galaxies Archives

May 28, 2013December 23, 2015 by David Dickinson

An Amazing Deep-Field View of Centaurus A

The Centaurus A Extreme Deep Field. (Image Courtesy of Astrophotography byRolf Oslen. Used with Permision).

Sometimes, you just have to say “Wow!”

The view you’re looking at above is of Centaurus A (NGC 5128), a galaxy about 10-16 million light years distant in the southern hemisphere sky. It’s a favorite of astrophotographers and professional observatories alike.

But what makes this image so special is that it was taken by an amateur astrophotographer.

To construct this amazing image, New Zealand-based astrophotographer Rolf Wahl Olsen exposed the field of view for 120 hours over 43 nights spanning February to May of this year.

Rolf recently shared his motivation to construct this image;

“Over the past few months I have been on a mission to achieve a long time dream of mine: taking a deep sky image with more than 100 hours of exposure.”

Rolf also noted that the stars in the frame are visible down to magnitude +25.45, which “appears to go deeper than the recent ESO release” and believes that it may well be “the deepest view ever obtained of Centaurus A,” As well as “the deepest image ever taken with amateur equipment.”

Not only is the beauty and splendor of the galaxy revealed in this stunning mosaic, but you can see the variations in the populations of stars in the massive regions undergoing an outburst of star formation.

One can also see the numerous globular clusters flocking around the galaxy, as well as the optical counterparts to the radio lobes and the faint trace of the relativistic jets. The extended halo of the outer shell of stars is also visible, along with numerous foreground stars visible in the star rich region of Centaurus.

Finally, we see the dusty lane bisecting the core of this massive galaxy as seen from our Earthly vantage point.

To our knowledge, many of these features have never been captured visually by backyard observers before, much less imaged. Congrats to Rolf Wahl Olsen on a spectacular capture and sharing his view of the universe with us!

Read more on the Centaurus A deep field on Google+.

-Check out the comparison images of the Centaurus A deep field showing the relativistic jet (!) background galaxies and clusters.

-Explore more of Rolf’s outstanding work at his website.

May 28, 2013December 23, 2015 by Elizabeth Howell

Early Galaxies Churned Out Stars Like Crazy

The Southern Cross, the Milky Way, and the Large Magellanic Cloud shine above the Atacama Large Millimeter/submillimeter Array (ALMA) as it observes on a clear night sky during its Early Science phase. Image credit: C. Padilla, NRAO/AUI/NSF

Talk about an assembly line! Some early-stage galaxies created stars thousands of times faster than our Milky Way does today, according to new research. And it’s puzzling astronomers.

“We want to understand how and why these galaxies are forming stars at such incredibly fast rates, so soon after the Big Bang,” stated Scott Chapman of Dalhousie University, one of the researchers behind the discovery. “This could partially answer how our own galaxy, the Milky Way, was born billions of years ago.”

This is just a hint of the high-definition view we’ll receive from Chile’s Atacama Large Millimeter/submillimeter Array (ALMA), its astronomers promise, since the array of dozens of telescopes was officially inaugurated this spring. (ALMA has been working for years, but slowly adding telescopes and definition as it goes.)

There were actually three papers released today about ALMA. So what did the observatory find out this time? Here’s the nut graf:

Gravitational microlensing method requires that you have two stars that lie on a straight line in relation to us here on Earth. Then the light from the background star is amplified by the gravity of the foreground star, which thus acts as a magnifying glass.

– The observed galaxies are “gravitationally lensed”. Galaxies are so massive that they can bend light from other galaxies, if put in the right spot with respect to Earth. We’ve seen this effect over and over again with the Hubble Space Telescope, but observations are less well-known in the millimeter spectrum of light in which ALMA observes. “Models of lens geometries in the sample indicate that the background objects are ultra-luminous infrared galaxies, powered by extreme bursts of star formation,” stated a Nature paper on the discovery.

– These galaxies are further away than we thought. By measuring the time it takes light from carbon monoxide molecules to reach us, the astronomers concluded these galaxies are much further away than previously measured, with some reaching as far back as 12 billion light-years away. (That’s just 1.7 billion years after the Big Bang created the universe.)

