Unlike our own lone Sun, most solar systems contain a pair of binary stars; researchers recently observed a pair of "wildly-misaligned" planet-forming disks in a young binary system called HK Tau.
The findings, published today in the journal Nature, were made using the Large Millimeter/submillimeter Array (ALMA), the National Radio Astronomy Observatory reported. The results reveal the clearest-ever picture of protoplanetary disks around double stars; potentially revealing information about the birth and orbit of planets in a multi-star system.
"ALMA has given us an unprecedented view of a main star and its binary companion sporting mutually misaligned protoplanetary disks," said Eric Jensen, an astronomer at Swarthmore College in Pennsylvania. "In fact, we may be seeing the formation of a solar system that may never settle down."
The stars located in this system are believed to be less than five billion years old, and are 58 billion kilometers apart (13 times the distance from Neptune to the Sun).
The smaller star, HK Tau B, is blocked by its disk of dust and gas but can be observed by the starlight it scatters at optical near-infrared wavelengths. The main star, HK Tau A, has a disc that is tilted in a way that makes it difficult to see optically, but the researchers were able to observe the millimeter-wavelength light emitted by the disk's dust and gas using ALMA.
ALMA was able to fully resolve the rotation of HK Tau A's disc for the first time in history. The researchers found the two discs were out of sync with the orbit of their host stars by about 60 degrees.
"Our results demonstrate that the necessary conditions exist to modify planetary orbits and that these conditions are present at the time of planet formation, apparently due to the binary formation process," noted Jensen. "We can't rule other theories out, but we can certainly rule in that a second star will do the job," said Rachel Akeson of the NASA Exoplanet Science Institute at the California Institute of Technology in Pasadena, California.
In the future researchers hope to determine whether or not these types of systems are typical or rare.
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