The Alan Sondheim Mail Archive

May 26, 2011

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Date: Thu, 26 May 2011 13:43:26
From: NASA Jet Propulsion Laboratory <>
To: "" <>
Subject: Spitzer Sees Crystal 'Rain' in Outer Clouds of Infant Star


         May 26, 2011

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

The full version of this story with accompanying images is at:

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 and .

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.

Trent Perrotto 202-358-0321

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