Cutting-edge Adaptive Optics Facility Sees First Light

Cutting-edge Adaptive Optics Facility Sees First Light:

The Unit Telescope 4 (Yepun) of ESO’s Very Large Telescope (VLT) has now been transformed into a fully adaptive telescope. After more than a decade of planning, construction and testing, the new Adaptive Optics Facility (AOF) has seen first light with the instrument MUSE, capturing amazingly sharp views of planetary nebulae and galaxies. The coupling of the AOF and MUSE forms one of the most advanced and powerful technological systems ever built for ground-based astronomy.

The Adaptive Optics Facility (AOF) is a long-term project on ESO’s Very Large Telescope (VLT) to provide an adaptive optics system for the instruments on Unit Telescope 4 (UT4), the first of which is MUSE (the Multi Unit Spectroscopic Explorer). Adaptive optics works to compensate for the blurring effect of the Earth’s atmosphere, enabling MUSE to obtain much sharper images and resulting in twice the contrast previously achievable. MUSE can now study even fainter objects in the Universe.

“Now, even when the weather conditions are not perfect, astronomers can still get superb image quality thanks to the AOF,” explains Harald Kuntschner, AOF Project Scientist at ESO.

Following a battery of tests on the new system, the team of astronomers and engineers were rewarded with a series of spectacular images. Astronomers were able to observe the planetary nebulae IC 4406, located in the constellation Lupus (The Wolf), and NGC 6369, located in the constellation Ophiuchus (The Serpent Bearer). The MUSE observations using the AOF showed dramatic improvements in the sharpness of the images, revealing never before seen shell structures in IC 4406.

The AOF, which made these observations possible, is composed of many parts working together. They include the Four Laser Guide Star Facility (4LGSF) and the very thin deformable secondary mirror of UT4. The 4LGSF shines four 22-watt laser beams into the sky to make sodium atoms in the upper atmosphere glow, producing spots of light on the sky that mimic stars. Sensors in the adaptive optics module GALACSI (Ground Atmospheric Layer Adaptive Corrector for Spectroscopic Imaging) use these artificial guide stars to determine the atmospheric conditions.

One thousand times per second, the AOF system calculates the correction that must be applied to change the shape of the telescope’s deformable secondary mirror to compensate for atmospheric disturbances. In particular, GALACSI corrects for the turbulence in the layer of atmosphere up to one kilometer above the telescope. Depending on the conditions, atmospheric turbulence can vary with altitude, but studies have shown that the majority of atmospheric disturbance occurs in this “ground layer” of the atmosphere.

“The AOF system is essentially equivalent to raising the VLT about 900 meters higher in the air, above the most turbulent layer of atmosphere,” explains Robin Arsenault, AOF Project Manager. “In the past, if we wanted sharper images, we would have had to find a better site or use a space telescope — but now with the AOF, we can create much better conditions right where we are, for a fraction of the cost!”

The corrections applied by the AOF rapidly and continuously improve the image quality by concentrating the light to form sharper images, allowing MUSE to resolve finer details and detect fainter stars than previously possible. GALACSI currently provides a correction over a wide field of view, but this is only the first step in bringing adaptive optics to MUSE. A second mode of GALACSI is in preparation and is expected to see first light early 2018. This narrow-field mode will correct for turbulence at any altitude, allowing observations of smaller fields of view to be made with even higher resolution.

“Sixteen years ago, when we proposed building the revolutionary MUSE instrument, our vision was to couple it with another very advanced system, the AOF,” says Roland Bacon, project lead for MUSE. “The discovery potential of MUSE, already large, is now enhanced still further. Our dream is becoming true.”

One of the main science goals of the system is to observe faint objects in the distant Universe with the best possible image quality, which will require exposures of many hours. Joël Vernet, ESO MUSE and GALACSI Project Scientist, comments: “In particular, we are interested in observing the smallest, faintest galaxies at the largest distances. These are galaxies in the making — still in their infancy — and are key to understanding how galaxies form.”

Furthermore, MUSE is not the only instrument that will benefit from the AOF. In the near future, another adaptive optics system called GRAAL will come online with the existing infrared instrument HAWK-I, sharpening its view of the Universe. That will be followed later by the powerful new instrument ERIS.

“ESO is driving the development of these adaptive optics systems, and the AOF is also a pathfinder for ESO’s Extremely Large Telescope,” adds Arsenault. “Working on the AOF has equipped us — scientists, engineers and industry alike — with invaluable experience and expertise that we will now use to overcome the challenges of building the ELT.”

Credit: ESO

New Simulations Could Help in Hunt for Massive Mergers of Neutron Stars, Black Holes

New Simulations Could Help in Hunt for Massive Mergers of Neutron Stars, Black Holes:

Now that scientists can detect the wiggly distortions in space-time created by the merger of massive black holes, they are setting their sights on the dynamics and aftermath of other cosmic duos that unify in catastrophic collisions. Working with an international team, scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed new computer models to explore what happens when a black hole joins with a neutron star – the superdense remnant of an exploded star.

The simulations, carried out in part at Berkeley Lab’s National Energy Research Scientific Computing Center (NERSC), are intended to help detectors home in on the gravitational-wave signals. Telescopes, too, can search for the brilliant bursts of gamma-rays and the glow of the radioactive matter that these exotic events can spew into surrounding space.

In separate papers published in a special edition of the scientific journal Classical and Quantum Gravity, Berkeley Lab and other researchers present the results of detailed simulations.

One of the studies models the first milliseconds (thousandths of a second) in the merger of a black hole and neutron star, and the other details separate simulations that model the formation of a disk of material formed within seconds of the merger, and of the evolution of matter that is ejected in the merger.

That ejected matter likely includes gold and platinum and a range of radioactive elements that are heavier than iron.

Any new information scientists can gather about how neutron stars rip apart in these mergers can help to unlock their secrets, as their inner structure and their likely role in seeding the universe with heavy elements are still shrouded in mystery.

“We are steadily adding more realistic physics to the simulations,” said – Foucart, who served as a lead author for one of the studies as a postdoctoral researcher in Berkeley Lab’s Nuclear Science Division.

