An O-star just behind a young, cooler star and its swirling disk of planet-forming material.

IMAGE SPECS: Royalty Free

Description:
This artist's concept illustrates an O-star, which can be seen near the top right, just behind a young, cooler star and its swirling disk of planet-forming material. Disks like this one, called protoplanetary disks, are where planets are born. Gas and dust in a disk clumps together into tiny balls that sweep through the material, growing in size to eventually become full-grown planets. The young star happens to lie within the danger zone around the O-star, which means that it is too close to the hot star to keep its disk. Radiation and winds from the O-star are boiling and blowing away the material, respectively. This process, called photoevaporation, takes anywhere from one hundred thousand to about one million years. Without a disk, the young star will not be able to produce planets. Our own sun and its suite of planets might have grown up on the edge of an O-star's danger zone before migrating to its current, spacious home. However, we know that our young sun didn't linger for too long in any hazardous territory, or our planets, and life, wouldn't be here today. The Spitzer Space Telescope surveyed the danger zones around five O-stars in the Rosette nebula. It was able to determine that the zones are spheres with a radius of approximately 1.6 light-years, or 10 trillion miles.