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Astronomers Recreate Stellar Jet With Laser Blast

Astronomers Recreate Stellar Jet With Laser Blast

With the trillions of watts contained in one brief pop of a powerful laser, the universe became a bit less mysterious.

Rice University Professor Patrick Hartigan and a team of laser scientists, physicists, astronomers and technicians used the beams at the University of Rochester's Laboratory for Laser Energetics to recreate, on a small scale, the highly supersonic velocities at work in newborn stars and simulated the fiery jets that burst from their poles.

What they got was confirmation that it's possible to recreate analogs of these stellar jets here on Earth and the ability to use these to help understand how stars form.

Hartigan, a professor of physics and astronomy, wanted to know how stellar jets affect their surroundings and to see if the series of experiments would match computer simulations as the jet impacts an obstacle along its path. He was also eager to compare the laboratory images to his infrared photos of Herbig-Haro 110, a supersonic jet of material driven from an active young star he observed last year using the four-meter telescope at Kitt Peak National Observatory in Arizona.

If Hartigan went to Rochester anticipating a bit of "Star Wars"-style dazzle, he was in for a disappointment. "You expect the lights to dim or something," said the enthusiastic professor, recalling one of a number of trips to the big laser. "But what happens is you watch the image of the target on a TV screen, they count down to zero and suddenly the target disappears. It happens too fast to see the laser beams vaporize the target."

But by using the equivalent of flash photography timed to a precision of a few billionths of a second, Hartigan's team was able to obtain images of the jet driven into a ball of foam as the laser destroyed the target and compare these with images of a jet driven from the young star.

The team, which was led by Hartigan and included Rice graduate student Robert Carver and a host of researchers and technicians from the other institutions, reported its results last month in a paper published in The Astrophysical Journal. (Hartigan has a second paper in the journal this month on the forces that launch stellar jets.)

Simulating a stellar jet requires a highly supersonic velocity, and that requires a lot of pressure to launch. One of the few ways to create a scale model of such a jet is to heat something very fast, atomize it and direct the plasma that results. The laser at Rochester filled that bill.

For Hartigan's experiment, the Omega laser, one of the most powerful in the world, was focused into a dozen fine beams at a target containing a plug of titanium sitting in the center of a gold-covered, half-dollar-sized cone. On the far side was a miniscule ball of foam-covered plastic representing a cloud of interstellar material.

Stellar jets

"The images at top, taken in a few billionths of a second, detail experiments at the Laboratory for Laser Energetics meant to simulate stellar jets and their effects on interstellar materials, as seen in the image above. (Credit: Image courtesy of Rice University)"

Source: Rice University

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