Posted on by Tammy Plotner

Ain’t Misbehavin’ – Turbulence, Solar Flares and Magnetism

In this image, the Solar Dynamics Observatory (SDO) captured an X1.2 class solar flare, peaking on May 15, 2013. Credit: NASA/SDO
In this image, the Solar Dynamics Observatory (SDO) captured an X1.2 class solar flare, peaking on May 15, 2013. Credit: NASA/SDO

What’s more fun than something that misbehaves? When it comes to solar dynamics, we know a lot, but there are many things we don’t yet understand. For example, when a particle filled solar flare lashes out from the Sun, its magnetic field lines can do some pretty unexpected things – like split apart and then rapidly reconnect. According to the flux-freezing theorem, these magnetic lines should simply “flow away in lock-step” with the particles. They should stay intact, but they don’t. It’s not just a simple rule they break… it’s a law of physics.

What can explain it? In a paper published in the May 23 issue of “Nature”, an interdisciplinary research team led by a Johns Hopkins mathematical physicist may just have found a plausible explanation. According to the group, the underlying factor is turbulence – the “same sort of violent disorder that can jostle a passenger jet when it occurs in the atmosphere” – or the one your brother leaves behind after he’s eaten baked beans. By employing a well-organized and logically constructed computer modeling technique, the researchers were able to simulate what happens when magnetic field lines meet up with turbulence in a solar flare. Armed with this information, they were then able to state their case.

“The flux-freezing theorem often explains things beautifully,” said Gregory Eyink, a Department of Applied Mathematics and Statistics professor who was lead author of the “Nature” study. “But in other instances, it fails miserably. We wanted to figure out why this failure occurs.”

Just what is the flux-freezing theorem? Maybe you’ve heard of Hannes Alfvén. He was a Swedish electrical engineer, plasma physicist and winner of the 1970 Nobel Prize in Physics for his work on magnetohydrodynamics (MHD). He’s the man responsible for explaining what we now know as Alfvén waves – a low-frequency travelling oscillation of the ions and the magnetic field in plasma. Well, some 70 years ago, he came up with the thought that magnetic lines of force sail along a locomotive fluid similar to snippets of thread flowing along a stream. It should be impossible for them to break and then join again. However, solar physicists have discovered this just isn’t the case when it comes to activity within a particularly violent solar flare. In their observations, they have determined that the magnetic field lines within these flares can stretch to the breaking point and then reconnect in a surprisingly quick amount of time – as little as 15 minutes. When this happens, it expels a copious amount of energy which, in turn, powers the flare.

“But the flux-freezing principle of modern plasma physics implies that this process in the solar corona should take a million years!” Eyink animatedly states. “A big problem in astrophysics is that no one could explain why flux-freezing works in some cases but not others.”

Of course, there has always been speculation that turbulence may have been the root source of the enigmatic behavior. Time for investigation? You bet. Eyink then joined forces – and minds – with other experts in astrophysics, mechanical engineering, data management and computer science, based at Johns Hopkins and other institutions. “By necessity, this was a highly collaborative effort,” Eyink said. “Everyone was contributing their expertise. No one person could have accomplished this.”

Gregory Eyink, professor of applied mathematics and statistics at Johns Hopkins. Photo by Nat Creamer.
Gregory Eyink, professor of applied mathematics and statistics at Johns Hopkins. Photo by Nat Creamer.
The next step was to create a computer simulation – a simulation which could duplicate the plasma state of solar flare activity and all the nuances the charged particles undergo during different conditions. “Our answer was very surprising,” stated Eyink. “Magnetic flux-freezing no longer holds true when the plasma becomes turbulent. Most physicists expected that flux-freezing would play an even larger role as the plasma became more highly conducting and more turbulent, but, as a matter of fact, it breaks down completely. In an even greater surprise, we found that the motion of the magnetic field lines becomes completely random. I do not mean ‘chaotic,’ but instead as unpredictable as quantum mechanics. Rather than flowing in an orderly, deterministic fashion, the magnetic field lines instead spread out like a roiling plume of smoke.”

