Cosmic Fireworks Display Seen Inside Helix Nebula 34
goran72 writes "A new image, taken with an infrared camera on the Subaru Telescope in Hawaii, has revealed a cosmic fireworks display, in the form of tens of thousands of previously unseen comet-shaped knots inside the Helix Nebula. Unlike previous optical images of the Helix Nebula knots, the infrared image shows thousands of clearly resolved knots, extending out from the central star at greater distances than previously observed. These images enable astronomers to estimate that there may be as many as 40,000 knots in the entire nebula, each of which are billions of kilometers/miles across. Their total mass may be as much as 30,000 Earths, or one-tenth the mass of our Sun."
Molecular clouds ? Planetary Comets ? (Score:5, Interesting)
Here is the original paper : http://arxiv.org/abs/0906.2870 [arxiv.org] . Note that HST detected about 3500 of these, so this is an advance, not an overturning, of older work. These knots are pretty strange.
The Helix Nebulae is a sphere of gas expelled by a dying star, probably in multiple episodes, with. many thousands of these "comet-like objects." Typical theoretical speculation is that they are gas instabilities as old gas is overtaken by new gas expulsions [arxiv.org], possibly with dusty cores [harvard.edu]. In addition, the knots are expanding (away from the central star) significantly slower [harvard.edu] than the gas of the nebulae. If you Google or go to Arxiv.org, you can find lots of speculation on these knots.
For myself, I have to wonder if these could be "planetary comets" - i.e., giant comets resulting from the heating of bodies in the Oort cloud of the star. The mass is about right, and that would explain their longevity, but it is not clear why they would be expanding away from the central star.