Posted on by Tammy Plotner

Hubble Vision: Galaxy DDO 68 – Young Or Old?

Image credit: NASA & ESA

Only astronomers know for sure… Or do they? In this assembly of images taken with Hubble’s Advanced Camera for Surveys, scientists have utilized both visible and infrared light to survey a most unusual galaxy. When looking for a newly formed galaxy in our “cosmic neighborhood”, they spied DDO 68 (a.k.a. UGC 5340). Normally to witness galactic evolution, we have to look over great distances to see back in time… but this particular collection of gas and stars seems to break the rules!

Researching galactic evolution isn’t a new concept. Over the last few decades astronomers have increased our understanding of how galaxies change with time. One of the most crucial players in this game has been the NASA/ESA Hubble Space Telescope. Through its eyes, scientists can see over almost incomprehensible distances – studying light that has taken billions of years to reach us. We are essentially looking back in time.

While this is great news on its own, studying progressively younger galaxies can sometimes pose more questions than it answers. For example, all the newly created galaxies reside a huge distance from us and thereby appear small and faint when imaged. On the other side of the coin, galaxies which are close to us appear to be far more mature.

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This video begins with a ground based view of the night sky, before zooming in on dwarf galaxy DDO 68 as the NASA/ESA Hubble Space Telescope sees it. This ragged collection of stars and gas clouds looks at first glance like a recently-formed galaxy in our own cosmic neighbourhood. But, is it really as young as it looks? Credit: NASA/ESA

DDO 68, imaged here by the NASA/ESA Hubble Space Telescope, would seem to be the best example of a nearby newly-formed galaxy. Just how nearby? Estimates place it at about 39 million light years distant. While this might seem like a very long way, it is still roughly 50 times closer than other galactic examples. Studying galaxies of different ages is important to our understanding of how the Universe works. Astronomers have discovered that young galaxies are quite different than those which have aged. In this case, DDO 68 gives off the appearance of being young. These findings come from examining its structure, appearance and composition. However, researchers question their findings. It is possible this galaxy may be considerably older than initial findings indicate.

“All of the available data are consistent with the fact that DDO 68 is a very rare candidate for young galaxies.” says S. A. Pustilnik (et al). “The bulk of its stars were formed during the recent (with the first encounter about 1 Gyr ago) merger of two very gas-rich disks.”

These common events – mergers and collisions – are part of galactic life and are generally responsible for older galaxies being more bulky. These “senior citizens” are normally laced with a wide variety of stellar types – young, old, large and small. The chemistry is also different, too. Very young galaxies are rich in hydrogen and helium, making them tantalizingly similar in composition to the primordial matter created by the Big Bang. Older galaxies have more experiences. Numerous stellar events have happened within them over their lifetimes, making them rich in heavy elements. This is what makes DDO 68 very exciting! It is the best local candidate found so far to be low in heavier elements.

“DDO 68 (UGC 5340) is the second most metal-poor star-forming galaxy,” explains Pustilnik. “Its peculiar optical morphology and its HI distribution and kinematics are indicative of a merger origin. We use the u, g, r, and i photometry based on the SDSS images of DDO 68 to estimate its stellar population ages.”

Step into the light? You bet. The Hubble observations were meant to examine the properties of this mysterious galaxy’s light – determine whether or not it contains any older stars. If they are discovered, which seems to be the case, this would disprove the theory that DDO 68 is singularly comprised of younger stars. If not, it will validate the unique nature of this nearby neighbor. While more computer modeling and studies are needed, we can still enjoy this incredible look at another cosmic enigma!

Original Story Source: A Galaxy Of Deception – Hubble/ESA

Posted on by Tammy Plotner

Lazy Giant Galaxies Gain Mass By Ingesting Smaller Neighbors

Some of the many thousands of merging galaxies identified within the GAMA survey. Credit: Professor Simon Driver and Dr Aaron Robotham, ICRAR.

