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Archive for July 5, 2013

Solar Dynamic Loops Reveal A Simultaneous Explosion And Implosion, Plus Evidence For Magnetic Reconnection


Credit: NASA / SDO / University of Glasgow

Credit: NASA / SDO / University of Glasgow

Movies of giant loops projecting from the surface of the Sun are giving new insights into the complex mechanisms that drive solar flares and Coronal Mass Ejections (CMEs). These eruptions release vast energy and electrically charged particles that can affect the Earth through space weather. Imagery from NASA’s Solar Dynamics Observatory (SDO), used in two separate studies, shows the dynamics of loops before, during and after eruptions. Results have been presented at the National Astronomy Meeting in St Andrews.

Coronal loops are giant magnetic arches filled with hot plasma at temperatures of over a million degrees Celsius. The structures are anchored in the dense photosphere, the visible surface of the Sun. The loops form the building blocks of the corona, the halo surrounding the Sun that can be seen during a total eclipse. They are dynamic structures that oscillate back and forth after explosive events such as solar flares.

Researchers from the University of Glasgow observed four groups of loops that contracted rapidly during a flare on 9 March 2012. The loops had a ‘staggered start’ to their collapse, showing delays of 60–80 seconds from the inner to the outer loops.

“This event is a great example of a simultaneous implosion and explosion,” said Dr Paulo Simões. “Our interpretation is that energy is transferred from the magnetic field to power the flare, leaving a pocket of reduced magnetic support that causes an implosion. The staggering between the loop contractions is caused by the time delay needed for the ‘information’ about the loss of support to travel outwards.”

Full Story: http://www.ras.org.uk/news-and-press/224-news-2013/2313-solar-dynamic-loops-reveal-a-simultaneous-explosion-and-implosion-plus-evidence-for-magnetic-reconnection
Full Video: http://www.astro.gla.ac.uk/users/paulo/implosion.avi

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ALMA Sheds Light On Planet-Forming Gas Streams


Artist’s impression. Credit: ESO/L. Calçada/ESA/AOES Medialab

Artist’s impression. Credit: ESO/L. Calçada/ESA/AOES Medialab

Astronomers using ESO’s Very Large Telescope have spotted a distant galaxy hungrily snacking on nearby gas. Gas is seen to fall inwards towards the galaxy, creating a flow that both fuels star formation and drives the galaxy’s rotation. This is the best direct observational evidence so far supporting the theory that galaxies pull in and devour nearby material in order to grow and form stars. The results will appear in the 5 July 2013 issue of the journal Science.

Astronomers have always suspected that galaxies grow by pulling in material from their surroundings, but this process has proved very difficult to observe directly. Now ESO’s Very Large Telescope has been used to study a very rare alignment between a distant galaxy and an even more distant quasar — the extremely bright centre of a galaxy powered by a supermassive black hole. The light from the quasar passes through the material around the foreground galaxy before reaching Earth, making it possible to explore in detail the properties of the gas around the galaxy. These new results give the best view so far of a galaxy in the act of feeding.

“This kind of alignment is very rare and it has allowed us to make unique observations,” explains Nicolas Bouché of the Research Institute in Astrophysics and Planetology (IRAP) in Toulouse, France, lead author of the new paper. “We were able to use ESO’s Very Large Telescope to peer at both the galaxy itself and its surrounding gas. This meant we could attack an important problem in galaxy formation: how do galaxies grow and feed star formation?”

Full Story: http://www.eso.org/public/news/eso1330/

Deep-Space Flashes Light Up A New Face Of Nature


CSIRO's 64-m Parkes radio telescope. Credit: John Sarkissian, CSIRO.

CSIRO’s 64-m Parkes radio telescope. Credit: John Sarkissian, CSIRO.

CSIRO’s Parkes radio telescope in eastern Australia has detected mysterious ‘flashes’ of radio energy from the distant Universe that may open up a whole new area of astrophysics. The surprising finding, made by a team of scientists from ten institutions in Australia, the USA, UK, Germany and Italy, is published in today’s issue of the journal Science.

