The Whole Sky Seen in Infrared

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Okay, shift your eyes into the infrared, and then look up into the night sky. What? You can’t see in infrared? Ah well, you’ll have to just enjoy this photograph of the entire sky, seen by the Japanese AKARI probe.

Launched back in February 2006, AKARI has been working away to map the entire sky in various wavelengths of infrared light. Just in the last year, it completed these all-sky observations in six different wavelength bands, and has now imaged 90 of the entire sky. It has also performed detailed observations on about 3,500 specific targets.

The picture attached to this story is the infrared sky at nine micrometres. The bright stripe extending across the middle of the image is disc of our own Milky Way galaxy. The bright regions in the disc are sites of newly born stars.

This sky map will give astronomers a much better understanding of the formation and evolution of galaxies, stars, and planetary systems.

Original Source: ESA News Release

Most Distant Galaxies Ever Seen

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Astronomers announced today that they’ve located the most distant galaxies ever seen, 13.2 billion light-years away, formed when the Universe was only 500 million years old.

Galaxies that far away can’t easily be seen directly with current telescopes. Instead, the researchers turned massive clusters of galaxies into natural telescopes, using a technique called gravitational lensing. As the light from the more distant galaxies passed the galaxy clusters, it was bent by gravity towards the Earth.

This allowed the (already powerful) 10-metre Keck II telescope to capture additional photons, and measure these distant galaxies. The researchers were able to locate 6 faint star forming galaxies, thanks to the assistance of the gravitational lens, which boosted the signal by about 20 times.

When the Universe was only 300,000 years old, it entered a period called the Dark Ages when no stars were shining. Astronomers have been trying to pinpoint the moment when it came out of this opaque period, and the first stars formed. The combined radiation of these galaxies should be strong enough to break apart the hydrogen atoms around them, ending the Dark Ages. So astronomers could be seeing these galaxies at the moment the Dark Ages ended.

Original Source:Caltech

Is There a Link Between Cosmic Rays and Global Warming?

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As you might know, I’ve got a side job blogging over at Wired Science on their space beat. I just posted an article there about new research that refutes a possible connection between global warming and cosmic rays.

The theory is that cosmic rays create ions in the atmosphere, forming the seeds that build into water droplets. If true, that would help explain global warming as a natural phenomenon, where increased cosmic rays create clouds to cool the planet. When the 11-year solar cycle is at its maximum, cosmic rays are pushed away from the Earth, and temperatures rise. No humans causing global warming.

Except we are.

A new presentation at the 30th International Cosmic Ray Conference by researchers from the UK tears holes in this theory, refuting it on several levels.

Check out the article over at Wired.

Black Holes are Key to the Evolution of the Universe

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A supercomputer simulation has retraced the evolution of the Universe, giving astronomers new clues on where they should point their telescopes. And it seems that one of the most important ingredients to this cosmic recipe is black holes.

The simulation is called BHCosmo, and it was performed on the Cray XT3 system at the Pittsburgh Supercomputing Center. The researchers tied up the whole system – 2,000 processors – for 4 weeks to run the simulation.

They started with initial conditions that matched the cosmic microwave background radiation. Next they seeded the area with 250 million particles of matter, and surrounded that with the gravitational force of dark matter. The researchers watched how the particles of matter collapsed to form galaxies and black holes.

One of the most important findings of the simulation was the impact of black holes. Galaxies look the way they do because of the supermassive black holes at their centres.

Eventually they hope to model the entire Universe with a resolution that matches the Sloan Digital Sky Survey, but that will take more computer power.

Original Source: Carnegie Mellon

Hubble View of a Galaxy Ablaze in Star Formation

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This latest image released from the Hubble Space Telescope shows the dwarf galaxy NGC 4449, located about 12.5 million light-years away. Although the galaxy has been around for billions of years, it recently went through a period of intense star formation.

Most starburst galaxies concentrate their stellar formation around the crowded galactic core, but in NGC 4449, the active regions extend out across more of the galaxy. This will only last for another billion years or so, when the gas supply that feeds the star forming regions runs out. It will then stay quiet until it has a close encounter with another galaxy, starting the process all over again.

