11 Aug 2016

50th Anniversary of Lunar Orbiter 1 Mission

Today is the 50th anniversary of the launch of the first of five lunar orbiters that returned images of 99 percent of both the near- and far-side surfaces of the moon. The orbiters sent back a total of 3,062 photos.

Lunar_Orbiter_NASM_medLunar Orbiter 1, built by The Boeing Co., was launched Aug. 10, 1966 on an Atlas SLV-3 Agena-D rocket from Cape Canaveral in Florida. It was designed primarily to photograph smooth areas of the moon’s surface for selection of landing sites for the Surveyor and Apollo missions.

Radiation experiments on the orbiters also confirmed that the design of Apollo spacecraft hardware would protect astronauts from short-term exposure to solar particle events.

The orbiters were commanded to crash on the moon before their attitude control gas ran out so they would not be a navigational or communications hazard to Apollo flights.

The program was managed by NASA Langley Research Center in Hampton, Virginia.

Young stars in Sagittarius cluster excite astronomers

The star cluster Messier 18 and its surroundings

M18 – NGC 6613 | RA 18h 17m  DEC – 5 deg 09’ | Mag +7.5 | Size 7 arc minutes |

Ashampoo_Snap_2016.08.09_23h34m54s_001_Messier 18 was discovered and catalogued in 1764 by Charles Messier — for whom the Messier Objects are named — during his search for comet-like objects. It lies within the Milky Way, approximately 4600 light-years away in the constellation of Sagittarius, and consists of many sibling stars loosely bound together in what is known as an open cluster.

There are over 1000 known open star clusters within the Milky Way, with a wide range of properties, such as size and age, that provide astronomers with clues to how stars form, evolve and die. The main appeal of these clusters is that all of their stars are born together out of the same material.

m18

[Click on the images to enlarge]

In Messier 18 the blue and white colours of the stellar population indicate that the cluster’s stars are very young, probably only around 30 million years old. Being siblings means that any differences between the stars will only be due to their masses, and not their distance from Earth or the composition of the material they formed from. This makes clusters very useful in refining theories of star formation and evolution.

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Astronomers now know that most stars do form in groups, forged from the same cloud of gas that collapsed in on itself due to the attractive force of gravity. The cloud of leftover gas and dust — or molecular cloud — that envelops the new stars is often blown away by their strong stellar winds, weakening the gravitational shackles that bind them. Over time, loosely bound stellar siblings like those pictured here will often go their separate ways as interactions with other neighbouring stars or massive gas clouds nudge, or pull, the stars apart. Our own star, the Sun, was most likely once part of a cluster very much like Messier 18 until its companions were gradually distributed across the Milky Way.

The dark lanes that snake through this image are murky filaments of cosmic dust, blocking out the light from distant stars. The contrasting faint reddish clouds that seem to weave between the stars are composed of ionised hydrogen gas. The gas glows because young, extremely hot stars like these are emitting intense ultraviolet light which strips the surrounding gas of its electrons and causes it to emit the faint glow seen in this image. Given the right conditions, this material could one day collapse in on itself and provide the Milky Way with yet another brood of stars — a star formation process that may continue indefinitely.

This mammoth 30 577 x 20 108 pixel image was captured using the OmegaCAM camera, which is attached to the VLT Survey Telescope (VST) at ESO’s Paranal Observatory in Chile.

9 Aug 2016

Celebrate the Royal Greenwich Observatory

45 Years-ago the magnificent 28 inch refractor returned to the Royal Greenwich Observatory after a period of safe keeping. It was housed at Herstmonceux Castle for a while, then on 23 October 1971 Sir Patrick Moore was on hand to record the event for the BBC Sky at Night program.

In July I went back to the Royal Greenwich Observatory to meet the Curator Dr Louise Devoy, who was kind enough to show me around and learn something about the other telescopes their. Then I went over to see the 28 inch refractor itself. It is the 10th biggest refractor telescope in the world today, and the only one that visitors can look through on observational nights at Greenwich.

The Royal Greenwich Observatory was established in 1675 by King Charles II to find a means of measuring Longitude so mariners would not get lost at sea. The King appointed John Flamsteed as the first astronomer Royal.

The Cassini Solstice mission roles on as planet’s shadow shortens

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Turning a midsummer night's dream into reality, NASA's Cassini spacecraft began its new mission extension -- the Cassini Solstice Mission – in September 2010. The mission extension takes Cassini a few months past Saturn's northern summer solstice (or midsummer) through September 2017.

A complete seasonal period on Saturn has never been studied at this level of detail.

The shadow of Saturn on the rings, which stretched across all of the rings earlier in Cassini's mission (see PIA08362), now barely makes it past the Cassini division.

The changing length of the shadow marks the passing of the seasons on Saturn. As the planet nears its northern-hemisphere solstice in May 2017, the shadow will get even shorter. At solstice, the shadow's edge will be about 28,000 miles (45,000 kilometres) from the planet's surface, barely making it past the middle of the B ring.

The moon Mimas is a few pixels wide, near the lower left in this image.

This view looks toward the sunlit side of the rings from about 35 degrees above the ring plane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on May 21, 2016.

The view was obtained at a distance of approximately 2.0 million miles (3.2 million kilometres) from Saturn. Image scale is 120 miles (190 kilometres) per pixel.

8 Aug 2016

Rainer Weiss wins Kavli Prize in Astrophysics

MIT-rainer-weiss_0

LIGO inventor shares award for direct detection of gravitational waves.

Rainer Weiss, emeritus professor of physics, is a recipient of the 2016 Kavli Prize in Astrophysics. The Kavli Prizes are awarded biennially to recognize scientists who have made seminal advances in three categories: astrophysics, nanoscience, and neuroscience.

Weiss will share the prize, including a cash award of $1 million, with Ronald Drever, emeritus professor of physics at Caltech, and Kip Thorne, Caltech’s Richard P. Feynman Professor of Theoretical Physics, emeritus. The three scientists, who are co-founders of the Laser Interferometer Gravitational-wave Observatory (LIGO), have received the prize for the direct detection of gravitational waves, according to the award citation:

“This detection has, in a single stroke and for the first time, validated Einstein’s General Theory of Relativity for very strong fields, established the nature of gravitational waves, demonstrated the existence of black holes with masses 30 times that of our sun, and opened a new window on the universe.”

