RSSArchive for June, 2011

Most distant quasar found

Artist’s impression of quasar ULAS J1120+0641

This artist’s impression shows how ULAS J1120+0641, a very distant quasar powered by a black hole with a mass two billion times that of the Sun, may have looked. This quasar is the most distant yet found and is seen as it was just 770 million years after the Big Bang.

ASTRONOMERS HAVE DISCOVERED the most distant quasar to date—a development that could help further our understanding of the universe when it was still in its infancy following the Big Bang.

Quasars are distant galaxies that have very bright cores, believed to be powered by supermassive black holes at their centres. Their brilliance makes them powerful beacons that may help to probe the era when the first stars and galaxies were forming.

“It is a very rare object that will help us to understand how supermassive black holes grew a few hundred million years after the Big Bang,” says Stephen Warren, the study’s team leader.

The quasar, named ULAS J1120+0641, is seen as it was only 770 million years after the Big Bang, giving it a redshift of 7.1. The light we see coming from it took 12.9 billion years to reach us.

Striking gold

Although more distant objects have been confirmed—such as a gamma-ray burst at redshift 8.2 and a galaxy at 8.6—the newly discovered quasar is hundreds of times brighter than these. In fact, amongst objects bright enough to be studied in detail, this is the most distant by a large margin.

Objects so away cannot be found in visible-light surveys because their light, stretched by the expansion of the Universe, falls mostly in the infrared part of the spectrum by the time it gets to Earth.

The European UKIRT Infrared Deep Sky Survey (UKIDSS) which uses the UK’s dedicated infrared telescope in Hawaii was designed to solve this problem. The team of astronomers hunted through millions of objects in the UKIDSS database to find those that could be the long-sought distant quasars, and eventually struck gold.

“It took us five years to find this object,” explains Bram Venemans, one of the authors of the study. “We were looking for a quasar with redshift higher than 6.5. Finding one that is this far away, at a redshift higher than 7, was an exciting surprise.”

A rare find

Because the object is comparatively bright it is possible to take a spectrum of it (which involves splitting the light from the object into its component colours). This technique enabled the astronomers to find out quite a lot about it.

These observations show that the mass of the black hole at the centre of ULAS J1120+0641 is about two billion times that of the Sun. This very high mass is hard to explain so early on after the Big Bang, as current theories for the growth of supermassive black holes predict a slow build-up in mass as the object pulls in matter from its surroundings.

“We think there are only about 100 bright quasars with redshift higher than 7 over the whole sky,” concludes Daniel Mortlock, the leading author of the paper. “Finding this object required a painstaking search, but it was worth the effort to be able to unravel some of the mysteries of the early Universe.”

Adapted from information issued by ESO / University of Nottingham / M. Kornmesser.

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What’s up? Night sky for July 2011

Telescope inside a dome at night

Stargazing during winter is chilly, but the nights can often be crisp and clear. And there's plenty to see this month!

THE INNERMOST PLANET, Mercury, has delighted us in the morning sky for the past couple of months, but this month it makes a reappearance in our evening skies, in the west after sunset. It’ll be quite easy to see, above the horizon for around 100 minutes after the Sun sets at the beginning of the month, increasing to almost two-and-a-half hours after the Sun sets by the end of the month.

Also in the evening sky, to the north-west, is Saturn. The famous ringed planet will be on show during the first half of the night, setting around 11:00pm by the end of the month.

In the morning sky to the east, Jupiter and Mars are still putting on a show before sunrise.

Venus is too close to the Sun to be seen this month.

Except where indicated, all of the phenomena described here can be seen with the unaided eye. And unless otherwise specified, dates and times are for the Australian Eastern Standard Time zone, and sky directions are from the point of view of an observer in the Southern Hemisphere.

