"The predominant theory says that jets are essentially fire hoses that shoot out matter in a steady stream, and the stream breaks up as it collides with gas and dust in space—but that doesn't appear to be so after all," says Adam Frank, professor of astrophysics at the University of Rochester, and co-author of the paper.
"These experiments are part of an unusal international collaboration of plasma physicists, astronomers and computational scientists. It's a whole new way of doing astrophysics. The experiments strongly suggest that the jets are fired out more like bullets or buckshot. They don't break into pieces—they are formed in pieces."
Frank says the experiment, conducted by Professor Sergey Lebedev's team in the Department of Physics at Imperial College London (www.imperial.ac.uk), may be the best astrophysical experiment that's ever been done. Replicating the physics of a star in a laboratory is exceptionally difficult, he says, but the Imperial experiment matches the known physics of stellar jets surprisingly well. "Lebedev's group at Imperial has absolutely pioneered the use of these experiments for studying astrophysical phenomena. The collaboration between Imperial and Rochester has been going on for almost 5 years and now it is bearing some extraordinary fruit."
At Imperial, Lebedev sent a high-powered pulse of energy into an aluminum disk. In less than a few billions of a second, the aluminum began to evaporate, creating a cloud of plasma very similar to the plasma cloud surrounding a young star. Where the energy flowed into the center of the disk, the aluminum eroded completely, creating a hole through which a magnetic field from beneath the disk could penetrate."
The field initially pushes aside the plasma, forming a bubble within it, says Frank, who carried out the astrophysical analysis of the experiment. As the field penetrates further and the bubble grows, however, the magnetic fields begin to warp and twist, creating a knot in the jet. Almost immediately, a new magnetic bubble forms inside the base of the first as the first is propelled away, and the process repeats.
Frank likens the magnetic fields' affect on the jet to a rubber band tightly wrapped around a tube of toothpaste—the field holds the jet together, but it also pinches the jet into bulges as it does.
"We can see these beautiful jets in space, but we have no way to see what the magnetic fields look like," says Frank. "I can't go out and stick probes in a star, but here we can get some idea—and it looks like the field is a weird, tangled mess."
Frank says other aspects of the experiment, such as the way in which the jets radiatively cool the plasma in the same way jets radiatively cool their parent stars, make the series of experiments an important tool for studying stellar jets. With this new model, he says, astrophysicists do not have to assume that the knotted jets they see in nature mean some unknown phenomenon interrupted the jets' flow of material.
Now, says Frank, some experiments that were once far beyond astrophysicists' reach have been, literally, brought down to Earth.About the University of Rochester
Jonathan Sherwood | EurekAlert!
First results of NSTX-U research operations
26.10.2016 | DOE/Princeton Plasma Physics Laboratory
Scientists discover particles similar to Majorana fermions
25.10.2016 | Chinese Academy of Sciences Headquarters
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
27.10.2016 | Life Sciences
27.10.2016 | Life Sciences
26.10.2016 | Power and Electrical Engineering