On September 14, 2015, LIGO’s two interferometers — one in Washington, the other in Louisiana — picked up a signal that lasted just one-fifth of a second. For the next few months, LIGO scientists around the world would carefully analyse, verify, and verify again, to determine that this signal represented the first direct detection of gravitational waves — ripples across the universe, created by extreme cataclysmic events billions of years ago.

The scientists determined that the incredibly faint signal was produced by the spectacularly violent collision of two black holes, each about 30 times as massive as the sun, 1.3 billion light years away.

Announcing the Kavli Astrophysics recipients, in an address in Oslo, Norway, Mats Carlsson, chair of the astrophysics committee, read from the award citation:

“The detection of gravitational waves is an achievement for which hundreds of scientists, engineers, and technicians around the world share credit. Drever, Thorne, and Weiss stand out: Their ingenuity, inspiration, intellectual leadership, and tenacity were the driving force behind this epic discovery.”

Pushing for a signal

In 1972, Weiss had worked out the basic concept for an interferometer to detect gravitational waves — an idea he originally drew up as an exercise for students in his general relativity course at MIT. His concept would eventually serve as the essential blueprint for LIGO.

From LIGO’s earliest days to its most recent detection, “Weiss provided technical leadership and devoted his extraordinary experimental acumen over the next decades, contributing to every aspect of the final apparatus,” the citation reads.

In 1974, a research team led by physicists Russell Hulse and Joseph Taylor made the first detection of gravitational waves, by analysing the behaviour of two orbiting neutron stars — a detection for which the pair was awarded the Nobel Prize in physics in 1993. The detection, however, was not a direct one.

In 1975, Weiss and Thorne met for the first time at a NASA committee meeting in Washington, D.C., where they began to think about how Weiss’ interferometer design could be scaled up to make a direct detection of gravitational waves. Since the 1960s, Thorne had been evaluating how extreme events such as colliding black holes and neutron stars generate gravitational waves, and how those waves might be detected from Earth.

Weiss and Thorne pushed the concept of LIGO through numerous hurdles in funding and design, and eventually oversaw the observatory’s construction, in the form of two identical and massive instruments, each 4 kilometres long and 3,000 kilometres apart.

In 1979, Drever joined the team as the third co-founder of LIGO, and helped to perfect the design and operation of the interferometers, devising ways to increase the power and efficiency of the optical systems central to LIGO’s sensitivity.

“For the first time in history we can explore the universe’s mysteries in three regimes: electromagnetic, particle, and gravitational regime,” said France Córdova, director of the National Science Foundation, who spoke as part of the awards announcement.

“Humming with signals”

Weiss received his BS in 1955 and his PhD in 1962, both from MIT. After appointments at Tufts University and Princeton University, Weiss returned to MIT as a faculty member in 1964. He has also served as an adjunct professor of physics at Louisiana State University since 2011. Weiss is a co-founder and science advisor of the NASA Cosmic Background Explorer (COBE) satellite mission, which measured the spectrum of cosmic microwave background radiation supporting the Big Bang scenario. 

Weiss has received numerous awards and honours, including the 2003 Medaille de l’ADION, the 2006 Gruber Prize in Cosmology, and the 2007 Einstein Prize of the American Physical Society. He is a fellow of the American Association for the Advancement of Science, the American Academy of Arts and Sciences, and the American Physical Society, as well as a member of the National Academy of Sciences. Earlier this year, Weiss received a Special Breakthrough Prize in Fundamental Physics and the 2016 Gruber Prize in Cosmology, both shared with Drever and Thorne. Most recently, the three co-founders were also awarded the Shaw Prize in Astronomy.

Today, Weiss and Thorne watched a live broadcast of the Kavli Prize announcement from New York, as part of the World Science Festival. As their names were announced, the pair, who are close friends, shared a hug, to a standing ovation.

In a panel held after the Kavli Prize announcement to discuss the significance of each Kavli Prize, Nergis Malvalvala, who is the Curtis and Kathleen Marble Professor of Astrophysics and associate head of the Department of Physics at MIT, a LIGO team member, and a former student of Weiss’, said of LIGO’s future: “We have so much still to do. We’ve really just uncovered the very first signal. The universe is humming with signals we have yet to pick up.”

7 Aug 2016

NASA peers inside a rocket plume imaged for the first time

You’ve never truly seen what a rocket plume looks like. They are extremely bright and therefore, have never been photographed properly and unless you want to stare directly into one, it’ll be nearly impossible to imagine. Although that’s difficult, considering there haven’t been cameras that could capture its image before.

However, NASA unveiled a new camera during its recent space launch test, which is able to show the detail in a rocket plume. And it looks pretty spectacular.

Normally cameras can’t properly capture something like a rocket plume. You can fiddle with the exposure settings, but reducing them darkens the rest of the image. Most cameras also only record one exposure at a time.

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However, the new High Dynamic Range Stereo X (HiDyRS-X) project overcomes this by being able to record multiple slow motion exposures at once and combining them into a more high-quality video. It uses a similar technique to what night photographers use when they splice multiple images together in post to get an impressive image.

The photo below is of the plume taken without the camera, so you can clearly see the difference.

Photo credit: NASA

According to a statement from NASA, scientists tried out the camera while testing its booster, QM-2. They monitored the camera from a safe distance, but its automatic timer failed to go off, meaning scientists had to start it manually.

And apparently, the force of the booster test was so great that it disconnected the camera’s power source. So NASA got confirmation that its camera works, but also that its rocket is very powerful.

Currently, this is just a prototype. Scientists plan to build a second one with more advanced capabilities, including with alignment. We’re looking forward to seeing more amazing photos, NASA! Don’t keep us waiting.

6 Aug 2016

Comet Panstarrs X1 is a spectacle in the celestial hare

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2016 July 24 18h04m UT, FLI PL16200, ASA 12" f/3.6. LRGB 8/4/4/4 min., Farm Tivoli, Namibia, Remote © 2016 Gerald Rhemann

panstars

Despite being rather faint, Mag 12, Panstarrs X1 is putting on a nice show for observers in the southern hemisphere. The comet is in the constellation of Hydra and lies close to the stat Pi Hydrae.