The Anglo-Australian Telescope in New South Wales has been watching how lazy giant galaxies gain size – and it isn’t because they create their own stars. In a research project known as the Galaxy And Mass Assembly (GAMA) survey, a group of Australian scientists led by Professor Simon Driver at the International Centre for Radio Astronomy Research (ICRAR) have found the Universe’s most massive galaxies prefer “eating” their neighbors.

According to findings published in the journal “Monthly Notices of the Royal Astronomical Society”, astronomers studied more than 22,000 individual galaxies to see how they grew. Apparently smaller galaxies are exceptional star producers, forming their stellar members from their own gases. However, larger galaxies are lazy. They aren’t very good at stellar creation. These massive monsters rarely produce new stars on their own. So how do they grow? They cannibalize their companions. Dr. Aaron Robotham, who is based at the University of Western Australia node of the International Centre for Radio Astronomy Research (ICRAR), explains that smaller ‘dwarf’ galaxies were being consumed by their heavyweight peers.

“All galaxies start off small and grow by collecting gas and quite efficiently turning it into stars,” he said. “Then every now and then they get completely cannibalized by some much larger galaxy.”

So how does our home galaxy stack up to these findings? Dr. Robotham, who led the research, said the Milky Way is at a tipping point and is expected to now grow mainly by eating smaller galaxies, rather than by collecting gas.

“The Milky Way hasn’t merged with another large galaxy for a long time but you can still see remnants of all the old galaxies we’ve cannibalized,” he said. “We’re also going to eat two nearby dwarf galaxies, the Large and Small Magellanic Clouds, in about four billion years.” Robotham also added the Milky Way wouldn’t escape unscathed. Eventually, in about five billion years, we’ll encounter the nearby Andromeda Galaxy and the tables will be turned. “Technically, Andromeda will eat us because it’s the more massive one,” he said.

Andromeda and the Milky Way Collide! from ICRAR on Vimeo.

This simulation shows what will happen when the Milky Way and Andromeda get closer together and then collide, and then finally come together once more to merge into an even bigger galaxy.

Simulation Credit: Prof Chris Power (ICRAR-UWA), Dr Alex Hobbs (ETH Zurich), Prof Justin Reid (University of Surrey), Dr Dave Cole (University of Central Lancashire) and the Theoretical Astrophysics Group at the University of Leicester. Video Production Credit: Pete Wheeler, ICRAR.

What exactly is going on here? Is it a case of mutual attraction? According to Dr. Robotham when galaxies grow, they acquire a heavy-duty gravitational field allowing them to suck in neighboring galaxies with ease. But why do they stop producing their own stars? Is it because they have exhausted their fuel? Robotham said star formation slow downs in really massive galaxies might be “because of extreme feedback events in a very bright region at the center of a galaxy known as an active galactic nucleus.”

“The topic is much debated, but a popular mechanism is where the active galactic nucleus basically cooks the gas and prevents it from cooling down to form stars,” Dr. Robotham said.

Will the entire Universe one day become just a single, large galaxy? In reality, gravity may very well cause galaxies groups and clusters to congeal into a limited number of super-giant galaxies, but that will take many billions of years to occur.

“If you waited a really, really, really long time that would eventually happen, but by really long I mean many times the age of the Universe so far,” Dr. Robotham said.

While the GAMA survey findings didn’t take billions of years, it didn’t happen overnight either. It took seven years and more than 90 scientists to complete – and it wasn’t a single revelation. From this work there have been over 60 publications and there are still another 180 in progress!

Original Story Souce: Monster galaxies gain weight by eating smaller neighbours – ICAR

Further reading: ‘Galaxy and Mass Assembly (GAMA): Galaxy close-pairs, mergers and the future fate of stellar mass’ in the Monthly Notices of the Royal Astronomical Society. Published online 19/9/2014 at: http://mnras.oxfordjournals.org/lookup/doi/10.1093/mnras/stu1604 . Preprint version accessible at: http://arxiv.org/abs/1408.1476 .