July 1

There will be a partial eclipse of the Sun today, but you’ll have to be an albatross or maybe a seal in order to see it. That’s because the Sun’s shadow will fall across a remote area of ocean between South Africa and Antarctica. Unless there are some fishing boats or a scientific expedition in the area, it’s entirely possible that no one will witness this eclipse which, at its maximum, will see less than 10% of the Sun’s disc covered by the Moon. And speaking of the Moon, New Moon occurs today at 6:54pm Sydney time (08:54 Universal Time).

 

View of the night sky for July 3, 2011

July 3, 2011, 5:15pm: The thin crescent Moon will sit just above the planet Mercury in the western sky after sunset.

 

July 3

Take a look out to the west after sunset, and you should see the planet Mercury above the horizon, and above it will be the thin crescent Moon.

July 5

Earth reaches aphelion today (or July 4 in the western hemisphere), which is the farthest point from the Sun in our orbit. The distance between Earth and Sun will be 152.1 million kilometres.

There’ll be an interesting sight out to the east in the morning sky today. The planet Mars will appear close to the star Aldebaran. Both are of similar brightness, and both have similar colouring—a sort of orangey-red.

In this evening’s sky, the Moon will sit above the bright star Regulus. Regulus is the brightest star in the constellation Leo. The amazing thing about Regulus is that, although to the naked eye it appears to be one star, in reality it is composed of four stars grouped into two pairs, all gravitationally bound to each other! This sort of thing is not too uncommon—many other stars are members of double, triple or quadruple systems too.

Position of the Moon, Spica and Saturn on July 8, 2011

July 8, 2011, 7:15pm: The Moon will be bracketed by the planet Saturn and the star Spica, in the north-western sky.

 

 

July 8

It is First Quarter Moon today at 4:29pm Sydney time (06:29 Universal Time). First Quarter is a good time to look at the Moon through a telescope, as the sunlight angle means the craters and mountains throw nice shadows, making it easier to get that 3D effect. Also today, the Moon will be at the closest point to Earth in its orbit, called perigee, at 12:05am (14:05 on July 7, Universal Time). The distance between the two bodies will be 369,565 kilometres. And finally, tonight the Moon will appear reasonably near the planet Saturn.

July 9

A little more than half full, the Moon will appear quite close to the star Spica tonight. Spica, a blue giant star, is the brightest star in the constellation Virgo and the 15th-brightest star in our night sky.

Position of the Moon and Antares on July 12, 2011

July 12, 2011, 8:00pm: High in the northern sky, the Moon and the star Antares (the brightest star in the constellation Scorpius) will appear close together.

 

 

July 12

The now almost-full Moon will appear quite close to the star Antares tonight. Antares means “the rival of Mars’, and it’s not hard to see why, as it’s ruddy colour makes it look just like the fourth planet from the Sun. Antares is a red supergiant star, 800 times bigger than the Sun!

Today, the eighth planet from the Sun, Neptune, has completed one full orbit of the Sun since its discovery in 1846. Neptune takes almost 165 years to complete one circuit of the Sun. Neptune is too faint to be seen with the naked eye, but it is within the range of medium-and-larger backyard telescopes, if you know exactly where to look. This chart, provided by the Royal Astronomical Society of New Zealand, will help you to find it.

July 15

Full Moon occurs today at 4:40pm Sydney time (06:40 Universal Time).

July 20

Mercury reaches its greatest angle from the Sun today, so if you have a clear evening sky, why not take the opportunity to go out and spot it in the west after sunset?

Position of Mercury on July 20, 2011

July 20, 2011, 5:20pm: Mercury will be at its greatest angle from the Sun today, and visible in the west after sunset.

July 22

Today the Moon will reach the farthest point in its orbit around the Earth, called apogee, at a distance of 404,356 kilometres at 8:48am Sydney time (22:48 on July 21, Universal Time).

July 23

It is Last Quarter Moon today at 3:02pm Sydney time (05:02 Universal Time).

July 24

Slightly less than half full, the Moon will appear close to the planet Jupiter in this morning’s sky. Jupiter will be about 12 Moon widths above the Moon. Look a little further east and you’ll see Mars too. In between will be the beautiful star cluster called the Pleiades, also known as the Seven Sisters. Use binoculars or a small telescope and you’ll be delighted with the view.