– The galaxies put star creation on fast-forward. Looking back that far is like looking in a time machine — we can see things that were happening only 1 billion years after the Big Bang. At the time, those galaxies were as bright as 40 trillion suns and created new stars at an extreme rate of 4,000 suns per year. (That, by the way, is 4,000 times faster than what our own galaxy does.)

You can read more about these results in Nature and the Astrophysical Journal (here and here.)

Source: Canadian Astronomical Society (CASCA)

May 22, 2013December 23, 2015 by Jason Major

A Mega-Merger of Massive Galaxies Caught in the Act

A rare and massive merging of two galaxies that took place when the Universe was just 3 billion years old.

Even though the spacecraft has exhausted its supply of liquid helium coolant necessary to observe the infrared energy of the distant Universe, data collected by ESA’s Herschel space observatory are still helping unravel cosmic mysteries — such as how early elliptical galaxies grew so large so quickly, filling up with stars and then, rather suddenly, shutting down star formation altogether.

Now, using information initially gathered by Herschel and then investigating closer with several other space- and ground-based observatories, researchers have found a “missing link” in the evolution of early ellipticals: an enormous star-sparking merging of two massive galaxies, caught in the act when the Universe was but 3 billion years old.

It’s been a long-standing cosmological conundrum: how did massive galaxies form in the early Universe? Observations of distant large elliptical galaxies full of old red stars (and few bright, young ones) existing when the Universe was only a few billion years old just doesn’t line up with how such galaxies were once thought to form — namely, through the gradual accumulation of many smaller dwarf galaxies.

But such a process would take time — much longer than a few billion years. So another suggestion is that massive elliptical galaxies could have been formed by the collision and merging of large galaxies, each full of gas, dust, and new stars… and that the merger would spark a frenzied formation of even more stars.

Investigation of a bright region first found by Herschel, named HXMM01, has identified such a merger of two galaxies, 11 billion light-years distant.

The enormous galaxies are linked by a bridge of gas and each has a stellar mass of about 100 billion Suns — and they are spawning new stars at the incredible rate of about 2,000 a year.

“We’re looking at a younger phase in the life of these galaxies — an adolescent burst of activity that won’t last very long,” said Hai Fu of the University of California at Irvine, lead author of a new study describing the results.

ESA's Herschel telescope used liquid helium to keep cool while it observed heat from the early Universe — ESA’s Herschel telescope used liquid helium to keep cool while it observed heat from the early Universe

Hidden behind vast clouds of cosmic dust, it took the heat-seeking eyes of Herschel to even spot HXMM01.

“These merging galaxies are bursting with new stars and completely hidden by dust,” said co-author Asantha Cooray, also of the University of California at Irvine. “Without Herschel’s far-infrared detectors, we wouldn’t have been able to see through the dust to the action taking place behind.”

Herschel first spotted the colliding duo in images taken with longer-wavelength infrared light, as shown in the image above on the left side. Follow-up observations from many other telescopes helped determine the extreme degree of star-formation taking place in the merger, as well as its incredible mass.

The image at right shows a close-up view, with the merging galaxies circled. The red data are from the Smithsonian Astrophysical Observatory’s Submillimeter Array atop Mauna Kea, Hawaii, and show dust-enshrouded regions of star formation. The green data, taken by the National Radio Astronomy Observatory’s Very Large Array, near Socorro, N.M., show carbon monoxide gas in the galaxies. In addition, the blue shows starlight.

Although the galaxies in HXMM01 are producing thousands more new stars each year than our own Milky Way does, such a high star-formation rate is not sustainable. The gas reservoir contained in the system will be quickly exhausted, quenching further star formation and leading to an aging population of low-mass, cool, red stars — effectively “switching off” star formation, like what’s been witnessed in other early ellipticals.

Dr. Fu and his team estimate that it will take about 200 million years to convert all the gas into stars, with the merging process completed within a billion years. The final product will be a massive red and dead elliptical galaxy of about 400 billion solar masses.

The study is published in the May 22 online issue of Nature.