Of course, other solar experts feel there may be alternative answers for this rule-breaking activity within solar flares, but as Eyink says, “I think we made a pretty compelling case that turbulence alone can account for field-line breaking.”

What is most exciting is the collaborative effort of the team members from such widely varied disciplines. It was a group effort which aided Eyink to come up with this new theory on the solar flare riddle. “We used ground-breaking new database methods, like those employed in the Sloan Digital Sky Survey, combined with high-performance computing techniques and original mathematical developments,” he said. “The work required a perfect marriage of physics, mathematics and computer science to develop a fundamentally new approach to performing research with very large datasets.”

In conclusion, Eyink noted this type of research work may very well give us a better understanding of solar flares and coronal mass ejections. As we know, this type of dangerous “space weather” can be harmful to astronauts, disrupt communications satellites, and even be responsible for the shut-down of electrical power grids on Earth. And you know what that means… no satellite TV and no power to watch it by. But, that’s O.K.

“I don’t stay out late. Don’t care to go. I’m home about eight… Just me and my radio. Ain’t misbehavin’.. Savin’ my love for you.”

Original Story Source: Johns Hopkins University News Release.

Posted on by Tammy Plotner

Orion’s Secret Fire Dance

In this image, the submillimetre-wavelength glow of dust clouds in the Orion A nebula is overlaid on a view of the region in the more familiar visible light, from the Digitized Sky Survey 2. The large bright cloud in the upper right of the image is the well-known Orion Nebula, also called Messier 42. Credit: ESO/Digitized Sky Survey 2

The Great Orion Nebula has captivated observers for at least four hundred years, but the ancient Mayans may have known about its secrets long before then. According to legend, the nebula might have been the smoke situated between the “Three Hearthstones” and the light of the emerging stars seen as the very embers of creation itself. Now the ESO-operated Atacama Pathfinder Experiment (APEX) in Chile has revealed what we cannot see. At wavelengths too long for human vision, this new image shows us an ancient fire dance painted in colors of cold interstellar dust.

As we know, deposits of gas and interstellar dust are virtual star factories. However, the very material which creates stars also masks them. So how do we peer behind the veil? The answer is to observe at alternative wavelengths of light. In this case, the submillimetre wavelength reveals what our eyes cannot see… dust grains igniting the view, even though they are just a few tens of degrees above absolute zero. This makes the APEX telescope with its submillimetre-wavelength camera LABOCA, located at an altitude of 5000 metres above sea level on the Chajnantor Plateau in the Chilean Andes, the perfect instrument to play the tune for this cold fire dance.

Take a look around the picture. It’s just a small portion of a vast complex known as the Orion Molecular Cloud. Wafting across hundreds of light years space some 1350 light years away, this rich arena of hot young stars, cold dust clouds and bright nebula is the epitome of stellar creation. The image reveals the submillimetre-wavelength glow in shades of orange and it is combined with visible light for a total visual experience. Note deep ribbons, sheets and bubbles… These are the product of gravitational collapse and the effects of stellar winds. Powerful stellar processes are at work here. The atmospheres of the stars are crafting the clouds much the same way a gentle breeze swirls the smoke from a fire.

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Credit: ESO/Nick Risinger (skysurvey.org), Digitized Sky Survey 2. Music: movetwo

As beautiful as it is, there is still science behind the imagery. Astronomers have employed the data taken with ESA’s Herschel Space Observatory, along with the APEX information, to aid them in their search for early star formation. At this point in time, the researchers have been able to verify more than a dozen candidate protostars – objects which appear far brighter at longer wavelengths rather than short. It’s a triumph for the researchers. These new observations could well be the youngest protostars so far observed and it brings astronomers just one step closer to witnessing the moment when a star ignites.

Original Story Source: ESO News Release.

