Shannon Hall, Author at Universe Today

July 4, 2014December 23, 2015 by Shannon Hall

Chandra Image May Rival July 4th Fireworks

A new composite of NGC 4258 features X-rays from Chandra (blue), radio waves from the VLA (purple), optical data from Hubble (yellow and blue), and infrared with Spitzer (red). Image Credit: Chandra

While Fourth of July festivities tonight may bring brilliant colors blazing across the night sky, only 23 million light-years away is another immense cosmic display, complete with a supermassive black hole, shock waves, and vast reservoirs of gas.

The night sky never ceases to amaze. And NGC 4258, also known as Messier 106, is a sight to be seen. A new image from NASA’s Chandra X-ray Observatory is shedding light on one of the galaxy’s most startling features: instead of two spiral arms, typical for any massive spiral galaxy, it appears to have four (imaged above in blue and purple).

Although the second pair of arms can be seen in visible light images as ghostly wisps of gas, they are prominent in images outside the visible spectrum, such as those using X-ray or radio waves. Unlike normal arms, they are made up of hot gas rather than stars, and their origin has remained a mystery.

Astronomers now think the arms — so-called anomalous for their atypical features — are indirectly caused by the supermassive black hole at NGC 4258’s heart.

Images from multiple telescopes help paint a complete picture. Radio data taken with the Very Large Array show that the supermassive black hole is producing powerful jets. As these jets travel through the galactic matter, they disrupt the surrounding gas and generate shock waves. These shock waves, seen by NASA’s Spitzer Space Telescope, heat the anomalous arms — composed of reservoirs of gas as massive as about 10 million Suns — to thousands of degrees.

Finally, the recent Chandra X-ray image also reveals huge bubbles of hot gas above and below the plane of the galaxy. These bubbles indicate that although much of the gas was originally in the disk of the galaxy, it was heated to such high temperatures that it was ejected into the outer regions by the jets from the supermassive black hole.

The results provide drastic implications for the fate of the galaxy. Most of the gas in the disk of the galaxy has been ejected, causing stars to form at a rate ten times slower than the Milky Way. Further, astronomers estimate that all of the remaining gas will be ejected within the next 300 million years.

Although NGC 4258 is currently a sight to be seen in any small telescope, like the best fireworks display followed by smoke, its death is inescapable.

The results were published in The Astrophysical Journal Letters and are available online.

June 26, 2014December 23, 2015 by Shannon Hall

Superluminous Supernova Puzzles Astronomers

Before (left) and after (center) images of the region where DES13S2cmm was discovered. On the right is a subtraction of these two images, showing a bright new object at the center -- a supernova. Credit: Dark Energy Survey

Supernovae are surprisingly dependable. These brilliant and powerful explosions that mark the end of massive stars’ lives tend to shine anywhere from one hundred million to a few billion times brighter than the Sun for weeks on end. And their intrinsic brightness is always well known.

But in recent years a rare class of cosmic explosions, which are tens to hundreds of times more luminous than ordinary supernovae, has been discovered. And now one of these odd superluminous supernovae is mystifying astronomers further, with characteristics that simply don’t add up.

The Dark Energy Survey (DES) came online in August 2013 in order to investigate millions of galaxies for the subtle effects of weak lensing, the phenomenon where intervening invisible matter causes distant galaxies to appear minutely sheared and stretched.

The survey started off with a bang; its first images revealed a rare superluminous supernova, dubbed DES13S2cmm, 7.8 billion light-years away.

“Fewer than forty such supernovae have ever been found and I never expected to find one in the first DES images,” said Andreas Papadopoulos from the University of Portsmouth in a press release. “As they are rare, each new discovery brings the potential for greater understanding — or more surprises.”

The problem is this: DES13S2cmm doesn’t easily match the typical characteristics of a superluminous supernova. The stellar explosion could be seen in the data six months later, much longer than most other superluminous supernovae observed to date.

“Its unusual, slow decline was not apparent at first,” said Mark Sullivan from Southampton University. “But as more data came in and the supernova stopped getting fainter, we would look at the light curve and ask ourselves, ‘what is this?’ ”

So Sullivan decided to investigate further. But understanding its origins are proving difficult.

For some supernovae, the optical light we see is actually created by radioactivity. In fact, supernovae tend to create large amounts of radioactive elements, which don’t occur naturally on Earth. Nickel-56, with a half-life of roughly six days, is a common example.

As the nickel decays into cobalt, it releases gamma rays, which are trapped by the other material ejected by the supernova. These trapped rays heat up the surrounding material until it radiates in the optical. In this case, the peak magnitude of the supernova is directly proportional to the amount of nickel-56 created in the explosion.

