Archive for the ‘Cosmic Rays’ Category

NASA’s Fermi Proves Supernova Remnants Produce Cosmic Rays

February 20, 2013 Leave a comment

The W44 supernova remnant. Credit: NASA/DOE/Fermi LAT Collaboration, NRAO/AUI, JPL-Caltech, ROSAT

The W44 supernova remnant. Credit: NASA/DOE/Fermi LAT Collaboration, NRAO/AUI, JPL-Caltech, ROSAT

A new study using observations from NASA’s Fermi Gamma-ray Space Telescope reveals the first clear-cut evidence the expanding debris of exploded stars produces some of the fastest-moving matter in the universe. This discovery is a major step toward understanding the origin of cosmic rays, one of Fermi’s primary mission goals.

“Scientists have been trying to find the sources of high-energy cosmic rays since their discovery a century ago,” said Elizabeth Hays, a member of the research team and Fermi deputy project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Md. “Now we have conclusive proof supernova remnants, long the prime suspects, really do accelerate cosmic rays to incredible speeds.”

Cosmic rays are subatomic particles that move through space at almost the speed of light. About 90 percent of them are protons, with the remainder consisting of electrons and atomic nuclei. In their journey across the galaxy, the electrically charged particles are deflected by magnetic fields. This scrambles their paths and makes it impossible to trace their origins directly.

Through a variety of mechanisms, these speedy particles can lead to the emission of gamma rays, the most powerful form of light and a signal that travels to us directly from its sources. Since its launch in 2008, Fermi’s Large Area Telescope (LAT) has mapped million- to billion-electron-volt (MeV to GeV) gamma-rays from supernova remnants. For comparison, the energy of visible light is between 2 and 3 electron volts.

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Super-TIGER Shatters Scientific Balloon Record In Antarctica

January 25, 2013 Leave a comment

Before he left for Antarctica in November, W. Robert Binns, PhD, research scientist at Washington University in St. Louis and principal investigator for Super-TIGER, said that he would be deliriously happy if the balloon carrying the cosmic-ray detector stayed up 30 days.

It has now been up 45 days, floating serenely in the polar vortex registering hits by cosmic rays. Over the weekend it shattered the previous record of 42 days set by Cream I, another cosmic ray experiment that flew during the winter of 2004-2005.

The Super-TIGER record will be hard to break. The experiment was launched from the Ross Ice Shelf on Dec. 9, 2012 and has circled the South Pole two and a half times at an altitude of about 130,000 feet, three or four times higher than passenger planes cruise.

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Rough Guide To Super-TIGER Watching: How To Participate Vicariously In A Cosmic-Ray Experiment

December 3, 2012 Leave a comment

It’s Dec. 3 and a scattering of people in St. Louis, Mo., Pasadena, Calif., and Greenbelt, Md., are getting antsy, clicking repeatedly on to see whether anything is up yet. Like a balloon, for example.

They’re waiting for a two-ton balloon-borne cosmic-ray experiment called Super-TIGER to be launched into the high-altitude polar vortex over Antarctica.

The experiment, which the scientists hope will confirm that cosmic rays are created in loosely organized groups of hot, massive stars called OB associations, is a collaboration of Washington University in St. Louis, the California Institute of Technology and NASA’s Goddard Space Flight Center. The team also includes people from the University of Minnesota and NASA’s Jet Propulsion Laboratory.

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NASA’S Fermi Measures Cosmic ‘Fog’ Produced By Ancient Starlight

November 5, 2012 Leave a comment

This plot shows the locations of 150 blazars (green dots) used in the EBL study. Credit: NASA/DOE/Fermi LAT Collaboration

Astronomers using data from NASA’s Fermi Gamma-ray Space Telescope have made the most accurate measurement of starlight in the universe and used it to establish the total amount of light from all of the stars that have ever shone, accomplishing a primary mission goal.

“The optical and ultraviolet light from stars continues to travel throughout the universe even after the stars cease to shine, and this creates a fossil radiation field we can explore using gamma rays from distant sources,” said lead scientist Marco Ajello, a postdoctoral researcher at the Kavli Institute for Particle Astrophysics and Cosmology at Stanford University in California and the Space Sciences Laboratory at the University of California at Berkeley.

Gamma rays are the most energetic form of light. Since Fermi’s launch in 2008, its Large Area Telescope (LAT) observes the entire sky in high-energy gamma rays every three hours, creating the most detailed map of the universe ever known at these energies.

The total sum of starlight in the cosmos is known to astronomers as the extragalactic background light (EBL). To gamma rays, the EBL functions as a kind of cosmic fog. Ajello and his team investigated the EBL by studying gamma rays from 150 blazars, or galaxies powered by black holes, that were strongly detected at energies greater than 3 billion electron volts (GeV), or more than a billion times the energy of visible light.

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The White Widow Model: A New Scenario For The Birth Of Type Ia Supernovae

October 26, 2012 Leave a comment

Supernova remnant 0509-67.5 was searched for a left-behind partner star without success. Image Credit: NASA, ESA, CXC, SAO, the Hubble Heritage Team (STScI/AURA), and J. Hughes (Rutgers University)

J. Craig Wheeler has studied the exploding stars called supernovae for more than four decades. Now he has a new idea on the identity of the “parents” of one of the most important types of supernovae — the Type Ia, those used as “standard candles” in cosmology studies that led to the discovery of dark energy, the mysterious force causing the universe’s expansion to speed up.

Wheeler lays out his case for supernova parentage in the current issue of The Astrophysical Journal. He explains why he thinks the parents of Type Ia could be a binary star made up of white dwarf star (the burnt-out remnant of a Sun-like star) and a particular type of small star called an “M dwarf.”

In the paper, he explains that current theories for Type Ia parents don’t correctly match up with telescope data on actual supernovae.

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Astronomers Measure Largest-Ever Magnetic Field Around Massive Star, Time Its Slow Rotation As It Drags Around Giant Cloak Of Trapped Particles

September 11, 2012 Leave a comment

A group of astronomers led by Gregg Wade of the Royal Military College of Canada have used the Hobby-Eberly Telescope (HET) at The University of Texas at Austin’s McDonald Observatory and the Canada-France Hawaii Telescope (CFHT) on Hawaii’s Mauna Kea to measure the most magnetic massive star yet. Their work is published in today’s issue of the research journal Monthly Notices of the Royal Astronomical Society.

The star’s magnetic field is 20,000 times stronger than the Sun’s, and almost 10 times stronger than that detected around any other high-mass star. At about 35 times the Sun’s mass, the O-type star NGC 1624-2 lies in the open star cluster NGC 1624, about 20,000 light-years away in the constellation Perseus.

This star is an extreme case study to help astronomers better understand all massive stars, which play an important role in the evolution of galaxies.

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University Of Iowa Instruments Aboard Twin NASA Spacecraft Set For Launch Aug. 24

August 22, 2012 1 comment

On Aug. 24, NASA will launch two identical satellites from Cape Canaveral, Fla., to begin its Radiation Belt Storm Probes (RBSP) mission to study the extremes of space weather and help scientists improve space weather forecasts.

Why should you care?

Because, says a University of Iowa space physics researcher, if you’ve ever used a cell phone, traveled by plane, or stayed up late to catch a glimpse of the northern lights, then you have been affected by space weather without even knowing about it.

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