Press Release

Livermore Lab Physicist to Discuss Exploration of Supernovae, Black Holes, New Planets and Beyond Using Laboratory Astrophysics

By SpaceRef Editor
February 15, 2002
Filed under , ,

Large lasers and Z-pinch
generators in laboratories are recreating conditions relevant to
astrophysical phenomena of the universe such as supernovae, black
holes, molecular clouds like the Eagle Nebula, and the creation of new
planets.

Lawrence Livermore National Laboratory physicist Bruce Remington
will be discussing this and other findings (Feb. 16) at 4:30 p.m. EST
in a presentation entitled: “Laboratory Astrophysics Using High- Power
Lasers,” during the “Visualizing and Looking Beyond Earth” track of
the annual meeting of the American Association for the Advancement of
Science in Boston.

“Modern laser and magnetic pinch facilities offer new
opportunities for pursuing experimental science under extreme
conditions of temperature and density,” Remington said. “The potential
of this new experimental capability is phenomenal when it comes to
applications in astrophysics and planetary physics.”

An understanding of supernovae, the cataclysmic death of a massive
star, relies on an understanding of macroscopic matter under extreme
conditions. Recreating aspects of the dynamics and energetics of
supernova explosions has already been achieved on lasers and z-pinch
facilities in laboratory experiments, thereby providing direct
measurements under relevant and controlled conditions.

Remington said the next generation “mega lasers” – the National
Ignition Facility in the United States and the Laser Mega Joule in
France – may be used to experimentally address questions of
thermonuclear ignition and rare nuclear reaction measurements that are
common occurrences in supernovae.

Supernova remnants (SNRs) are the vestiges of supernovae
explosions. These remnants evolve for centuries, producing glowing
filamentary structures in the galaxy and are widely believed to
produce most of the cosmic rays that irradiate the Earth. Lab
experiments can help improve the understanding of several of the
mechanisms present in SNRs and can test aspects of the computational
models developed to interpret their behavior. Experiments on
high-energy density facilities can address uncertainties in remnant
evolution such as the radiative hydrodynamics of SNRs. In the future,
experiments may be able to address issues of collisionless shocks and
particle acceleration (the first step in cosmic ray generation).

Galactic and extragalactic jets present some of the most visually
captivating images encountered in modern astronomy. Using lasers and
pulsed power facilities, Remington said scientists have already
demonstrated how high Mach number hydrodynamic jets and radiatively
collapsing jets evolve and interact

Cold, dense molecular clouds illuminated by bright, young nearby
massive starts serve as the stellar incubators of the universe. The
radiation on the cloud creates high pressure at the surface by
ablation and ram pressure from the stellar wind. Such systems are
thought to be “cosmic nurseries” where active star formation takes
place. Through lab experiments with large lasers and pulsed power
facilities, scientists can recreate the dominant ablation-front
hydrodynamics of radiatively driven molecular clouds, the best known
example being the Eagle Nebula.

“With driven molecular clouds, the possibility to form an
integrated program of theory, modeling, test-bed laboratory
experiments, and astronomical observations is very real,” Remington
said. “Such an integrated program would have been undreamed of just a
decade ago.”

Scientists have moved one step closer to understanding the
immediate vicinity of black holes, where matter is relentlessly swept
down a singular gravitational abyss. Astronomers use high-resolution
spectroscopy of the X-ray emissions from heated matter as it is tugged
down the black hole to conditions close to the black hole. Laboratory
scientists have demonstrated on Z-pinch facilities that scaled
versions of these accretion disk conditions can be recreated for
close-up scrutiny.

As for new planets, experimental techniques are being developed on
pulsed power facilities, lasers, gas guns and diamond anvil cells to
probe the properties of matter under the relevant extreme conditions
of pressure and compression. These laboratory conditions reproduce
those of the interiors of terrestrial and giant gas planets, brown
dwarfs, low mass stars and the envelopes of white dwarfs

Gamma-ray bursts – which are detected at a rate of more than one
per day from random directions in the sky – have typical burst
durations of a few seconds, but exhibit fluctuations as short as a
millisecond. Laboratory experiments using ultra-intense, short-pulse
lasers offer the most promising means for accessing the relativistic
plasma dynamics and directed flow of gamma-ray bursts

“Lab experiments and computer simulations are helping to identify
and understand some of the dominant physics that are taking place in
the vast universe that, until now, we’ve only been able to observe
from afar from an astronomical viewpoint,” Remington said.

Founded in 1952, Lawrence Livermore National Laboratory is a
national security laboratory, with a mission to ensure national
security and apply science and technology to the important issues of
our time. Lawrence Livermore National Laboratory is managed by the
University of California for the U.S. Department of Energy’s National
Nuclear Security Administration.

Laboratory news releases and photos are also available
electronically on the World Wide Web of the Internet at URL
http://www.llnl.gov/PAO and on UC Newswire.

SpaceRef staff editor.