Spitzer Sees Crystal 'Rain' in Outer Clouds of Infant Star

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News release: 2011-161 May 26, 2011

Spitzer Sees Crystal 'Rain' in Outer Clouds of Infant Star

The full version of this story with accompanying images is at:
http://www.jpl.nasa.gov/news/news.cfm?release=2011-161&cid=release_2011-161

PASADENA, Calif. -- Tiny crystals of a green mineral called olivine are falling down like rain
on a burgeoning star, according to observations from NASA's Spitzer Space Telescope.

This is the first time such crystals have been observed in the dusty clouds of gas that collapse
around forming stars. Astronomers are still debating how the crystals got there, but the most
likely culprits are jets of gas blasting away from the embryonic star.

"You need temperatures as hot as lava to make these crystals," said Tom Megeath of the
University of Toledo in Ohio. He is the principal investigator of the research and the second
author of a new study appearing in Astrophysical Journal Letters. "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."

Spitzer's infrared detectors spotted the crystal rain around a distant, sun-like embryonic star, or
protostar, referred to as HOPS-68, in the constellation Orion.

The crystals are in the form of forsterite. They belong to the olivine family of silicate minerals
and can be found everywhere from a periodot gemstone to the green sand beaches of Hawaii to
remote galaxies. NASA's Stardust and Deep Impact missions both detected the crystals in their
close-up studies of comets.

"If you could somehow transport yourself inside this protostar's collapsing gas cloud, it would be
very dark," said Charles Poteet, lead author of the new study, also from the University of Toledo.
"But the tiny crystals might catch whatever light is present, resulting in a green sparkle against a
black, dusty backdrop."

Forsterite crystals were spotted before in the swirling, planet-forming disks that surround young
stars. The discovery of the crystals in the outer collapsing cloud of a proto-star is surprising
because of the cloud's colder temperatures, about minus 280 degrees Fahrenheit (minus 170
degrees Celsius). This led the team of astronomers to speculate the jets may in fact be
transporting the cooked-up crystals to the chilly outer cloud.

The findings might also explain why comets, which form in the frigid outskirts of our solar
system, contain the same type of crystals. Comets are born in regions where water is frozen,
much colder than the searing temperatures needed to form the crystals, approximately 1,300
degrees Fahrenheit (700 degrees Celsius). The leading theory on how comets acquired the
crystals is that materials in our young solar system mingled together in a planet-forming disk. In
this scenario, materials that formed near the sun, such as the crystals, eventually migrated out to
the outer, cooler regions of the solar system.

Poteet and his colleagues say this scenario could still be true but speculate that jets might have
lifted crystals into the collapsing cloud of gas surrounding our early sun before raining onto the
outer regions of our forming solar system. Eventually, the crystals would have been frozen into
comets.
The Herschel Space Observatory, a European Space Agency-led mission with important NASA
contributions, also participated in the study by characterizing the forming star.

"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
Bill Danchi, senior astrophysicist and program scientist at NASA Headquarters in Washington.

The Spitzer observations were made before it used up its liquid coolant in May 2009 and began
its warm mission.

NASA's Jet Propulsion Laboratory in Pasadena, Calif., manages the Spitzer Space Telescope
mission for the agency's Science Mission Directorate in Washington. Science operations are
conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena.
Caltech manages JPL for NASA.

For more information about Spitzer, visit http://www.nasa.gov/spitzer and
http://spitzer.caltech.edu/ .

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