On 14 August the comet can be found at:

RA 14h 19m 52.7s DEC –29 53’ 08”

The above photograph was taken on the night of 24 July 2016 when Panstarrs X1 was in the constellation of Centaurus.

5 Aug 2016

The Night Sky for 15 August

tonights sky 2

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This is the night sky at 10pm for the middle of August. The Summer Triangle is prominent, it is made up from the bright stars Deneb in Cygnus, Vega in Lyra, and Altair in Aquila the eagle. The constellations of Autumn are now rising in the East, so the great Andromeda galaxy (M31) is on display for binocular observers. Scan across the Milky Way and you will many nice star clusters, and in the constellation of Hercules try to view the bright globular cluster (M13). Click on the image for more detailed information about the planets & constellations now on view in The Sky at Night.

4 Aug 2016

A postcard from Dawn: Liber crater

PIA20863Another postcard from NASA’s Dawn spacecraft.

This view features Liber Crater (14 miles, 23 kilometres wide) in Ceres' northern hemisphere, at right.

Dawn took this image on June 17, 2016, from its low-altitude mapping orbit, at a distance of about 240 miles (385 kilometres) above the surface. The image resolution is 120 feet (35 meters) per pixel.

Image Credit: NASA/JPL Caltech/UCLA/MPS/DLR/IDA

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In the next program of Astronomy & Space we will be looking at the Asteroids of the solar system. Including NASA's new asteroid-sampling mission OSIRIS-REx. It will be available to watch from 29 August.

Scientists discover Ceres to be an icy ‘slush ball’ in space

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The minor planet Ceres is the largest of the Minor planets, situated in the large gap between the planets Mars & Jupiter. It is 427 miles in diameter and takes just over 4 1/2 years to orbit around the Sun.

NASA’s Dawn spacecraft has been in orbit around Ceres for the last year taking hundreds of photographs, and making careful science observations.

Since gravity dominates Dawn's orbit at Ceres, scientists can measure variations in Ceres’ gravity by tracking subtle changes in the motion of the spacecraft. Using data from Dawn, scientists have mapped the variations in Ceres' gravity for the first time in a new study in the journal Nature, which provides clues to the dwarf planet's internal structure.

"The new data suggest that Ceres has a weak interior, and that water and other light materials partially separated from rock during a heating phase early in its history," said Ryan Park, the study’s lead author and the supervisor of the solar system dynamics group at NASA’s Jet Propulsion Laboratory, Pasadena, California.

Ceres' gravity field is measured by monitoring radio signals sent to Dawn, and then received back on Earth, by NASA’s Deep Space Network. This network is a collection of large antennas at three locations around the globe that communicate with interplanetary spacecraft. Using these signals, scientists can measure the spacecraft's speed to a precision of 0.004 inches (0.1 millimetres) per second, and then calculate the details of the gravity field.

Ceres has a special property called "hydrostatic equilibrium," which was confirmed in this study. This means that Ceres' interior is weak enough that its shape is governed by how it rotates. Scientists reached this conclusion by comparing Ceres' gravity field to its shape. Ceres' hydrostatic equilibrium is one reason why astronomers classified the body as a dwarf planet in 2006.

The data indicate that Ceres is “differentiated,” which means that it has compositionally distinct layers at different depths, with the densest layer at the core. Scientists also have found that, as they suspected, Ceres is much less dense than Earth, the moon, giant asteroid Vesta (Dawn’s previous target) and other rocky bodies in our solar system. Additionally, Ceres has long been suspected to contain low-density materials such as water ice, which the study shows separated from the rocky material and rose to the outer layer along with other light materials.

pia20358_main"We have found that the divisions between different layers are less pronounced inside Ceres than the moon and other planets in our solar system," Park said. “Earth, with its metallic core, semi-fluid mantle and outer crust, has a more clearly defined structure than Ceres," Park said.

Scientists also found that high-elevation areas on Ceres displace mass in the interior. This is analogous to how a boat floats on water: the amount of displaced water depends on the mass of the boat. Similarly, scientists conclude that Ceres’ weak mantle can be pushed aside by the mass of mountains and other high topography in the outermost layer as though the high-elevation areas "float" on the material below. This phenomenon has been observed on other planets, including Earth, but this study is the first to confirm it at Ceres.

The internal density structure, based on the new gravity data, teaches scientists about what internal processes could have occurred during the early history of Ceres. By combining this new information with previous data from Dawn about Ceres' surface composition, they can reconstruct that history: Water must have been mobile in the ancient subsurface, but the interior did not heat up to the temperatures at which silicates melt and a metallic core forms.

"We know from previous Dawn studies that there must have been interactions between water and rock inside Ceres," said Carol Raymond, a co-author and Dawn’s deputy principal investigator based at JPL. "That, combined with the new density structure, tells us that Ceres experienced a complex thermal history."

3 Aug 2016

The Fluctuating Atmosphere of Jupiter’s Volcanic Moon

nh-io-seriesJupiter’s volcanic moon Io has a thin atmosphere that collapses in the shadow of Jupiter, condensing as ice, according to a new study by NASA-funded researchers. The study reveals the freezing effects of Jupiter’s shadow during daily eclipses on the moon’s volcanic gases.

“This research is the first time scientists have observed this remarkable phenomenon directly, improving our understanding of this geologically active moon,” said Constantine Tsang, a scientist at the Southwest Research Institute in Boulder, Colorado. The study was published Aug. 2 in the Journal of Geophysical Research.

Io is the most volcanically active object in the solar system. The volcanoes are caused by tidal heating, the result of gravitational forces from Jupiter and other moons. These forces result in geological activity, most notably volcanoes that emit umbrella-like plumes of sulphur dioxide gas that can extend up to 300 miles (480 kilometres) above Io and produce extensive basaltic lava fields that can flow for hundreds of miles.

io_sulfur_dioxide_geyser_1280The new study documents atmospheric changes on Io as the giant planet casts its shadow over the moon’s surface during daily eclipses. Io’s thin atmosphere, which consists primarily of sulphur dioxide (SO2) gas emitted from volcanoes, collapses as the SO2 freezes onto the surface as ice when Io is shaded by Jupiter, then is restored when the ice warms and sublimes (I.e. transforms from solid back to gas) when the moon moves out of eclipse back into sunlight.