Posted on by Elizabeth Howell

Surprise! Tiny Galaxy Sports A Huge Black Hole, And There Could Be More Like It

Artist's conception of a supermassive black hole in a galaxy's center. Credit: NASA/JPL-Caltech

In a finding that could turn supermassive black hole formation theories upside-down, astronomers have spotted one of these beasts inside a tiny galaxy just 157 light-years across — about 500 times smaller than the Milky Way.

The clincher will be if the team can find more black holes like it, and that’s something they’re already starting to work on after the discovery inside of galaxy M60-UCD1. The ultracompact galaxy is one of only about 50 known to astronomers in the nearest galaxy clusters.

“It’s very much like a pinprick in the sky,” said lead researcher Anil Seth, an astrophysicist at the University of Utah, of M60-UCD1 during an online press briefing Tuesday (Sept. 16).

Seth said he realized something special was happening when he saw the plot for stellar motions inside of M60-UCD1, based on data from the Gemini North Telescope in Hawaii. The stars in the center of the galaxy were orbiting much more rapidly than those at the edge. The velocity was unexpected given the kind of stars that are in the galaxy.

“Immediately when I saw the stellar motions map, I knew we were seeing something exciting,” Seth said. “I knew pretty much right away there was an interesting result there.”

Ultracompact dwarf galaxy M60-UCD1 shines in the inset image based on images from the Hubble Space Telescope and Chandra X-Ray Telescope. Chandra data is pink, and Hubble data is red, green and blue. The large galaxy dominating the field of view of M60. At the right edge is NGC 4647. Credit: X-ray: NASA/CXC/MSU/J.Strader et al, Optical: NASA/STScI
Ultracompact dwarf galaxy M60-UCD1 shines in the inset image based on images from the Hubble Space Telescope and Chandra X-Ray Telescope. Chandra data is pink, and Hubble data is red, green and blue. The large galaxy dominating the field of view is M60. At the right edge is NGC 4647. Credit: X-ray: NASA/CXC/MSU/J.Strader et al, Optical: NASA/STScI

In its weight class, M60-UCD1 is a standout. Last year, Seth was second co-author on a group that announced that it was the densest nearby galaxy, with stars jam-packed 25 times closer than in the Milky Way. It’s also one of the brightest they know of, a fact that is helped by the galaxy’s relative closeness to Earth. It’s roughly 54 million light-years away, as is the massive galaxy it orbits: M60. The two galaxies are only 20,000 light-years apart.

Supermassive black holes are known to lurk in the centers of most larger galaxies, including the Milky Way. How they got there in the first place, however, is unclear. The find inside of M60-UCD1 is especially intriguing given the relative size of the black hole to the galaxy itself. The black hole is about 15% of the galaxy’s mass, with an equivalent mass of 21 million Suns. The Milky Way’s black hole, by contrast, takes up less than a percentage of our galaxy’s mass.

Given so few ultracompact galaxies are known to astronomers, some basic properties are a mystery. For example, the mass of these galaxy types tends to be higher than expected based on their starlight.

Some astronomers suggest it’s because they have more massive stars than other galaxy types, but Seth said measurements of stars within M60-UCD1 (based on their orbital motion) show normal masses. The extra mass instead comes from the black hole, he argues, and that will likely be true of other ultracompact galaxies as well.

A Hubble Space Telescope image of ultracompact galaxy M60-UCD1 (inset), which is suspected to host a supermassive black hole at its center. It is orbiting the nearby massive galaxy M60. Within the same field of view is NGC 4647. Credit: NASA/Space Telescope Science Institute/European Space Agency
A Hubble Space Telescope image of ultracompact galaxy M60-UCD1 (inset), which is suspected to host a supermassive black hole at its center. It is orbiting the nearby massive galaxy M60. Within the same field of view is NGC 4647. Credit: NASA/Space Telescope Science Institute/European Space Agency

“It’s a new place to look for black holes that was previously not recognized,” he said, but acknowledged the idea of black holes existing in similar galaxies will not be widely accepted until the team makes more finds. An alternative explanation to a black hole could be a suite of low-mass stars or neutron stars that do not give off a lot of light, but Seth said the number of these required in M60-UCD1 is “unreasonably high.”