Read more on the ESA Herschel news release here, as well as on the NASA site here. Also, check out an animation of the galactic merger below:

Main image credit: ESA/NASA/JPL-Caltech/UC Irvine/STScI/Keck/NRAO/SAO

May 8, 2013December 23, 2015 by Tammy Plotner

Hydrogen Clouds Discovered Between Andromeda And Triangulum Galaxies

This combined graphic shows new, high-resolution GBT imaging (in box) of recently discovered hydrogen clouds between M31 (upper right) and M33 (bottom left). Credit: Bill Saxton, NRAO/AUI/NSF.

Score another point for the National Science Foundation’s Green Bank Telescope (GBT) at the National Radio Astronomy Observatory (NRAO) in Green Bank. They have opened our eyes – and ears – to previously undetected region of hydrogen gas clouds located in the area between the massive Andromeda and Triangulum galaxies. If researchers are correct, these dwarf galaxy-sized sectors of isolated gases may have originated from a huge store of heated, ionized gas… Gas which may be associated with elusive and invisible dark matter.

“We have known for some time that many seemingly empty stretches of the Universe contain vast but diffuse patches of hot, ionized hydrogen,” said Spencer Wolfe of West Virginia University in Morgantown. “Earlier observations of the area between M31 and M33 suggested the presence of colder, neutral hydrogen, but we couldn’t see any details to determine if it had a definitive structure or represented a new type of cosmic feature. Now, with high-resolution images from the GBT, we were able to detect discrete concentrations of neutral hydrogen emerging out of what was thought to be a mainly featureless field of gas.”

So how did astronomers detect the extremely faint signal which clued them to the presence of the gas pockets? Fortunately, our terrestrial radio telescopes are able to decipher the representative radio wavelength signals emitted by neutral atomic hydrogen. Even though it is commonplace in the Universe, it is still frail and not easy to observe. Researchers knew more than 10 years ago that these repositories of hydrogen might possibly exist in the empty space between M33 and M32, but the evidence was so slim that they couldn’t draw certain conclusions. They couldn’t “see” fine grained structure, nor could they positively identify where it came from and exactly what these accumulations meant. At best, their guess was it came from an interaction between the two galaxies and that gravitational pull formed a weak “bridge” between the two large galaxies.

The animation demonstrates the difference in resolution from the original Westerbork Radio Telescope data (Braun & Thilker, 2004) and the finer resolution imaging of GBT, which revealed the hydrogen clouds between M31 and M33. Bill Saxton, NRAO/AUI/NSF Credit: Bill Saxton, NRAO/AUI/NSF.

Just last year, the GBT observed the tell-tale fingerprint of hydrogen gas. It might be thin, but it is plentiful and it’s spread out between the galaxies. However, the observations didn’t stop there. More information was gathered and revealed the gas wasn’t just ethereal ribbons – but solid clumps. More than half of the gas was so conspicuously aggregated that they could even have passed themselves off as dwarf galaxies had they a population of stars. What’s more, the GBT also studied the proper motion of these gas pockets and found they were moving through space at roughly the same speed as the Andromeda and Triangulum galaxies.

“These observations suggest that they are independent entities and not the far-flung suburbs of either galaxy,” said Felix J. Lockman, an astronomer at the NRAO in Green Bank. “Their clustered orientation is equally compelling and may be the result of a filament of dark matter. The speculation is that a dark-matter filament, if it exists, could provide the gravitational scaffolding upon which clouds could condense from a surrounding field of hot gas.”

And where there is neutral hydrogen gas, there is fuel for new stars. Astronomers also recognize these new formations could eventually be drawn into M31 and M33, eliciting stellar creation. To add even more interest, these cold, dark regions which exist between galaxies contain a large amount of “unaccounted-for normal matter” – perhaps a clue to dark matter riddle and the reason behind the amount of hydrogen yet to revealed in universal structure.

“The region we have studied is only a fraction of the area around M31 reported to have diffuse hydrogen gas,” said D.J. Pisano of West Virginia University. “The clouds observed here may be just the tip of a larger population out there waiting to be discovered.”

Original Story Source: National Radio Astronomy Observatory News Release.