Position of the Moon, Jupiter and Mars on July 24, 2011

July 24, 2011, 6:20am: The Moon and two planets—Jupiter and Mars—will be visible in the north-eastern sky before sunrise. See if you can spot the Pleiades star cluster as well.

July 25-28

In the western sky after sunset, the planet Mercury will appear close to the star Regulus (see July 5 for more information on this star).

July 28

The crescent Moon will appear very close to the planet Mars in this morning’s sky. They’ll be separated by only three Moon widths.

July 31

New Moon occurs today at 4:40am Sydney time (18:40 on July 30, Universal Time).

If you have any questions or comments on the night sky, we’d be happy to answer them. Please use the Feedback Form below. Happy stargazing!

Images courtesy IAU.

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Neutron star bites off more than it can chew

Artist's impression of a neutron star partially devouring a massive clump of matter.

Artist's impression of a neutron star partially devouring a massive clump of matter spat out by its companion star.

ASTRONOMERS HAVE SEEN a faint star flare up at X-ray wavelengths to almost 10,000 times its normal brightness…caused, they think, by the star trying to eat a giant clump of matter.

The flare took place on a neutron star, the collapsed heart of a once much larger star, and part of a binary star system. Only 10 kilometres in diameter, the neutron star is so dense that it generates a strong gravitational field.

The clump of matter was much larger than the neutron star and came from its enormous, blue supergiant companion star.

“This was a huge bullet of gas that the star shot out, and it hit the neutron star…,” says Enrico Bozzo, ISDC Data Centre for Astrophysics, University of Geneva, Switzerland, and team leader of the research.

The flare lasted four hours. The X-rays came from the gas in the clump as it was heated to millions of degrees while being pulled into the neutron star’s intense gravity field.

Because the clump was much bigger than the neutron star, only some of it was swallowed.

An artist's impression of XMM-Newton.

An artist's impression of XMM-Newton.

A lucky observation

The European Space Agency’s XMM-Newton space observatory caught the flare during a scheduled 12.5-hour observation of the system, which is known only by its catalogue number IGR J18410-0535.

But the astronomers were not immediately aware of their catch.

The telescope works through a sequence of observations carefully planned to make the best use of its time, then sends the data to Earth.

It was about 10 days after the observation that Dr Bozzo and his colleagues received the data and quickly realised they had something special. Not only was the telescope pointing in the right direction to see the flare, but the observation had lasted long enough for them to see it from beginning to end.

“I don’t know if there is any way to measure luck, but we were extremely lucky,” says Dr Bozzo. He estimates that an X-ray flare of this magnitude can be expected a few times a year at the most for this particular star system.

The duration of the flare allowed them to estimate the size of the gas clump. It was much larger than the star, probably 16 million kilometres across—that’s about 100 billion times the volume of the Moon, yet it had probably only 1/1,000th of the Moon’s mass.

Adapted from information issued by ESA / AOES Medialab / C. Carreau.

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Mars mission launch gets closer

NASA’S MARS SCIENCE LABORATORY will leave Earth later this year, on target for a landing on Mars in August 2012. This new animation details some of the dramatic events we can expect from the mission, including the spacecraft separating from its launch vehicle near Earth and the mission’s rover, Curiosity, zapping rocks with a laser and examining samples of powdered rock on Mars.

Curiosity’s landing will use a different method than any previous Mars landing, with the rover suspended on tethers from a rocket-powered “sky crane.”

Here’s a shorter, narrated version of the video:

Adapted from information issued by NASA / JPL.

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Asteroid rendezvous nears

Dawn and Hubble images of Vesta

Already, Dawn's images of Vesta (left) are better even than the Hubble Space Telescope can obtain (right). The protoplanet Vesta is the second-most massive object in the main asteroid belt.

NASA’S DAWN SPACECRAFT is on track to begin the first extended visit to a large asteroid. The mission expects to go into orbit around Vesta on July 16 and begin gathering science data in early August.