His team plans to look at several other ultracompact galaxies such as M60-UCD1, but perhaps only seven to eight others would be bright enough from Earth to perform these measurements, he said. (Further work would likely require an instrument such as the forthcoming Thirty-Meter Telescope, he said.) Additionally, Seth has research interests in globular clusters — vast collections of stars — and plans a visit to Hawaii next month to search for black holes in these objects as well.

Results were published today (Sept. 17) in the journal Nature.

Posted on by Elizabeth Howell

Elemental Mystery: Lithium Is Also Rare Outside Of The Milky Way

An image of globular cluster M54 taken by the Very Large Telescope Survey Telescope at the European Southern Observatory's Paranal Observatory in northern Chile. Credit: ESO

This new picture of M54 — a part of a satellite galaxy to the Milky Way called the Sagittarius Dwarf Galaxy — is part of a “test case” astronomers have to figure out a mystery of missing lithium.

For decades, astronomers have been aware of a dearth of lithium in our own galaxy, the Milky Way. This image from the Very Large Telescope’s Survey Telescope represents the first effort to probe for the element outside of our galaxy.

“Most of the light chemical element lithium now present in the Universe was produced during the Big Bang, along with hydrogen and helium, but in much smaller quantities,” the European Southern Observatory stated.

“Astronomers can calculate quite accurately how much lithium they expect to find in the early Universe, and from this work out how much they should see in old stars. But the numbers don’t match — there is about three times less lithium in stars than expected. This mystery remains, despite several decades of work.”

In any case, observations of M54 show that the amount of lithium there is similar to the Milky Way — meaning that the lithium problem is not confined to our own galaxy. A paper based on the research was published in the Monthly Notices of the Royal Astronomical Society. The research was led by Alessio Mucciarelli at the University of Bologna in Italy.

Source: European Southern Observatory

Posted on by Elizabeth Howell

How Dark Matter Could Reduce The Fleet Of Galaxies Following The Milky Way

On either side of the white line in the picture are two models of how dark matter is distributed in a galaxy similar to the Milky Way. At left, non-interacting cold dark matter creates satellite galaxies. At right, dark matter interacting with other particles makes the number of observed satellite galaxies smaller. Credit: Durham University

Funny how small particle interactions can have such a big effect on the neighbors of the Milky Way. For a while, scientists have been puzzled about the dearth of small satellite galaxies surrounding our home galaxy.

They thought that cold dark matter in our galaxy should encourage small galaxies to form, which created a puzzle. Now, a new set of research suggests the dark matter actually interacted with small bits of normal matter (photons and neutrinos) and the dark matter scattered away, reducing the amount of material available for building galaxies.

“We don’t know how strong these interactions should be, so this is where our simulations come in,” stated Celine Boehm, a particle physicist at Durham University who led the research. “By tuning the strength of the scattering of particles, we change the number of small galaxies, which lets us learn more about the physics of dark matter and how it might interact with other particles in the Universe.”

Artist's conception of the Milky Way galaxy based on the latest survey data from ESO’s VISTA telescope at the Paranal Observatory. A prominent bar of older, yellower stars lies at galaxy center surrounded by a series of spiral arms. The galaxy spans some 100,000 light years. Credit: NASA/JPL-Caltech, ESO, J. Hurt
Artist’s conception of the Milky Way galaxy based on the latest survey data from ESO’s VISTA telescope at the Paranal Observatory. A prominent bar of older, yellower stars lies at galaxy center surrounded by a series of spiral arms. The galaxy spans some 100,000 light years. Credit: NASA/JPL-Caltech, ESO, J. Hurt

Dark matter is a poorly understood part of the Universe, which is frustrating for scientists because it (along with dark energy) is believed to make up the majority of our Cosmos. There are several postulated types of it, but the main thing to understand is dark matter is hard to detect (except, in certain cases, through its interactions with gravity.)