“We have tried to explain the supernova as a result of the decay of the radioactive isotope nickel-56,” said coauthor Dr Chris D’Andrea of the University of Portsmouth. “But to match the peak brightness, the explosion would need to produce more than three times the mass of our Sun of the element. And even then the behavior of the light curve doesn’t match up.”

So the team is now investigating other explanations. In one intriguing scenario the supernova was relatively normal but created a magnetar — an extremely dense and highly magnetic neutron star that’s millions of times more powerful than the strongest magnets on Earth — whose energy made the explosion exceptionally bright.

But this explanation doesn’t match the data either.

A few months ago a team of astronomers led by Robert Quimby explained a superluminous supernovae, PS1-10afx, by a chance cosmic alignment, where intervening matter worked like a lens to deflect and intensify the background light for a typical Type Ia supernova. D’Andrea, however, doesn’t believe this is the case here.

“DES13S2cmm looks nothing like a normal type of supernova, either in its photometric evolution or its spectroscopy,” D’Andrea told Universe Today. “So while we can never be sure that a very faint but very massive galaxy lies between us and another object and is serendipitously brightening the object, there is no need to adopt that assumption in the case of DES13S2cmm.”

chance cosmic alignment — where intervening matter worked like a lens to deflect and intensify the background light – See more at: http://www.skyandtelescope.com/astronomy-news/stellar-science/mysteriously-bright-supernova-explained/#sthash.m7Z8PJ3k.dpuf

So astronomers are heading back to the drawing board.

“With so few known, it’s hard to really understand their properties in detail,” said Bob Nichol from the University of Portsmouth. “DES should find enough of these objects to allow us to understand superluminous supernovae as a population. But if some of these discoveries prove as difficult to interpret as DES13S2cmm, we’re prepared for the unusual.”

The results will be presented today at the National Astronomy Meeting 2014 in Portsmouth.

June 25, 2014December 23, 2015 by Shannon Hall

Three Supermassive Black Holes Tango in a Distant Galaxy, Marking a Huge Discovery

"Helical jets from one supermassive black hole caused by a very closely orbiting companion (see blue dots). The third black hole is part of the system, but farther away and therefore emits relatively straight jets." Credit: Roger Deane (large image); NASA Goddard (inset bottom left; modified from original)

In a galaxy four billion light-years away, three supermassive black holes are locked in a whirling embrace. It’s the tightest trio of black holes known to date and even suggests that these closely packed systems are more common than previously thought.

“What remains extraordinary to me is that these black holes, which are at the very extreme of Einstein’s Theory of General Relativity, are orbiting one another at 300 times the speed of sound on Earth,” said lead author Roger Deane from the University of Cape Town in a press release.

“Not only that, but using the combined signals from radio telescopes on four continents we are able to observe this exotic system one third of the way across the Universe. It gives me great excitement as this is just scratching the surface of a long list of discoveries that will be made possible with the Square Kilometer Array.”

The system, dubbed SDSS J150243.091111557.3, was first identified as a quasar — a supermassive black hole at the center of a galaxy, which is rapidly accreting material and shining brightly — four years ago. But its spectrum was slightly wacky with its doubly ionized oxygen emission line [OIII] split into two peaks instead of one.

A favorable explanation suggested there were two active supermassive black holes hiding in the galaxy’s core.

An active galaxy typically shows single-peaked narrow emission lines, which stem from a surrounding region of ionized gas, Deane told Universe Today. The fact that this active galaxy shows double-peaked emission lines, suggests there are two surrounding regions of ionized gas and therefore two active supermassive black holes.

But one of the supermassive black holes was enshrouded in dust. So Deane and colleagues dug a little further. They used a technique called Very Long Baseline Interferometry (VLBI), which is a means of linking telescopes together, combining signals separated by up to 10,000 km to see detail 50 times greater than the Hubble Space Telescope.

Observations from the European VLBI network — an array of European, Chinese, Russian, and South American antennas — revealed that the dust-covered supermassive black hole was once again two instead of one, making the system three supermassive black holes in total.

The VLBI network. Image Credit: Deane — The VLBI network. Image Credit: Roger Deane

“This is what was so surprising,” Deane told Universe Today. “Our aim was to confirm the two suspected black holes. We did not expect one of these was in fact two, which could only be revealed by the European VLBI Network due [to the] very fine detail it is able to discern.”