A galaxy like NGC 4449 resembles what the first primordial galaxies probably looked like, formed shortly after the Big Bang when the Universe was young. Many small galaxies merged together forming larger and larger galaxies until they became the majestic spirals we see today. Each new merger brings in a fresh supply of raw materials as well as the gravitational interactions to force gas clouds to collapse.

Original Source:Hubble

Before the Big Bang?

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The scientific consensus is that the Universe is expanding, having gotten its start in a single point 13.7 billion years ago. There are several lines of evidence to support this theory: the movement of galaxies away from us, the cosmic microwave background radiation, and the quantities of hydrogen and helium in the Universe.

But what came before the Big Bang? Since all matter and energy was tangled up into a single point of infinite volume and density, it’s hard to imagine how you could look to a time before that.

Cosmologist Martin Bojowald and others from Penn State University thinks it’s possible. His ideas are published in a new paper as part of the July 1st edition of the journal Nature Physics.

According to Bojowald, a mathematical technique called Loop Quantum Gravity, which combines relativity and quantum mechanics, gives a different view of the early Universe. Instead of being infinitely small and dense, it was compacted down into a ball of some volume and density.

The researchers believes that a previous Universe collapsed down to a tiny ball, and then had a Big Bounce to expand again. The previous Universe was very similar to the space-time geometry we have in our current Universe.

I’d try and explain this better, but Phil beat me to the punch and did a great article about it.

Original Source : Penn State University

Double Supernovae Discovered

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Supernovae are rare events, only occurring once every 25-100 years in galaxy. So it came as a complete surprise when NASA’s Swift satellite turned up two supernovae going off at the same time in a galaxy – separated by only 16 days.

Until now, astronomers have never seen a supernova going off in the galaxy MCG +05-43-16, and then suddenly: kaboom kaboom. The twin supernovae have been categorized SN 2007ck and SN 2007co.

And they’re completely different events. The first, SN 2007ck, is a Type II supernova, where a star with many times the mass of our own Sun runs out of fuel and collapses catastrophically. This creates a black hole or neutron star, and blows the outer layers of the star into space.

The second, SN 2007co is a Type Ia event. This is where a white dwarf star steals material from a binary partner until it can’t hold any more material, and detonates in a massive blast.

This is a complete coincidence. The two events are separated by tens of thousands of light years of space. In fact, an astronomer in the galaxy might see the two events separated by thousands of years.

Original Source: NASA

The Cosmic Horseshoe, a Nearly Complete Einstein Ring

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If you want to peer into the furthest reaches of space, a regular telescope won’t do. You need to harness the power of a massive galaxy to bend light from an even more distant galaxy – a gravitational lens. And a team of European astronomers have found one of the luckiest discoveries of all, an Einstein ring, where the lens and more distant galaxy line almost perfectly. Because of its unique shape, they’re calling it “The Cosmic Horseshoe”.

The discovery was made by more than a dozen astronomers from a handful of European universities, from England to Russia. They published their discovery in a research paper called The Cosmic Horseshoe: Discovery of an Einstein Ring around a Giant Luminous Red Galaxy, which has been submitted to the Astrophysics Journal.

They turned up the object after poring through data in the massive Sloan Digital Sky Survey. This survey uses robotic telescopes to capture images of the night sky; eventually it will map out 25% of the sky, seeing 100 million objects. Astronomers regularly look through this vast quantity of data, and pull out all kinds of interesting objects.

Such as the Cosmic Horseshoe.

Then they did follow-up observations using the 2.5 metre Isaac Newton Telescope in La Palma and the 6 metre BTA telescope in Russia. This gave the detailed image attached to this story, as well as the spectral information to determine the chemical constituents of the lens and lensed object.

Look at the picture, and you can see a red spherical galaxy surrounded almost completely by a blue ring. In reality, this is a relatively nearby galaxy, located 4.6 billion light-years away (the lens), and then a more distant blue galaxy located 10.9 billion light-years away (the lensed object).

The two line up perfectly from our point of view, so that light from the blue galaxy is focused by the gravity of the lens. Light that would head off into space is turned back towards the Earth. All this additional light allows astronomers to see what would normally be an invisible object. In fact, the two are lined up so perfectly, that the lensed galaxy has been turned into a ring that wraps 300-degrees around the lens.

The lens is an extremely massive luminous red galaxy, containing 5 trillion times the mass of the Sun. For comparison, our own Milky Way only contains 580 billion solar masses.

