This interested me. Astronomers in Baltimore (led by Christine Chen) have managed to image what they believe to be a Kuiper Belt around another star. HD 181327 in the constellation of Pictor is a young Sun-like star 165 light years away, and you have to admit, this image makes some compelling evidence.
While I like to theorise that all stars are likely to exhibit similar features to the Sun (like planets, starspots, asteroid belts…) it’s nice to know that these things are actually being confirmed by observations!
Stars, as I’ve said before, are dusty things. Lots of stars are swathed in a circle of dust. It’s actually quite easy to spot; the dust is heated by the star and shines brightly in infrared. Better than that, you can tell a lot about what’s there by the wavelength of the light given off. More importantly, you can look at the light that isn’t given off. The green blotches on that image are where water molecules have absorbed light in the infrared at around 63 microns. That far from the star, that water would almost definitely be ice, encrusted into comets and other objects.
Impressively, this team have used a lot of scopes. Hubble, Gemini South and Spitzer were used to confirm this! Three of the big ones… Evidently, their proposal writing skills are formidable. They also suggest that this icy dust needs to be replenished, and that perhaps that big blotch to the left of the star is the remnant of a recent collision, causing all of that ice. Those green clouds do seem to be trailing the blotch.
It might be wild speculation, but… Personally, I quite like the idea that all of that dust might be gravitationally bound to a planet, leaving a trail in it’s wake. The trailing cloud does seem like it could be being swept up in a lagrange L5 point (like the asteroids that share Jupiter’s orbit). Could an ice giant like neptune do that?
Those ice clouds are around 90AU from the central star, so around three times as far out as Neptune. Though it is vaguely reminiscent of the sub-nebula in orbit around AB Aurigae. But there’s no clearing. Mind you, that could be because these ice clouds are being swept up but not actually accreted.
I don’t know. Exoplanets aren’t exactly my specialty, even if dust is. But it’s an interesting idea.
The paper, sans any flagrant conjecture on my part, is available on arXiv:
[Chen at al (2008)]