“But we still don’t know what’s happening inside neutron stars. The complicated physics that we need to model make the simulations very computationally intensive.”

Foucart, who will soon be an assistant professor at the University of New Hampshire, added, “We are trying to move more toward actually making models of the gravitational-wave signals produced by these mergers,” which create a rippling in space-time that researchers hope can be detected with improvements in the sensitivity of experiments including Advanced LIGO, the Laser Interferometer Gravitational-Wave Observatory.

In February 2016, LIGO scientists confirmed the first detection of a gravitational wave, believed to be generated by the merger of two black holes, each with masses about 30 times larger than the sun.

The signals of a neutron star merging with black holes or another neutron star are expected to generate gravitational waves that are slightly weaker but similar to those of black hole–black hole mergers, Foucart said.

Daniel Kasen, a scientist in the Nuclear Science Division at Berkeley Lab and associate professor of physics and astronomy at UC Berkeley who participated in the research, said that inside neutron stars “there may be exotic states of matter unlike anything realized anywhere else in the universe.”

In some computer simulations the neutron stars were swallowed whole by the black hole, while in others there was a fraction of matter coughed up into space. This ejected matter is estimated to range up to about one-tenth of the mass of the sun.

While much of the matter gets sucked into the larger black hole that forms from the merger, “the material that gets flung out eventually turns into a kind of radioactive ‘waste,’” he said. “You can see the radioactive glow of that material for a period of days or weeks, from more than a hundred million light years away.” Scientists refer to this observable radioactive glow as a “kilonova.”

The simulations use different sets of calculations to help scientists visualize how matter escapes from these mergers. By modeling the speed, trajectory, amount and type of matter, and even the color of the light it gives off, astrophysicists can learn how to track down actual events.

The size range of neutron stars is set by the ultimate limit on how densely matter can be compacted, and neutron stars are among the most superdense objects we know about in the universe.

Neutron stars have been observed to have masses up to at least two times that of our sun but measure only about 12 miles in diameter, on average, while our own sun has a diameter of about 865,000 miles. At large enough masses, perhaps about three times the mass of the sun, scientists expect that neutron stars must collapse to form black holes.

A cubic inch of matter from a neutron star is estimated to weigh up to 10 billion tons. As their name suggests, neutron stars are thought to be composed largely of the neutrally charged subatomic particles called neutrons, and some models expect them to contain long strands of matter – known as “nuclear pasta” – formed by atomic nuclei that bind together.

Neutron stars are also expected to be almost perfectly spherical, with a rigid and incredibly smooth crust and an ultrapowerful magnetic field. They can spin at a rate of about 43,000 revolutions per minute (RPMs), or about five times faster than a NASCAR race car engine’s RPMs.

The researchers’ simulations showed that the radioactive matter that first escapes the black hole mergers may be traveling at speeds of about 20,000 to 60,000 miles per second, or up to about one-third the speed of light, as it is swung away in a long “tidal tail.”

“This would be strange material that is loaded with neutrons,” Kasen said. “As that expanding material cools and decompresses, the particles may be able to combine to build up into the heaviest elements.” This latest research shows how scientists might find these bright bundles of heavy elements.

“If we can follow up LIGO detections with telescopes and catch a radioactive glow, we may finally witness the birthplace of the heaviest elements in the universe,” he said. “That would answer one of the longest-standing questions in astrophysics.”

Most of the matter in a black hole–neutron star merger is expected to be sucked up by the black hole within a millisecond of the merger, and other matter that is not flung away in the merger is likely to form an extremely dense, thin, donut-shaped halo of matter.

The thin, hot disk of matter that is bound by the black hole is expected to form within about 10 milliseconds of the merger, and to be concentrated within about 15 to 70 miles of it, the simulations showed. This first 10 milliseconds appears to be key in the long-term evolution of these disks.

Over timescales ranging from tens of milliseconds to several seconds, the hot disk spreads out and launches more matter into space. “A number of physical processes – from magnetic fields to particle interactions and nuclear reactions – combine in complex ways to drive the evolution of the disk,” said Rodrigo Fernández, an assistant professor of physics at the University of Alberta in Canada who led one of the studies.

Simulations carried out on NERSC’s Edison supercomputer were crucial in understanding how the disk ejects matter and in providing clues for how to observe this matter, said Fernández, a former UC Berkeley postdoctoral researcher.

Eventually, it may be possible for astronomers scanning the night sky to find the “needle in a haystack” of radioactive kilonovae from neutron star mergers that had been missed in the LIGO data, Kasen said.

“With improved models, we are better able to tell the observers exactly which flashes of light are the signals they are looking for,” he said. Kasen is also working to build increasingly sophisticated models of neutron star mergers and supernovae through his involvement in the DOE Exascale Computing Project.

As the sensitivity of gravitational-wave detectors improves, Foucart said, it may be possible to detect a continuous signal produced by even a tiny bump on the surface of a neutron star, for example, or signals from theorized one-dimensional objects known as cosmic strings.

“This could also allow us to observe events that we have not even imagined,” he said.

Credit: lbl.gov

Hubble Detects Exoplanet with Glowing Water Atmosphere

Hubble Detects Exoplanet with Glowing Water Atmosphere:

An international team of researchers, led by the University of Exeter, made the new discovery by observing glowing water molecules in the atmosphere of the exoplanet WASP-121b with NASA’s Hubble Space Telescope. In order to study the gas giant’s stratosphere - a layer of atmosphere where temperature increases with higher altitudes - scientists used spectroscopy to analyse how the planet’s brightness changed at different wavelengths of light.

Water vapor in the planet's atmosphere, for example, behaves in predictable ways in response to different wavelengths of light, depending on the temperature of the water. At cooler temperatures, water vapor in the planet’s upper atmosphere blocks light of specific wavelengths radiating from deeper layers towards space. But at higher temperatures, the water molecules in the upper atmosphere glow at these wavelengths instead.