“Staggeringly, we estimate there could be one of these flashes going off every ten seconds somewhere in the sky,” said research team member Dr Simon Johnston, Head of Astrophysics at CSIRO Astronomy and Space Science.

Four flashes were detected, each from a different direction and each lasting for only a millisecond (a thousandth of a second).

The characteristics of the radio signal — how it is ‘smeared out’ in frequency from travelling through space — indicate that the flashes came from up to 11 billion light-years away.

Full Story: http://www.csiro.au/Portals/Media/Deep-space-flashes-light-up-a-new-face-of-Nature.aspx

Solar Prominences Put On Strange And Beautiful Show In The Sun’s Sky


Rotating disc in solar prominence. Credit: NASA / SDO / Li / Smith / Aberystwyth University

Rotating disc in solar prominence. Credit: NASA / SDO / Li / Smith / Aberystwyth University

Cloud spotting seems to be growing in popularity as a hobby here on Earth. Now scientists studying the solar atmosphere are building their own collection of fascinating moving features that they’ve spotted in the Sun’s sky. The unusual solar prominences include a giant disc that rotates for several hours, feathery streamers as long as fifty Earths, a super-heated jet striking the top of a prominence and twisted ribbons flowing in opposite directions at a million kilometres per hour.

The features were discovered by Dr Xing Li and PhD student, Jeff Smith, of Aberystwyth University using the Atmospheric Imaging Assembly (AIA) telescope on board the Solar Dynamics Observatory (SDO) satellite. The findings have been presented at the RAS National Astronomy Meeting in St Andrews.

Prominences are – relatively – cold gaseous features, with temperatures around 5000 degrees Celsius compared to the surrounding the hot solar atmosphere of about 1-2 million degrees. They can be seen as towering features extending outwards from the Sun’s surface, often in the shape of a loop. They are called filaments when viewed against the solar disc, appearing as dark stripes because the cold gases they contain absorb the light emitted from below. Solar prominences and filaments supply most of the material released in coronal mass ejections, vast eruptions from the Sun’s atmosphere that can cause space weather and create geomagnetic storms on Earth.

Full Story: http://www.ras.org.uk/news-and-press/224-news-2013/2315-solar-prominences-put-on-strange-and-beautiful-show-in-the-suns-sky

Super-Freezer Supernova 1987A Is A Dust Factory


Hubble Space Telescope image of supernova 1987A. Credit: ESA, NASA, P. Challis and R. Kirshner

Hubble Space Telescope image of supernova 1987A. Credit: ESA, NASA, P. Challis and R. Kirshner

Surprisingly low temperatures detected in the remnant of the supernova 1987A may explain the mystery of why space is so abundant with dust grains and molecules. The results will be presented by Dr Mikako Matsuura at the National Astronomy Meeting 2013 in St Andrews on Friday 5 July.

In 1987, an explosion of a massive star was detected in our neighbouring galaxy, the Large Magellanic Cloud, just 170,000 light years away. This supernova, dubbed 1987A, released approximately thousand million times more energy than that emitted by the Sun in one year. Twenty five years later, an international team of astronomers has used the Herschel Space Observatory and Atacama Millimeter and Submillimeter Array (ALMA) to study the supernova remnant. They found a vast reservoir of unexpectedly cold molecules and dust.

“The powerful explosion we saw in 1987 scattered elements made by star into space in the form of a very hot plasma. The gas has now cooled down to temperatures between -250 to -170 degrees Celsius. That’s surprisingly cold, comparable to the icy surface of Pluto at the edge of our Solar System. The gas has formed molecules and some has even condensed into solid grains of dust. The supernova has now become a super freezer!” said Dr Matsuura.

Full Story: http://www.ras.org.uk/news-and-press/224-news-2013/2311-super-freezer-supernova-1987a-is-a-dust-factory