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Kepler's first view of planet hunting territory

...NASA's Kepler spacecraft has opened its eyes and blinked at the rich star field where it will search for extraterrestrial planets like Earth...

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Four-way cosmic

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...Combining images from space- and ground-based telescopes, astronomers have revealed the first cosmic collision of four separate galaxy clusters...

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Hubble witnesses flaring in black

hole jet

...A flare of matter blasting out from a monster black hole is outshining even the core of its host galaxy, M87...

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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.

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 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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Outbursting star creates double-lobed nebula



Posted: 22 April, 2009

An artist's impression of the RS Oph system. Image: David Hardy (

A cataclysmic variable that outburst three years ago now has debris expanding into a 'peanut-shaped' nebula, according to new Hubble Space Telescope images that have been released today at the National Astronomy Meeting, part of the European Week of Astronomy and Space Science at the University of Hertfordshire.

The star, RS Ophiuchi (RS Oph for short), is actually two stars: a swollen red giant orbited closely by the remnant of a dead star, a white dwarf. The white dwarf is so close that it is actually inside the peripheral layers of the red giant's atmosphere, and so it manages to gather up quite a large amount of the red giant's gas on its surface. Over time the build-up of material on the surface of the white dwarf eventually reaches catastrophic proportions and a thermonuclear reaction takes place resulting in a huge explosion on its surface. This happens every 20 years or so, and since 2006 new observations and understanding of the nova - termed a cataclysmic variable because it brightens dramatically in the sky during its outbursts from an increase in energy output 100,000 times greater than the Sun - have become a mainstay of the National Astronomy Meeting.

During each outburst, enough gas and dust is ejected from the white dwarf to make the equivalent of several Earth-mass planets, and this debris races away at up to 3,000 kilometres per second.

Hubble Space Telescope image of the double-lobed nebula in RS Ophiuchi. Image: NASA/HST and Valerio Ribeiro.

The Hubble images, taken 155 and 449 days after the outburst, were backed up by ground-based spectroscopy, and show how the outburst debris is evolving as it expands into a double-lobed, peanut-shaped nebula. The nebula is elongated perpendicular to the plane of the RS Oph system, where there is less gas to stop its expansion.

There will be more outbursts to occur in the RS Oph system during the coming decades, but eventually there may be one outburst too many, and a chain reaction will possibly rip the white dwarf apart. "There are some astronomers who believe systems like this will ultimately explode as supernovae," says Valerio Ribeiro from Liverpool John Moores University, who presented the images. "Our continuing work will help us find out if that is possible."