The phenomenon is similar to what happens with fireworks, which get their colors from chemicals emitting light. When metallic substances are heated and vaporized, their electrons move into higher energy states. Depending on the material, these electrons will emit light at specific wavelengths as they lose energy: sodium produces orange-yellow and strontium produces red in this process, for example.

The water molecules in the atmosphere of WASP-121b similarly give off radiation as they lose energy, but it is in the form of infrared light, which the human eye is unable to detect.

The research is published in leading scientific journal Nature.

“Theoretical models have suggested that stratospheres may define a special class of ultra-hot exoplanets, with important implications for the atmospheric physics and chemistry,” said Dr Tom Evans, lead author and research fellow at the University of Exeter. “When we pointed Hubble at WASP-121b, we saw glowing water molecules, implying that the planet has a strong stratosphere.”

WASP-121b, located approximately 900 light years from Earth, is a gas giant exoplanet commonly referred to as a ‘hot Jupiter’, although with a greater mass and radius than Jupiter, making it much puffier. The exoplanet orbits its host star every 1.3 days, and is around the closest distance it could be before the star's gravity would start ripping it apart.

This close proximity also means that the top of the atmosphere is heated to a blazing hot 2,500 degrees Celsius – the temperature at which iron exists in gas rather than solid form.

In Earth's stratosphere, ozone traps ultraviolet radiation from the sun, which raises the temperature of this layer of atmosphere. Other solar system bodies have stratospheres, too - methane is responsible for heating in the stratospheres of Jupiter and Saturn's moon Titan, for example. In solar system planets, the change in temperature within a stratosphere is typically less than 100 degrees Celsius. However, on WASP-121b, the temperature in the stratosphere rises by 1000 Celsius.

“We’ve measured a strong rise in the temperature of WASP-121b’s atmosphere at higher altitudes, but we don’t yet know what’s causing this dramatic heating,” says Nikolay Nikolov, co-author and research fellow at the University of Exeter. “We hope to address this mystery with upcoming observations at other wavelengths.”

Vanadium oxide and titanium oxide gases are candidate heat sources, as they strongly absorb starlight at visible wavelengths, similar to ozone absorbing UV radiation. These compounds are expected to be present in only the hottest of hot Jupiters, such as WASP-121b, as high temperatures are required to keep them in the gaseous state. Indeed, vanadium oxide and titanium oxide are commonly seen in brown dwarfs, ‘failed stars’ that have some commonalities with exoplanets.

Previous research spanning the past decade has indicated possible evidence for stratospheres on other exoplanets, but this is the first time that glowing water molecules have been detected, the clearest signal yet for an exoplanet stratosphere. It is one of the first results to come out of a new observing program being carried out by an international team of scientists, led by Associate Professor David Sing at the University of Exeter and Dr. Mercedes Lopez-Mórales at the Smithsonian Institution. The program has been awarded 800 hours to study and compare 20 different exoplanets, representing one of the largest time allocations for a single program in the entire 27 year history of Hubble.

“This new research is the smoking gun evidence scientists have been searching for when studying hot exoplanets. We have discovered this hot Jupiter has a stratosphere, a common feature seen in most of our solar system planets.” says Professor David Sing, co-author and Associate Professor of Astrophysics at the University of Exeter. “It’s a truly exciting find as we’re seeing dramatic differences planet-to-planet which is giving valuable clues in figuring out how planets behave under different conditions, and we’re only just scratching the surface of all the new Hubble data.”

NASA's forthcoming James Webb Space Telescope will be able to follow up on the atmospheres of planets like WASP-121b with higher sensitivity than any telescope currently in space.

"This super-hot exoplanet is going to be a benchmark for our atmospheric models, and will be a great observational target moving into the Webb era," said Hannah Wakeford, co-author and Research Fellow at the University of Exeter.

“A stratosphere in an ultra-hot gas giant exoplanet” is published in Nature on Thursday, August 3, 2017.

Credit: exeter.ac.uk

New Clue to Solving the Mystery of the Sun’s Hot Atmosphere

New Clue to Solving the Mystery of the Sun’s Hot Atmosphere:

The elemental composition of the Sun’s hot atmosphere known as the ‘corona’ is strongly linked to the 11-year solar magnetic activity cycle, a team of scientists from UCL, George Mason University and Naval Research Laboratory has revealed for the first time.

The study, published in Nature Communications and funded by the NASA Hinode program, shows that an increase in magnetic activity goes hand in hand with an increase of certain elements, such as Iron, in the solar corona. It is thought that the results could have significant implications for understanding the process leading to the heating of the Sun’s corona.

“Elemental composition is an important component of the flow of mass and energy into the atmospheres of the Sun and other stars. How that composition changes, if it does indeed change, as material flows from the surface of the Sun to its corona influences ideas we have about the heating and activity in atmospheres of other stars,” said Dr Deborah Baker (UCL Space & Climate Physics).

Through its 11-year cycle, the Sun moves from relatively quiet periods at solar minimum, to intense magnetic activity at solar maximum, when large numbers of sunspots appear and there is an increase in radiation. 

“Previously, many astronomers thought that elemental composition in a star’s atmosphere depended on the properties of the star that don’t change, such as the rotation rate or surface gravity. Our results suggest that it may also be linked with the magnetic activity and heating processes in the atmosphere itself, and they change with time, at least in the Sun,” said the study’s lead author, Dr David H. Brooks (George Mason University). 

The Sun’s surface, the photosphere, has a temperature of around 6000 degrees, but the outer atmosphere, the corona – best seen from Earth during total solar eclipses – is several hundred times hotter. How the corona is heated to millions of degrees is one of the most significant unsolved problems in astrophysics. The solution will help scientists better understand the heating of other stars.

“Why the Sun’s corona is so hot is a long-standing puzzle. It’s as if a flame were coming out of an ice cube. It doesn’t make any sense! Solar astronomers think that the key lies in the magnetic field, but there are still arguments about the details,” added Dr Brooks.

The team of scientists analysed observations from the Solar Dynamics Observatory at a time of low activity (solar minimum) starting in 2010, and through till 2014 when huge magnetic active regions crossing the solar disk were common. 

