Tag Archives: gamma ray

The Era of Neutrino Astronomy has Begun

COLLEGE PARK, Md. – Astrophysicists using a telescope embedded in Antarctic ice have succeeded in a quest to detect and record the mysterious phenomena known as cosmic neutrinos – nearly massless particles that stream to Earth at the speed of light from outside our solar system, striking the surface in a burst of energy that can be as powerful as a baseball pitcher’s fastball. Next, they hope to build on the early success of the IceCube Neutrino Observatory to detect the source of these high-energy particles, said Physics Professor Gregory Sullivan, who led the University of Maryland’s 12-person team of contributors to the IceCube Collaboration.

“The era of neutrino astronomy has begun,” Sullivan said as the IceCube Collaboration announced the observation of 28 very high-energy particle events that constitute the first solid evidence for astrophysical neutrinos from cosmic sources.  (more…)

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You’re Beautiful, Vesta

NASA’s UCLA-led Dawn mission shows protoplanet’s surprising surface

When UCLA’s Christopher T. Russell looks at the images of the protoplanet Vesta produced by NASA’s Dawn mission, he talks about beauty as much as he talks about science.

“Vesta looks like a little planet. It has a beautiful surface, much more varied and diverse than we expected,” said Russell, a professor in UCLA’s Department of Earth and Space Sciences and the Dawn mission’s principal investigator. “We knew Vesta’s surface had some variation in color, but we did not expect the diversity that we see or the clarity of the colors and textures, or their distinct boundaries. We didn’t find gold on Vesta, but it is still a gold mine.”

Dawn has been orbiting Vesta and collecting data on the protoplanet’s surface since July 2011. Vesta, which is in the doughnut-shaped asteroid belt between Mars and Jupiter, is currently some 321 million miles from Earth. (more…)

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Physicists Set Strongest Limit on Mass of Dark Matter

*Brown University physicists have set the strongest limit for the mass of dark matter, the mysterious particles believed to make up nearly a quarter of the universe. The researchers report in Physical Review Letters that dark matter must have a mass greater than 40 giga-electron volts. The distinction is important because it casts doubt on recent results from underground experiments that have reported detecting dark matter.*

PROVIDENCE, R.I. [Brown University] — If dark matter exists in the universe, scientists now have set the strongest limit to date on its mass.

In a paper to be published on Dec. 1 in Physical Review Letters (available in pdf), Brown University assistant professor Savvas Koushiappas and graduate student Alex Geringer-Sameth report that dark matter must have a mass greater than 40 giga-electron volts in dark-matter collisions involving heavy quarks. (The masses of elementary particles are regularly expressed in term of electron volts.) Using publicly available data collected from an instrument on NASA’s Fermi Gamma-ray Space Telescope and a novel statistical approach, the Brown pair constrained the mass of dark matter particles by calculating the rate at which the particles are thought to cancel each other out in galaxies that orbit the Milky Way galaxy. (more…)

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Dawn Reaches Milestone Approaching Asteroid Vesta

PASADENA, Calif. — NASA’s Dawn spacecraft has reached its official approach phase to the asteroid Vesta and will begin using cameras for the first time to aid navigation for an expected July 16 orbital encounter. The large asteroid is known as a protoplanet — a celestial body that almost formed into a planet.

At the start of this three-month final approach to this massive body in the asteroid belt, Dawn is 1.21 million kilometers (752,000 miles) from Vesta, or about three times the distance between Earth and the moon. During the approach phase, the spacecraft’s main activity will be thrusting with a special, hyper-efficient ion engine that uses electricity to ionize and accelerate xenon. The 12-inch-wide ion thrusters provide less thrust than conventional engines, but will provide propulsion for years during the mission and provide far greater capability to change velocity. (more…)

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Spacecraft Catches Thunderstorms Hurling Antimatter into Space

WASHINGTON — Scientists using NASA’s Fermi Gamma-ray Space Telescope have detected beams of antimatter produced above thunderstorms on Earth, a phenomenon never seen before.

Scientists think the antimatter particles were formed in a terrestrial gamma-ray flash (TGF), a brief burst produced inside thunderstorms and shown to be associated with lightning. It is estimated that about 500 such flashes occur daily worldwide, but most go undetected. (more…)

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