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Archive for March 6, 2013

Gravitational Telescope Creates Space Invader Mirage


Credit: NASA & ESA. Acknowledgement: N. Rose

Credit: NASA & ESA. Acknowledgement: N. Rose

The NASA/ESA Hubble Space Telescope is one of the most powerful available to astronomers, but sometimes it too needs a helping hand. This comes in the form of Einstein’s general theory of relativity, which makes galaxy clusters act as natural lenses, amplifying the light coming from very distant galaxies.

Abell 68, pictured here in infrared light, is one of these galaxy clusters, and it greatly boosts the power of Hubble, extending the telescope’s ability to observe distant and faint objects.

The effect of this huge concentration of matter is to deform the fabric of spacetime, which in turn distorts the path that light takes when it travels through the cluster. For galaxies that are even further away than the cluster — which is already at the impressive distance of two billion light-years — and which are aligned just right, the effect is to turn galaxies that might otherwise be invisible into ones that can be observed with relative ease.

Although the resulting images projected to us of these distant galaxies are typically heavily deformed, this process, called gravitational lensing, is a hugely valuable tool in cosmology, the branch of astronomy which deals with the origins and evolution of the Universe.

Full Story: http://www.spacetelescope.org/news/heic1304/
Also: http://hubblesite.org/newscenter/archive/releases/2013/09/image/a/

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Astronomers Open Window Into Europa’s Ocean


Artist's concept. Credit: NASA/JPL-Caltech

Artist’s concept. Credit: NASA/JPL-Caltech

With data collected from the mighty W. M. Keck Observatory, California Institute of Technology (Caltech) astronomer Mike Brown — known as the Pluto killer for discovering a Kuiper-belt object that led to the demotion of Pluto from planetary status — and Kevin Hand from the Jet Propulsion Laboratory (JPL) have found the strongest evidence yet that salty water from the vast liquid ocean beneath Europa’s frozen exterior actually makes its way to the surface.

The data suggests there is a chemical exchange between the ocean and surface, making the ocean a richer chemical environment, and implies that learning more about the ocean could be as simple as analyzing the moon’s surface. The work is described in a paper that has been accepted for publication in the Astronomical Journal.

The findings were derived from spectroscopy delivered from the Keck Observatory, which operates the largest and most scientifically productive telescopes on Earth.

“We now have the best spectrum of this thing in the world,” Brown says. “Nobody knew there was this little dip in the spectrum because no one had the resolution to zoom in on it before.”

Full Story: http://keckobservatory.org/news/keck_observatory_helps_open_window_into_europas_ocean
Also: http://www.caltech.edu/content/window-europas-ocean-lies-right-surface

Measuring The Universe More Accurately Than Ever Before


After nearly a decade of careful observations an international team of astronomers has measured the distance to our neighbouring galaxy, the Large Magellanic Cloud, more accurately than ever before. This new measurement also improves our knowledge of the rate of expansion of the Universe — the Hubble Constant — and is a crucial step towards understanding the nature of the mysterious dark energy that is causing the expansion to accelerate. The team used telescopes at ESO’s La Silla Observatory in Chile as well as others around the globe. These results appear in the 7 March 2013 issue of the journal Nature.

Astronomers survey the scale of the Universe by first measuring the distances to close-by objects and then using them as standard candles to pin down distances further and further out into the cosmos. But this chain is only as accurate as its weakest link. Up to now finding an accurate distance to the Large Magellanic Cloud (LMC), one of the nearest galaxies to the Milky Way, has proved elusive. As stars in this galaxy are used to fix the distance scale for more remote galaxies, it is crucially important.

But careful observations of a rare class of double star have now allowed a team of astronomers to deduce a much more precise value for the LMC distance: 163 000 light-years.

Full Story: http://www.eso.org/public/news/eso1311/

Third Radiation Belt Discovered With UNH-led Instrument Suite


On Aug. 31, 2012, a giant prominence on the sun erupted. Credit: NASA/SDO/AIA/Goddard Space Flight Center

On Aug. 31, 2012, a giant prominence on the sun erupted. Credit: NASA/SDO/AIA/Goddard Space Flight Center

Although scientists involved in NASA’s Van Allen Probes mission were confident they would eventually be able to rewrite the textbook on Earth’s twin radiation belts, getting material for the new edition just two days after launch was surprising, momentous, and gratifying.

The Radiation Belt Storm Probes mission, subsequently renamed in honor of the belts’ discoverer, astrophysicist James Van Allen, was launched in the pre-dawn hours of August 30, 2012. Shortly thereafter, and well ahead of schedule in normal operational protocol, mission scientists turned on the Relativistic Electron-Proton Telescope (REPT) to gather data in parallel with another, aging satellite that was poised to fall from orbit and reenter Earth’s atmosphere. It was a fortuitous decision.

The telescope, which is part of the Energetic Particle, Composition, and Thermal Plasma (ECT) instrument suite led by the Space Science Center at the University of New Hampshire, immediately sent back data that at first confounded scientists but then provided a eureka moment: seen for the first time was a transient third radiation belt of high-energy particles formed in the wake of a powerful solar event that happened shortly after REPT began taking data.

Full Story: http://www.eos.sr.unh.edu/news/indiv_news.shtml?NEWS_ID=1373
Also: http://www.nasa.gov/home/hqnews/2013/feb/HQ_13-065_Van_Allen_Probes_Belts.html
Also: http://www.nasa.gov/mission_pages/rbsp/news/third-belt.html