An unknown mechanism preferentially transports certain elements, such as Iron, into the corona instead of others, giving the corona its own distinctive elemental signature. The team think that the mechanism that separates the elements and supplies material to the corona may also be closely related to the transport of energy, and that understanding it may provide clues to explain the whole coronal heating process.

“Our observations started in 2010, near the last solar minimum, and so observations of the global coronal spectrum for a complete solar cycle have not been possible. The fact that we detected this variation of the Sun in a relatively small period of time really highlights the importance of observing stars over complete stellar cycles, which we hope to do in the future. Currently we tend to just have snapshots of stars, but these are potentially missing some important clues,” said Dr Baker. 

Whilst it would require long-term planning, the scientists expect that observing full stellar cycles would provide new insight into the nature of the atmospheres of stars and how they are heated to million degree temperatures.

Credit: ucl.ac.uk

Standard Model of the Universe Withstands Most Precise Test by Dark Energy Survey

Standard Model of the Universe Withstands Most Precise Test by Dark Energy Survey:

Astrophysicists have a fairly accurate understanding of how the universe ages: That’s the conclusion of new results from the Dark Energy Survey (DES), a large international science collaboration, including researchers from the Department of Energy’s SLAC National Accelerator Laboratory, that put models of cosmic structure formation and evolution to the most precise test yet.

The survey’s researchers analyzed light from 26 million galaxies to study how structures in the universe have changed over the past 7 billion years – half the age of the universe. The data were taken with the DECam, a 570-megapixel camera attached to the 4-meter Victor M. Blanco Telescope at the Cerro Tololo Inter-American Observatory in Chile.

Previously, the most precise test of cosmological models came from measurements with the European Space Agency’s Planck satellite of what is known as the cosmic microwave background (CMB) – a faint glow in the sky emitted 380,000 years after the Big Bang.

“While Planck looked at the structure of the very early universe, DES has measured structures that evolved much later,” said Daniel Gruen, a NASA Einstein postdoctoral fellow at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC), a joint institute of Stanford University and SLAC. “The growth of these structures from the early ages of the universe until today agrees with what our models predict, showing that we can describe cosmic evolution very well.”

Gruen will present the results, which are based on the first year of data from the 5-year-long survey, today at the 2017 Division of Particles and Fields meeting of the American Physical Society at the DOE’s Fermi National Accelerator Laboratory.

KIPAC faculty member Risa Wechsler, a founding member of DES, said, “For the first time, the precision of key cosmological parameters coming out of a galaxy survey is comparable to the ones derived from measurements of the cosmic microwave background. This allows us to test our models independently and combine both approaches to obtain parameter values with unprecedented precision.” 

The standard model of cosmology, called Lambda-CDM, includes two key ingredients. Cold dark matter (CDM), an invisible form of matter that is five times more prevalent than regular matter, clumps together and is at the heart of the formation of structures such as galaxies and galaxy clusters. Lambda, the cosmological constant, describes the accelerated expansion of the universe, driven by an unknown force referred to as dark energy.

Astrophysicists need precise tests of the model because its ingredients are not completely certain. Dark matter has never been directly detected. Dark energy is even more mysterious, and it’s not known whether it actually is a constant or changes over time.

DES has now succeeded in carrying out such a precision test. The scientists used the fact that images of faraway galaxies get slightly distorted by the gravity of galaxies in the foreground – an effect known as weak gravitational lensing. This analysis led to the largest map ever constructed for the distribution of mass – both regular and dark matter – in the universe, as well as its evolution over time.

“Within an error bar of less than 5 percent, the combined Planck and DES results are consistent with Lambda-CDM,” Wechsler said. “This also means that, so far, we don’t need anything but a constant form of dark energy to describe the expansion history of the universe.” 

In addition to Gruen, who led the weak lensing working group, and Wechsler, whose group provided realistic simulations of the survey critical to testing several aspects of the cosmological analysis, a large number of KIPAC scientists, postdoctoral fellows, graduate students and alumni have made crucial contributions to DES – from building the instrument to developing theory and simulations and analyzing the data.

Postdoctoral fellow Elisabeth Krause, for example, leads the DES theory and combined probes working group. In that role, she led the charge in developing theoretical models that match the experimental precision obtained with the DES data. This involved writing computer codes that calculate what weak gravitational lensing should look like for a given model.

“Different people develop slightly different codes that are meant to do the same thing,” she said. “I helped bring code developers together to cross-check their results and to make sure that we get the most precise theory codes possible.”

Another key to the creation of the mass distribution map was to accurately determine the distances to the observed galaxies – information that is usually derived from independent surveys that analyze the properties of light coming from those objects or from exploding stars.

“We’ve shown that we can use the color of certain red galaxies – red is the color they would have if you were right in front of them – to determine how far they are away,” said SLAC staff scientist Eli Rykoff, who had a leading role in this part of the analysis. “It turns out that if we map where these red galaxies are in the sky, we can use them to calibrate the distances of the lenses and background galaxies used in the study.” 

In the near future, more DES data will allow astrophysicists to test their cosmological models with even more precision. The analysis of data collected during the first three years of the survey will begin soon, and the fifth year of observations will also soon be underway. 

With even better data, the researchers said, we might find out if the relatively simple Lambda-CDM model needs to be modified.

“The methods developed for DES and the experience its researchers are gaining along the way will also benefit the natural flow of ever-evolving experiments,” said KIPAC faculty member David Burke, head of SLAC’s DES group.

Both will prepare scientists for future surveys, including ones with the Large Synoptic Survey Telescope (LSST). With its 3.2-gigapixel camera, which is under construction at SLAC, astrophysicists will be able to explore the depths of our universe like never before.

DES is a collaboration of more than 400 scientists from 26 institutions in seven countries. Part of the funding has been provided by the U.S. Department of Energy Office of Science. A full list of collaborating institutions can be found at:

www.darkenergysurvey.org/collaboration.

