too far away to actually see if gas is being blown out of their disk.

ALMA, however, is big enough to study the disks in detail. In one case, it has indeed found that gas is moving away, out of the disk of a newborn star. It’s an important discovery: if the disk is being stirred up and if it’s losing gas, this may affect the formation of planets. Maybe there won’t be enough gas left for the birth of giant planets like Jupiter.

There’s one remaining mystery, though. The astronomers are not really hundred percent sure if they have discovered windy weather. The star that they studied is part of a binary system. So maybe the gas is being pulled away by the gravity of the companion star, in stead of being blown away by a wind.

Future studies of this interesting star, and of other baby suns that glow bright in the infrared, may solve the issue once and for all.

The ‘windy’ baby sun is a so-called T Tauri star, known as AS 205 N. It is part of a star-forming region in the constellation Ophiuchus (the Serpent Bearer), at a distance of 407 lightyears. The companion star is known as AS 205 S (N and S denote north and south).

The observations were carried out by a team of astronomers from the United States and Chili, led by Colette Salyk of the National Optical Astronomy Observatory (NOAO) in Tucson, Arizona. Salyk and her colleagues have published their results in The Astrophysical Journal.