The study used the large eight-meter Gemini North telescope in Hawaii and an instrument called the Texas Echelon Cross Echelle Spectrograph (TEXES). Data showed that Io’s atmosphere begins to “deflate” when the temperatures drop from -235 degrees Fahrenheit in sunlight to -270 degrees Fahrenheit during eclipse. Eclipse occurs two hours of every Io day (1.7 Earth days). In full eclipse, the atmosphere effectively collapses, as most of the sulphur dioxide gas settles as frost on the moon’s surface. The atmosphere redevelops as the surface warms once the moon returns to full sunlight.

“This confirms that Io’s atmosphere is in a constant state of collapse and repair, and shows that a large fraction of the atmosphere is supported by sublimation of SO2 ice,” said John Spencer, a co-author of the new study, also at the Southwest Research Institute. “Though Io’s hyperactive volcanoes are the ultimate source of the SO2, sunlight controls the atmospheric pressure on a daily basis by controlling the temperature of the ice on the surface.  We’ve long suspected this, but can finally watch it happen.”

Io_diagram_svgPrior to the study, no direct observations of Io’s atmosphere in eclipse had been possible because Io’s atmosphere is difficult to observe in the darkness of Jupiter’s shadow.  This breakthrough was possible because TEXES measures the atmosphere using heat radiation, not sunlight, and the giant Gemini telescope can sense the faint heat signature of Io’s collapsing atmosphere.

The observations occurred over two nights in November 2013, when Io was more than 420 million miles (675 million kilometres) from Earth. On both occasions, Io was observed moving into Jupiter’s shadow for a period about 40 minutes before and after the start of the eclipse.

The research was funded by NASA’s Solar System Workings and Solar System Observations programs.

27 Jul 2016

Loneliest Young Star Seen by NASA’s Spitzer and WISE space telescopes

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Alone on the cosmic road, far from any known celestial object, a young, independent star is going through a tremendous growth spurt.

The unusual object, called CX330, was first detected as a source of X-ray light in 2009 by NASA's Chandra X-Ray Observatory while it was surveying the bulge in the central region of the Milky Way. Further observations indicated that this object was emitting optical light as well. With only these clues, scientists had no idea what this object was.

But when Chris Britt, postdoctoral researcher at Texas Tech University in Lubbock, and colleagues were examining infrared images of the same area taken with NASA's Wide-field Infrared Survey Explorer (WISE), they realized this object has a lot of warm dust around it, which must have been heated by an outburst.

Comparing WISE data from 2010 with Spitzer Space Telescope data from 2007, researchers determined that CX330 is likely a young star that had been out bursting for several years. In fact, in that three-year period its brightness had increased by a few hundred times.

Astronomers looked at data about the object from a variety of other observatories, including the ground-based SOAR, Magellan, and Gemini telescopes. They also used the large telescope surveys VVV and the OGLE-IV to measure the intensity of light emitted from CX330. By combining all of these different perspectives on the object, a clearer picture emerged.

"We tried various interpretations for it, and the only one that makes sense is that this rapidly growing young star is forming in the middle of nowhere," said Britt, lead author of a study on CX330 recently published in the Monthly Notices of the Royal Astronomical Society.

The lone star's behaviour has similarities to FU Orionis, a young out bursting star that had an initial three-month outburst in 1936-7. But CX330 is more compact, hotter and likely more massive than the FU Orionis-like objects known. The more isolated star launches faster "jets," or outflows of material that slam into the gas and dust around it.

"The disk has probably heated to the point where the gas in the disk has become ionized, leading to a rapid increase in how fast the material falls onto the star," said Thomas Maccarone, study co-author and associate professor at Texas Tech.

Most puzzling to astronomers, FU Orionis and the rare objects like it -- there are only about 10 of them -- are located in star-forming regions. Young stars usually form and feed from their surrounding gas and dust-rich regions in star-forming clouds. By contrast, the region of star formation closest to CX330 is over a thousand light-years away.

"CX330 is both more intense and more isolated than any of these young out bursting objects that we've ever seen," said Joel Green, study co-author and researcher at the Space Telescope Science Institute in Baltimore. "This could be the tip of the iceberg -- these objects may be everywhere."

In fact, it is possible that all stars go through this dramatic stage of development in their youth, but that the outbursts are too short in cosmological time for humans to observe many of them.

How did CX330 become so isolated? One idea is that it may have been born in a star-forming region, but was ejected into its present lonely pocket of the galaxy. But this is unlikely, astronomers say. Because CX330 is in a youthful phase of its development -- likely less than 1 million years old -- and is still eating its surrounding disk, it must have formed near its present location in the sky.

"If it had migrated from a star-forming region, it couldn't get there in its lifetime without stripping its disk away entirely," Britt said.

CX330 may also help scientists study the way stars form under different circumstances. One scenario is that stars form through turbulence. In this "hierarchical" model, a critical density of gas in a cloud causes the cloud to gravitationally collapse into a star. A different model, called "competitive accretion," suggests that stars begin as low-mass cores that fight over the mass of material left in the cloud. CX330 more naturally fits into the first scenario, as the turbulent circumstances would theoretically allow for a lone star to form.

It is still possible that other intermediate- to low-mass stars are in the immediate vicinity of CX330, but have not been detected yet.

When CX330 was last viewed in August 2015, it was still out bursting. Astronomers plan to continue studying the object, including with future telescopes that could view it in other wavelengths of light.

Outbursts from a young star change the chemistry of the star's disk, from which planets may eventually form. If the phenomenon is common, that means that planets, including our own, may carry the chemical signatures of an ancient disk of gas and dust scarred by stellar outbursts.

But as CX330 is continuing to devour its disk with increasing voracity, astronomers do not expect that planets are forming in its system.

"If it's truly a massive star, its lifetime is short and violent, and I wouldn't recommend being a planet around it," Green said. "You could experience some pretty intense heat for a few centuries."

The Chandra X-ray satellite Finds Evidence for Violent Stellar Merger

Coordinates (J2000) RA 15h 52m 03.27s | Dec +27° 36' 09.30" Constellation Corona Borealis

coGamma-ray bursts, or GRBs, are some of the most violent and energetic events in the Universe. Although these events are the most luminous explosions in the universe, a new study using NASA's Chandra X-ray Observatory, NASA's Swift satellite and other telescopes suggests that scientists may be missing a majority of these powerful cosmic detonations.