Credit: slac.stanford.edu

Naval Research Laboratory Brightens Perspective of Mysterious Mini-Halos

Naval Research Laboratory Brightens Perspective of Mysterious Mini-Halos:

The largest gravitationally bound objects in the universe are galaxy clusters that form at the intersection of cosmic web filaments. These entities are shaped and grow through massive collisions as material streams into their gravitational pull. Within the heart of some galaxy clusters are mysterious and little known radio mini-halos. These rare, dispersed, and steep-spectrum (brighter at low frequencies) radio sources surround a bright central radio galaxy and are highly luminous at radio wavelengths.

Studying this phenomenon is Dr. Tracy Clarke, a radio astronomer at the U.S. Naval Research Laboratory (NRL) Radio Astrophysics and Sensing Section and co-author of research on the topic titled, "Deep 230-470 [megahertz] VLA Observations of the mini-halo in the Perseus Cluster." She works in conjunction with the National Radio Astronomy Observatory (NRAO), the research team uses the upgraded Karl G. Jansky Very Large Array (JVLA) to peer into the cluster of galaxies in the constellation Perseus, 250 million light-years from Earth.

"In 2011, an upgrade to the receivers on the JVLA sacrificed the observatory's capability for operation at frequencies between 30 MHz and 300 MHz," said Clarke. "However, in 2013 all 27 of the 25-meter antennas of the JVLA were outfitted with new receivers, providing the bandwidth necessary for these observations."

According to Clarke the Perseus cluster is one of the most massive objects in the known universe, containing thousands of galaxies immersed in a vast cloud of multimillion-degree gas and harbors a mini­halo. Mini-halo systems are thought to provide a window on the otherwise elusive turbulence driven by minor mergers between galaxy clusters and less massive systems.

Funded by NRL, the new broadband low frequency receivers have widened the VHF/UHF receiver bandwidth from 300-340 MHz to 230-470 MHz, significantly increasing the sensitivity of the telescope. The new JVLA facilities have also produced an order of magnitude of deeper image quality than previous high fidelity data, which lets the mini-halo emissions be seen clearly at the 270-430 MHz range.

“Overall, the recently upgraded JVLA has enabled a breakthrough in radio astronomy by providing a radio telescope with unprecedented sensitivity, resolution, and imaging capabilities," said Julie Hlavacek­ Larrondo, Universite de Montreal astrophysicist and a lead author of the paper. "The new JVLA images of the Perseus cluster demonstrate the unique and state-of-the-art capabilities that this telescope offers to the community."

The deep JVLA observations of the Perseus cluster, combined with the cluster's properties, offer researchers a unique opportunity to study mini-halo structures. Lead author Marie-Lou Gendron-Marsolais, Ph.D. student at Universite de Montreal notes, "The results demonstrate the sensitivity of the new low frequency JVLA receivers, as well as the necessity to obtain deeper, higher-fidelity radio images of mini­halos in clusters to trace complex structures and further understand their origin."

Recognizing the power of the new VHF/UHF receiver, NRL wanted to enhance the availability of this new resource. In 2014, NRL and NRAO researchers worked to develop the VLA Low Band Ionospheric and Transient Experiment (VLITE) to tap into the new broadband low frequency receivers and piggyback on the $300 million dollar infrastructure of the JVLA.

"The data stream from this new system can be tapped to expand our understanding of objects such as these mini-halos while at the same time providing real-time monitoring of ionospheric weather conditions over the U.S. southwest," Clarke said.

At present, VLITE is being further expanded (eVLITE) to more than double the number of baselines from the original 45 baselines to 104 and should be fully operational by the end of August 2017. The expansion, to date, has brought a total of 66 baselines to VLITE.

Astronomers use VLITE for a wide range of astrophysics, which includes exploring the sky for short­lived bursts of radio waves. This type of research continues to grow in importance, since a small number of such events have led astronomers to suspect still-undiscovered phenomena in the universe may be producing many such powerful bursts.

Credit: nrl.navy.mil

Our Solar System’s 'Shocking' Origin

Our Solar System’s 'Shocking' Origin:

According to one longstanding theory, our Solar System’s formation was triggered by a shock wave from an exploding supernova. The shock wave injected material from the exploding star into a neighboring cloud of dust and gas, causing it to collapse in on itself and form the Sun and its surrounding planets.

New work from Carnegie’s Alan Boss offers fresh evidence supporting this theory, modeling the Solar System’s formation beyond the initial cloud collapse and into the intermediate stages of star formation. It is published by The Astrophysical Journal.

One very important constraint for testing theories of Solar System formation is meteorite chemistry. Meteorites retain a record of the elements, isotopes, and compounds that existed in the system’s earliest days. One type, called carbonaceous chondrites, includes some of the most-primitive known samples.

An interesting component of chondrites’ makeup is something called short-lived radioactive isotopes. Isotopes are versions of elements with the same number of protons, but a different number of neutrons. Sometimes, as is the case with radioactive isotopes, the number of neutrons present in the nucleus can make the isotope unstable. To gain stability, the isotope releases energetic particles, which alters its number of protons and neutrons, transmuting it into another element.

Some isotopes that existed when the Solar System formed are radioactive and have decay rates that caused them to become extinct within tens to hundreds of million years. The fact that these isotopes still existed when chondrites formed is shown by the abundances of their stable decay products—also called daughter isotopes—found in some primitive chondrites. Measuring the amount of these daughter isotopes can tell scientists when, and possibly how, the chondrites formed.

A recent analysis of chondrites by Carnegie’s Myriam Telus was concerned with iron-60, a short-lived radioactive isotope that decays into nickel-60. It is only created in significant amounts by nuclear reactions inside certain kinds of stars, including supernovae or what are called asymptotic giant branch (AGB) stars.

Because all the iron-60 from the Solar System’s formation has long since decayed, Telus’ research, published in Geochimica et Cosmochimica Acta, focused on its daughter product, nickel-60. The amount of nickel-60 found in meteorite samples—particularly in comparison to the amount of stable, “ordinary” iron-56—can indicate how much iron-60 was present when the larger parent body from which the meteorite broke off was formed. There are not many options for how an excess of iron-60—which later decayed into nickel-60—could have gotten into a primitive Solar System object in the first place—one of them being a supernova. 