This isn’t the only explanation for why the galaxies are missing, the scientists caution. Perhaps the universe’s first stars were so hot that they affected the gas that other stars formed from, for example.

A paper on the research was published in the Monthly Notices of the Royal Astronomical Society and is also available in preprint version on Arxiv.

Source: Royal Astronomical Society

Posted on by Shannon Hall

First Glimpse of a Young Galactic Core Forming in the Early Universe

This image shows observations of a newly discovered galaxy core dubbed GOODS-N-774, taken by the NASA/ESA Hubble Space Telescope's Wide Field Camera 3 and Advanced Camera for Surveys. The core is marked by the box inset, overlaid on a section of the Hubble GOODS-N, or GOODS North, field (Great Observatories Origins Deep Survey). Credit: NASA, ESA, and E. Nelson (Yale University, USA)

Astronomers have spotted, for the first time, a dense galactic core blazing with the light of millions of newborn stars in the early universe.

The finding sheds light on how elliptical galaxies, the large, gas-poor gatherings of older stars, may have first formed in the early universe. It’s a question that has eluded astronomers for decades.

The research team first uncovered the compact galactic core, dubbed GOODS-N-774, in images from the Hubble Space Telescope. Later observations from the Spitzer Space Telescope, the Herschel Space Observatory, and the W.M. Keck Observatory helped make this a true scientific finding.

The core formed 11 billion years ago, when the universe was less than 3 billion years old. Although only a fraction of the size of the Milky Way, at that time it already contained above twice as many stars as our own galaxy.

Theoretical simulations suggest that giant elliptical galaxies form from the inside out, with a large core marking the very first stages of formation. But most searches for these forming cores have come up empty handed, making this a first observation and a phenomenal find.

“We really hadn’t seen a formation process that could create things that are this dense,” explained lead author Erica Nelson from Yale University in a press release. “We suspect that this core-formation process is a phenomenon unique to the early universe because the early universe, as a whole, was more compact. Today, the universe is so diffuse that it cannot create such objects anymore.”

Alongside determining the galaxy’s size from the Hubble images, the team dug into archived far-infrared images from Spitzer and Herschel to calculate how fast the compact galaxy is creating stars. It seems to be producing 300 stars per year, a rate 30 times greater than the Milky Way.

The frenzied star formation likely occurs because the galactic core is forming deep inside a gravitational well of dark matter. Its unusually high mass constantly pulls gas in, compressing it and sparking star formation.

But these bursts of star formation create dust, which blocks the visible light. This helps explain why astronomers haven’t seen such a distant core before, as they may have been easily missed in previous surveys.

The team thinks that shortly after the early time period we can see, the core stopped forming stars. It likely then merged with other smaller galaxies, until it transformed into a much greater galaxy, similar to the more massive and sedate elliptical galaxies we see today.

“I think our discovery settles the question of whether this mode of building galaxies actually happened or not,” said coauthor Pieter van Dokkum from Yale University. “The question now is, how often did this occur?”

The team suspects that other galactic cores are abundant, but hidden behind their own dust. Future infrared telescopes, such as the James Webb Space Telescope, should be able to find more of these early objects.

The paper was published Aug. 27 in Nature and is available online.

Posted on by Shannon Hall

A Cosmic Collision: Our Best View Yet of Two Distant Galaxies Merging

The Atacama Large Millimeter/submillimeter Array (ALMA) and many other telescopes on the ground and in space have been used to obtain the best view yet of a collision that took place between two galaxies when the Universe was only half its current age. The astronomers enlisted the help of a galaxy-sized magnifying glass to reveal otherwise invisible detail. These new studies of the galaxy H-ATLAS J142935.3-002836 have shown that this complex and distant object looks surprisingly like the well-known local galaxy collision, the Antennae Galaxies. In this picture you can see the foreground galaxy that is doing the lensing, which resembles how our home galaxy, the Milky Way, would appear if seen edge-on. But around this galaxy there is an almost complete ring — the smeared out image of a star-forming galaxy merger far beyond. This picture combines the views from the NASA/ESA Hubble Space Telescope and the Keck-II telescope on Hawaii (using adaptive optics). Credit: ESO/NASA/ESA/W. M. Keck Observatory

An international team of astronomers has obtained the best view yet of two galaxies colliding when the universe was only half its current age.

