Protoplanetary disk

A Baby Star surrounded by Protoplanetary Disc

A protoplanetary disk is a rotating circumstellar disk of dense gas surrounding a young newly formed star, a T Tauri star, or Herbig Ae/Be star. The protoplanetary disk may be considered an accretion disc because gaseous material may be falling from the inner edge of the disk onto the surface of the star, but this process should not be confused with the accretion process thought to build up the planets themselves. Externally illuminated photo-evaporating protoplanetary disks are called proplyds.

Formation and evolution of the Solar System

Artist's conception of a protoplanetary disk

The formation of the Solar System is estimated to have begun 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed.

Dr. Michael E. Brown

Mike Brown is the Richard and Barbara Rosenberg Professor of Planetary Astronomy at the California Institute of Technology and has been on the faculty there since 1996. He specializes in the discovery and study of bodies at the edge of the solar system. Among his numerous scientific accomplishments, he is best known for his discovery of Eris, the largest object found in the solar system in 150 years, and the object which led to the debate and eventual demotion of Pluto from a real planet to a dwarf planet. Feature articles about Brown and his work have appeared in the New Yorker, the New York Times, and Discover, and his discoveries have been covered on front pages of countless newspapers worldwide.

Mid-Sized Planetary Body in Kuiper Belt Could Float In Water

 

Planetary scientist Michael Brown has measured the density of a planetary body in the Kuiper Belt that is 650 km wide - and he found that its density is lower than water. This largest rock found in solar system can float in water. Brown published the results in this week's The Astrophysical Journal Letters.