While her research did not find a “smoking gun,” definitively proving that the radioactive isotopes were injected by a shock wave, Telus did show that the amount of Fe-60 present in the early Solar System is consistent with a supernova origin. 

Taking this latest meteorite research into account, Boss revisited his earlier models of shock wave-triggered cloud collapse, extending his computational models beyond the initial collapse and into the intermediate stages of star formation, when the Sun was first being created, an important next step in tying together Solar System origin modeling and meteorite sample analysis.

“My findings indicate that a supernova shock wave is still the most-plausible origin story for explaining the short lived radioactive isotopes in our Solar System,” Boss said.

Boss dedicated his paper to the late Sandra Keiser, a long-term collaborator, who provided computational and programming support at Carnegie’s Department of Terrestrial Magnetism for more than two decades. Keiser died in March.

Credit: carnegiescience.edu

New Horizons' Next Target Just Got a Lot More Interesting

New Horizons' Next Target Just Got a Lot More Interesting:

Could the next flyby target for NASA’s New Horizons spacecraft actually be two targets? New Horizons scientists look to answer that question as they sort through new data gathered on the distant Kuiper Belt object (KBO) 2014 MU69, which the spacecraft will fly past on Jan. 1, 2019. That flyby will be the most distant in the history of space exploration, a billion miles beyond Pluto.

The ancient KBO, which is more than four billion miles (6.5 billion kilometers) from Earth, passed in front of a star on July 17, 2017. A handful of telescopes deployed by the New Horizons team in a remote part of Patagonia, Argentina were in the right place at the right time to catch its fleeting shadow — an event known as an occultation – and were able to capture important data to help mission flyby planners better determine the spacecraft trajectory and understand the size, shape, orbit and environment around MU69. 

Based on these new occultation observations, team members say MU69 may not be not a lone spherical object, but suspect it could be an “extreme prolate spheroid” – think of a skinny football – or even a binary pair. The odd shape has scientists thinking two bodies may be orbiting very close together or even touching – what’s known as a close or contact binary – or perhaps they’re observing a single body with a large chunk taken out of it. The size of MU69 or its components also can be determined from these data. It appears to be no more than 20 miles (30 kilometers) long, or, if a binary, each about 9-12 miles (15-20 kilometers) in diameter.

“This new finding is simply spectacular. The shape of MU69 is truly provocative, and could mean another first for New Horizons going to a binary object in the Kuiper Belt,” said Alan Stern, mission principal investigator from the Southwest Research Institute (SwRI) in Boulder, Colorado. “I could not be happier with the occultation results, which promise a scientific bonanza for the flyby.” 

The July 17 stellar occultation event that gathered these data was the third of a historic set of three ambitious occultation observations for New Horizons. The team used data from the Hubble Space Telescope and European Space Agency’s Gaia satellite to calculate and pinpoint where MU69 would cast a shadow on Earth's surface. “Both of these space satellites were crucial to the success of the entire occultation campaign,” added Stern.

Said Marc Buie, the New Horizons co-investigator who led the observation campaign, "These exciting and puzzling results have already been key for our mission planning, but also add to the mysteries surrounding this target leading into the New Horizons encounter with MU69, now less than 17 months away.”

Credit: NASA

Two Weeks in the Life of a Sunspot

Two Weeks in the Life of a Sunspot:

On July 5, 2017, NASA’s Solar Dynamics Observatory watched an active region — an area of intense and complex magnetic fields — rotate into view on the Sun. The satellite continued to track the region as it grew and eventually rotated across the Sun and out of view on July 17.

With their complex magnetic fields, sunspots are often the source of interesting solar activity: During its 13-day trip across the face of the Sun, the active region — dubbed AR12665 — put on a show for NASA’s Sun-watching satellites, producing several solar flares, a coronal mass ejection and a solar energetic particle event. Watch the video below to learn how NASA’s satellites tracked the sunspot over the course of these two weeks.

Such sunspots are a common occurrence on the Sun, but less frequent at the moment, as the Sun is moving steadily toward a period of lower solar activity called solar minimum — a regular occurrence during its approximately 11-year cycle. Scientists track such spots because they can help provide information about the Sun’s inner workings. Space weather centers, such as NOAA’s Space Weather Prediction Center, also monitor these spots to provide advance warning, if needed, of the radiation bursts being sent toward Earth, which can impact our satellites and radio communications. 

On July 9, a medium-sized flare burst from the sunspot, peaking at 11:18 a.m. EDT. Solar flares are explosions on the Sun that send energy, light and high-speed particles out into space — much like how earthquakes have a Richter scale to describe their strength, solar flares are also categorized according to their intensity. This flare was categorized as an M1. M-class flares are a tenth the size of the most intense flares, the X-class flares. The number provides more information about its strength: An M2 is twice as intense as an M1, an M3 is three times as intense and so on.

Days later, on July 14, a second medium-sized, M2 flare erupted from the Sun. The second flare was long-lived, peaking at 10:09 a.m. EDT and lasting over two hours.

This was accompanied by another kind of solar explosion called a coronal mass ejection, or CME. Solar flares are often associated with CMEs — giant clouds of solar material and energy. NASA’s Solar and Heliospheric Observatory, or SOHO, saw the CME at 9:36 a.m. EDT leaving the Sun at speeds of 620 miles per second and eventually slowing to 466 miles per second.

Following the CME, the turbulent active region also emitted a flurry of high-speed protons, known as a solar energetic particle event, at 12:45 p.m. EDT.

Research scientists at the Community Coordinated Modeling Center — located at NASA’s Goddard Space Flight Center in Greenbelt, Maryland — used these spacecraft observations as input for their simulations of space weather throughout the solar system. Using a model called ENLIL, they are able to map out and predict whether the solar storm will impact our instruments and spacecraft, and send alerts to NASA mission operators if necessary.