May 1, 2013December 23, 2015 by Tammy Plotner

NGC 6240: Gigantic Hot Gas Cloud Sheaths Colliding Galaxies

Credit: X-ray (NASA/CXC/SAO/E.Nardini et al); Optical (NASA/STScI)

Looking almost like a cosmic hyacinth, this image is anything but a cool, Spring flower… it’s a portrait of an enormous gas cloud radiating at more than seven million degrees Kelvin and enveloping two merging spiral galaxies. This combined image glows in purple from the Chandra X-ray information and is embellished with optical sets from the Hubble Space Telescope. It flows across 300,000 light years of space and contains the mass of ten billion Suns. Where did it come from? Researchers theorize it was caused by a rush of star formation which may have lasted as long as 200 million years.

What we’re looking at is known in astronomical terms as a “halo” – a glorious crown which is located in a galactic system cataloged as NGC 6240. This is the site of an interacting set of of spiral galaxies which have a close resemblance to our own Milky Way – each with a supermassive black hole for a heart. It is surmised the black holes are headed towards each other and may one day combine to create an even more incredible black hole.

However, that’s not all this image reveals. Not only is this pair of galaxies combining, but the very act of their mating has caused the collective gases to be “violently stirred up”. The action has caused an eruption of starbirth which may have stretched across a period of at least 200 million years. This wasn’t a quiet event… During that time, the most massive of the stars fled the stellar nursery, evolving at a rapid pace and blowing out as supernovae events. According to the news release, the astronomers who studied this system argue that the rapid pace of the supernovae may have expelled copious quantities of significant elements such as oxygen, neon, magnesium and silicon into the gaseous envelope created by the galactic interaction. Their findings show this enriched gas may have expanded into and combined with the already present cooler gas.

Now, enter a long time frame. While there was an extensive era of star formation, there may have been more dramatic, shorter bursts of stellar creation. “For example, the most recent burst of star formation lasted for about five million years and occurred about 20 million years ago in Earth’s time frame.” say the paper’s authors. However, they are also quick to point out that the quick thrusts of star formation may not have been the sole producer of the hot gases.

Perhaps one day these two interactive spiral galaxies will finish their performance… ending up as rich, young elliptical galaxy. It’s an act which will take millions of years to complete. Will the gas hang around – or will it be lost in space? No matter what the final answer is, the image gives us a first-hand opportunity to observe an event which dominated the early Universe. It was a time “when galaxies were much closer together and merged more often.”

Original Story Source: Chandra X-Ray Observatory News Release.

April 25, 2013April 26, 2016 by Tammy Plotner

Entire Galaxies Feel The Heat Of Newborn Stars

This illustration shows a messy, chaotic galaxy undergoing bursts of star formation. This star formation is intense; it was known that it affects its host galaxy, but this new research shows it has an even greater effect than first thought. The winds created by these star formation processes stream out of the galaxy, ionising gas at distances of up to 650 000 light-years from the galactic centre. Credit: ESA, NASA, L. Calçada

If you think that star-formation only has an impact within the confines of a host galaxy, then think again. Thanks to the magic of the NASA/ESA Hubble Space Telescope, astronomers are now realizing starburst activity can change the properties of galactic gases at distances almost twenty times larger than a galaxy’s visible boundaries. Not only does this affect galactic evolution, but it has ramifications on how matter and energy ripple across the cosmos.

What’s going on here? Once upon a time in the early Universe, galaxies would form new stars in huge blasts of activity known as starbursts. While it happened frequently long ago, it’s much less common now. During these starburst episodes, hundreds of millions of stars spring to light and their combined energy sets off massive stellar winds that push outward into space. While these winds were known to have effects on the parent galaxy, new research shows they have an even greater effect than anyone knew.

Recently a team of international astronomers took on twenty galaxies which are known to be hosting starburst activity. What they found was the starburst stellar winds were able to ionize gas at huge distances – up to 650,000 light years from the galaxy’s nucleus – and around twenty times beyond the galaxy’s visible perimeter. For the first time, researchers were able to verify that starburst activity could impact the gas around the parent galaxy. This new observational evidence shows just how important each phase a galaxy goes through can impact the way it form stars and how it evolves.

“The extended material around galaxies is hard to study, as it’s so faint,” says team member Vivienne Wild of the University of St. Andrews. “But it’s important — these envelopes of cool gas hold vital clues about how galaxies grow, process mass and energy, and finally die. We’re exploring a new frontier in galaxy evolution!”