Astronomers think that some GRBs are the product of the collision and merger of two neutron stars or a neutron star and a black hole. The new research gives the best evidence to date that such collisions will generate a very narrow beam, or jet, of gamma rays. If such a narrow jet is not pointed toward Earth, the GRB produced by the collision will not be detected.

Collisions between two neutron stars or a neutron star and black hole are expected to be strong sources of gravitational waves that could be detected whether or not the jet is pointed towards the Earth. Therefore, this result has important implications for the number of events that will be detectable by the Laser Interferometry Gravitational-Wave Observatory (LIGO) and other gravitational wave observatories.

On September 3, 2014, NASA's Swift observatory picked up a GRB - dubbed GRB 140903A due to the date it was detected. Scientists used optical observations with the Gemini Observatory telescope in Hawaii to determine that GRB 140903A was located in a galaxy about 3.9 billion light years away, relatively nearby for a GRB.

Chandra Finds Evidence for Violent Stellar Merger

The large panel in the graphic is an illustration showing the aftermath of a neutron star merger, including the generation of a GRB. In the center is a compact object - either a black hole or a massive neutron star - and in red is a disk of material left over from the merger, containing material falling towards the compact object. Energy from this infalling material drives the GRB jet shown in yellow. In orange is a wind of particles blowing away from the disk and in blue is material ejected from the compact object and expanding at very high speeds of about one tenth the speed of light.

The image on the left of the two smaller panels shows an optical view from the Discovery Channel Telescope (DCT) with GRB 140903A in the middle of the square and a close-up X-ray view from Chandra on the right. The bright star in the optical image is unrelated to the GRB.

The gamma-ray blast lasted less than two seconds. This placed it into the "short GRB" category, which astronomers think are the output from neutron star-neutron star or black hole-neutron star collisions eventually forming either a black hole or a neutron star with a strong magnetic field. (The scientific consensus is that GRBs that last longer than two seconds result from the collapse of a massive star.)

About three weeks after the Swift discovery of GRB 140903A, a team of researchers led by Eleonora Troja of the University of Maryland, College Park (UMD), observed the aftermath of the GRB in X-rays with Chandra. Chandra observations of how the X-ray emission from this GRB decreases over time provide important information about the properties of the jet.

Specifically, the researchers found that the jet is beamed into an angle of only about five degrees based on the X-ray observations, plus optical observations with the Gemini Observatory and the DCT and radio observations with the National Science Foundation's Karl G. Jansky Very Large Array. This is roughly equivalent to a circle with the diameter of your three middle fingers held at arms length. This means that astronomers are detecting only about 0.4% of this type of GRB when it goes off, since in most cases the jet will not be pointed directly at us.

Previous studies by other astronomers had suggested that these mergers could produce narrow jets. However, the evidence in those cases was not as strong because the rapid decline in light was not observed at multiple wavelengths, allowing for explanations not involving jets.

Several pieces of evidence link this event to the merger of two neutron stars, or between a neutron star and black hole. These include the properties of the gamma ray emission, the old age and the low rate of stars forming in the GRB's host galaxy and the lack of a bright supernova. In some previous cases strong evidence for this connection was not found.

New studies have suggested that such mergers could be the production site of elements heavier than iron, such as gold. Therefore, the rate of these events is also important to estimate the total amount of heavy elements produced by these mergers and compare it with the amounts observed in the Milky Way galaxy.

NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

Magnetic reconnection on the Sun caught in the act

When two magnetic field lines connect and form a new one that “short-circuits” the magnetic field, one speaks of magnetic reconnection. These events can release large amounts of energy and play an important role in heating the upper layers of the solar atmosphere where they frequently occur. The direct observation of this phenomenon is difficult as reconnections occur on short time scales. Besides this, the structures that need to be observed are very small. An international team of researchers with participation from the Max Planck Institute for Solar System Research (MPS) now succeeded in in observing such a reconnection directly and in detail. With their results which appear today in the journal “Nature Physics” they confirm theoretical calculations.

Magnetic fields play a crucial role everywhere in the universe, be it during the formation of the first structures in the early universe, during star formation, or in activity cycles of the Sun and other stars. Often magnetic fields are visualized as strings connecting poles of opposite magnetic polarities. However, unlike strings magnetic field lines can reconnect and through this reconfigure the magnetic structure. This phenomenon is termed magnetic reconnection. During such a reconnection significant amounts of magnetic energy are converted into other forms of energy, e.g. into kinetic energy through particle acceleration of internal energy through heating. Theoretical models predict how magnetic reconnections should proceed in detail. However, a confirmation of the theory via observations proves to be difficult. Now a direct observation was made for the first time.

standard_sans_both

Temperature enhancements (shown as red and yellow colours) of the plasmids in the X-type reconnection region. The dashed and dotted lines indicate the location of the magnetic field lines forming the X-shaped reconnection regions. In the red regions the temperature rises to several million degrees. L2 and L3 point out the location of pre-existing coronal structures that eventually recombine. The field-of-view of the region corresponds to a side length of 90.000 km. The small regions with high temperatures near the green or red arrows have diameters of about 3000 km, I.e. they are bigger than Europe.

Image: Key Laboratory of Solar Activity/NAO, Chinese Academy of Sciences

 

 

 

Through the release of energy magnetic reconnection is one of the key mechanisms for the heating of the outermost layer of the solar atmosphere, the so-called corona. For reasons not entirely understood, this layer is more than a million degrees hot, much hotter than layers below. To the naked eye the corona is only visible during a total solar eclipse. In the extreme ultraviolet it can be observed at all times with adequate instruments, for example with the Atmospheric Imaging Assembly (AIA) instrument on board the Solar Dynamics Observatory (SDO).

It was images taken by this satellite, together with magnetic field measurements provided by the Helioseismic and Magnetic Imager (HMI) – also on board SDO - that the researchers have analysed for their study. They found a particularly important variety of magnetic reconnection, the so-called X-type reconnection. In this variety, the field lines are arranged in an X-like shape for a short time.