By the time the CME made contact with Earth’s magnetic field on July 16, the sunspot’s journey across the Sun was almost complete. As for the solar storm, it took this massive cloud of solar material two days to travel 93 million miles to Earth, where it caused charged particles to stream down Earth’s magnetic poles, sparking enhanced aurora.

Credit: NASA

Primordial Black Holes May Have Helped to Forge Heavy Elements

Primordial Black Holes May Have Helped to Forge Heavy Elements:

Astronomers like to say we are the byproducts of stars, stellar furnaces that long ago fused hydrogen and helium into the elements needed for life through the process of stellar nucleosynthesis. As the late Carl Sagan once put it: “The nitrogen in our DNA, the calcium in our teeth, the iron in our blood, the carbon in our apple pies were made in the interiors of collapsing stars. We are made of star stuff.” But what about the heavier elements in the periodic chart, elements such as gold, platinum and uranium?

Astronomers believe most of these “r-process elements”—elements much heavier than iron—were created, either in the aftermath of the collapse of massive stars and the associated supernova explosions, or in the merging of binary neutron star systems.

“A different kind of furnace was needed to forge gold, platinum, uranium and most other elements heavier than iron,” explained George Fuller, a theoretical astrophysicist and professor of physics who directs UC San Diego’s Center for Astrophysics and Space Sciences. “These elements most likely formed in an environment rich with neutrons.”

In a paper published August 7 in the journal Physical Review Letters, he and two other theoretical astrophysicists at UCLA—Alex Kusenko and Volodymyr Takhistov—offer another means by which stars could have produced these heavy elements: tiny black holes that came into contact with and are captured by neutron stars, and then destroy them.

Neutron stars are the smallest and densest stars known to exist, so dense that a spoonful of their surface has an equivalent mass of three billion tons.

Tiny black holes are more speculative, but many astronomers believe they could be a byproduct of the Big Bang and that they could now make up some fraction of the “dark matter”—the unseen, nearly non-interacting stuff that observations reveal exists in the universe.

If these tiny black holes follow the distribution of dark matter in space and co-exist with neutron stars, Fuller and his colleagues contend in their paper that some interesting physics would occur.

They calculate that, in rare instances, a neutron star will capture such a black hole and then devoured from the inside out by it. This violent process can lead to the ejection of some of the dense neutron star matter into space.

“Small black holes produced in the Big Bang can invade a neutron star and eat it from the inside,” Fuller explained. “In the last milliseconds of the neutron star's demise, the amount of ejected neutron-rich material is sufficient to explain the observed abundances of heavy elements.”

“As the neutron stars are devoured,” he added, “they spin up and eject cold neutron matter, which decompresses, heats up and make these elements.” This process of creating the periodic table’s heaviest elements would also provide explanations for a number of other unresolved puzzles in the universe and within our own Milky Way galaxy.

“Since these events happen rarely, one can understand why only one in ten dwarf galaxies is enriched with heavy elements,” said Fuller. “The systematic destruction of neutron stars by primordial black holes is consistent with the paucity of neutron stars in the galactic center and in dwarf galaxies, where the density of black holes should be very high.”

In addition, the scientists calculated that ejection of nuclear matter from the tiny black holes devouring neutron stars would produce three other unexplained phenomenon observed by astronomers.

“They are a distinctive display of infrared light (sometimes termed a “kilonova”), a radio emission that may explain the mysterious Fast Radio Bursts from unknown sources deep in the cosmos, and the positrons detected in the galactic center by X-ray observations,” said Fuller.

“Each of these represent long-standing mysteries. It is indeed surprising that the solutions of these seemingly unrelated phenomena may be connected with the violent end of neutron stars at the hands of tiny black holes.” Funding for this project was provided by the National Science Foundation (PHY-1614864) at UC San Diego and by the U.S. Department of Energy (DE-SC0009937) at UCLA. Alex Kusenko was also supported, in part, by the World Premier International Research Center Initiative (WPI), MEXT, Japan.

Credit: ucsd.edu

Scientists Demonstrate First Space Quantum Communication Using a Microsatellite

Scientists Demonstrate First Space Quantum Communication Using a Microsatellite:

A team of researchers from the National Institute of Information and Communications Technology (NICT) in Tokyo, Japan, has recently reported that they succeeded in the demonstration of the first quantum communication between a microsatellite and a ground station. The signal was sent by a quantum-communication transmitter onboard the SOCRATES satellite.

The instrument, known as the Small Optical TrAnsponder, or SOTA, is the world's smallest and lightest quantum-communication transmitter. It has a mass of roughly 13.22 lbs. (6 kilograms) and its dimensions are 7 x 4.5 x 10.6 inches (17.8 x 11.4 x 26.8 centimeters). This shoebox-sized tool is capable of transmitting a laser signal to the ground at a rate of 10 million bits per second from an altitude of about 370 miles (600 kilometers) at a speed of approximately 15,660 mph.

SOTA was launched into space as part of the Space Optical Communications Research Advanced TEchnology Satellite (SOCRATES) microsatellite in May 2014. The mission’s main goal was to test a standard microsatellite bus technology applicable to missions of various purposes. SOTA has successfully completed its objectives by demonstrating its quantum communication capabilities.

“We are proud to say that the SOTA mission fulfilled all the success levels as foreseen, and more-than-doubled its originally-designed working life of one year,” Alberto Carrasco-Casado of NICT’s Space Communications Laboratory told Astrowatch.net.

According to Carrasco-Casado, four different success levels were established for the SOTA instrument: minimum success, success, full success, and extra success. The minimum success level required a basic check-up of all the lasercom subsystems, while the success level consisted of acquiring the laser beams transmitted from SOTA to the ground station by using different wavelengths and performing basic communication tests.

In order to achieve the full success level a real data transmission from SOTA to the ground station by using error correcting codes to deal with variable atmospheric conditions was needed. When it comes to the most desired extra success level, SOTA needed to successfully conduct lasercom experiments with different ground stations around the world and the quantum-limited communication experiment that was recently described in the Nature Photonics journal.