Vesta is considered a protoplanet, or body that didn’t quite become a full-fledged planet. It lives in the main asteroid belt between Mars and Jupiter, and is thought to be the source of a large number of meteorites that fall to Earth.

After travelling nearly four years and 2.7 billion kilometres, Dawn is approximately 150,000 kilometres away from Vesta. When Vesta captures Dawn into its orbit on July 16, there will be approximately 16,000 kilometres between them. When orbit is achieved, they will be approximately 188 million kilometres away from Earth.

Artist's impression of the Dawn spacecraft

Artist's impression of the Dawn spacecraft

“The spacecraft is right on target,” said Robert Mase, Dawn project manager at NASA’s Jet Propulsion Laboratory. “We look forward to exploring this unknown world during Dawn’s one-year stay in Vesta’s orbit.”

Peeling back the layers

After Dawn enters Vesta’s orbit, engineers will need a few days to determine the exact time of capture. Unlike other missions where a dramatic, nail-biting propulsive burn results in orbit insertion around a planet, Dawn has been using its placid ion propulsion system to subtly shape its path for years to match Vesta’s orbit around the Sun.

Images from Dawn’s framing camera, taken for navigation purposes, show the slow progress toward Vesta. Made into a movie (below), they are about twice as sharp as the best images of Vesta from NASA’s Hubble Space Telescope, but the surface details Dawn will obtain are still a mystery.

“We can’t wait for Dawn to peel back the layers of time and reveal the early history of our Solar System,” said Christopher Russell, Dawn principal investigator, at UCLA.

During the initial reconnaissance orbit, at a distance of approximately 2,700 kilometres, the spacecraft will get a broad overview of Vesta with colour pictures and data in different wavelengths of reflected light.

The spacecraft will then move drop lower into a mapping orbit about 680 kilometres above the surface to systematically map the parts of Vesta’s surface illuminated by the Sun.

It will collect stereo images to see topographic highs and lows, acquire higher-resolution data to map rock types at the surface; and learn more about Vesta’s thermal properties.

Up close and personal

Dawn then will move even closer, to a low-altitude mapping orbit approximately 200 kilometres above the surface. The primary science goals of this orbit are to detect the by-products of cosmic rays hitting the surface and help scientists determine the many kinds of atoms there, and probe the protoplanet’s internal structure.

“We’ve packed our year at Vesta chock-full of science observations to help us unravel the mysteries of Vesta,” said Carol Raymond, Dawn’s deputy principal investigator at JPL.

Following a year at Vesta, the spacecraft will depart for its second destination, the dwarf planet Ceres, in July 2012.

As Dawn spirals away from Vesta, it will pause again at the high-altitude mapping orbit. Because the Sun’s angle on the surface will have progressed, scientists will be able to see previously hidden terrain while obtaining different views of surface features.

Dawn was launched in September 2007.

More information about Dawn:

http://www.nasa.gov/dawn

http://dawn.jpl.nasa.gov/

Follow the mission on Twitter:

http://www.twitter.com/NASA_Dawn

Adapted from information issued by NASA / JPL-Caltech. Images courtesy NASA / JPL-Caltech / UCLA / MPS / DLR / PSI and NASA / ESA / STScI / Umd.

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Superstar spreads its wings

Nebula surrounding Betelgeuse

A nebula surrounds the red supergiant star Betelgeuse. The nebula forms as the behemoth sheds material into space. The black disc corresponds to a very bright part of the image that was masked to allow the fainter nebula to be seen. Earlier observations of the heart of the nebula can be seen in the central disc.

ASTRONOMERS HAVE IMAGED a complex and bright nebula around the supergiant star Betelgeuse in greater detail than ever before. This structure, which resembles flames emanating from the star, is formed as the behemoth sheds its gas into space.

Betelgeuse, a red supergiant in the constellation Orion, is one of the brightest stars in the night sky. It is also one of the biggest, being almost the size of the orbit of Jupiter—about four and half times the diameter of the Earth’s orbit.