Posted on by Tammy Plotner

Hubble Observes Planet-“Polluted” Dead Stars In Hyades

Artist Impression of debris around a white dwarf star. Image credit: NASA, ESA, STScI, and G. Bacon (STScI)

For those of us who practice amateur astronomy, we’re very familiar with the 150 light-year distant Hyades star cluster – one of the jewels in the Taurus crown. We’ve looked at it countless times, but now the NASA/ESA Hubble Space Telescope has taken its turn observing and spotted something astronomers weren’t expecting – the debris of Earth-like planets orbiting white dwarf stars. Are these “burn outs” being polluted by detritus similar to asteroids? According to researchers, this new observation could mean that rocky planet creation is commonplace in star clusters.

“We have identified chemical evidence for the building blocks of rocky planets,” said Jay Farihi of the University of Cambridge in England. He is lead author of a new study appearing in the Monthly Notices of the Royal Astronomical Society. “When these stars were born, they built planets, and there’s a good chance they currently retain some of them. The material we are seeing is evidence of this. The debris is at least as rocky as the most primitive terrestrial bodies in our solar system.”

So what makes this an uncommon occurrence? Research tells us that all stars are formed in clusters, and we know that planets form around stars. However, the equation doesn’t go hand in hand. Out of the hundreds of known exoplanets, only four are known to have homes in star clusters. As a matter of fact, that number is a meager half percent, but why? As a rule, the stars contained within a cluster are young and active. They are busy producing stellar flares and similar brilliant activity which may mask signs of emerging planets. This new research is looking to the “older” members of the cluster stars – the grandparents which may be babysitting.

To locate possible candidates, astronomers have employed Hubble’s Cosmic Origins Spectrograph and focused on two white dwarf stars. Their return showed evidence of silicon and just slight levels of carbon in their atmospheres. This observation was important because silicon is key in rocky materials – a prime ingredient on Earth’s list and other similar solid planets. This silicon signature may have come from the disintegration of asteroids as they wandered too close to the stars and were torn apart. A lack of carbon is equally exciting because, while it helps shape the properties and origins of planetary debris, it becomes scarce when rocky planets are formed. This material may have formed a torus around the defunct stars which then drew the matter towards them.

“We have identified chemical evidence for the building blocks of rocky planets,” said Farihi. “When these stars were born, they built planets, and there’s a good chance they currently retain some of them. The material we are seeing is evidence of this. The debris is at least as rocky as the most primitive terrestrial bodies in our solar system.”

Ring around the rosie? You bet. This leftover material swirling around the white dwarf stars could mean that planet formation happened almost simultaneously as the stars were born. At their collapse, the surviving gas giants may have had the gravitational “push” to relocate asteroid-like bodies into “star-grazing orbits”.

This image shows the region around the Hyades star cluster, the nearest open cluster to us. The Hyades cluster is very well-studied due to its location, but previous searches for planets have produced only one. A new study led by Jay Farihi of the University of Cambridge, UK, has now found the atmospheres of two burnt-out stars in this cluster — known as white dwarfs — to be “polluted” by rocky debris circling the star. Inset, the locations of these white dwarf stars are indicated — stars known as WD 0421+162, and WD 0431+126. Credit: NASA, ESA, STScI, and Z. Levay (STScI)
This image shows the region around the Hyades star cluster, the nearest open cluster to us. The Hyades cluster is very well-studied due to its location, but previous searches for planets have produced only one. A new study led by Jay Farihi of the University of Cambridge, UK, has now found the atmospheres of two burnt-out stars in this cluster — known as white dwarfs — to be “polluted” by rocky debris circling the star.
Inset, the locations of these white dwarf stars are indicated — stars known as WD 0421+162, and WD 0431+126. Credit: NASA, ESA, STScI, and Z. Levay (STScI)

“We have identified chemical evidence for the building blocks of rocky planets,” explains Farihi. “When these stars were born, they built planets, and there’s a good chance that they currently retain some of them. The signs of rocky debris we are seeing are evidence of this — it is at least as rocky as the most primitive terrestrial bodies in our Solar System. The one thing the white dwarf pollution technique gives us that we won’t get with any other planet detection technique is the chemistry of solid planets. Based on the silicon-to-carbon ratio in our study, for example, we can actually say that this material is basically Earth-like.”