"We see here a clear example of X-type reconnection on the Sun with all the details predicted by theory" says Hardi Peter from MPS. He worked on the interpretation of the data relating them to theory, and is particularly intrigued by the clearly visible plasmids. These are pockets that are isolated from their surroundings by the magnetic fields. "The magnetic field lines have the form of an X with an elongated line at the crossing of the X. Here we can see small islands of magnetic field where we see an enhanced temperature, just as theory predicts". While observers looked for these roundish enhancements of temperature, it was rare that hints for these were found and never with this clarity.

This observation confirms that hot plasmids play an important role in magnetic reconnections in the solar atmosphere. It also opens new aspects in the interpretation of other phenomena on the Sun. For example they support the theory according to which spectroscopic signatures in the smallest, unresolved structures could also be caused by plasmids.

The Sun’s hidden magnetic field during grand minimum

The Sun has an 11-year cycle that involves, among other things, the occurrence and disappearance of sunspots as well as strong changes in the global magnetic field of the Sun. A study conducted by the ReSoLVE Centre of Excellence at Aalto University in Finland with participation of the Max Planck Institute for Solar System Research (MPS) in Göttingen now investigated the mechanisms underlying these long-term variations in solar activity. The research team lead by Maarit Käpylä ran a global computer model of the Sun on Finland’s most powerful super computer over a period of six months. Their results surprisingly show that the Sun's magnetic field during a grand minimum is in fact at maximum. At the same time, they created the world’s longest numerical simulation that produces a solar-like dynamo solution complete with its long-term variation.

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The most striking result of the study which was published in the May issue of the journal "Astronomy & Astrophysics" relates to the Sun’s silent periods known as grand minima, of which the Maunder Minimum is perhaps the best known. During this minimum which occurred between the years 1650 and 1700 astronomers could barely detect any sunspots despite their dedicated observing efforts. At the same time, the climate changed, and the Little Ice Age is known to have occurred in Europe, North America and China. The solar magnetic field was thought to wither during such grand minima and be so weak as not being capable of generating sunspots or other activity. The study now shows that in fact, the magnetic field was at its maximum during the Maunder Minimum.

‘The phenomena that occur in the Sun – including the cycle – change with time, so the behaviour need to be investigated over a long time span. Short-term variation is not interesting for the purposes of studying the space climate, for example,’ says Maarit Käpylä, who is the head of the DYNAMO team in the ReSoLVE (Research on SOlar Long-term Variability and Effects) Centre of Excellence and also conducts astroinformatics or computational astrophysics and data-analysis at the Department of Computer Science at Aalto University.

For their study the researchers used computer codes to simulate the processes taking place in our Sun. With their computation they created the world’s longest numerical simulation that produces a solar-like dynamo solution complete with its long-term variation. 'The increasing computer power enables us to model the Sun and its magnetic evolution in great detail. We hope that in a few years our models can answer the long standing question why we have an 11-years cycle.' says co-author Jörn Warnecke who is a Marie-Curie fellow at the MPS. Unlike observations the simulations allow to study not only the surface but provide a three-dimensional representation of the magnetically active part of the Sun.

'Thus far, we have only been able to examine what is visible on the solar surface, but simulations enable us to see below the surface. During the Maunder Minimum, the magnetic field sinks to the bottom of the convection zone and is very strong there,’ says Käpylä.

The outer layer of the Sun, the convection zone, is like a boiling kettle with its moving and heat-transferring bubbles. This not only generates a magnetic field, but also makes the entire area turbulent and extremely challenging to model. ‘The Sun as such is impossible to replicate on present-day computers – or those of the near future – due to its strong turbulence. And indeed we are not claiming that this modelling would really be the Sun. Instead, it is a 3D construction of various solar phenomena by means of which the star that runs our space climate can be better understood,’ Käpylä explains.

Maarit Käpylä will start as an independent group leader at the MPS in June 2016. From September onwards her newly formed group will conduct research on solar and stellar magnetic activity. This involves 3D numerical simulation using high performance computing modelling the Sun and other stars as well as the observation of solar-like stars to determine the properties of their magnetic cycles. The operations of the Aalto DYNAMO team  will continue under Käpylä’s direction, and both the German and the Finnish teams will focus on even larger simulations using graphical processing units.

All Sun type stars rotate in the same way

standard_fullOur Sun is an ordinary star. It is 186,000 miles in diameter, and is an incandescent ball of mainly hydrogen gas. It does not rotate as a sold body, at the equator the rotation period is about 25 earth days.

The Sun is a G-type main-sequence star (G2V) based on spectral class and is informally referred to as a yellow dwarf, making it yellowish in colour. It has a regular sunspot cycle of 11 years (we are presently edging towards sunspot minimum). Up until now astronomers did not know for certain whether others stars like the Sun had a similar rotation period.

Dr. Martin Bo Nielsen  of the International Max Planck Research School for Solar System Science, has for the first time been able to narrow in his thesis how much the rotation inside sun like stars changed. The change in rotation inside the sun is regarded as one of the principal mechanisms that drive the magnetic activity of the sun. Dr. Nielsen used current data from NASA’s Kepler satellite over several years. He determined the surface rotation by the movement of star spots and measured the rotation in deeper layers by studying vibrations inside the stars. By combining both methods, he succeeded for the first time to determine an upper limit on the change in rotation in depth and latitude of five sun-like stars.

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Indeed the rotation period matched that of the Sun, which is significant. We now know that most sun type stars behave in a similar way, which helps astronomers in the hunt for Earth like habitable planets.

The thesis was supervised by Prof. Dr. Laurent Gizon from the Institute of Astrophysics of the University of Göttingen and Dr. Hannah Schunker from Göttingen Max Planck Institute for Solar System Research.

Kontaktadressen:
Zur Absolventenfeier:
Veronika Lemburg
Georg-August-Universität Göttingen
Fakultät für Physik – Studiendekanat
E-Mail: veronika.lemburg@phys.uni-goettingen.de

Sky Diary August 2016

Aug 15 11pm N HemAug 15 11pm S Hem

 

 

 

 

 

 

 

 

 

 

 

 

 

NORTHERN HEMISPHERE AUGUST 15TH AT 23:00 UT ---- SOUTHERN HEMISPHERE AUGUST 15TH AT 23:00 UT
Click on all images to enlarge


MARS Aug 2016During August the nights are steadily getting longer. Here in the UK sunset on 1 August is at 7:48pm UT and at the end of the month the sun sets an hour earlier. In the southern hemisphere at latitude -30° the sunsets at 5:28pm on 1 August and 5:44pm at the end of the month. The time difference is due to the Earth’s axial tilt of 23½°; it is summer in the northern hemisphere so the North Pole is pointing sunwards, and the South Pole is pointing away from the Sun.

