Astronomers have observed the initial phase in the formation of an earth-like planet.

The discovery was documented by a team of astronomers led by William Herbst, the Van Vleck Professor of Astronomy professor at Wesleyan, and Catrina Hamilton PhD '03, professor of physics and astronomy at Dickenson College.

What Herbst and other astronomers on his team observed was that a protoplanitary disk, or ring, around the binary star known as KH 15D, is composed of solid particles larger than what is usually observed in space.

The disk orbiting KH 15D is at least the size of Jupiter's orbit and composed of sand-sized grains that have grown from microscopic-sized particles to form the larger grains. These grains are now approximately 1 mm in diameter, much larger than the tiny particles typically seen in space. This is also the characteristic size of "chondrules," small glassy spherules that are found in the most primitive solar system, the so-called carbonaceous chondrite meteorites.

The observations of the disk were made over several years using some of the largest telescopes in the world, including the 10-meter telescope of the W.M. Keck Observatory in Hawaii. More modest telescopes, including the one at Wesleyan University's Van Vleck observatory and the Maidanak Observatory in Uzbekistan, were also used in the study.

What Herbst, Hamilton and the rest of the team observed recently is that the disk is slowly hiding the stars from view and putting them in a permanent state of faintness, though still visible by the reflection off the disk.

The members of Herbst's team documenting the observations include Catrina Hamilton, who received her Ph.D. degree in Physics from Wesleyan University in 2003 with Herbst as her advisor and is now on the faculty of Dickinson College; Katherine LeDuc, M.A.'07; Joshua N. Winn of M.I.T.; Christopher M. Johns-Krull of Rice University; Reinhard Mundt of the Max-Planck-Institute for Astronomy in Heidelberg, Germany; and Mansur Ibrahimov of the Ulugh Bek Astronomical Institute in Tashkent, Uzbekistan. Support for the work has come over the years from NASA's Origins of Solar Systems program and from the W. M. Keck Observatory Principal Investigator's Fund.

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