Dusty shock waves might create raw materials for planet formation

November 12th, 2008 - 12:32 pm ICT by ANI  

Washington, Nov 12 (ANI): New observations from NASA’’s Spitzer Space Telescope have indicated that shock waves around dusty, young stars might be creating the raw materials for planets.
The evidence comes in the form of tiny crystals called cristobalite and tridymite, which are known to reside in comets, in volcanic lava flows on Earth, and in some meteorites that land on Earth.
Spitzer detected these crystals, similar in make-up to quartz, around young stars just beginning to form planets.
These crystals require flash heating events, such as shock waves, to form.
The findings suggest that the same kinds of shock waves that cause sonic booms from speeding jets are responsible for creating the stuff of planets throughout the universe.
“By studying these other star systems, we can learn about the very beginnings of our own planets 4.6 billion years ago,” said William Forrest of the University of Rochester, New York.
“Spitzer has given us a better idea of how the raw materials of planets are produced very early on,” said Forrest and University of Rochester graduate student Ben Sargent, who led the research.
Planets are born out of swirling pancake-like disks of dust and gas that surround young stars. They start out as mere grains of dust swimming around in a disk of gas and dust, before lumping together to form full-fledged planets.
During the early stages of planet development, the dust grains crystallize and adhere together, while the disk itself starts to settle and flatten.
This occurs in the first millions of years of a star’’s life.
When Forrest and his colleagues used Spitzer to examine five young planet-forming disks about 400 light-years away, they detected the signature of silica crystals.
Silica is made of only silicon and oxygen and is the main ingredient in glass. When melted and crystallized, it can make the large hexagonal quartz crystals often sold as mystical tokens.
When heated to even higher temperatures, it can also form small crystals like those commonly found around volcanoes.
It is this high-temperature form of silica crystals, specifically cristobalite and tridymite, that Forrest’’s team found in planet-forming disks around other stars for the first time.
“Cristobalite and tridymite are essentially high-temperature forms of quartz,” said Sargent. “If you heat quartz crystals, you”ll get these compounds,” he added.
Because the crystals require heating followed by rapid cooling to form, astronomers theorized that shock waves could be the cause.
Shock waves, or supersonic waves of pressure, are thought to be created in planet-forming disks when clouds of gas swirling around at high speeds collide. (ANI)

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