The team relied heavily on space- and ground-based telescopes, including the Hubble Space Telescope, the Atacama Large Millimeter/submillimeter Array (ALMA), the Keck Observatory, and the Karl Jansky Very Large Array (VLA). But the greatest asset was a chance cosmic alignment.

“While astronomers are often limited by the power of their telescopes, in some cases our ability to see detail is hugely boosted by natural lenses created by the universe,” said lead author Hugo Messias of the Universidad de Concepción in Chile and the Centro de Astronomia e Astrofísica da Universidade de Lisboa in Portugal.

Such a rare cosmic alignment plays visual tricks, where the intervening lens (be it a galaxy or a galaxy cluster) appears to bend and even magnify the distant light. This effect, called gravitational lensing, allows astronomers to study objects which would not be visible otherwise and to directly compare local galaxies with much more remote galaxies, seen when the universe was significantly younger.

The distant object in question, dubbed H-ATLAS J142935.3-002836, was originally spotted in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS). Although very faint in visible light pictures, it is among the brightest gravitationally lensed objects in the far-infrared regime found so far.

The Hubble and Keck images reveal that the foreground galaxy is a spiral galaxy, seen edge-on. Although the galaxy’s large dust clouds obscure part of the background light, both ALMA and VLA can observe the sky at longer wavelengths, which are unaffected by dust.

Using the combined data, the team discovered that the background system was actually an ongoing collision between two galaxies.

The Antennae galaxies. Credit: Hubble / ESA
The Antennae galaxies. Credit: Hubble / ESA

First, the team noticed that these two galaxies resembled a much closer system: the Antennae galaxies, two galaxies that have spent the past few hundred million years in a whirling embrace as they merge together. The similarity suggested a collision, but ALMA — with its high sensitivity and spatial resolution — was able to verify it.

ALMA has the unique ability to detect the emission from carbon monoxide, as opposed to other telescopes, which might only be able to probe the absorption along the line of sight. This allowed astronomers to measure the velocity of the gas in the more distant object. With this information, they were able to show that the lensed galaxy is indeed an ongoing galactic collision.

Such collisions naturally enhance star formation. Any gas within the galaxies will feel a headwind, much as a runner feels a wind even on the stillest day, and become compressed enough to spark star formation. Sure enough, ALMA shows that the two galaxies are forming hundreds of new stars each year.

“ALMA enabled us to solve this conundrum because it gives us information about the velocity of the gas in the galaxies, which makes it possible to disentangle the various components, revealing the classic signature of a galaxy merger,” said ESO’s Director of Science and coauthor of the new study, Rob Ivison. “This beautiful study catches a galaxy merger red handed as it triggers an extreme starburst.”

The findings have been published in the Aug. 26 issue of Astronomy & Astrophysics and is available online.

Posted on by Elizabeth Howell

Feel The Beat: Black Hole’s Pulse Reveals Its Mysterious Size

A view of the core of Messier 82 (M82), also known as the Cigar Galaxy. Credit: ESA/Hubble & NASA

There’s a bit of a mystery buried in the heart of the Cigar Galaxy, known more formally as M82 or Messier 82. Shining brightly in X-rays is a black hole (called M82 X-1) that straddles an unusual line between small and huge black holes, new research has revealed.

The new study reveals for the first time just how big this black hole is — about 400 times the mass of the sun — after about a decade of struggling to figure this out.

“Between the two extremes of stellar and supermassive black holes, it’s a real desert, with only about half a dozen objects whose inferred masses place them in the middle ground,” stated Tod Strohmayer, an astrophysicist at NASA’s Goddard Space Flight Center in Maryland.