What of future plans? According to Farihi and the research team, by continuing to observe with methods like those employed by Hubble, they can take an even deeper look at the atmospheres around white dwarf stars. They will be searching for signs of solid planet “pollution” – exploring the white dwarf chemistry and analyzing stellar composition. Right now, the two “polluted” Hyades white dwarfs are just a small segment of more than a hundred future candidates which will be studied by a team led by Boris Gansicke of the University of Warwick in England. Team member Detlev Koester of the University of Kiel in Germany is also contributing by using sophisticated computer models of white dwarf atmospheres to determine the abundances of various elements that can be traced to planets in the Hubble spectrograph data.

“Normally, white dwarfs are like blank pieces of paper, containing only the light elements hydrogen and helium,” Farihi said. “Heavy elements like silicon and carbon sink to the core. The one thing the white dwarf pollution technique gives us that we just won’t get with any other planet-detection technique is the chemistry of solid planets.”

The team also plans to look deeper into the stellar composition as well. “The beauty of this technique is that whatever the Universe is doing, we’ll be able to measure it,” Farihi said. “We have been using the Solar System as a kind of map, but we don’t know what the rest of the Universe does. Hopefully with Hubble and its powerful ultraviolet-light spectrograph COS, and with the upcoming ground-based 30- and 40-metre telescopes, we’ll be able to tell more of the story.”

And we’ll be listening…

Original Story Source: Hubble News Release.

Posted on 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.

Posted on by Tammy Plotner

Anarchic Star Formation Found In Dust Cloud

The Danish 1.54-metre telescope located at ESO’s La Silla Observatory in Chile has captured a striking image of NGC 6559, an object that showcases the anarchy that reigns when stars form inside an interstellar cloud. Credit: ESO

If you think that breaking all the rules is cool, then you’ll appreciate one of the latest observations submitted by the Danish 1.54 meter telescope housed at ESO’s La Silla Observatory in Chile. In this thought-provoking image, you’ll see what kind of mayhem occurs when stars are forged within an interstellar nebula.

Towards the center of the Milky Way in the direction of the constellation of Sagittarius, and approximately 5000 light-years from our solar system, an expansive cloud of gas and dust await. By comparison with other nebulae in the region, this small patch of cosmic fog known as NGC 6559 isn’t as splashy as its nearby companion nebula – the Lagoon (Messier 8). Maybe you’ve seen it with your own eyes and maybe you haven’t. Either way, it is now coming to light for all of us in this incredible image.

Comprised of mainly hydrogen, this ethereal mist is the perfect breeding ground for stellar creation. As areas contained within the cloud gather enough matter, they collapse upon themselves to form new stars. These neophyte stellar objects then energize the surrounding hydrogen gas which remains around them, releasing huge amounts of high energy ultraviolet light. However, it doesn’t stop there. The hydrogen atoms then merge into the mix, creating helium atoms whose energy causes the stars to shine. Brilliant? You bet. The gas then re-emits the energy and something amazing happens… an emission nebula is created.

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This zoom starts with a broad view of the Milky Way. We head in towards the centre, where stars and the pink regions marking star formation nurseries are concentrated. We see the huge gas cloud of the Lagoon Nebula (Messier 8) but finally settle on the smaller nebula NGC 6559. The colourful closing image comes from the Danish 1.54-metre telescope located at ESO’s La Silla Observatory in Chile. Credit: ESO/Nick Risinger (skysurvey.org)/S. Guisard. Music: movetwo

In the center of the image, you can see the vibrant red ribbon of the emission nebula, but that’s not the only thing contained within NGC 6559. Here swarms of solid dust particles also exist. Consisting of tiny bits of heavier elements, such as carbon, iron and silicon, these minute “mirrors” scatter the light in multiple directions. This action causes NGC 6559 to be something more than it first appears to be… now it is also a reflection nebula. It appears to be blue thanks to the magic of a principle known as Rayleigh scattering – where the light is projected more efficiently in shorter wavelengths.