Hubble image of the surface of Betelgeuse

This image of Betelgeuse, released in 1996, was the first direct image of a star other than the Sun, and it was made with the Hubble Space Telescope. The image revealed a mysterious hot spot—more than ten times the diameter of Earth—on the stellar behemoth's surface.

The Very Large Telescope (VLT) image shows the surrounding nebula, which is much bigger than the supergiant itself, stretching 60 billion kilometres away from the star’s surface—about 400 times the distance of the Earth from the Sun.

Red supergiants like Betelgeuse represent one of the last stages in the life of a massive star. In this short-lived phase, the star increases in size, and expels gas into space at a tremendous rate—it sheds immense quantities of material (about the mass of the Sun) in just 10,000 years.

The process by which material is shed from a star like Betelgeuse involves two processes. The first is the formation of huge plumes of gas (although much smaller than the nebula now imaged) extending into space from the star’s surface.

The other, which is behind the ejection of the plumes, is the vigorous up and down movement of giant bubbles in Betelgeuse’s atmosphere—like boiling water circulating in a pot.

Raw material for new planets

Earlier images using an instrument called NACO, revealed the plumes close in to the star. The new results show that those plumes are probably connected to structures in the outer nebula now imaged at infrared wavelengths with a different instrument, VISIR.

The nebula cannot be seen at visible light wavelengths, as the glare of Betelgeuse completely outshines it.

The irregular shape of the nebula indicates that the star did not eject its material in a symmetric way. The bubbles of stellar material and the giant plumes they originate may be responsible for the clumpy look of the nebula.

The material visible in the new image is most likely made of silicate and alumina dust. This is the same material that forms most of the crust of the Earth and other rocky planets. At some time in the distant past, the silicates that eventually formed the Earth were expelled by a massive (and now extinct) star similar to Betelgeuse.

Adapted from information issued by ESO / P. Kervella / Andrea Dupree (Harvard-Smithsonian CfA), Ronald Gilliland (STScI), NASA and ESA.

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Satellites needed for NBN

Artist's impression of an Optus satellite in orbit

With Australia's increasing reliance on space technology, including the NBN, there is a need for 2 or 3 extra satellites.

  • Australia is heavily reliant on space technology
  • 2 or 3 extra satellites will be needed to provide services

WHEN WE THINK OF SPACE, most of us think of rockets and robots and, whether or not we realise it, these and other space technologies form a fundamental part of our lives.

With Australia’s investment in new communications satellites as part of creating the National Broadband Network (NBN), it is more important than ever to understand the benefits of space technology.

Dr Rosalind Dubs, Chair of the Australian Government’s Space Industry Innovation Council, stresses the importance of driving productivity and innovation through space technologies.

“It’s estimated the global space market will be worth one trillion dollars by 2020,” Dr Dubs said. “If Australian companies can capture just a few percent of this business, this would represent a worthwhile contribution to the national economy, strengthen national self-reliance and deliver broader spin-off benefits.”

Dr Dubs said while most of the NBN’s high speed internet will be delivered by fibre optic cables, 3 to 4 per cent of Australians live in regional areas where this would be prohibitively expensive. Two to three satellites will be acquired to provide high-speed internet services (around 12 Mbps) where the fibre optic cables or wireless will not reach.

These new satellites will make the NBN an important milestone in Australia’s space infrastructure. They are expected to provide opportunities for the development of Australian space capabilities and downstream applications.

Space provides value for money

“International experience suggests that every $1 million invested in space-borne capability results in around $6 million of downstream services application revenue,” Dr Dubs said. “For example, think of the many GPS-receiver and accurate positioning-related businesses that have grown out of the US Global Positioning System.”

Australia from space

The space sector is likely to become crucial for Australia in the coming decade.

Australians in remote areas will reap huge benefits from the NBN’s satellites, but satellite technology can also improve city dwellers’ mobile internet, phone and television services, and improve the ability for navigation devices to receive GPS signals in high rise cities where some satellites are out of view.

