Planetary Formation is though to occur via an accretion process in a disk of gas and dust that settles into orbit about the host star. Small grains or ices, as they orbit, collide at low relative velocity and stick. As objects a few kilometers in diameter form, their cross-section for accretion becomes larger than their physical size as their gravitational pull is sufficient to capture adjacent material. After a 100-200 million years, an object of 0.1-10 earth masses can form in this manner. There is much evidence that this process occured in our solar system (details later). The identification of dusty disks around young stars would constitute excellent evidence that this process is common and that planetary formation is a natural consequence of star formation.

The image below shows a young star in Orion. The black ring around the star represents the blockage of the background light of the Orion Nebula by dust which is in orbit about this star. The total mass of dust, while still uncertain, is at least several earth masses. This discovery, courtest of Dr. C. O'Dell at Rice University, is consistent with previous discoveries of dusty disks around nearby stars. However, this particular discovery is intriguing in the sense that several stars in the Orion region of current star formation exhibit these disks. Some of us look forward to the day, a few billion years from now, when a future generation of question marks arise in what we, on earth, call the constellation of Orion.

The discovery image is reproduced below:

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The Electronic Universe Project
e-mail: nuts@moo.uoregon.edu