Deane and colleagues looked through six similar galaxies before finding their first trio. The fact that they found one so quickly suggests that they’re more common than previously thought.

The inner pair of black holes of the triple system as seen by the European VLBI Network (EVN). Contours show radio emission at 1.7 GHz, the colour scale show radio emission at 5 GHz frequency. Credit: R.P. Deane et al. — The inner pair of black holes of the triple system as seen by the European VLBI Network (EVN). Image Credit: R.P. Deane et al.

Before today, only four triple black hole systems were known, with the closest pair being 2.4 kiloparsecs apart — roughly 2,000 times the distance from Earth to the nearest star, Proxima Centauri. But the closest pair in this trio is separated by only 140 parsecs — roughly 10 times that same distance.

Although Deane and colleagues relied on the phenomenal resolution of the VLBI technique in order to spatially separate the two close-in black holes, they also showed that their presence could be inferred from larger-scale features. The orbital motion of the black hole, for instance, is imprinted on its large jets, twisting them into a helical-like shape. This may provide smaller telescopes with a tool to find them with much greater efficiency.

“If the result holds up, it’ll be very cool,” binary supermassive black hole expert Jessie Runnoe from Pennsylvania State University told Universe Today. This research has multiple implications for understanding further phenomena.

The first sheds light on galaxy evolution. Two or three supermassive black holes are the smoking gun that the galaxy has merged with another. So by looking at these galaxies in detail, astronomers can understand how galaxies have evolved into their present-day shapes and sizes.

The second sheds light on a phenomenon known as gravitational radiation. Einstein’s General Theory of Relativity predicts that when one of the two or three supermassive black holes spirals inward, gravitational waves — ripples in the fabric of space-time itself — propagate out into space.

Future radio telescopes should be able to measure gravitational waves from such systems as their orbits decay.

“Further in the future, the Square Kilometer Array will allow us to find and study these systems in exquisite detail, and really allow us [to] gain a much better understanding of how black holes shape galaxies over the history of the Universe,” said coauthor Matt Jarvis from the Universities of Oxford and Western Cape.

The research was published today in the journal Nature.

June 24, 2014December 23, 2015 by Shannon Hall

Titan’s Atmosphere May be Older than Saturn, a New Study Suggests

Titan's atmosphere makes Saturn's largest moon look like a fuzzy orange ball in this natural-color view from the Cassini spacecraft. Cassini captured this image in 2012. Image Credit: NASA/JPL-Caltech/Space Science Institute — According to a study from UCLA, Titan experiences severe methane rainstorms, leading to a the alluvial fans found found in both hemispheres. Credit: NASA/JPL-Caltech/Space Science Institute

It’s well accepted that moons form after planets. In fact, only a few months ago, astronomers spotted a new moon forming deep within Saturn’s rings, 4.5 billion years after the planet initially formed.

But new research suggests Saturn’s icy moon Titan — famous for its rivers and lakes of liquid methane — may have formed before its parent planet, contradicting the theory that Titan formed within the warm disk surrounding an infant Saturn.

A combined NASA and ESA-funded study has found firm evidence that the nitrogen in Titan’s atmosphere originated in conditions similar to the cold birthplace of the most ancient comets from the Oort cloud — a spherical shell of icy particles that enshrouds the Solar System.

The hint comes in the form of a ratio. All elements have a certain number of known isotopes — variants of that element with the same number of protons that differ in their number of neutrons. The ratio of one isotope to another isotope is a crucial diagnostic tool.

In planetary atmospheres and surface materials, the amount of one isotope relative to another isotope is closely tied to the conditions under which materials form. Any change in the ratio will allow scientists to deduce an age for that material.

Kathleen Mandt from the Southwest Research Institute in San Antonio and colleagues analyzed the ratio of nitrogen-14 (seven protons and seven neutrons) to nitrogen-15 (seven protons and eight neutrons) in Titan’s atmosphere.

“When we looked closely at how this ratio could evolve with time, we found that it was impossible for it to change significantly,” Mandt said in a press release. “Titan’s atmosphere contains so much nitrogen that no process can significantly modify this tracer even given more than four billion years of Solar System history.”

The team found that our Solar System is not old enough for this nitrogen isotope ratio to have changed as much as it has. By comparing the small change within this ratio, Mandt and colleagues found that it seemed more similar to Oort cloud comets than to Solar System bodies including planets and comets born in the Kuiper belt. The team is eager to see whether their findings are supported by data from ESA’s Rosetta mission, which will study comet 67P/Churyumov-Gerasimenko later this year.