Scientists figured this out by looking at changes in brightness in X-rays, which fluctuate according to how gas behaves as it falls towards a black hole. At the event horizon — that spot where you’re doomed, even if you’re light — is where the fluctuation happen most frequently. In general, larger black holes have these fluctuations less frequently, but they weren’t sure if this would apply to something that is of M82 X-1’s size.

But by going through old data from NASA’s Rossi X-ray Timing Explorer (RXTE) satellite — which ceased operations in 2012 — the scientists uncovered a similar pulsing relationship to what you see in larger black holes.

Specifically, they saw X-ray variations repeating 5.1 and 3.3 times a second, which is a similar 3:2 ratio to other black holes studied. This allows them to extend the measurement scale to this black hole, NASA stated.

Results of the study were published this week in Nature. The research was led by Dheeraj Pasham, a graduate student at the University of Maryland, College Park.

Source: NASA

Posted on by Elizabeth Howell

Wow! Gas Bridge In The Universe Stretches 2.6 Million Light-Years Across

A stream of gas 2.6 million light-years long stretches in green across this picture. The insets are of galaxies in the neighborhood, while the green circle represents the Arecibo telescope beam. Credit: Rhys Taylor/Arecibo Galaxy Environment Survey/The Sloan Digital Sky Survey Collaboration

How the heck did all that gas get there? Researchers have discovered an astonishing amount of it bridging galaxies, stretching across a stream that is 2.6 million light-years across. This is more than a million light-years longer than a similar stream that was previously found in the Virgo Cluster.

“This was totally unexpected,” stated Rhys Taylor, a researcher at the Czech Academy of Sciences who led the research. “We frequently see gas streams in galaxy clusters, where there are lots of galaxies close together, but to find something this long and not in a cluster is unprecedented.”

The atomic hydrogen gas is about 500 million light-years away and was spotted with the William E. Gordon Telescope at the Arecibo Observatory in Puerto Rico.

Its origins are unknown, but one hypothesis postulateas that a larger galaxy passed close to smaller galaxies in the distant past, drawing out the gas as the larger galaxy moved apart again. Alternately, the large galaxy could have pushed through the group and disturbed the gas within it.

The research will be published shortly in the Monthly Notices of the Royal Astronomical Society.

Source: Royal Astronomical Society

Posted on by Elizabeth Howell

Cosmic Fireworks: A Supernova Feast And Google+ Hangout For Chandra’s 15th Anniversary

A collection of images from the Chandra X-Ray Observatory marking its 15th anniversary in space. Top, from left: the crab Nebula, supernova remnant G292.0+1.8 and the Crab Nebula. At bottom, supernova remnant 3C58. Credit: NASA/CXC/SAO

It’s well past the Fourth of July, but you can still easily find fireworks in the sky if you look around. The Chandra X-Ray Observatory has been doing just that for the past 15 years, revealing what the universe looks like in these longer wavelengths that are invisible to human eyes.

Just in time for the birthday, NASA released four pictures that Chandra took of supernova (star explosion) remnants it has observed over the years. The pictures stand as a symbol of what the telescope has shown us so far.

“Chandra changed the way we do astronomy. It showed that precision observation of the X-rays from cosmic sources is critical to understanding what is going on,” stated Paul Hertz, NASA’s Astrophysics Division director, in a press release. “We’re fortunate we’ve had 15 years – so far – to use Chandra to advance our understanding of stars, galaxies, black holes, dark energy, and the origin of the elements necessary for life.”

The telescope launched into space in 1999 aboard the space shuttle and currently works at an altitude as high as 86,500 miles (139,000 miles). It is named after Indian-American astrophysicist Subrahmanyan Chandrasekhar; the name “Chandra” also means “moon” or “luminous” in Sanskrit.

And there’s more to come. You can learn more about Chandra’s greatest discoveries and its future in this Google+ Hangout, which will start at 3 p.m. EDT (7 p.m. EDT) at this link.