Planetary embryos circling in oncoming traffic
Dust clumps growing into planets do not always orbit their central stars in an orderly manner, measurements with the Very Large Array revealed. Using the data, researchers caught chunks of matter in a young star's protoplanetary dust disk as it orbited both clockwise and counterclockwise.
This is what scientists from NASA and the US Radio Astronomical Observatory report after analyzing 43 gigahertz radio waves intercepted from the dust shell around a star 500 light-years away in the Ophiuchus. The Doppler shift in the frequency typical of silicon monoxide molecules gave them information about the direction of movement of the particles in the dust disk of the star. According to the scientists, the inner regions near the center and a ring further out apparently orbit in the opposite direction. Should planets form from sufficient amounts of dust, their orbits would also go in opposite directions.
Possibly the protoplanetary matter was formed from two colliding, differently rotating, prestellar precursor dust clouds, the researchers suspect. And probably such counter-rotating protostellar clouds are not even rare, although the observation now made is the first of its kind. On a larger scale - in the case of disks of matter from entire galaxies - something similar has already been described.
