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| Credit: www.futurity.org |
Picture above shows a disk of gas and dust circulating around a Sun-like star. A structure like spiral arms could mean the existence of planets which haven't been detected yet. Computer simulation has shown that gravitational force from a planet in the disk could disturb the trajectory of gases and dusts which form spiral arms.
The picture above is a disk surrounding SAO 206462 which is a magnitude 8.7 star which is 450 light year away in Lupus constellation. Astronomers estimate that this system is only 9 million years old. The disk spreads over 22.5 x 10^9 kilometer which is twice the orbit of Pluto in our Solar system.Picture taken in infrared wavelength shows a face-on disk which is not perfectly circle but has two spiral arms curve in the same direction as the outer part of the disk making it similar to a spiral galaxy. Theoretical simulation shows that a planet could make two spiral arms which is symmetric. However, spiral arms in SAO 206462 is not symmetric which could mean that there are two hidden planets - each planet is responsible for each arm. It is important to be warned that other events could be a reason of this structure.
Astronomers have closely studied this star for several decades since they found infrared energy for faraway star which could be described by a star only. They explain that the excessive infrared comes from ring of ski surrounding the star which is less than 9 million years old. In 1995, an observer said that dusts are composed of carbon pointing to organic substances. Recent study suggests that embedded planet has orbital period of a couple of year.
The picture above is taken by High Contrast Instrument for the Subaru Next Generation Adaptive Optics (HiCIAO) which is designed to block out light from the star with adaptation of mirror system which takes out imperfection from Earth's atmosphere.
From:
astronomy.com: spiral arms point to possible planets in a star's dusty disk
skyandtelescope.com: a dusty young stars "spiral arms"
wow, really cool! It's like a mini galaxy! I wonder how they detected the embedded planet? also, I wonder if having asymmetric spiral arms could cause some sort of radial velocity signal, the same way a planet does? and would the arms rotate at a constant angular velocity, or do the inner parts go around faster?
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