Don’t stop there. NGC 6559 has a dark side, too. Contained within the cloud are sectors where dust totally obscures the light being projected behind them. In the image, these appear as bruises and dark veins seen to the bottom left-hand side and right-hand side. In order to observe what they cloak, astronomers require the use of longer wavelengths of light – ones which wouldn’t be absorbed. If you look closely, you’ll also see a myriad of saffron stars, their coloration and magnitude also effected by the maelstrom of dust.

It’s an incredible portrait of the bedlam which exists inside this very unusual interstellar cloud…

Original Story Source: ESO News Release.

Posted on 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.

Posted on 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.

Posted on by Tammy Plotner

Bright Blazar’s Emission Defies Explanations

Artist's concept of the Hubble Space Telescope viewing ultraviolet light from the jet of the active galactic nucleus of PKS 1424+240. Clouds of hydrogen gas along the line of sight absorb the light at known frequencies, allowing the redshift and distance of each cloud to be determined. The most distant gas cloud determines the minimum distance to PKS 1424+240. Data from the Fermi Gamma-ray Space Telescope, shown on the horizon at the left, were also used for this study. (Image composition by Nina McCurdy, component images courtesy of NASA)

When it comes to sheer wattage, blazars definitely rule. As the brightest of active galactic nuclei, these sources of extreme high-energy gamma rays are usually associated with relativistic jets of material spewing into space and enabled by matter falling into a host galaxy’s black hole. The further away they are, the dimmer they should be, right? Not necessarily. According to new observations of blazar PKS 1424+240, the emission spectrum might hold a new twist… one that can’t be readily explained.

David Williams, adjunct professor of physics at UC Santa Cruz, said the findings may indicate something new about the emission mechanisms of blazars, the extragalactic background light, or the propagation of gamma-ray photons over long distances. “There may be something going on in the emission mechanisms of the blazar that we don’t understand,” Williams said. “There are more exotic explanations as well, but it may be premature to speculate at this point.”

The Fermi Gamma-ray Space Telescope was the first instrument to detect gamma rays from PKS 1424+240, and the observation was then seconded by VERITAS (Very Energetic Radiation Imaging Telescope Array System) – a terrestrially based tool designed to be sensitive to gamma-rays in the very high-energy (VHE) band. However, these weren’t the only science gadgets in action. To help determine the redshift of the blazar, researchers also employed the Hubble Space Telescope’s Cosmic Origins Spectrograph.

To help understand what they were seeing, the team then set a lower limit for the blazar’s redshift, taking it to a distance of at least 7.4 billion light-years. If their guess is correct, such a huge distance would mean that the majority of the gamma rays should have been absorbed by the extragalactic background light, but again the answers didn’t add up. For that amount of absorption, the blazar itself would be creating a very unexpected emission spectrum.

“We’re seeing an extraordinarily bright source which does not display the characteristic emission expected from a very high-energy blazar,” said Amy Furniss, a graduate student at the Santa Cruz Institute for Particle Physics (SCIPP) at UCSC and first author of a paper describing the new findings.

Bright? You bet. In this circumstance it has to over-ride the ever-present extragalactic background light (EBL). The whole Universe is filled with this “stellar light pollution”. We know it’s there – produced by countless stars and galaxies – but it’s just hard to measure. What we do know is that when a high-energy gamma ray photo meets with a low-energy EBL photon, they essentially cancel each other out. It stands to reason that the further a gamma ray has to travel, the more likely it is to encounter the EBL, putting a limit on the distance to which we can detect high-energy gamma ray sources. By lowering the limit, the new model was then used to ” calculate the expected absorption of very high-energy gamma rays from PKS 1424+240″. This should have allowed Furniss’ team to gather an intrinsic gamma-ray emission spectrum for the most distant blazar yet captured – but all it did was confuse the issue. It just doesn’t coincide with expected emissions using current models.

