- White-Light Solar Flares Finally Explained
- Congress Opens Investigation Into Genetic Testing Companies
- First Hints of Comets Circling Other Stars
Posted: 21 May 2010 03:49 PM PDT
The flashes of white light accompanying some solar flares are caused by the sun's acceleration of electrons to speeds greater than half the speed of light.
The phenomenon's new explanation derives from data recorded from a 2006 solar flare. The presence of high-energy X-rays in the same spot that scientists saw visible light tipped them off that some kind of non-thermal process was generating the light.
"These explosions are particle accelerators," said Säm Krucker, of the Space Science Laboratories at the University of California, Berkeley. "The whole surprising thing with these flares' light is that it could simply be heat. But that's not the case."
Solar flares occur when the sun's magnetic field lines rearrange and reconnect, releasing tremendous amounts of energy. There are different types of flares, which can generate geomagnetic storms of Earth, and only some of them are accompanied by the white light flares. These were first observed in 1859 by astronomer Richard Carrington, but no one really knew how they were produced until the new observations by the Japanese satellite Hinode and the NASA SMEX mission RHESSI.
Now, it looks as if the extremely powerful electromagnetic fields somehow deliver enormous amounts of energy into particles in the sun's photosphere. It's not unlike what humans do at a much, much smaller scale in particle accelerators like the Large Hadron Collider.
"As opposed to the LHC where you accelerate a few particles, it would be like accelerating the whole building basically," said Hugh Hudson, also of Berkeley's Space Science Laboratories, who worked with Krucker.
Astronomers haven't figured out how exactly the sun works as a particle accelerator just yet. "It's being done by electromagnetic effects that are not really understood," Hudson admitted.
It's possible that as the sun eases into a more active state over the next year, scientists will have more opportunities to study the flares.
A paper on the new work, with Kyoko Watanabe of Japan Aerospace Exploration Agency as lead author, appeared May 20 in The Astrophysical Journal.
Citation: "G-band and Hard X-ray Emissions of the 2006 December 14 Flare Observed by Hinode/SOT and RHESSI," by Kyoko Watanabe, Säm Krucker, Hugh Hudson, Toshifumi Shimizu, Satoshi Masuda, Kiyoshi Ichimoto. The Astrophysical Journal, No.715, pp. 651-655, 2010.
Posted: 21 May 2010 12:43 PM PDT
A Congressional committee opened an investigation of three direct-to-consumer genetic testing companies this week.
The House's Committee on Energy and Commerce sent requests to the CEOs of 23andme, Navigenics and Pathway Genomics for a wide array of information about the companies' services.
The letters, co-signed by Henry Waxman (D-California), Joe Barton (R-Texas), Bart Stupak (D-Michigan), and Michael Burgess (R-Texas), ask for all documents dating from January 1, 2007 to the present.
First, the committee wants "a chart listing the conditions, diseases, consumer drug responses, and adverse reactions" for which the companies' test and "all policy documents, training manuals, or written guidance" about their counseling policies. They also requested all documents related to how the companies identify the risk to consumers based on their genomic profiles, and how they process and use individual DNA samples.
Add it all up and the documents could be the starting point for a wide-ranging investigation, if the committee decides to go down that road.
The companies have until June 4 to return all the requested documents to the Subcommittee on Oversight and Investigations, chaired by Stupak.
The moves appear to be a response to media reports that Pathway Genomics hoped to sell its genetic testing kits in retail locations like Walgreens, "despite concern from the scientific community regarding the accuracy of the test results." The House committee letter cited two New York Times stories about the plans.
Requests for comment from 23andme, Navigenics, Pathway Genomics and the House committee were not answered. Personal genomics company 23andme released a short statement but would not answer questions.
"We will comply with the Committee on Energy and Commerce's request for information," the statement reads. "We look forward to sharing information detailing what individuals can learn about their own bodies through personal genetic testing and how our company is facilitating important scientific research in the field."
The direct-to-consumer genetic testing companies briefly found themselves in hot water with state regulators in New York and California in the summer of 2008. After they resolved those situations, they've had a relatively free ride from regulators, which appears to be ending.
