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Giant waves twisting in solar atmosphere

...Scientists have detected giant waves twisting in the Sun's lower atmosphere, shedding light on the mystery of why the solar corona is hotter than the Sun's visible surface...

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The latest theory-defying supernova

...A star one hundred solar masses and one million times brighter than our Sun before it exploded, should not have self-destructed so early in its life, according to the fundamental theories of stellar evolution...

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Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.


STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.


STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.


Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

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Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

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Home computers to search for new pulsars



Posted: 24 March, 2009

First there was SETI@Home, now there is Einstein@Home, an initiative that calls on the general public to donate computational time to searching for gravitational wave data that could help detect new pulsars.

SETI@Home was launched in May 1999, and uses a screensaver package to analyse blocks of data recorded by the Arecibo Observatory, the largest single-aperture radio telescope on the planet, that could contain extraterrestrial radio signals. The concept was based on the fact that more computing power enables searches to cover greater frequency ranges with more sensitivity. The same applies to Einstein@Home, which also uses the Arecibo Observatory to search for radio pulsars, as well as the Laser Interferometer Gravitational Wave Observatory (LIGO) gravitational wave detector to search for gravitational waves.

Double pulsars are rare in the Universe, but the impressive computing power of Einstein@Home could help detect them. Image: John Rowe Animations.

Gravitational waves were first predicted by Einstein in 1916 as a consequence of his general theory of relativity, but have not yet been directly detected. They can be described as the ripples in the fabric of space and time that are produced by violent events in the distant Universe, such as the collision of two black holes or by the cores of supernova explosions. As these ripples propagate towards the Earth, they bring with them information about their violent origins and about the nature of gravity.

More than 200,000 volunteers have already signed up to the Einstein@Home initiative, and this week, Bruce Allen, Director of the Einstein@Home project, and Jim Cordes, Chair of the Arecibo PALFA (Pulsar Arecibo L-band Feed Array) Consortium, announced that the project is beginning to analyse data taken by the PALFA Consortium at the Arecibo Observatory in Puerto Rico.

“While our long-term goal is to detect gravitational waves, in the shorter term we hope to discover at least a few new radio pulsars per year, which should be a lot of fun for Einstein@Home participants and should also be very interesting for astronomers,” says Allen. “We expect that most of the project’s participants will be eager to do both types of searches.” Einstein@Home participants will automatically receive work for both the radio and gravitational-wave searches.

The Crab Nebula as seen from the ground (left) and its interior pulsar as seen by Hubble. The Crab Pulsar is a rapidly rotating neutron star. Image: Jeff Hester and Paul Scowen (Arizona State University) and NASA.

Radio pulsars are rapidly spinning neutron stars that emit a lighthouse-like beam of radio waves that bathe the Earth in radiation as frequently as 600 times per second. Radio
pulsars in short-period binary systems are especially interesting
because the effects of general relativity can be very strong. Systems that have already been discovered have been used to verify that Einstein’s predictions about gravitational wave emission are correct to better than 1%. The discovery of new pulsars in much shorter-period binaries would improve estimates of the rates at which binary star systems form and disappear in our Galaxy, and also provide new targets to search for with gravitational wave detectors.

Einstein@Home will search Arecibo radio data to find binary systems consisting of the most extreme objects in the Universe: a spinning neutron star orbiting another neutron star or a black hole. Current searches of radio data lose sensitivity for orbital periods shorter than about 50 minutes. But the enormous
computational capabilities of the Einstein@Home project mean that data can be analysed using the equivalent of tens of thousands of computers, meaning that pulsars in binary systems with orbital periods as short as 11 minutes could eventually be detected.

“Discovery of a pulsar orbiting a neutron star or black hole, with a sub-hour orbital period, would provide tremendous opportunities to test General Relativity and to estimate how often such binaries merge,” says Cordes. The mergers of such systems are among the rarest and most spectacular events in the Universe, emitting bursts of gravitational waves that current detectors might be able to detect, as well as gamma rays just before the merged stars collapse to form a black hole. “The Einstein@Home computing resources are a perfect complement to the data management systems at the Cornell Center for Advanced Computing and the other PALFA institutions.”