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This animation shows the method used to probe the gas around distant galaxies. Astronomers can use tools such as Hubble’s Cosmic Origins Spectrograph (COS) to probe faint galactic envelopes by exploiting even more distant objects — quasars, the intensely luminous centres of distant galaxies powered by huge black holes. As the light from the distant quasar passes through the galaxy’s halo, the gas absorbs certain frequencies – making it possible to study the region around the galaxy in detail. This new research utilised Hubble’s COS to peer through the very thin outskirts of galactic halos, much further out than shown in this representation, to explore galactic gas at distances of up to twenty times greater than the visible size of the galaxy itself. Credit: ESA, NASA, L. Calçada

So how did they do it? According to the news release, the researchers employed the Cosmic Origins Spectrograph (COS) instrument located on the NASA/ESA Hubble Space telescope. By examining the spectral signature of a variety of starbirth and control galaxies, the team was able to carefully examine the regions of gas surrounding the galaxies. However, they had a little boost, too… quasars. By adding the light of the intensely luminous galactic cores to the mix, they were able to further refine their observations by watching the quasar’s light as it passed through foreground galaxies. This method allowed them to even more closely examine their targets.

“Hubble is the only observatory that can carry out the observations necessary for a study like this,” says lead author Sanchayeeta Borthakur, of Johns Hopkins University. “We needed a space-based telescope to probe the hot gas, and the only instrument capable of measuring the extended envelopes of galaxies is COS.”

The eureka moment came when the astronomers found the starburst galaxies in their samples showed abnormal amounts of highly ionized gases in their halos. By comparison, the control galaxies – those known to have no starburst activity – did not. Now they knew… the ionization had to be the product of the energetic winds which accompanied the birth of new stars. Armed with this information, researchers can now confidently say that galaxies which host starburst activity has taken on new parameters. Since galaxies enlarge by feeding on gas from the space around them and convert this into new stars, we realize that the ionization process will regulate future star formation.

“Starbursts are important phenomena — they not only dictate the future evolution of a single galaxy, but also influence the cycle of matter and energy in the Universe as a whole,” says team member Timothy Heckman, of Johns Hopkins University. “The envelopes of galaxies are the interface between galaxies and the rest of the Universe — and we’re just beginning to fully explore the processes at work within them.”

Burn, baby, burn…

Original Story Source: NASA/ESA Hubble Space Telescope News Release. Further reading: The Impact of Starbursts on the Circumgalactic Medium.

April 18, 2013December 23, 2015 by Tammy Plotner

Fast Working ALMA Resolves Star-Forming Galaxies

A team of astronomers has used ALMA (the Atacama Large Millimeter/submillimeter Array) to pinpoint the locations of over 100 of the most fertile star-forming galaxies in the early Universe. Credit:: ALMA (ESO/NAOJ/NRAO), J. Hodge et al., A. Weiss et al., NASA Spitzer Science Center

In a scenario where millions of years are considered a short period of time, hours are barely a blink of an eye. While it might take ten years or more to observe a group of galaxies with a modicum of detail for telescopes around the world, the Atcama Large Millimeter/submillimeter Array (ALMA) telescope was able to do the job at amazing speed. In just a matter of hours, a team of astronomers using this super-powerful telescope homed in on the location of over a hundred star-forming galaxies in the early Universe.

Once upon a time, huge amounts of star birth occurred in early galaxies which were rich in cosmic dust. Studying these galaxies is imperative to our understanding of galactic formation and evolution – but it has proved difficult in visible light because the very dust which supports star formation also cloaks the galaxies in which they are formed. However, thanks to telescopes like ALMA, we’re able to identify and observe these galaxies by focusing on longer wavelengths. Light that comes in around one millimetre is the perfect playground for such study.

“Astronomers have waited for data like this for over a decade. ALMA is so powerful that it has revolutionised the way that we can observe these galaxies, even though the telescope was not fully completed at the time of the observations,” said Jacqueline Hodge (Max-Planck-Institut für Astronomie, Germany), lead author of the paper presenting the ALMA observations.