Finally, the study also has implications for Earth. In the past, researchers assumed a connection between comets, Titan and Earth. But these results show that the nitrogen isotope ratio is different on Titan and Earth, suggesting the sources of Earth’s and Titan’s nitrogen must have been different.

It’s unclear whether Earth received nitrogen from early meteorites or if it was captured directly from the disk of gas that formed the Solar System.

“This exciting result is a key example of Cassini science informing our knowledge of the history of [the] Solar System and how Earth formed,” said Scott Edgington, Cassini deputy project scientist at NASA’s Jet Propulsion Laboratory.

The research was published this week in the Astrophysical Journal Letters.

June 23, 2014December 23, 2015 by Shannon Hall

An Earth-size Diamond in the Sky: The Coolest Known White Dwarf Detected

Artist impression of a white dwarf star in orbit with pulsar PSR J2222-0137. It may be the coolest and dimmest white dwarf ever identified. Credit: B. Saxton (NRAO/AUI/NSF)

We live in a vast, dark Universe, which makes the smallest and coolest objects extremely difficult to detect, save for a stroke of luck. Often times this luck comes in the form of a companion. Take, for example, the first exoplanet detected due to its orbit around a pulsar — a rapidly spinning neutron star.

A team of researchers using the National Radio Astronomy Observatory’s Green Bank Telescope and the Very Long Baseline Array (VLBA), as well as other observatories have repeated the story, detecting an object in orbit around a distant pulsar. Except this time it’s the coldest, faintest white dwarf ever detected. So cool, in fact, its carbon has crystallized.

The punch line is this: with the help of a pulsar, astronomers have detected an Earth-size diamond in the sky.

“It’s a really remarkable object,” said lead author David Kaplan from the University of Wisconsin-Milwaukee in a press release. “These things should be out there, but because they are so dim they are very hard to find.”

The story begins when Dr. Jason Boyles, then a graduate student at West Virginia University, identified a pulsar, dubbed PSR J2222-0127, 900 light-years away in the constellation Aquarius.

When the core of a massive star runs out of energy, it collapses to form an incredibly dense neutron star or black hole. Bring a teaspoon of neutron star to Earth and it would outweigh Mount Everest at about a billion tons. A pulsar is simply a spinning neutron star.

But as a pulsar spins, lighthouse-like beams of radio waves stream from the poles of its powerful magnetic field. If they sweep past the Earth, they’ll give rise to blips of radio waves, so regular that you could set your watch by them. But if the pulsar carries a companion in tow, the tiny gravitational tugs can offset that timing slightly.

The first observations of PSR J2222-0137 identified that it was spinning more than 30 times each second. It was then observed over a two-year period with the VLBA. By applying Einstein’s theory of relativity — which predicts that light slows in the presence of a gravitational field — the researchers studied how the gravity of the companion warped space, causing delays in the radio signal as the pulsar passed behind it.

The delayed travel times helped the researchers determine the individual masses of the two stars. The pulsar has a mass of 1.2 times that of the Sun and the companion a mass 1.05 times that of the Sun. Previously, researchers had thought the companion was likely another neutron star, or a white dwarf, the remnant of a Sun-like star.

But the timing variations made the neutron star scenario unlikely. The orbits were too orderly for a second supernova to have taken place. So knowing the typical brightness of a white dwarf and its distance, astronomers initially thought they would be able to detect the elusive companion in optical and infrared light.

An image taken in visible light at the SOAR telescope of the field of the pulsar/white dwarf pair. There is no evidence for the white dwarf at the position of the pulsar in this deep image, indicating that the white dwarf is much fainter, and therefore cooler, than any such known object. (The two large white circles mask bright, overexposed stars.) — An image taken in visible light at the SOAR telescope of the field of the pulsar/white dwarf pair. The exact location of the white dwarf is known to a pixel. But it’s not there. Image Credit: NOAO

However, neither the Southern Astrophysical Research telescope in Chile nor the 10-meter Keck telescope in Hawaii was able to detect it.

“Our final image should show us a companion 100 times fainter than any other white dwarf orbiting a neutron star and about 10 times fainter than any known white dwarf, but we don’t see a thing,” said coauthor Bart Dunlap, a graduate student at the University of North Carolina. “If there’s a white dwarf there, and there almost certainly is, it must be extremely cold.”

The research team calculated that the white dwarf would be no more than 3,000 degrees Kelvin. At such a low temperature, the collapsed star would be largely crystallized carbon, similar to diamond.

The paper has been accepted for publication in the Astrophysical Journal and may be viewed here.

