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Spitzer has detected tiny green crystals thought to be raining on a developing star, HOPS-68. This graphic shows the star, and an artist's concept of how the 'rain' might look. The top arrow points to HOPS-68. Astronomers say the crystals are raining back down onto the swirling disk of planet-forming dust circling the star, as in the final panel. (NASA/JPL-Caltech/University of Toledo)
Tiny green gemstones are falling like rain in the constellation of Orion, seen by Spitzer, NASA’s infrared space telescope.
Amid clouds of gas surrounding the distant baby star, HOPS-68, crystals of the silicate mineral forsterite are creating the green showers.
According to NASA, the crystals form at around 1,300 degrees Fahrenheit (700 degrees Celsius), but the environment of a newly forming star is around minus 280 F (minus 130 C).
"You need temperatures as hot as lava to make these crystals," said principal investigator Tom Megeath at the University of Toledo (UT) in Ohio in a NASA press release. "We propose that the crystals were cooked up near the surface of the forming star, then carried up into the surrounding cloud where temperatures are much colder, and ultimately fell down again like glitter."
Forsterite is a member of the olivine family, and occurs in a variety of forms including Hawaii’s green sand beaches, and the gem peridot, found in lava and meteorites.
Forsterite crystals have been observed in various comets during Stardust and Deep Impact’s flyby missions. They have also been seen in planet-forming discs around young stars.
However, this is the first time they have been observed during the formation of a star.
"If you could somehow transport yourself inside this protostar’s collapsing gas cloud, it would be very dark," said lead author Charles Poteet at UT in the release. "But the tiny crystals might catch whatever light is present, resulting in a green sparkle against a black, dusty backdrop."
The astronomers believe jets of gas from the embryonic star may be propelling the crystals into the cold outer gas clouds.
They speculate that similar crystals inside comets may have originated from a collapsing cloud of gas around our sun when it formed, beginning as a green rain on the edge of our early solar system. Over time, these crystals would have frozen and gathered material, forming the heart of comets.
"Infrared telescopes such as Spitzer and now Herschel are providing an exciting picture of how all the ingredients of the cosmic stew that makes planetary systems are blended together," said NASA’s Bill Danchi in the release.The findings from the new study will be published in Astrophysical Journal Letters.
