When the disks of gas and dust that surround young stars are misaligned, a phenomenon predicted by models - known as "disk tearing" - does appear to occur, according to a new observational study of a young triple-star system located in the constellation of Orion. The study provides evidence for this process, which could give rise to planetary systems with widely dispersed planets on oblique or retrograde orbits, the authors say. In our Solar System, the eight known planets formed in a circumstellar disk of dust and gas that is flat. While misaligned disks have been observed previously, it has not been possible to directly link their structure to disk-tearing effects. Stefan Kraus and colleagues observed the GW Orionis system's disk and monitored the orbital motion of its stars over 11 years using several near-infrared and submillimeter telescopes. By combining the techniques of interferometry and polarimetry, the authors identified the system's misaligned inner ring and imaged the shadow that it casts on the rest of the disk. From this, Kraus et al. developed a three-dimensional model and simulation of the system, which reproduces the eccentric inner ring and a strongly warped intermediate region of the disk. The results show that disk tearing is responsible for the highly deformed disk and misaligned rings that precess around the system's inner trinary star. By transporting material out of the disk plane, they say, the disk-tearing effect could provide a mechanism for forming planets on oblique or retrograde orbits.
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Journal
Science