June 20, 2014December 23, 2015 by Shannon Hall

A New Mantra: Follow the Methane — May Advance Search for Extraterrestrial Life

Extrasolar planet HD189733b rises from behind its star. Is there methane on this planet? Image Credit: ESA

The search for life is largely limited to the search for water. We look for exoplanets at the correct distances from their stars for water to flow freely on their surfaces, and even scan radiofrequencies in the “water hole” between the 1,420 MHz emission line of neutral hydrogen and the 1,666 MHz hydroxyl line.

When it comes to extraterrestrial life, our mantra has always been to “follow the water.” But now, it seems, astronomers are turning their eyes away from water and toward methane — the simplest organic molecule, also widely accepted to be a sign of potential life.

Astronomers at the University College London (UCL) and the University of New South Wales have created a powerful new methane-based tool to detect extraterrestrial life, more accurately than ever before.

In recent years, more consideration has been given to the possibility that life could develop in other mediums besides water. One of the most interesting possibilities is liquid methane, inspired by the icy moon Titan, where water is as solid as rock and liquid methane runs through the river valleys and into the polar lakes. Titan even has a methane cycle.

Astronomers can detect methane on distant exoplanets by looking at their so-called transmission spectrum. When a planet transits, the star’s light passes through a thin layer of the planet’s atmosphere, which absorbs certain wavelengths of the light. Once the starlight reaches Earth it will be imprinted with the chemical fingerprints of the atmosphere’s composition.

But there’s always been one problem. Astronomers have to match transmission spectra to spectra collected in the laboratory or determined on a supercomputer. And “current models of methane are incomplete, leading to a severe underestimation of methane levels on planets,” said co-author Jonathan Tennyson from UCL in a press release.

So Sergei Yurchenko, Tennyson and colleagues set out to develop a new spectrum for methane. They used supercomputers to calculate about 10 billion lines — 2,000 times bigger than any previous study. And they probed much higher temperatures. The new model may be used to detect the molecule at temperatures above that of Earth, up to 1,500 K.

“We are thrilled to have used this technology to significantly advance beyond previous models available for researchers studying potential life on astronomical objects, and we are eager to see what our new spectrum helps them discover,” said Yurchenko.

The tool has already successfully reproduced the way in which methane absorbs light in brown dwarfs, and helped correct our previous measurements of exoplanets. For example, Yurchenko and colleagues found that the hot Jupiter, HD 189733b, a well-studied exoplanet 63 light-years from Earth, might have 20 times more methane than previously thought.

The paper has been published in the Proceedings of the National Academy of Sciences and may be viewed here.

June 19, 2014December 23, 2015 by Shannon Hall

Powerful Starbursts in Dwarf Galaxies Helped Shape the Early Universe, a New Study Suggests

GOODS field containing distant dwarf galaxies forming stars at an incredible rate. Image Credit: ESO

Massive galaxies in the early Universe formed stars at a much faster clip than they do today — creating the equivalent of a thousand new suns per year. This rate reached its peak 3 billion years after the Big Bang, and by 6 billion years, galaxies had created most of their stars.

New observations from the Hubble Space Telescope show that even dwarf galaxies — the small, low mass clusters of several billion stars — produced stars at a rapid rate, playing a bigger role than expected in the early history of the Universe.

Today, we tend to see dwarf galaxies clinging to larger galaxies, or sometimes engulfed within, rather than existing as blazing collections of stars alone. But astronomers have suspected that dwarfs in the early Universe could turn over stars quickly. The trouble is, most images aren’t sharp enough to reveal the faint, faraway galaxies we need to observe.

“We already suspected that dwarf starbursting galaxies would contribute to the early wave of star formation, but this is the first time we’ve been able to measure the effect they actually had,” said lead author Hakim Atek of the École Polytechnique Fédérale de Lausanne (EPFL) in a press release. “They appear to have had a surprisingly significant role to play during the epoch where the Universe formed most of its stars.”

Previous studies of starburst galaxies in the early Universe were biased toward massive galaxies, leaving out the huge number of dwarf galaxies that existed in this era. But the highly sensitive capabilities of Hubble’s Wide Field Camera 3 have now allowed astronomers to peer at low-mass dwarf galaxies in the distant Universe.