Just how do we know where these galaxies are located? Through the use of the ESO-operated Atacama Pathfinder Experiment telescope (APEX), astronomers were able to map these dust obscured targets to a certain degree. APEX focused its capabilities on an area of sky about the size of the full Moon in the constellation of Fornax. The study – Chandra Deep Field South – has been taken on by a variety of telescopes located both here on Earth and in space. Here is where APEX has been credited with locating 126 dusty galaxies. However, these images aren’t all they could be. Star forming areas appeared as blobs and sometimes could over-ride better images made at other wavelengths. Through the use of ALMA, these observations have been augmented, furthering the resolution in the millimetre/submillimetre portion of the spectrum and assisting astronomers in knowing precisely which galaxies are forming stars.

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This video sequence starts with a broad view of the sky, including the famous constellation of Orion (The Hunter). We gradually close in on an unremarkable patch of sky called the Chandra Deep Field South that has been studied by many telescopes on the ground and in space. Credit: ALMA (ESO/NAOJ/NRAO), APEX (MPIfR/ESO/OSO), J. Hodge et al., A. Weiss et al., NASA Spitzer Science Center, Digitized Sky Survey 2, and A. Fujii. Music: Movetwo

As all backyard astronomers know, the larger the aperture – the better the resolution. To improve their observations of the early Universe, astronomers needed a bigger telescope. APEX consists of a twelve meter diameter dish-shaped antenna, but ALMA consists of many dishes spread over long distances. The signals from all of its parts are then combined and the result is the same as if it were a giant telescope which measured the same size as the entire array. A super dish!

With the assistance of ALMA, the astronomers then took on the galaxies from the APEX map. Even though the ALMA array is still under construction and using less than a quarter of its capabilities, the team was able to complete this beginning phase of scientific observations. Speedy ALMA was up to the task. At only two minutes per galaxy, this “Super Scope” was able to resolve each one within a minuscule area two hundred times smaller than the original APEX blobs… and with 300% more sensitivity! With a track record like that, ALMA was able to double the number of observations in a matter of hours. Now the researchers were able to clearly see which galaxies contained active star forming regions and distinguish cases where multiple star-forming galaxies had melded to appear as one in earlier studies.

“We previously thought the brightest of these galaxies were forming stars a thousand times more vigorously than our own galaxy, the Milky Way, putting them at risk of blowing themselves apart. The ALMA images revealed multiple, smaller galaxies forming stars at somewhat more reasonable rates,” said Alexander Karim (Durham University, United Kingdom), a member of the team and lead author of a companion paper on this work.

Apparently ALMA is going to be a huge success. These new observations have helped to confidently document dusty star-forming galaxies from the early Universe and help to create a more detailed catalog than ever before. These new findings will assist future astronomical observations by giving researchers a reliable base on these galaxies’ properties at different wavelengths. No longer will astronomers have to “guess” at which galaxies may have melded together in images… ALMA has made it clear. However, don’t rule out the use of other venues such as APEX. The combination of both play a powerful part in observing the early Universe.

“APEX can cover a wide area of the sky faster than ALMA, and so it’s ideal for discovering these galaxies. Once we know where to look, we can use ALMA to locate them exactly,” concluded Ian Smail (Durham University, United Kingdom), co-author of the new paper.

Original Story Source: ESO Science News Release.

April 17, 2013December 23, 2015 by Nancy Atkinson

Ancient Galaxy ‘Bursting’ with Stars

The galaxy HFLS3 appears as a small red dot in these Herschel submillimeter images (main image, and panels on right). Subsequent observations with ground-based telescopes, ranging from optical to millimeter wavelengths (insets), revealed two galaxies appearing very close together. The two are actually at very different distances, however, and HFLS3 (blue, in millimeter wavelengths) is so far away that we are seeing it as it was when the universe was just 880 million years old. Credit: ESA/Herschel/HerMES/IRAM/GTC/W.M. Keck Observatory.

Most of the early galaxies that astronomers have been able to observe are small with a low-to-moderate amount of star production. But now the Herschel Space Observatory has found a massive dust-filled galaxy churning out stars at an incredible rate, with all of this taking place back when the cosmos was a just 880 million years old. The galaxy is about as massive as our Milky Way, but produces stars at a rate 2,000 times greater, prompting the researchers to call it a “maximum-starburst” galaxy.