Beyond these day-to-day benefits, satellites collect data about weather, climate, oceans, land, geology, ecosystems, and natural and human-induced hazards.

“Integrating this data into real-world applications is essential if we are to effectively manage our planet and its resources, particularly as we tackle natural disasters and climate change,” Dr Dubs said.

Crucial for Australia

Satellites provide us with infrastructure that can improve our quality of life and increase our knowledge of the world around us. But to do so, both government and commercial organisations must invest in building expertise, strengthening capabilities, and developing real, practical applications for satellite data. The payoff will be worthwhile.

“Space capability is much like IT. It is an enabling technology that will lead to productivity increases,” Dr Dubs said. “The Australian Government has recognised that more active involvement in the space sector is likely to become crucial for Australia in the coming decade, not just for defence and national security reasons, but because everyday life depends more and more on satellite services.”

To find out more about Australia’s space-related activities or the Space Industry Innovation Council, visit http://www.space.gov.au/

Adapted from information issued by SIIC.

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Hubble sees a southern wonder

Close-up image of the central region of NGC 5128

Resembling looming rain clouds on a stormy day, dark lanes of dust crisscross the heart of the giant elliptical galaxy NGC 5128. Hubble's reveals the vibrant glow of young, blue star clusters and a glimpse into regions normally obscured by the dust.

THE GALAXY KNOWN AS NGC 5128 is a favourite of amateur astronomers in the Southern Hemisphere. Easily visible through a small telescope, it has a rounded shape with a prominent “dark lanes” running through its centre.

Those lanes are composed of interstellar “rivers” of dust encircling the galaxy.

Astronomers have now used the Hubble Space Telescope’s Wide Field Camera 3 to zoom in on this region of NGC 5128 in multi-wavelength observations, resulting in the most detailed view ever of this galaxy.

As well as features in the visible spectrum, the composite shows ultraviolet light from young stars, and near-infrared light, which lets us glimpse some of the detail otherwise obscured by the dust.

The dark dust lane that crosses Centaurus A does not show an absence of stars, but rather a relative lack of starlight, as the opaque clouds block the light of background stars from reaching us.

Hubble’s Wide Field Camera 3 has focused on these dusty regions, which span from corner to corner in this image.

It is thought that at some point in the past, NGC 5128 collided and merged with another galaxy. The shockwaves of this event caused hydrogen gas clouds to coalesce and sparked intense areas of star formation, as seen in its outlying regions and in red patches visible in this Hubble close-up.

Wide-field image of NGC 5128

This wide-field image shows the full extent of galaxy NGC 5128 and its dark, central dust lanes. NGC 5128 is more than 11 million light-years from Earth.

The galaxy’s compact core contains a very active giant black hole. Powerful jets emanating from the vicinity of the black hole are emitting vast amounts of radio and X-ray radiation (although these are invisible here as Hubble’s instruments).

At just over 11 million light-years distant, NGC 5128is relatively nearby in astronomical terms. However, it is not only close, it is also bright. This makes it a very attractive target for amateur astronomers in the Southern Hemisphere, where it is visible. Stargazers can see the galaxy through binoculars, while larger amateur telescopes begin to unveil the distinctive dusty lanes.

Editor’s note: You’ll often see this galaxy called Centaurus A, but this is not strictly correct. Centaurus A is the name given to a region within the galaxy that is emitting large amounts of radio waves. The overall galaxy is called NGC 5128.

Adapted from information issued by NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration. Acknowledgment: R. O’Connell (University of Virginia) and the WFC3 Scientific Oversight Committee. Wide-angle NGC 5128 image courtesy ESO.

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Chilly test for new space telescope

THE FIRST OF 18 SEGMENTS that will form NASA’s James Webb Space Telescope’s primary mirror for space observations, have completed final cryogenic testing.

The ten-week test series included two tests cycles where the mirrors were chilled down to -228 degrees Celsius, then back to ambient temperature to ensure the mirrors respond as expected to the extreme temperatures of space.