This image represents the data that comes from using the NASA/ESA Hubble Space Telescop's highly-sensitive Wide Field Camera 3 in its grism spectroscopy mode. A grism is a combination of a grating and a prism, and it splits up the light from a galaxy into its constituent colours, producing a spectrum. In this image the continuum of each galaxy is shown as a "rainbow". Astronomers can look at a galaxy’s spectrum and identify light emitted by the hydrogen gas in the galaxy. If there are stars being formed in the galaxy then the intense radiation from the newborn stars heats up the hydrogen gas and makes it glow. All of the light from the hydrogen gas is emitted in a small number of very narrow and bright emission lines. For dwarf galaxies in the early Universe the emission lines are much easier to detect than the faint, almost invisible, continuum. Image Credit: NASA and ESA — This image represents the data that comes from using the NASA/ESA Hubble Space Telescope’s highly-sensitive Wide Field Camera 3 in its grism spectroscopy mode. Image Credit: NASA / ESA

Atek and colleagues looked at 1000 galaxies from roughly three billion years to 10 billion years after the Big Bang. They dug through their data, in search of the H-alpha line: a deep-red visible spectral line, which occurs when a hydrogen electron falls from its third to second lowest energy level.

In star forming regions, the surrounding gas is continually ionized by radiation from the newly formed stars. Once the gas is ionized, the nucleus and removed electron can recombine to form a new hydrogen atom with the electron typically in a higher energy state. This electron will then cascade back to the ground state, a process that produces H-alpha emission about half the time.

So the H-alpha line is an effective probe of star formation and the brightness of the H-alpha line (which is much easier to detect than the faint, almost invisible, continuum) is an effective probe of the star formation rate. From this single line, Attek and colleagues found that the rate at which stars are turning on in early dwarfs is surprisingly high.

“These galaxies are forming stars so quickly that they could actually double their entire mass of stars in only 150 million years — this sort of gain in stellar mass would take most normal galaxies 1-3 billion years,” said co-author Jean-Paul Kneib, also of EPFL.

The team doesn’t yet know why these small galaxies are producing such a vast number of stars. In general, bursts of star formation are thought to follow somewhat chaotic events like galactic mergers or the shock of a supernova. But by continuing to study these dwarf galaxies, astronomers hope to shed light on galactic evolution and help paint a consistent picture of events in the early Universe.

The paper has been published today in the Astrophysical Journal and may be viewed here. The latest Hubblecast (below) also covers this exciting result.

June 12, 2014December 23, 2015 by Shannon Hall

“Carbon Copy” Spacecraft Ready to Track Global Carbon Dioxide

Artist's rendering of NASA's Orbiting Carbon Observatory (OCO)-2, one of five new NASA Earth science missions set to launch in 2014, and one of three managed by JPL. Image Credit: NASA-JPL/Caltech

On February 24, 2009, the launch of the Orbiting Carbon Observatory (OCO) mission — designed to study the global fate of carbon dioxide — resulted in failure. Shortly after launch, the rocket nose didn’t separate as expected, and the satellite could not be released.

But now, a carbon copy of the original mission, called OCO-2 is slated to launch on July 1, 2014.

The original failure ended in “heartbreak. The entire mission was lost. We didn’t even have one problem to solve,” said OCO-2 Project Manager Ralph Basilio in a press conference earlier today. “On behalf of the entire team that worked on the original OCO mission, we’re excited about this opportunity … to finally be able to complete some unfinished business.”

The motivation for the mission is simple: in the last few hundred years, human beings have played a large role in the planet-wide balancing act called the carbon cycle. Our activities, such as fossil fuel burning and deforestation are pushing the cycle out of its natural balance, adding more carbon dioxide to the atmosphere.

“There’s a steady increase in atmospheric carbon dioxide concentrations over time,” said OCO-2 Project Scientist Mike Gunson. “But at the same time, we can see that this has an annual cycle of dropping every summer, in this case in the northern hemisphere, as the forests and plants grow. And this is the Earth breathing.”

Time series of atmospheric carbon dioxide over the northern hemisphere retrieved from the Sciamachy instrument on Envisat and the TANSO instrument on Japan’s GOSAT. While carbon dioxide increases over the ten-year period, it experiences annual fluctuations caused by vegetation’s absorption and release of the gas due to photosynthesis and respiration. The different colours represent different methods of extracting carbon dioxide measurements from the measured spectra of reflected solar radiation. Credit: University Bremen/ESA Read more at: http://phys.org/news/2013-09-planet-earth-carbon-dioxide-space.html#jCp — Time series of atmospheric carbon dioxide over the northern hemisphere retrieved from the Sciamachy instrument on Envisat and the TANSO instrument on Japan’s GOSAT. The different colours represent different methods of extracting carbon dioxide measurements from the measured spectra of reflected solar radiation. Credit: University Bremen/ESA

Carbon dioxide is both one of the best-measured greenhouse gases and least-measured. Half of the emissions in the atmosphere become largely distributed around the globe in a matter of months. But the other half of the emissions — the half that is being absorbed through natural processes into the land or the ocean — is not evenly distributed.

