A messy planetary construction zone appears to encircle the bright autumn star Fomalhaut, as seen in this recent infrared image from Herschel Space Telescope, in which a broad disk of gas and dust encircles the star. The disk may include a vast reservoir of icy comets, hundreds of which may slam into each other every day, adding fresh ice to the debris ring. Images from Hubble Space Telescope reveal a possible planet inside the disk. [ESA/Herschel/PACS/Bram Acke, KU Leuven]
Building a planetary system is messy. It starts with small grains of rock and ice that come together to form larger and larger blocks. Some of those big blocks may eventually merge to make planets. But while some of the impacts are slow enough for the blocks to stick together, others are high-speed collisions that rip them apart, scattering debris back into space.
That process appears to be taking place around Fomalhaut, the brightest star of Piscis Austrinus, the southern fish. It’s low in the southeast by around 9 o’clock, and due south around midnight. There are no other bright stars around it, so it’s hard to miss.
A broad disk of dust encircles the star, which is quite young. The disk appears to have given birth to at least one planet. It’s about three times as massive as Jupiter, the giant of our own solar system, and it’s far, far away from Fomalhaut itself.
Observations by space telescopes gave conflicting readings on the size of the dust grains in the disk. One said they were tiny, another said they were larger.
Earlier this year, a team of European astronomers reported a possible solution. It said the grains must be large but fluffy — like the debris from comets in our own solar system. But there’s so much of this material that the supply must be constantly renewed by collisions. And the collisions wouldn’t be rare — up to hundreds of them every day — keeping things messy in a planetary building zone.
Script by Damond Benningfield, Copyright 2012
For more skywatching tips, astronomy news, and much more, read StarDate magazine.