“We’re finding very high-energy gamma-ray sources at greater distances than we thought we might, and in doing so we’re finding some things we don’t entirely understand,” Williams said. “Having a source at this distance will allow us to better understand how much background absorption there is and test the cosmological models that predict the extragalactic background light.”

Original Story Source: University of California Santa Cruz News Release. For further reading: The Firm Redshift Lower Limit of the Most Distant TeV-Detected Blazar PKS 1424+240.

Posted on 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.

Posted on by Tammy Plotner

Looking Into The Green Eye Of Planetary Nebula IC 1295

This intriguing picture from ESO’s Very Large Telescope shows the glowing green planetary nebula IC 1295 surrounding a dim and dying star. It is located about 3300 light-years away in the constellation of Scutum (The Shield). This is the most detailed picture of this object ever taken. Credit: ESO

Located on Cerro Paranal in the Atacama Desert of northern Chile, the ESO’s Very Large Telescope was busy using the FORS instrument (FOcal Reducer Spectrograph) to achieve one of the most detailed observations ever taken off a lonely, green planetary nebula – IC 1295. Exposures taken through three different filters which enhanced blue light, visible green light, and red light were melded together to make this 3300 light year distant object come alive.

Located in the constellation of Scutum, this jewel in the “Shield” is a miniscule star that’s at the end of its life. Much like our Sun will eventually become, this white dwarf star is softly shedding its outer layers, like an unfolding flower in space. It will continue this process for a few tens of thousands of years, before it ends, but until then IC 1295 will remain something of an enigma.

“The range of shapes observed up to today has been reproduced by many theoretical works using arguments such as density enhancements, magnetic fields, and binary central systems. Despite this, no complete agreement between models and properties of a given morphological group has been achieved. One of the main reasons for this is selection criteria and completeness of studied samples.” say researchers at Georgia State University. “The samples are usually limited by available images in few bands such as Ha, [NII] and [OIII]. Of course they are also limited by distance, since the further away the object is, the harder it is to resolve its structure. Even with the modern telescopes, obtaining a truly complete sample is far from being achieved.”

Why is this common deep space object like IC 1295 such a mystery? Blame it on its structure. It is comprised of multiple shells.- gaseous layers which once were the star’s atmosphere. As the star aged, its core became unstable and it erupted in unexpected releases of energy – like expansive blisters breaking open. These waves of gas are then illuminated by the ancient star’s ultraviolet radiation, causing it to glow. Each chemical acts as a pigment, resulting in different colors. In the case of IC 1295, the verdant shades are the product of ionised oxygen.

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This video sequence starts with a broad panorama of the Milky Way and closes in on the small constellation of Scutum (The Shield), home to many star clusters. The final detailed view shows the strange green planetary nebula IC 1295 in a new image from ESO’s Very Large Telescope. This faint object lies close to the brighter globular star cluster NGC 6712. Credit: ESO/Nick Risinger (skysurvey.org)/Chuck Kimball. Music: movetwo

However, green isn’t the only color you see here. At the heart of this planetary nebula beats a bright, blue-white stellar core. Over the course of billions of years, it will gently cool – becoming a very faint, white dwarf. It’s just all part of the process. Stars similar to the Sun, and up to eight times as large, are all theorized to form planetary nebulae as they extinguish. How long does a planetary nebula last? According to astronomers, it’s a process that could be around 8 to 10 thousand years.

“Athough planetary nebulae (PNe) have been discovered for over 200 years, it was not until 30 years ago that we arrived at a basic understanding of their origin and evolution.” says Sun Kwok of the Institute of Astronomy and Astrophysics. “Even today, with observations covering the entire electromagnetic spectrum from radio to X-ray, there are still many unanswered questions on their structure and morphology.”

Original Story Source: ESO Photo Release.