To understand carbon dioxide absorption, we need a high-resolution global map.

This is where the launch failure of OCO proved to be a blessing in disguise. It gave OCO-2 scientists a chance to work with project managers of the Japanese Greenhouse Gases Observing Satellite (GOSAT), which successfully launched in 2009. The unexpected collaboration allowed them to stumble upon a hidden surprise.

“A couple of my colleagues made what I think is a fantastic discovery,” said Gunson. They discovered fluorescent light from vegetation.

As plants absorb sunlight, some of the light is dissipated as heat, while some is re-emitted at longer wavelengths as fluorescence. Although scientists have measured fluorescence in laboratory settings and ground-based experiments, they have never done so from space.

Measuring the fluorescent glow proves to be a challenge because the tiny signal is overpowered by reflected sunlight. Researchers found that by tuning their GOSAT spectrometer — an instrument that can measure light across the electromagnetic spectrum — to look at very narrow channels, they could see parts of the spectrum where there was fluorescence but less reflect sunlight.

This surprise will give OCO-2 an unexpected global view from space, shedding new light on the productivity of vegetation on land. It will provide a regional map of absorbed carbon dioxide, helping scientists to estimate photosynthesis rates over vast scales and better understand the second half of the carbon cycle.

Ralph Basilio, OCO-2 project manager with NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California, left, and Mike Gunson, OCO-2 project scientist at JPL, discuss the Orbiting Carbon Observatory-2 (OCO-2), NASA’s first spacecraft dedicated to studying carbon dioxide, during a press briefing, Thursday, June 12, 2014, at NASA Headquarters in Washington. Credit: NASA.

“The OCO-2 satellite has one instrument: a three-channel grating spectrometer,” said OCO-2 Program Executive Betsy Edwards. “But with this one instrument we’re going to collect hundreds of thousands of measurements each day, which will then provide a global description of carbon dioxide in the atmosphere. It’s going to be an unprecedented level of coverage and resolution, something we have not seen before with previous spacecraft.”

OCO-2 will result in nearly 100 times more observations of both carbon dioxide and fluorescence than GOSAT. It will launch from Vandenberg Air Force Base in California at 2:56 a.m. on July 1.

“Climate change is the challenge of our generation,” said Edwards. “NASA is particularly ready to … provide information, on documenting and understanding what these changes are on the climate, in predicting the impact of these changes to the Earth, and in sharing all of this information that we gather for the benefit of society.”

June 11, 2014December 23, 2015 by Shannon Hall

ALMA Sheds New Light on ‘Dark’ Gamma-ray Bursts

An artist’s conception of the environment around GRB 020819B based on ALMA observations. Image Credit: NAOJ

Gamma-ray bursts (GRBs) represent the most powerful explosions in the cosmos, sending out as much energy in a matter of seconds as our Sun will give off during its entire 10-billion-year lifespan.

These powerful explosions are thought to be triggered when dying stars collapse into jet-spewing black holes. Yet no one has ever witnessed a GRB directly. Instead astronomers are left to study their fading light.

But some GRBs mysteriously seem to have no afterglow. Now, observations from the Atacama Large Millimeter/submillimeter Array (ALMA) are shedding light on these so-called dark bursts.

One possible explanation is that dark bursts explode so far away their visible light is extinguished due to the expansion of the Universe. Another possible explanation is that dark bursts explode in galaxies with unusually thick amounts of interstellar dust, which absorb a burst’s light.

Neither explanation, however, seems likely as astronomers anticipate that GRB progenitors — massive stars — are found in active star-forming regions surrounded by large amounts of molecular gas. But unfortunately there has never been an observational result to back up this theory either.

So astronomers have been working hard to better understand GRBs by studying their host galaxies. Now, a Japanese team of astronomers led by Bunyo Hatsukade from the National Astronomical Observatory in Japan, has used ALMA to report the first-ever map of molecular gas and dust in two galaxies that were previously rocked by GRBs.

Hatsukade and colleagues detected the radio emission from molecular gas and dust in two dark host galaxies — GRB 020819B and GRB 051022 — at about 4.3 billion and 6.9 billion light-years away, respectively.

“We have been searching for molecular gas in GRB host galaxies for over 10 years using various telescopes around the world,” said Kotaro Kohno from the University of Tokyo in a press release. “As a result of our hard work, we finally achieved a remarkable breakthrough using the power of ALMA. We are very excited with what we have achieved.”