“The main achievement of SOTA was to be the first lasercom terminal in a microsatellite. Being such a tiny lasercom terminal, we could test several technologies, and perform different experiments,” Carrasco-Casado noted.

The scientists used three wavelengths for communications (800-nm band, 980 nm, and 1550 nm), each of them through a different aperture (small lenses to transmit the 800-nm band and 980 nm lasers, and a 5-cm Cassegrain telescope to transmit the 1550-nm laser), and two different pointing technologies (a coarse-pointing gimbal for the 800-nm band and 980 nm lasers and an additional fine-pointing system for the 1550-nm, being able to deliver a higher power to the ground).

The researchers were able to gather a great deal of atmospheric-propagation data using these technologies, which is critical to characterize the atmospheric channel for future missions. They managed to replicate the experiments in different ground stations around the world (Canada, Germany and France), achieving promising results. For instance, when it comes to the French ground station, the French Space Agency (CNES) group demonstrated an adaptive-optic system to compensate the atmospheric perturbations suffered by the SOTA signals. Finally, they were able to carry out the first quantum-limited communication experiment from space.

“All these technologies are key for the future development of space optical communications and quantum communications,” Carrasco-Casado said.

He underlined that space lasercom will play a more and more important role in satellite communications in the future, and all the technologies that SOTA demonstrated are key to these future developments. For example, the SpaceX constellation plans to use over 4,000 satellites and those satellites will use laser communications to communicate with each other. Moreover, many other constellations and communication networks are being designed at the moment where free-space lasercom plays a key role, with private companies like Google or Facebook investing a great deal of effort in their deployment.

“If Quantum Key Distribution (QKD) and lasercom systems can be miniaturized following the heritage of SOTA, this technology could be spread massively, enabling a truly-secure global communication network. Prior to the commercialization of this technology, research organizations like NICT have to demonstrate its feasibility, which was the goal of the SOTA mission. In line of this endeavor, NICT is also actively collaborating in the standardization of lasercom technologies through the Consultative Committee for Space Data Systems (CCSDS), and the data obtained with SOTA is another important result of this mission,” Carrasco-Casado concluded.

Currently, the Space Communications Laboratory and the Quantum ICT Advanced Development Center in NICT are working together towards future missions that will leverage the expertise and knowledge acquired with the SOCRATES/SOTA mission in technologies related to space laser communications, quantum communications and physical-layer cryptography.

New Horizons’ KBO target may be a binary

New Horizons’ KBO target may be a binary:

Artist’s impression of NASA’s New Horizons spacecraft, en route to a January 2019 encounter with Kuiper Belt Object 2014 MU₆₉. Image & Caption Credit: NASA / JHU-APL / SwRI

New Horizons’ second target – Kuiper Belt Object (KBO) 2014 MU₆₉ – may actually be a binary system composed of two objects that either touch one another or orbit very close together, according to observations conducted by mission scientists when the KBO passed in front of a star on July 17, 2017.

Members of the New Horizons team observed the occultation by deploying a network of telescopes along the path of MU69’s shadow in a remote part of Argentina.

Their goal was to capture its shadow, thereby obtaining data about the KBO’s size, shape, orbit, and environment as well as information that will enable accurate refining of the spacecraft’s trajectory.

MU69 is the second target of NASA’s New Horizons spacecraft and part of its approved extended mission by the space agency. It will be the most distant object ever visited by a spacecraft.

The probe famously flew by the Pluto system on July 14, 2015, obtaining a plethora of images and data about the binary Pluto-Charon and their four small moons.

The July 17, 2017, occultation was the third of three such events this year, all of which were carefully observed by mission scientists after they used both the Hubble Space Telescope and the European Space Agency’s (ESA) Gaia satellite to pinpoint exactly where MU69’s shadow would fall on Earth each time.

Based on data collected during the first occultation in June, mission scientists raised the possibility that MU69, located a billion miles (1.6 billion kilometers) beyond Pluto and more than four billion miles (6.5 billion kilometers) from Earth, might actually be a swarm of many small objects rather than a single object.

However, observations conducted during the third occultation indicate the object is either two objects closely orbiting each other, a contact binary in which the two objects actually touch one another, or a single, strangely shaped object missing a large chunk of material.

Mission scientists think it or both objects may be shaped like a “skinny football” – a shape formally described as an “extreme prolate spheroid”.

LEFT: An artist’s concept of Kuiper Belt Object 2014 MU69, the next flyby target for NASA’s New Horizons mission. This binary concept is based on telescope observations made at Patagonia, Argentina, on July 17, 2017, when MU69 passed in front of a star. New Horizons scientists theorize that it could be a single body with a large chunk taken out of it, or two bodies that are close together or even touching. RIGHT: Another artist’s concept of Kuiper Belt Object 2014 MU69, which is the next flyby target for NASA’s New Horizons mission. Scientists speculate that the Kuiper Belt object could be a single body with a large chunk taken out of it, or two bodies that are close together or even touching. Images & Captions Credit: NASA / JHU-APL / SwRI / Alex Parker

Two of Pluto’s small moons, Kerberos and Hydra, as well as Comet 67P/Churyumov–Gerasimenko, are single objects composed of two lobes.

“This new finding is simply spectacular. The shape of MU69 is truly provocative, and could mean another first for New Horizons going to a binary object in the Kuiper Belt,” said mission Principal Investigator Alan Stern of the Southwest Research Institute (SwRI) in Boulder, Colorado. “I could not be happier with the occultation results, which promise a scientific bonanza for the flyby.”

New Horizons will fly by MU69 on January 1, 2019.

From observations of the third occultation, scientists now have a better handle on MU69’s size, which they estimate to be no longer than 20 miles (30 kilometers) if the KBO is a single object.

If MU69 is a binary composed of two objects, each one is estimated to have a diameter of nine to twelve miles (15–20 kilometers).

Stern credited the successes of the occultation observations to the Hubble Space Telescope and Gaia Observatory, which provided crucial information about the path of MU69’s shadow on Earth on all three occasions.

Occultation data and images are available on New Horizons’ KBO Chasers site.



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