Sunday, August 30, 2009

Circumstellar debris disk orbiting HD 32297

This is the circumstellar debris disk that orbits the star HD 32997, imaged with the Palomar 5m telescope by Dimitri Mawet and colleagues. The star lies at the cross, but its light has been blocked by a phase mask coronograph, which is a device that shifts the phase some of that starlight so that the star's light waves interfere with itself destructively, effectively making the very bright star dissapear from this image. This is very useful, since it also reveals the light from the much fainter circumstellar material.

The colored blobs indicate that there is a ring or perhaps a disk of dust in orbit about this star, with that disk/ring seen nearly edge on. The dust grains are visible because they are reflecting starlight, and the colors indicate the intensity of that reflected light. Of particular interest to me is the asymmetry seen in this disk, with one side being brighter than the other by ~50%.

These dusty disks usually have rather short lifetimes, since dust grains destroy each other when the collide with each other. Consequently, other unseen `planetesimals' are implicated here, since collisions by these asteroidal or cometary bodies are needed to continually resupply the disk with the dust seen here. And since comets or asteroids are evidently forming in this system, it seems plausible that larger planets might have formed here, too. Additional details are also available in the paper by Mawet et al.

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