Beyond the Congressional inquiry, the Food and Drug Administration recently went after Pathway for its retail plan. That spooked the would-be retailers, who decided offering genetic tests on their shelves was not such a good idea.
"We think this would be an illegally marketed device if they proceed," Alberto Gutierrez, director of the FDA's office of in-vitro diagnostics told the Washington Post. "They are making medical claims. We don't know whether the test works and whether patients are taking actions that could put them in jeopardy based on the test."
While many industry watchers have long suspected regulators would eventually pay more attention to the industry, but so far, it's unclear what Congress or the FDA have in store for the genetic testing companies.
Image: flickr/Drew Olanoff
Posted: 21 May 2010 10:40 AM PDT
A flying observatory has taken the first ultrasharp images of rings of cold debris around sunlike stars. The doughnut-shaped rings appear to be extrasolar analogues of the Kuiper belt, the outer solar system's reservoir of comets and other frozen bodies.
The newly observed rings are either left over from the planet-making process or were generated when planets collided. Astronomers used the European Space Agency's infrared Herschel Space Observatory, which sports the largest light-collecting mirror in space and is exquisitely sensitive to cold, sand-grain-sized dust, to photograph the belts.
"The Herschel images are the highest resolution far-infrared measurements ever made for debris disks" like the Kuiper belt, says infrared astronomer George Rieke of the University of Arizona in Tucson, who was not involved in the study.
René Liseau of the Chalmers Institute of Technology in Sweden, Carlos Eiroa of the Universidad Autónoma de Madrid in Spain and their colleagues posted their findings on debris belts surrounding two sunlike stars online May 19 and reported evidence of belts around more stars May 20. Some of their findings will also appear in an upcoming Astronomy & Astrophysics.
One of the sunlike stars, called q1Eridani or HD 10647, lies 57 light-years from Earth and has a Jupiter-sized planet orbiting it at about twice Earth's distance from the sun. The bright ring surrounding the star is a frigid 30 kelvins, lies an average of 85 astronomical units from the star (1 AU is the Earth-sun distance) and is about 40 AU wide. In comparison, the solar system's Kuiper belt, which lies beyond the orbit of Neptune, resides about 30 to 55 AU from the sun.
Strong infrared emissions from q1Eridani, recorded as far back as 1983 with the Infrared Astronomical Satellite, had already indicated the presence of an infrared-emitting belt of debris. Although expected, "it's nonetheless lovely to see" an actual belt, says Alycia Weinberger of the Carnegie Institution for Science in Washington, D.C. "Herschel is the first telescope to have the spatial resolution and sensitivity" at an infrared wavelength of 100 micrometers to resolve infrared emissions into bona fide belts or disks, she adds.
A much fainter belt appears to surround the star Zeta2 Reticuli, about 39 light-years from Earth, Liseau and his colleagues report. The belt lies at an average distance of 100 AU from the star, which is not known to harbor a planet.
Weinberger says the existence of this second belt is on shakier ground. "The high level of asymmetry [of the imaged belt], very cold temperature of the dust and possibility of confusion with a background object all give me an uneasy feeling," she says.
Nonetheless, the Herschel images provide the best estimate of the amount of mass in a debris disk and the size of the grains that populate it, says Weinberger. The observatory also has the best chance of glimpsing a tenuous, far-away Kuiper belt similar to the solar system's, Weinberger adds.
Astronomers believe the solar system's Kuiper belt formed several billion years ago, when some of the outer planets, then packed tightly together, were suddenly hurled into the path of existing planetary debris, pushing the debris outward and sculpting it into a ring-shaped reservoir. By comparing the many examples of Kuiper belts that Herschel is expected to find with the locations of massive outer planets around sunlike stars, astronomers may learn if a similarly violent story unfolded in other planetary systems, Weinberger says.
Image: Liseau et al. Portrait of a ring of debris around the sunlike star q1Eridani was taken at an infrared wavelength of 160 micrometers by the Herschel Space Observatory.
Citation: "Resolving the cold debris disc around a planet-hosting star: PACS photometric imaging observations of q1 Eri (HD10647, HR506)" Posted on Arxiv.
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