From mid month the planet Venus shining at Mag -3.9 becomes visible in the western sky after sunset. Its elongation from the sun increases from 16° to 23° during the month. Its phase is almost full, while is angular size is about 10.4 arc seconds. There are two nice photo opportunities to look forward to this month. Venus is 1.1°N of Regulus on 5 August and just 0.07°N of Jupiter on the 27th when it will be nice to see both planets close together. Incidentally, the NASA JUNO probe will passing close to Jupiter on 27th making its first science observation.

The planet Mars lies in the constellation of Scorpius during August, and is slowly fading from Mag -0.7 to -0.3. The planets small angular size is also decreasing, and this will be 11.6 arc seconds mid month so that a moderate size telescope will be needed to observe the planet. Mars is 1.8° N of Antares on 24 August and 4 ° S of Saturn on 25th August.

The planet Jupiter shining at -1.7 is visible through out August, and continues to be a lovely sight in small telescopes. There will be an occultation of Jupiter by the Moon at 04 h UT on 6th August, which will be visible from: South East Asia, Papua New Guinea, NW Australia, and Pacific Islands.

The planet Saturn shining at Mag +0.3 is visible throughout the night. It will be 12°S of the Moon on 12 August.

The planet Uranus shining at Mag 5.8 lies in the middle of Pisces (The fishes). On Aug 1st RA 01h 31m 42s DEC +8° 55’ 04” & Aug 15th RA 01h 31m 19s DEC +8° 52’ 28”

The planet Neptune shining at Mag 7.8 lies next to the star Lambda-Aquarii. On Aug 1st Mag +7.8 RA 22h 52m 56s DEC -8° 03’ 54.8”

SKY DIARY [All times are UT : Universal Time]

02 21h : New Moon 18 09h ; Full Moon
04 06h : Venus 4 deg N of the Moon 19 12h : Neptune 1.1 deg S of Moon (Occultation)
04 22h : Mercury 0.6 deg N of the Moon 20 12h : Pallas at opposition
05 09h : Venus 1.1 deg N of Regulus 22 10h : Uranus 3 deg S of the Moon
06 04h :Jupiter 0.2 deg N of Moon (Occultation) 24 04h : Mars 1.8 deg N of Antares
10 00h : Moon at apogee 25 04h : Last Quarter
10 18h : First Quarter 25 17h : Aldebaran 0.2 deg S of Moon (Occultation)
11 22h : Mars 8 deg S of the Moon 25 18h : Mars 4 deg S of the Moon
12 12h : Saturn 4 deg S of the Moon 27 05h : Mercury 5 deg S of Venus
13 18h : Saturn stationary 27 22h : Venus 0.07 deg N of Jupiter
16 21h : Mercury greatest Elong E (27 degrees) 30 01h : Mercury stationary

Moons phases

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26 Jul 2016

The 28 inch telescope return’s to Greenwich

FOURTY FIVE years ago the 28 inch refractor telescope was returned to the the Royal Greenwich Observatory from Herstmonceux, after a period of safe keeping.

The telescope was originally housed at the Royal Greenwich Observatory up until the start of World War 2, then the telescope was stored in a safe place. Just as well because a bomb fell nearby damaging the telescope dome it was housed in. Following the last war the move to Herstmonceux was planned because Greenwich Park had become unsuitable a site for observations. The onion dome was taken down and the 28 inch was set up at a new dome at Herstmonceux castle.

Sir Patrick Moore was on hand to see the 28 inch return to the Royal Greenwich Observatory on 23 October 1971, and he made a Sky at Night program about it that was broadcast that December. These exclusive images are from Patrick Moore’s photo archive.

This month I went along to meet the Curator of the Royal Greenwich Observatory, Dr Louise Devoy, to see the magnificent 28 inch refractor in its onion shape dome, and learn about the other equatorial telescopes that was housed at the observatory; you can see my program on 29 July ….

Richard Pearson F.R.A.S.

25 Jul 2016

Our New YouTube Channel is up & running

I have now set up a new YouTube site for all of my Astronomy programs, a one stop shop for everyone to enjoy watching FREE educational programs on various topics relating to Astronomy & Space.

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Here you will also find 6 dedicated playlist that will allow you to spend an evening watching some of the best Astronomy programs while the skies outside are cloudy or it’s raining, and you just wish to pass the time.

Astronomy & Space 2016: All of the programs that have been broadcast since January of this year. My new program for August ‘Equatorial telescopes at the Royal Greenwich Observatory’ can also bee found here.

Astronomy & Space 2015: All of season two programs of Astronomy & Space

Astronomy & Space 2014: All of season one programs of Astronomy & Space

History of Astronomy: A channel dedicated to various aspects of the history of Astronomy

The Stars: Guides to the Winter, Spring, Summer & Autumn constellations. Stars of the far south, Supernovae and gravitational waves, along with a look at the oldest stars and the origin of the Universe.

The planets: The Sun, Moon, and planets of our Solar System.

18 Jul 2016

NASA release New image of Zadeni crater on Ceres taken by the DAWN spacecraft

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With an extended mission NASA’s DAWN spacecraft is still in orbit around Ceres, the largest of the minor planets. This moody scene on Ceres, above right, is located within Zadeni Crater, named for the ancient Georgian god of bountiful harvest. Zadeni is approximately 76 miles (120 kilometres) in diameter. Dawn took this image on June 15, 2016, from its low-altitude mapping orbit, at a distance of about 240 miles (385 kilometres) above the surface. The image resolution is 120 feet (35 meters) per pixel.

The image on the left is of the same crater taken at a greater height above the surface. For more information about the Dawn mission, visit http://dawn.jpl.nasa.gov.

Image Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

13 Jul 2016

Outburst Brings Water Snow Line Into View

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The constellation of Orion is in the news for the second time this week.

