In the game of cosmic hide-and-seek astronomers play with planets, it can be particularly difficult to locate the huge worlds in very bright, young star systems. These systems are surrounded by a disk full of gas and dust swirling around their star. If planets are forming in the disk, they're obscured by the dust, so astronomers have to get.
But there seems to be an even more obvious sign a planet may be lurking in the space mist: gigantic waterfalls of gas.
At least according to a new study published in Nature on Wednesday by a team of US researchers. Using the Atacama Large Millimeter/submillimeter Array (ALMA) in northern Chile to image the star HD 163296, which is considered young at about 4 million years old, the team closely watched how gas moved around its surrounding disk. Analyzing the flows, the astronomers found gas cascading from the upper reaches of the disk and flowing into gaps further out in space. In those gaps? Baby planets, first discovered a year ago by the very same team.
Confusing? OK, let's talk about it... with food.
If you think of the gaseous disk as a stack of three pancakes, the middle pancake is the area in which baby planets are forming. Gas, like maple syrup, seems to be leaking from the upper pancake onto the middle one wherever that formation is occurring. The astronomers were able to detect this steady flow of gas for the very first time and believe protoplanets -- young planets -- are pushing the gas around in this way.
"The patterns of these gas flows are unique and it is very likely that they can only be caused by planets," said Jaehan Bae, a co-author on the paper and astronomer at the Carnegie Institution for Science.
Bae used computer models of the disk to show how certain-sized planets would affect the gas flow. The models lined up with the observations from ALMA, helping confirm the theory three hidden, baby planets are forming in the system.
"Looking ahead, analyzing the movement of material in a disk around a young star could help us find exoplanets while they are still in their most-formative stages," Bae said.
"This could really help us understand how the architecture of a planetary system comes to be and maybe even unlock mysteries about the evolution of our own Solar System."