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Archive for May 21, 2013

Orion’s Hidden Fiery Ribbon


Credit: ESO/Digitized Sky Survey 2

Credit: ESO/Digitized Sky Survey 2

Clouds of gas and interstellar dust are the raw materials from which stars are made. But these tiny dust grains block our view of what lies within and behind the clouds — at least at visible wavelengths — making it difficult to observe the processes of star formation.

This is why astronomers need to use instruments that are able to see at other wavelengths of light. At submillimetre wavelengths, rather than blocking light, the dust grains shine due to their temperatures of a few tens of degrees above absolute zero. The APEX telescope with its submillimetre-wavelength camera LABOCA, located at an altitude of 5000 metres above sea level on the Chajnantor Plateau in the Chilean Andes, is the ideal tool for this kind of observation.

This spectacular new picture shows just a part of a bigger complex called the Orion Molecular Cloud, in the constellation of Orion (The Hunter). A rich melting pot of bright nebulae, hot young stars and cold dust clouds, this region is hundreds of light-years across and located about 1350 light-years from us. The submillimetre-wavelength glow arising from the cold dust clouds is seen in orange in this image and is overlaid on a view of the region taken in the more familiar visible light.

The dust clouds form beautiful filaments, sheets, and bubbles as a result of processes including gravitational collapse and the effects of stellar winds. These winds are streams of gas ejected from the atmospheres of stars, which are powerful enough to shape the surrounding clouds into the convoluted forms seen here.

Full Story and Images: http://www.eso.org/public/news/eso1321/

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Storms On Uranus, Neptune Confined To Upper Atmosphere


The Voyager 2 spacecraft photographed bands of clouds around Neptune during its flyby in 1989. Photo: NASA

The Voyager 2 spacecraft photographed bands of clouds around Neptune during its flyby in 1989. Photo: NASA

Similar to the giant gas planets Jupiter and Saturn, their smaller cousins, Uranus and Neptune, have long been known to harbor swirling clouds and violent winds churning up their atmospheres. Massive bands of jet streams encircling the entire planet have been observed in both cases. But given that Uranus’ atmosphere is believed to be thick enough to swallow the entire Earth, it was not known just how far the weather perturbations reach into the planet’s interior.

Now a team of planetary scientists with the University of Arizona’s Lunar and Planetary Laboratory, including William Hubbard and Adam Showman, has published the results of new analyses that put an upper limit to the weather zone on Uranus and Neptune. According to their data, reported in the journal Nature, the atmosphere on both planets goes from screaming winds of infernal violence to dead-quiet at a much shallower depth than previously thought.

“Our analyses show that the dynamics are confined to a thin weather layer no more than about 680 miles deep,” said Hubbard. “This number is an upper limit, so in reality, it is possible that the atmosphere quiets down even shallower than that.”

Full Story: http://www.uanews.org/story/storms-on-uranus-neptune-confined-to-upper-atmosphere