|scienceclub||Date: Saturday, 22-Nov-2014, 9:13 AM | Message # 1|
|Planets stake their claim around infant star |
As a baby, our solar system probably looked something like this.
At the center of this newly released telescope image is HL Tau, a star located about 450 light-years away in the constellation Taurus. A dense disk of gas and dust surrounds the star, which is a youthful million years old.
But the most striking features are the dark gaps, which astronomers suspect are carved out by developing planets that sweep up material as they loop around their sun. In only a million years or so, planetary embryos that began as pebbles have apparently grown massive enough to clear out their own orbital paths.
This unprecedented image of a nascent planetary system comes from the Atacama Large Millimeter/submillimeter Array, or ALMA, a network of several dozen radio dishes located in the high-elevation desert of northern Chile. The dishes detect wavelengths of light that are sensitive to cosmic dust grains; the spacing between dishes — as much as 16 kilometers — allows astronomers to capture incredibly fine detail such as the thin grooves. (For scale, the innermost ring is about 10 times as far from the star as Earth is from the sun.)
Hints of gaps around young stars have been seen before, but this is the sharpest image of them to date. Seeing rings around such a juvenile star probably means that planets can grow faster than theorists have predicted. Scientists hope to combine the observations of HL Tau with those of other nurseries to figure out how planetary systems like our own form.