The astronomers involved in its discovery say its mere existence challenges our theories of galaxy evolution.

“Massive, intense starburst galaxies are expected to only appear at later cosmic times,” says Dominik Riechers, currently an assistant professor at Cornell. “Yet, we have discovered this colossal starburst just 880 million years after the Big Bang, when the universe was at little more than 6 percent of its current age. Riechers is the first author of the paper describing the findings in the April 18 issue of the journal Nature.

The prevailing thought on early galaxy and star formation has been that the first galaxies to form were relatively small and lightweight, containing only a few billion times the mass of our Sun. They form their first stars at rates of a few times that experienced by the Milky Way today, and the galaxies would grow by merging with other small galaxies. In theory, galaxies as massive as the newly found galaxy – named HFLS3 — should not be present so soon after the Big Bang.

HFLS3 appears as little more than a faint, red smudge in images from the Herschel Multi-tiered Extragalactic Survey (HerMES).
The extreme distance to HFLS3 means that its light has travelled for almost 13 billion years across space before reaching us. We therefore see it as it existed in the infant Universe, just 880 million years after the Big Bang or at 6.5% of the Universe’s current age.

This artist's impression shows the "starburst" galaxy HFLS3. The galaxy appears as little more than a faint, red smudge in images from the Herschel space observatory. Image credit: ESA-C. Carreau. — This artist’s impression shows the “starburst” galaxy HFLS3. The galaxy appears as little more than a faint, red smudge in images from the Herschel space observatory. Image credit: ESA-C. Carreau.

Even at that young age, HFLS3 was already close to the mass of the Milky Way, with roughly 140 billion times the mass of the Sun in the form of stars and star-forming material. After another 13 billion years, it should have grown to be as big as the most massive galaxies known in the local Universe.

“Looking for the first examples of these massive star factories is like searching for a needle in a haystack; the Herschel dataset is extremely rich,” said Riechers.

Tens of thousands of massive, star-forming galaxies have been detected by Herschel as part of HerMES and sifting through them to find the most interesting ones is a challenge.

“This particular galaxy got our attention because it was bright, and yet very red compared to others like it,” said co-investigator Dave Clements of Imperial College London.

While the discovery of this single galaxy isn’t enough to overturn current theories of galaxy formation, finding more galaxies like this one could challenge those theories, the astronomers say. At the very least, theories will have to be modified to explain how this galaxy formed, Riechers says.

“This galaxy is just one spectacular example, but it’s telling us that extremely vigorous star formation was possible early in the universe,” says Jamie Bock, professor of physics at Caltech and a coauthor of the paper.

Read the team’s paper: A Dust-Obscured Massive Maximum-Starburst Galaxy at a Redshift of 6.34

Sources: ESA, JPL, Caltech

April 3, 2013December 23, 2015 by Tammy Plotner

Wrapping Around The Mystery Of Spiral Galaxy Arms

Credit: Thiago Ize & Chris Johnson (Scientific Computing and Imaging Institute)

How disk galaxies form their spiral arms have been puzzling astrophysicists for almost as long as they have been observing them. With time, they have come to two conclusions… either this structure is caused by differences in gravity sculpting the gas, dust and stars into this familiar shape, or its just a random occurrence which comes and goes with time.

Now researchers are beginning to wrap their conclusions around findings based on new supercomputer simulations – simulations which involve the motion of up to 100 million “stellar particles” that mimic gravitational and astrophysical forces which shape them into natural spiral structure. The research team from the University of Wisconsin-Madison and the Harvard-Smithsonian Center for Astrophysics are excited about these conclusions and report the simulations may hold the essential clues of how spiral arms are formed.

“We show for the first time that stellar spiral arms are not transient features, as claimed for several decades,” says UW-Madison astrophysicist Elena D’Onghia, who led the new research along with Harvard colleagues Mark Vogelsberger and Lars Hernquist.

“The spiral arms are self-perpetuating, persistent, and surprisingly long lived,” adds Vogelsberger.

