A planetesimal that could look very closely like Earth or Mars is forming around one of the stars of a binary star system called HD 113766, which is about 424 light-years away from us. It was found with the use of NASA's Spitzer Space Telescope.
The article confirming the discovery was written by Dr. Carey M. Lisse, a research scientist in the Space Department of the Applied Physics Laboratory, at The Johns Hopkins University, Laurel, Maryland. It is called "Circumstellar Dust Created by Terrestrial Planet Formation in HD 113766." The article will be published in a future issue of Astrophysical Journal.
Lisse's finding will also be presented at the 39th annual meeting of the American Astronomical Society's Division for Planetary Sciences (DPS) in Orlando, Florida, which will be held between October 7 to 12, 2007.
According to Lisse, the star system is ten to sixteen million years old, which makes it ideal for forming a rocky planet like Earth or Mars. The planetesimal, a body that is likely to evolve into a planet, is within the system's terrestrial habitable zone-that is, a region (with regards to distance and temperature) around a star where liquid water could exist on surfaces of any of the rocky planets that might eventually develop. Earth, by comparison, is centrally located within the Sun's terrestrial habitable zone. Such regions around stars are likely areas for life to eventually develop.
One of the stars of the HD 113766 system has a large warm dust belt around it that looks to be forming planets. The materials in the dust belt have yet to totally separate into distinct areas of heavy metals and rocks, which is expected in early development of planets.
In fact, Lisse states, "The timing for this system to be building an Earth is very good. If the system was too young, its planet-forming disk would be full of gas, and it would be making gas-giant planets like Jupiter instead. If the system was too old, then dust aggregation or clumping would have already occurred and all the system's rocky planets would have already formed."
The HD 113766 star system is located in the direction of the Scorpio-Centaurus (Sco-Cen) Association-that is, an association means that it is classified as a moving group, or a very loosely based star cluster. It is visible on Earth from the southern hemisphere. The HD 113766 system is specifically one of the outer members of the Scorpio-Centaurus Association.
Both stars in the system are somewhat hotter, larger, and more luminous, than Earth's Sun-but, generally very similar to it.