And this is just the “telescope”.

The more distant, lensed object is a starburst galaxy undergoing furious rates of star formation – evidenced by the blue spectrum of its light. If it weren’t behind the lens, astronomers wouldn’t even know it was there. But because it’s directly behind the lens, its light has been focused into a nearly complete ring around the lens. Since it’s 10.9 billion light-years away, we see it at a time when the Universe was less than 3 billion years old.

This discovery gives astronomers two useful directions for further research: dark matter distribution around luminous red galaxies, and the formation of stars in the early Universe.

Original Source: Arxiv

No Stars Shine in This Dark Galaxy

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An international team of astronomers have conclusive new evidence that a recently discovered “dark galaxy” is, in fact, an object the size of a galaxy, made entirely of dark matter. Although the object, named VIRGOHI21, has been observed since 2000, astronomers have been slowly ruling out every alternative explanation.

In a new research paper, entitled 21-cm synthesis observations of VIRGOHI 21 – a possible dark galaxy in the Virgo Cluster, researchers provide updated evidence about this mysterious galaxy.

They have now performed a high resolution observations of VIRGOHI21 using the Westerbork Synthesis Radio Telescope (WSRT), to better pin down the quantities of neutral hydrogen gas. They also did followup observations with the Hubble Space Telescope, looking for any evidence of stars.

Astronomers first suspected there was an invisible galaxy out there when they spied galaxy NGC 4254. This unusual-looking galaxy appears to be one partner in a cosmic collision. All the normal evidence is there: gas is being siphoned away into a tenuous stream, and one of its spiral arms is being stretched out.

But the other partner in this collision is nowhere to be seen.

The researchers’ calculated that an object with 100 billion solar masses must have careened past NGC 4254 within the last 100 million years, creating the gas stream, and tearing at one of its arms. This was the clue that an invisible dark matter galaxy might be lurking nearby.

A detailed search turned up a mysterious object called VIRGOHI21, located about 50 million light-years from Earth. Were it a normal galaxy, you would be able to see it in a powerful amateur telescope. But there’s nothing there. Even in the Hubble Space Telescope, not a single star is shining from this massive region of space.

It was only visible in radio telescopes, which could detect the radio emissions from neutral hydrogen gas located in the cloud.

When they first published their research a few years ago, the astronomy community was understandably skeptical, and proposed several alternative theories to explain the mysterious object.

For example, there could be additional mass associated with VIRGOHI21, and not just dark matter. The discovery of red giant stars in the region would give some indication that this was a more normal interaction. But Hubble turned up nothing.

Dr. Robert Minchin, lead researcher from the Arecibo Observatory, said, “not even the power of Hubble has been able to see any stars in it.”

It’s possible that VIRGOHI21 has always been this way, formed from primordial dark matter and neutral hydrogen after the Big Bang. It’s been cruising the Universe ever since, disrupting galaxies as it goes.

However, there do seem to be ways that galaxies and their dark matter can be separated. Only a few months ago, a ring of dark matter was found surrounding a group of colliding galaxy clusters by the Hubble Space Telescope. Perhaps VIRGOHI21 is the wreckage from one of these cluster collisions; a shred of dark matter hurled out into space.

It could be that there are many of these dark galaxies out there. A new sky survey, carried out with the 305-metre (1000-foot) Aricebo radio telescope in Puerto Rico should tease out more of these objects in the future. The survey is called the Arecibo Galaxy Environment Survey (AGES).

This most recent paper has been accepted for publication in the Astrophysical Journal.

Massive Star Dies Twice

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Kaboom kaboom. That’s what an international team of astronomers saw when they tracked the death of one of the most massive stars that can exist.

Japanese supernova hunter, Koichi Itagaki, first discovered an exploding star in the galaxy UGC4904 back in 2004. It flared briefly and then faded away over the course of 10 days. Two years later, he discovered another supernova in exactly the same location.

Subsequent observations with larger telescopes confirmed that the supernova, named SN2006jc, did indeed happen at exactly the same location as the previous detonation. The 2004 event must have just been a large outburst, similar to what was seen on Eta-Carinae back in the 1850s.

The researchers think this kind of event could actually be more common than previously believed. A new survey called Pan-STARRS may check up on previous supernova events to see if there’s any new activity.

Original Source: Queen’s University Belfast News Release