When it comes to spiral structure, it’s probably the most widely occurring of universal shapes. Our own Milky Way galaxy is considered to be a spiral galaxy and around 70% of the galaxies near to us are also spiral structured. When we think in a broader sense, just how many things take on this common formation? Whisking up dust with a broom causes particles to swirl into a spiral shape… draining water invokes a swirling pattern… weather formations go spiral. It’s a universal happening and it happens for a reason. Apparently that reason is gravity and something to perturb it. In the case of a galaxy, it’s a giant molecular cloud – the star-forming regions. Introduced into the simulation, the clouds, says D’Onghia, a UW-Madison professor of astronomy, act as “perturbers” and are enough to not only initiate the formation of spiral arms but to sustain them indefinitely.

“We find they are forming spiral arms,” explains D’Onghia. “Past theory held the arms would go away with the perturbations removed, but we see that (once formed) the arms self-perpetuate, even when the perturbations are removed. It proves that once the arms are generated through these clouds, they can exist on their own through (the influence of) gravity, even in the extreme when the perturbations are no longer there.”

So, what of companion galaxies? Can spiral structure be caused by proximity? The new research also takes that into account and models for “stand alone” galaxies as well. However, that’s not all the study included. According to Vogelsberger and Hernquist, the new computer-generated simulations are focusing on clarifying observational data. They are taking a closer look at the high-density molecular clouds and the “gravitationally induced holes in space” which act as ” the mechanisms that drive the formation of the characteristic arms of spiral galaxies.”

Until then, we know spiral structure isn’t just a chance happening and – to wrap things up – it’s probably the most common form of galaxy in our Universe.

Original Story Source: Harvard-Smithsonian Center for Astrophysics.

April 3, 2013December 23, 2015 by Jason Major

How Big Are Galaxies?

Galaxy size comparison chart by astrophysicist Rhys Taylor

I’m going to refrain from the initial response that comes to mind… actually, no I won’t — they’re really, really, really big!!!!

</Kermit arms>

Ok, now that that’s out of the way check out this graphic by Arecibo astrophysicist Rhys Taylor, which neatly illustrates the relative sizes of 25 selected galaxies using images made from NASA and ESA observation missions… including a rendering of our own surprisingly mundane Milky Way at the center for comparison. (Warning: this chart may adversely affect any feelings of bigness you may have once held dear.) According to Taylor on his personal blog, Physicists of the Caribbean (because he ~~works~~ had worked at the Arecibo Observatory in Puerto Rico) “Type in ‘asteroid sizes’ into Google and you’ll quickly find a bunch of images comparing various asteroids, putting them all next to each at the same scale. The same goes for planets and stars. Yet the results for galaxies are useless. Not only do you not get any size comparisons, but scroll down even just a page and you get images of smartphones, for crying out loud.” So to remedy that marked dearth of galactic comparisons, Taylor made his own. Which, if you share my personal aesthetics, you’ll agree is quite nicely done.

“I tried to get a nice selection of well-known, interesting objects,” Taylor explains. “I was also a little limited in that I needed high-resolution images which completely mapped the full extent of each object… still, I think the final selection has a decent mix, and I reckon it was a productive use of a Saturday.” And even with the dramatic comparisons above, Taylor wasn’t able to accurately portray to scale one of the biggest — if not the biggest — galaxies in the observable universe: IC 1101.

For an idea of how we measure up to that behemoth, he made this graphic:

Galaxy sizes including IC 1101, the largest-known galaxy. Click for a zoomable version. (Credit: Rhys Taylor)

That big bright blur in the center? That’s IC 1101, the largest known galaxy — in this instance created by scaling up an image of M87, another supersized elliptical galaxy that just happens to be considerably closer to our own (and thus has had clearer images taken of it.) But the size is right — IC 1101 is gargantuan.

At an estimated 5.5 million light-years wide, over 50 Milky Ways could fit across it! And considering it takes our Solar System about 225 million years to complete a single revolution around the Milky Way… well… yeah. Galaxies are big. Really, really, really, really big!

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Now if you’ll pardon me, I need to go stop my head from spinning… Read this and more on Rhys Taylor’s blog here, and add Rhys to your awesome astronomy Google+ circles here. And you can find out more about IC 1101 in the video below from Tony Darnell, aka DeepAstronomy: