Solar Flare Surprise

Solar flares are the most powerful explosions in the solar system. Packing a punch equal to a hundred million hydrogen bombs, they obliterate everything in their immediate vicinity. Not a single atom should remain intact.

At least that’s how it’s supposed to work.

"We’ve detected a stream of perfectly intact hydrogen atoms shooting out of an X-class solar flare," says Richard Mewaldt of the California Institute of Technology. "What a surprise! If we can understand how these atoms were produced, we'll be that much closer to understanding solar flares."

The event occurred on Dec. 5, 2006. A large sunspot rounded the sun’s eastern limb and with little warning it exploded. On the "Richter scale" of flares, which ranks X1 as a big event, the blast registered X9, making it one of the strongest flares of the past 30 years.

NASA managers braced themselves. Such a ferocious blast usually produces a blizzard of high-energy particles dangerous to both satellites and astronauts. An hour later they arrived, but they were not the particles researchers expected.

NASA’s twin Solar TErrestrial RElations Observatory (STEREO) spacecraft made the discovery: "It was a burst of hydrogen atoms," says Mewaldt. "No other elements were present, not even helium (the sun’s second-most abundant atomic species). Pure hydrogen streamed past the spacecraft for a full 90 minutes."

Next came 30 minutes of quiet. The burst subsided and STEREO’s particle counters returned to low levels. The event seemed to be over when a second wave of particles enveloped the spacecraft. These were the "broken atoms" flares are supposed to produce—protons and heavier ions such as helium, oxygen and iron. "Better late than never," he says.

At first, this unprecedented sequence of events baffled scientists, but now Mewaldt and colleagues believe they’re getting to the bottom of the mystery.

First, how did the hydrogen atoms resist destruction?

"They didn’t," says Mewaldt. "We believe they began their journey to Earth in pieces, as protons and electrons. Before they escaped the sun’s atmosphere, however, some of the protons captured an electron, forming intact hydrogen atoms. The atoms left the sun in a fast, straight shot before they could be broken apart again." (For experts: The team believes the electrons were recaptured by some combination of radiative recombination and charge exchange.)

Second, what delayed the ions?

"Simple," says Mewaldt. "Ions are electrically charged and they feel the sun’s magnetic field. Solar magnetism deflects ions and slows their progress to Earth. Hydrogen atoms, on the other hand, are electrically neutral. They can shoot straight out of the sun without magnetic interference."

Imagine two runners dashing for the finish line. One (the ion) is forced to run in a zig-zag pattern with zigs and zags as wide as the orbit of Mars. The other (the hydrogen atom) runs in a straight line. Who’s going to win?

"The hydrogen atoms reached Earth almost two hours before the ions," says Mewaldt.

Mewaldt believes that all strong flares might emit hydrogen bursts, but they simply haven’t been noticed before. He’s looking forward to more X-flares now that the two STEREO spacecraft are widely separated on nearly opposite sides of the Sun. (In 2006 they were still together near Earth.) STEREO-A and –B may be able to triangulate future bursts and pinpoint the source of the hydrogen. This would allow the team to test their ideas about the surprising phenomenon.

"All we need now," he says, "is some solar activity."

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Worlds In Collision

Two terrestrial planets orbiting a mature sun-like star some 300 light-years from Earth recently suffered a violent collision, astronomers at UCLA, Tennessee State University (TSU) and the California Institute of Technology will report in a December issue of the Astrophysical Journal.

"It's as if Earth and Venus collided with each other," says Benjamin Zuckerman, UCLA professor of physics and astronomy and a co-author on the paper. "Astronomers have never seen anything like this before. Apparently, major catastrophic collisions can take place in a fully mature planetary system."

"If any life was present on either planet, the massive collision would have wiped out everything in a matter of minutes — the ultimate extinction event," says co-author Gregory Henry, an astronomer at TSU. "A massive disk of infrared-emitting dust circling the star provides silent testimony to this sad fate."

Zuckerman, Henry and Michael Muno, an astronomer at Caltech at the time of the research, were studying a star known as BD+20 307, which is surrounded by a shocking 1 million times more dust than is orbiting our sun. The star is located in the constellation Aries. The astronomers gathered X-ray data using the orbiting Chandra X-ray Observatory and brightness data from one of TSU's automated telescopes in southern Arizona, hoping to measure the age of the star.

"We expected to find that BD+20 307 was relatively young, a few hundred million years old at most, with the massive dust ring signaling the final stages in the formation of the star's planetary system," Muno says.

Those expectations were shown to be premature, however, when Carnegie Institution of Washington astronomer Alycia Weinberger announced in the May 20, issue of the Astrophysical Journal that BD+20 307 is actually a close binary star — two stars orbiting around their common center of mass.

"That discovery radically revised the interpretation of the data and transformed the star into a unique and intriguing system," says TSU astronomer Francis Fekel who, along with TSU's Michael Williamson, was asked to provide additional spectroscopic data from another TSU automated telescope in Arizona to assist in comprehending this exceptional binary system.

The new spectroscopic data confirmed that BD+20 307 is composed of two stars, both very similar in mass, temperature and size to our own sun. They orbit about their common center of mass every 3.42 days.

"The patterns of element abundances in the stars show that they are much older than a few hundred million years, as originally thought," Fekel says. "Instead, the binary system appears to have an age of several billion years, comparable to our solar system."

"The planetary collision in BD+20 307 was not observed directly but rather was inferred from the extraordinary quantity of dust particles that orbit the binary pair at about the same distance as Earth and Venus are from our sun," Henry says. "If this dust does indeed point to the presence of terrestrial planets, then this represents the first known example of planets of any mass in orbit around a close binary star."

Zuckerman and colleagues first reported in the journal Nature in July 2005 that BD+20 307, then still thought to be a single star, was surrounded by more warm orbiting dust than any other sun-like star known to astronomers. The dust is orbiting the binary system very closely, where Earth-like planets are most likely to be and where dust typically cannot survive long. Small dust particles get pushed away by stellar radiation, while larger pieces get reduced to dust in collisions within the disk and are then whisked away. Thus, the dust-forming collision near BD+20 307 must have taken place rather recently, probably within the past few hundred thousand years and perhaps much more recently, the astronomers said.

"This poses two very interesting questions," Fekel says. "How do planetary orbits become destabilized in such an old, mature system, and could such a collision happen in our own solar system?"

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Scientists Create DNA Tubes With Programmable Sizes for Nanoscale Manufacturing

Scientists at the California Institute of Technology (Caltech) have developed a simple process for mass producing molecular tubes of identical--and precisely programmable--circumferences. The technological feat may allow the use of the molecular tubes in a number of nanotechnology applications.

The molecular tubes are composed of wound-up strands of DNA. DNA has been considered an ideal construction material for self-assembling molecular structures and devices because two complementary DNA strands can automatically recognize and bind with each other. DNA has been used to form rigid building blocks, known as tiles, and these tiles can further assemble into extended lattice structures, including tubes. However, it has been difficult to control the diameters of such tubes.

Peng Yin, a senior postdoctoral scholar in bioengineering and computer science at Caltech's Center for Biological Circuit Design, along with his colleagues has designed a series of flexible, single-stranded DNA molecules, called single-stranded DNA tiles. Each single-stranded tile is exactly 42 bases long and contains four modular binding sites. By pairing up the complementary binding sites, these single-stranded tiles bind with each other in a particular orientation like Lego pieces snapped together, forming a tube composed of parallel DNA helices.

The circumference of the resulting tube is determined by the number of different 42-base pieces used in its construction. For example, four pieces create a tube with a circumference of 12 billionths of a meter (or 12 nanometers); five pieces, a 15-nanometer-circumference tube; and six pieces, an 18-nanometer tube.

"We are not the first to make DNA tubes with controlled circumferences. However, compared with previous approaches, our method is distinctively simple and modular," says Yin. The simplicity and modularity of their approach permits the description of the tube design using a simple graphical abstraction system developed earlier this year in the laboratory of Niles Pierce, associate professor_of applied and computational mathematics and bioengineering at Caltech.

Just as a variety of wood sizes are used in construction projects--two by four inches for framing walls, two by eight inches for roof rafters, or four by four inches for fence posts--having nanotubes of various, precisely controlled sizes provides their user with more options. In addition, nanotubes of different sizes have varying mechanical properties; for example, tubes with a smaller diameter are more flexible and tubes with a larger diameter are more rigid. The nanotubes might eventually serve as templates for manufacturing nanowires with controlled diameters; the diameters of electron-conducting nanowires would help determine the electronic properties of the devices they are used to construct.

"The simplicity of the single-stranded tile approach promises to enable us to design ever more complex self-assembling molecular systems. The work is simultaneously elegant and useful," says Erik Winfree, associate professor of computer science, computation and neural systems, and bioengineering at Caltech. Winfree's laboratory was the primary host of Yin's research at Caltech.

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Company Commercializes Caltech Tech To Improve Security

A company that commercializes technologies from NASA and the US Department of Defense, announced that the company has made significant strides leveraging so-called "SHINE" expert system technology licensed from Caltech to pursue major opportunities in the commercial, defense, and homeland security sectors.

To penetrate the growing market formaritime container screening, port security, automated threat detection, real-time sensor fusion and embedded diagnostics/prognostics applications, VIASPACE Security says it is identifying and developing relationships with potential new customers, adding staff and resources to its SHINE-based development efforts, executing on its contract with L-3 Communications forthe US Department of Homeland Security's Advanced Container Security Device project, and teaming with Raytheon Company's Network Centric Systems on security and surveillance applications.

VIASPACE has an exclusive license from Caltech to commercialize SHINE technology for most major applications including container security, diagnostics/prognostics, sensor fusion and homeland defense. SHINE is areal-time inference engine and software platform originally developed by NASA's Jet Propulsion Laboratory for space flight operations, and is used in several NASA applications including the Mars Exploration Rover and Spacecraft Health Automatic Reasoning Pilot (SHARP) program.

Security Inc. is leveraging the technology along with its own development efforts to deliver high performance, real-time inference andsensor data fusion-based technologies, products and services. Sensor fusion combines large volumes of data, observations, and inferences derived frommultiple sources and sensors to generate reliable decision-supportinformation in critical applications where speed, accuracy and ease of deployment are crucial, the company says.


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