A second set of six mirror assemblies will arrive at Marshall in late July to begin testing, and the final set of six will arrive in the later in 2011.

The X-ray and Cryogenic Facility at NASA’s Marshall Space Flight Centre in Huntsville, Alabama, provides the space-like environment to help engineers measure how well the telescope will image infrared sources once in orbit.

Engineers and technicians with some of the JWST's mirror segments

Engineers and technicians guide check some of the James Webb Space Telescope’s mirror segments following cryogenic testing.

Each mirror segment measures approximately 1.3 metres in diameter to form the 6.5 metres, hexagonal telescope mirror assembly critical for infrared observations. Each of the 18 hexagonal-shaped mirror assemblies weighs approximately 40 kilograms.

The mirrors are made of a light and strong metal called beryllium, and covered with a microscopically thin coating of gold to enabling the mirror to efficiently collect infrared light.

The NASA’s James Webb Space Telescope is expected to be launched in 2017 or 2018. Placed over 1 million kilometres from Earth, it will observe primarily the infrared light from faint and very distant objects.

It will be the premier observatory of the next decade, serving thousands of astronomers worldwide. It will study every phase in the history of our Universe, ranging from the first luminous glows after the Big Bang, to the formation of planetary systems capable of supporting life on planets like Earth, to the evolution of our own Solar System.

The telescope is a combined project of NASA, the European Space Agency and the Canadian Space Agency. Northrop Grumman is the prime contractor under NASA’s Goddard Space Flight Centre. Ball Aerospace & Technologies Corp. in Boulder, Colorado, is responsible for mirror development. L-3- Tinsley Laboratories Inc. in Richmond, California is responsible for mirror grinding and polishing.

Adapted from information issued by NASA / Emmett Given.

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Black hole eats a star

Artist's impression of a star being eaten by a black hole

The aftermath of a black hole's banquet of a star, was jets of energy blasted from the black hole, fortuitously pointed in our direction and detected by the Swift satellite. (Artist's impression)

A BRIGHT FLASH OF GAMMA RAYS observed on March 28 by the Swift satellite may have been the death rattle of a star falling into a massive black hole and being ripped apart.

When Swift detected the flash, astronomers initially thought it was a gamma-ray burst from a collapsing star.

However, research led by astronomers at the University of Warwick has confirmed that the flash—one of the biggest and brightest bangs yet recorded by astronomers—came from a massive black hole at the centre of a distant galaxy.

The black hole appears to have ripped apart a star that wandered too close, creating a powerful beam of energy that crossed the 3.8 billion light years to Earth.

Gamma-ray flare in a distant galaxy

A gamma-ray flare seen in a distant galaxy is thought to have been the death throes of a star being eaten by a black hole.

Careful analysis of the data and subsequent observations by the Hubble Space Telescope and the Chandra X-ray Observatory confirmed Bloom’s initial insight.

“Despite the power of this the cataclysmic event we still only happen to see this event because our Solar System happened to be looking right down the barrel of this jet of energy,” said Dr Andrew Levan, lead researcher from the University of Warwick.

What made this gamma-ray flare, called Sw 1644+57, stand out from a typical burst were its long duration and the fact that it appeared to come from the centre of a galaxy nearly 4 billion light-years away.

Since most, if not all, galaxies are thought to contain a massive black hole at the centre, a long-duration burst could conceivably come from the relatively slow disruption of an infalling star, the astronomers said.

“This burst produced a tremendous amount of energy over a fairly long period of time, and the event is still going on more than two and a half months later,” said Joshua Bloom, an associate professor of astronomy at the University of California Berkeley. “That’s because as the black hole rips the star apart, the mass swirls around like water going down a drain, and this swirling process releases a lot of energy.”

Adapted from information issued by the University of California, Berkeley, and University of Warwick. Images courtesy NASA / Swift / Stefan Immler / ESA / A. Fruchter, STScI / Mark A. Garlick.

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