Watch the video below for an artist concept animation of the environment around GRB 020819B based on ALMA observations:

The telescope’s high sensitivity enabled the team of astronomers to detect the emission from molecular gas, as opposed to most telescopes, which can only probe absorption along the line of sight. This combined with its high spatial resolution provided the first detailed map of the molecular gas and dust throughout a GRB host galaxy.

Surprisingly, less gas was observed than expected, and correspondingly much more dust. The ratio of dust to molecular gas at the GRB site is 10 times higher than in normal environments.

Observations of the host galaxy for GRB 020819B. Radio measurements of molecular gas (left) and dust (middle), both of which are observed with ALMA. An image in visible-light captured by the Frederick C. Gillett Gemini North Telescope (right). The cross indicates the location of the GRB site. Image Credit: Bunyo Hatsukade(NAOJ), ALMA (ESO/NAOJ/NRAO)

“We didn’t expect that GRBs would occur in such a dusty environment with a low ratio of molecular gas to dust,” said Hatsukade. “This indicates that the GRB occurred in an environment quite different from a typical star-forming region.”

The research team thinks the high proportion of dust compared to molecular gas is likely due to the intense ultraviolet radiation from the young, massive stars, which will break up any molecular gas while leaving the dust relatively undisturbed.

It’s becoming clear that dust absorbs the afterglow radiation, causing these dark gamma-ray bursts. The team plans to carry out further observations and is excited to use ALMA’s incredible sensitivity to probe other host galaxies.

The results are published today in the journal Nature. You can read more from the National Radio Astronomy Observatory and ESO.

June 5, 2014December 23, 2015 by Shannon Hall

First Precise Measurement of Antihydrogen

Hydrogen’s electron and proton have oppositely charged antimatter counterparts in the antihydrogen: the positron and antiproton. Image credit: NSF.

The best science — the questions that capture and compel any human being — is enshrouded in mystery. Here’s an example: scientists expect that matter and antimatter were created in equal quantities shortly after the Big Bang. If this had been the case, the two types of particles would have annihilated each other, leaving a Universe permeated by energy.

As our existence attests, that did not happen. In fact, nature seems to have a one-part in 10 billion preference for matter over antimatter. It’s one of the greatest mysteries in modern physics.

But the Large Hadron Collider is working hard, literally pushing matter to the limit, to solve this captivating mystery. This week, CERN created a beam of antihydrogen atoms, allowing scientists to take precise measurements of this elusive antimatter for the first time.

Antiparticles are identical to matter particles except for the sign of their electric charge. So while hydrogen consists of a positively charged proton orbited by a negatively charged electron, antihydrogen consists of a negatively charged antiproton orbited by a positively charged anti-electron, or a positron

While primordial antimatter has never been observed in the Universe, it’s possible to create antihydrogen in a particle accelerator by mixing positrons and low energy antiprotons.

In 2010, the ALPHA team captured and held atoms of antihydrogen for the first time. Now the team has successfully created a beam of antihydrogen particles. In a paper published this week in Nature Communications, the ALPHA team reports the detection of 80 antihydrogen atoms 2.7 meters downstream from their production.

“This is the first time we have been able to study antihydrogen with some precision,” said ALPHA spokesperson Jeffrey Hangst in a press release. “We are optimistic that ALPHA’s trapping technique will yield many such insights in the future.”

One of the key challenges is keeping antihydrogen away from ordinary matter, so that the two don’t annihilate each other. To do so, most experiments use magnetic fields to trap antihydrogen atoms long enough to study them.

However, the strong magnetic fields degrade the spectroscopic properties of the antihydrogen atoms, so the ALPHA team had to develop an innovative set-up to transfer antihydrogen atoms to a region where they could be studied, far from the strong magnetic field.

To measure the charge of antihydrogen, the ALPHA team studied the trajectories of antihydrogen atoms released from the trap in the presence of an electric field. If the antihydrogen atoms had an electric charge, the field would deflect them, whereas neutral atoms would be undeflected.

The result, based on 386 recorded events, gives a value of the antihydrogen electric charge at -1.3 x 10^-8. In other words, its charge is compatible with zero to eight decimal places. Although this result comes as no surprise, since hydrogen atoms are electrically neutral, it is the first time that the charge of an antiatom has been measured to such high precision.

In the future, any detectable difference between matter and antimatter could help solve one of the greatest mysteries in modern physics, opening up a window into a new realm of science.

The paper has been published in Nature Communications.