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Archive for April 24, 2013

Herschel Links Water In Jupiter’s Stratosphere To 1994 Comet Impact


Distribution of water in Jupiter's stratosphere. Credit: Water map: ESA/Herschel/T. Cavalié et al.; Jupiter image: NASA/ESA/Reta Beebe (New Mexico State University)

Distribution of water in Jupiter’s stratosphere. Credit: Water map: ESA/Herschel/T. Cavalié et al.; Jupiter image: NASA/ESA/Reta Beebe (New Mexico State University)

Astronomers have finally found direct proof that almost all water present in Jupiter’s stratosphere was delivered by comet Shoemaker-Levy 9, which struck the planet in 1994. The result is based on new data from Herschel that revealed more water in Jupiter’s southern hemisphere, where the impacts occurred, than in the north as well as probing the vertical distribution of water in the planet’s stratosphere.

The origin of water in the upper atmospheres of the Solar System’s giant planets has been debated for almost two decades. Astronomers were quite surprised at the discovery of water in the stratosphere – an intermediate atmospheric layer – of Jupiter, Saturn, Uranus and Neptune, which dates to observations performed with ESA’s Infrared Space Observatory (ISO) in 1997. While the source of water in the lower layers of their atmospheres can be explained as internal, the presence of this molecule in their upper atmospheric layers is puzzling due to the scarcity of oxygen there – its supply must have an external origin. Since then, astronomers have investigated several possible candidates that may have delivered water to these planets, from icy rings and satellites to interplanetary dust particles and cometary impacts.

Answers are now starting to flow in from studies using ESA’s Herschel space observatory. Herschel boasts unprecedented sensitivity as well as high spatial and spectral resolution at the far-infrared wavelengths, where many water emission lines can be observed.

Full Story: http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=51720
Also: http://www.esa.int/Our_Activities/Space_Science/Herschel/Herschel_links_Jupiter_s_water_to_comet_impact
Also: http://www.aanda.org/index.php?option=com_content&task=view&id=922&Itemid=277

Star Factory In The Early Universe Challenges Galaxy Evolution Theory


A team including Mat Page (UCL Space and Climate Physics) has discovered an extremely distant galaxy making stars more than 2000 times faster than our own Milky Way. Seen at a time when the Universe was less than a billion years old, its mere existence challenges our theories of galaxy evolution. The observations were carried out using the European Space Agency’s Herschel Space Observatory.

The galaxy, known as HFLS3, appears as little more than a faint, red smudge in images from the Herschel Multi-tiered Extragalactic Survey (HerMES). Yet appearances can be deceiving: this small smudge is actually a star-building factory, furiously transforming gas and dust into new stars.

Our own Milky Way makes stars at a rate equivalent to one solar mass per year, but HFLS3 is seen to be churning out new stars at more than two thousand times more rapidly. This is one of the highest star formation rates ever seen in any galaxy.

Full Story: https://www.ucl.ac.uk/maps-faculty/maps-news-publication/maps1306

Dying Supergiant Stars Implicated In Hours-long Gamma-Ray Bursts


GRB 111209A exploded on Dec. 9, 2011. Credit: NASA/Swift/B. Gendre (ASDC/INAF-OAR/ARTEMIS)

GRB 111209A exploded on Dec. 9, 2011. Credit: NASA/Swift/B. Gendre (ASDC/INAF-OAR/ARTEMIS)

Three unusually long-lasting stellar explosions discovered by NASA’s Swift satellite represent a previously unrecognized class of gamma-ray bursts (GRBs). Two international teams of astronomers studying these events conclude that they likely arose from the catastrophic death of supergiant stars hundreds of times larger than the sun.

GRBs are the most luminous and mysterious explosions in the universe. The blasts emit surges of gamma rays — the most powerful form of light — as well as X-rays, and they produce afterglows that can be observed at optical and radio energies. Swift, Fermi and other spacecraft detect an average of about one GRB each day.

“We have seen thousands of gamma-ray bursts over the past four decades, but only now are we seeing a clear picture of just how extreme these extraordinary events can be,” said Bruce Gendre, a researcher now associated with the French National Center for Scientific Research who led this study while at the Italian Space Agency’s Science Data Center in Frascati, Italy.

Full Story: http://www.nasa.gov/mission_pages/swift/bursts/supergiant-stars.html

Hubble Captures Comet ISON

April 24, 2013 1 comment

Credit: NASA, ESA, J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science Team

Credit: NASA, ESA, J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science Team

This NASA Hubble Space Telescope image of Comet C/2012 S1 (ISON) was photographed on April 10, when the comet was slightly closer than Jupiter’s orbit at a distance of 386 million miles from the Sun (394 million miles from Earth).

Even at that great distance the comet is already active as sunlight warms the surface and causes frozen volatiles to sublimate. A detailed analysis of the dust coma surrounding the solid, icy nucleus reveals a strong jet blasting dust particles off the sunward-facing side of the comet’s nucleus.

Preliminary measurements from the Hubble images suggest that the nucleus of ISON is no larger than three or four miles across. This is remarkably small considering the high level of activity observed in the comet so far, said researchers. Astronomers are using these images to measure the activity level of this comet and constrain the size of the nucleus, in order to predict the comet’s activity when it skims 700,000 miles above the Sun’s roiling surface on November 28.

Full Story: http://hubblesite.org/newscenter/archive/releases/2013/14/image/a/
Also: http://www.umdrightnow.umd.edu/news/hubble-brings-faraway-comet-view

SOFIA Observations Reveal A Surprise In Massive Star Formation


Researchers using the airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) have captured the most detailed mid-infrared images yet of a massive star condensing within a dense cocoon of dust and gas.

The star is G35.20-0.74, more commonly known as G35. It is one of the most massive known protostars and is located relatively close to Earth at a distance of 8,000 light years.

Until now, scientists expected the formation process of massive stars would be complicated by the turbulent, chaotic environments in the centers of new star clusters where they form. But observations of G35 suggest this giant star, more than 20 times the mass of our sun, is forming by the same orderly process as do stars with the same mass as the sun. Stars most like the sun are understood to form by simple, symmetric collapse of interstellar clouds.

Full Story: http://www.sofia.usra.edu/News/news_2013/04_16_13/index.html

Dark Matter Search Results Indicate First Hint Of WIMP-Like Signal

April 24, 2013 1 comment

An international collaboration whose search for dark matter is powered by detectors being fabricated at Texas A&M University has for the first time observed a concrete hint of what physicists believe to be the particle behind dark matter and therefore nearly a quarter of the universe — a WIMP, or weakly interacting massive particle.

Scientists with the international Super Cryogenic Dark Matter Search (SuperCDMS) experiment involving Texas A&M high-energy physicist Rupak Mahapatra are reporting a WIMP-like signal at the 3-sigma level, indicating a 99.8 percent chance — or, in high-energy parlance, a hint of the mysterious substance dark matter that is believed to hold the cosmos together but to date has never been directly observed.

“In high-energy physics, a discovery is only claimed at 5-sigma or better,” Mahapatra said. “So this is certainly very exciting, but not fully convincing by the standards. We just need more data to be sure. For now, we have to live with this tantalizing hint of one of the biggest puzzles of our time.”

Full Story: http://www.science.tamu.edu/articles/1052