Space

November 22, 2013

NASA missions study ‘watershed’ cosmic explosion in unparalleled detail

https://www.youtube.com/watch?v=7uN1AjMui5k&feature=player_embedded
nasa-star
On April 27, a blast of light from a dying star in a distant galaxy became the focus of astronomers around the world. The explosion, known as a gamma-ray burst and designated GRB 130427A, tops the charts as one of the brightest ever seen.

A trio of NASA satellites, working in concert with ground-based robotic telescopes, captured never-before-seen details that challenge current theoretical understandings of how gamma-ray bursts work.

“We expect to see an event like this only once or twice a century, so we’re fortunate it happened when we had the appropriate collection of sensitive space telescopes with complementary capabilities available to see it,” said Paul Hertz, director of NASA’s Astrophysics Division in Washington.

Gamma-ray bursts are the most luminous explosions in the cosmos, thought to be triggered when the core of a massive star runs out of nuclear fuel, collapses under its own weight, and forms a black hole. The black hole then drives jets of particles that drill all the way through the collapsing star and erupt into space at nearly the speed of light.

Gamma-rays are the most energetic form of light. Hot matter surrounding a new black hole and internal shock waves produced by collisions within the jet are thought to emit gamma-rays with energies in the million-electron-volt (MeV) range, or roughly 500,000 times the energy of visible light. The most energetic emission, with billion-electron-volt (GeV) gamma rays, is thought to arise when the jet slams into its surroundings, forming an external shock wave.

The Gamma-ray Burst Monitor aboard NASA’s Fermi Gamma-ray Space Telescope captured the initial wave of gamma rays from GRB 130427A shortly after 3:47 a.m., EDT, April 27. In its first three seconds alone, the “monster burst” proved brighter than almost any burst previously observed.

“The spectacular results from Fermi GBM show that our widely accepted picture of MeV gamma rays from internal shock waves is woefully inadequate,” said Rob Preece, a Fermi team member at the University of Alabama in Huntsville who led the GBM study.

NASA’s Swift Gamma-ray Burst Mission detected the burst almost simultaneously with the GBM and quickly relayed its position to ground-based observatories.

Telescopes operated by Los Alamos National Laboratory in New Mexico as part of the Rapid Telescopes for Optical Response Project quickly turned to the spot. They detected an optical flash that peaked at magnitude 7 on the astronomical brightness scale, easily visible through binoculars. It is the second-brightest flash ever seen from a gamma-ray burst.

Just as the optical flash peaked, Fermi’s Large Area Telescope detected a spike in GeV gamma-rays reaching 95 GeV, the most energetic light ever seen from a burst. This relationship between a burst’s optical light and its high-energy gamma-rays defied expectations.

“We thought the visible light for these flashes came from internal shocks, but this burst shows that it must come from the external shock, which produces the most energetic gamma-rays,” said Sylvia Zhu, a Fermi team member at the University of Maryland in College Park.

The LAT detected GRB 130427A for about 20 hours, far longer than any previous burst. For a gamma-ray burst, it was relatively nearby. Its light traveled 3.8 billion years before arriving at Earth, about one-third the travel time for light from typical bursts.

“Detailed observations by Swift and ground-based telescopes clearly show that GRB 130427A has properties more similar to typical distant bursts than to nearby ones,” said Gianpiero Tagliaferri, a Swift team member at Brera Observatory in Merate, Italy.

This extraordinary event enabled NASA’s newest X-ray observatory, the Nuclear Spectroscopic Telescope Array (NuSTAR), to make a first-time detection of a burst afterglow in high-energy, or “hard,” X-rays after more than a day. Taken together with Fermi LAT data, these observations challenge long-standing predictions.

GRB 130427A is the subject of five papers published online Nov. 21. Four of these, published by Science Express, highlight contributions by Fermi, Swift and RAPTOR. The NuSTAR study is published in The Astrophysical Journal Letters.

NASA’s Fermi Gamma-ray Space Telescope is an international and multi-agency astrophysics and particle physics partnership managed by NASA’s Goddard Space Flight Center in Greenbelt, Md., and supported by the U.S. Department of Energy’s Office of Science. Goddard also manages NASA’s Swift mission, which is operated in collaboration with Pennsylvania State University in University Park, Pa., and international partners. NASA’s NuSTAR mission is led by the California Institute of Technology and managed by NASA’s Jet Propulsion Laboratory, both in Pasadena, with contributions from international partners.




All of this week's top headlines to your email every Friday.


 
 

 

Headlines October 22, 2014

News: Northrop challenges 3DELRR contract award - Northrop Grumman has formally issued a protest against the US Air Force’s decision to award its next-generation ground based radar to competitor Raytheon.   Business: Defense firms prefer GOP, but spread campaign cash between political parties - For every campaign contribution from a major arms manufacturer to a Republican candidate...
 
 

News Briefs October 22, 2014

Military converges on scene of Kansas jet crash Military personnel are investigating at the site in southeast Kansas where an Oklahoma Air National Guard fighter jet crashed after a midair collision with another one during a training exercise. The F-16 crashed Oct. 20 in a pasture about three miles northeast of Moline, an Elk County...
 
 
Courtesy photograph

Upgrades ‘new normal’ for armor in uncertain budget environment

Courtesy photograph The current Paladin is severely under-powered and overweight so its speed of cross-country mobility is pretty restricted. The Paladin Integrated Management program is designed to address a number of these we...
 

 

ISR: A critical capability for 21st century warfare

The progressive adaptations and breakthroughs made in the intelligence, surveillance and reconnaissance arena have changed the way wars are fought, and the way commanders think about the battlespace. “Whether we have airmen exploiting full motion video data or serving downrange in the (Central Command) area of responsibility, these individuals make up an enterprise of 30,000...
 
 

Lockheed Martin teams with Roketsan of Turkey on new standoff missile for F-35

Roketsan and Lockheed Martin signed a teaming agreement Oct. 22 for collaboration on the SOM-J, a new generation air-to-surface Standoff Cruise Missile for the F-35 Lightning II. The SOM system is an autonomous, long-range, low-observable, all-weather, precision air-to-surface cruise missile. The SOM-J variant is tailored for internal carriage on the F-35 aircraft. The companies will...
 
 

Army Operating Concept expands definition of combined arms

The Army Operating Concept, published Oct. 7, expands the idea of joint combined-arms operations to include intergovernmental and special operations capabilities, said Gen. Herbert R. McMaster Jr. The new concept includes prevention and shaping operations at the strategic level across domains that include maritime, air, space and cyberspace, he said. It’s a “shift in emphasis,”...
 




0 Comments


Be the first to comment!


Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>