The Atacama Large radio telescope Array (ALMA) has made the first ever resolved observation of a water snow line within a protoplanetary disc. This line marks where the temperature in the disc surrounding a young star drops sufficiently low for snow to form. A dramatic increase in the brightness of the young star V883 Orionis flash heated the inner portion of the disc, pushing the water snow line out to a far greater distance than is normal for a protostar, and making it possible to observe it for the first time. The results are published in the journal Nature on 14 July 2016.

Young stars are often surrounded by dense, rotating discs of gas and dust, known as protoplanetary discs, from which planets are born. The heat from a typical young solar-type star means that the water within a protoplanetary disc is gaseous up to distances of around 3 au from the star [280 m miles] — less than 3 times the average distance between the Earth and the Sun. Further out, due to the extremely low pressure, the water molecules transition directly from a gaseous state to form a patina of ice on dust grains and other particles. The region in the protoplanetary disc where water transitions between the gas and solid phases is known as the water snow line.

Shifting water snowline in V883 OrionisBut the star V883 Orionis is unusual. A dramatic increase in its brightness has pushed the water snow line out to a distance of around 40 au (about 6 billion kilometres or roughly the size of the orbit of the dwarf planet Pluto in our Solar System). This huge increase, combined with the resolution of ALMA at long baselines, has allowed a team led by Lucas Cieza (Millennium ALMA Disk Nucleus and Universidad Diego Portales, Santiago, Chile) to make the first ever resolved observations of a water snow line in a protoplanetary disc.

The sudden brightening that V883 Orionis experienced is an example of what occurs when large amounts of material from the disc surrounding a young star fall onto its surface. V883 Orionis is only 30% more massive than the Sun, but thanks to the outburst it is experiencing, it is currently a staggering 400 times more luminous — and much hotter.

The star V883 Orionis in the constellation of OrionLead author Lucas Cieza explains: “The ALMA observations came as a surprise to us. Our observations were designed to look for disc fragmentation leading to planet formation. We saw none of that; instead, we found what looks like a ring at 40 au. This illustrates well the transformational power of ALMA, which delivers exciting results even if they are not the ones we were looking for.”

The bizarre idea of snow orbiting in space is fundamental to planet formation. The presence of water ice regulates the efficiency of the coagulation of dust grains — the first step in planet formation. Within the snow line, where water is vaporised, smaller, rocky planets like our own are believed to form. Outside the water snow line, the presence of water ice allows the rapid formation of cosmic snowballs, which eventually go on to form massive gaseous planets such as Jupiter.

The discovery that these outbursts may blast the water snow line to about 10 times its typical radius is very significant for the development of good planetary formation models. Such outbursts are believed to be a stage in the evolution of most planetary systems, so this may be the first observation of a common occurrence. In that case, this observation from ALMA could contribute significantly to a better understanding of how planets throughout the Universe formed and evolved.

The Earth in Space

Running Time: 40 minutes

Acknowledgements: The European Space Agency, The European Southern Observatory, NASA/Goddard, and Tom Pickett.

On 18 June 2015 British astronaut Tim Peake safely returned home after spending the last 6 months on board the International Space Station. Tim has had a unique vantage point to see the Earth from space, so now seems a good time to mark the occasion by taking a look at our planet in more detail.

In August our program comes from The Royal Greenwich Observatory. We will be joined by special guest Dr. Louise Devoy who is the curator of instruments there. She will be showing us the magnificent 28 inch refractor telescope, and describing the scopes’ fascinating history.

Richard Pearson F.R.A.S.

Astronomers study the inside of rotating Black Holes

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This artist's impression depicts the accretion disc surrounding a black hole, in which the inner region of the disc precesses. "Precession" means that the orbit of material surrounding the black hole changes orientation around the central object.

Ashampoo_Snap_2016.07.13_12h09m26s_001_The European Space Agency's orbiting X-ray observatory, XMM-Newton, has proved the existence of a "gravitational vortex" around a black hole. The discovery, aided by NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) mission, solves a mystery that has eluded astronomers for more than 30 years, and will allow them to map the behaviour of matter very close to black holes. It could also open the door to future investigations of Albert Einstein's general relativity.

Matter falling into a black hole heats up as it plunges to its doom. Before it passes into the black hole and is lost from view forever, it can reach millions of degrees. At that temperature it shines X-rays into space.

In the 1980s, pioneering astronomers using early X-ray telescopes discovered that the X-rays coming from stellar-mass black holes in our galaxy flicker. The changes follow a set pattern. When the flickering begins, the dimming and re-brightening can take 10 seconds to complete. As the days, weeks and then months progress, the period shortens until the oscillation takes place 10 times every second. Then, the flickering suddenly stops altogether.

The phenomenon was dubbed the Quasi Periodic Oscillation (QPO). "It was immediately recognized to be something fascinating because it is coming from something very close to a black hole," said Adam Ingram, University of Amsterdam, the Netherlands, who began working to understand QPOs for his doctoral thesis in 2009.

During the 1990s, astronomers had begun to suspect that the QPOs were associated with a gravitational effect predicted by Einstein's general relativity: that a spinning object will create a kind of gravitational vortex.

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"It is a bit like twisting a spoon in honey. Imagine that the honey is space and anything embedded in the honey will be "dragged" around by the twisting spoon," explained Ingram.  "In reality, this means that anything orbiting a spinning object will have its motion affected." In the case of an inclined orbit, it will "precess." This means that the whole orbit will change orientation around the central object. The time for the orbit to return to its initial condition is known as a precession cycle.

In 2004, NASA launched Gravity Probe B to measure this so-called Lens-Thirring effect around Earth. After painstaking analysis, scientists confirmed that the spacecraft would turn through a complete precession cycle once every 33 million years.

Around a black hole, however, the effect would be much more noticeable because of the stronger gravitational field. The precession cycle would take just a matter of seconds or less to complete. This is so close to the periods of the QPOs that astronomers began to suspect a link.

Ingram began working on the problem by looking at what happened in the flat disc of matter surrounding a black hole. Known as an accretion disc, it is the place where material gradually spirals inwards towards the black hole. Scientists had already suggested that, close to the black hole, the flat accretion disc puffs up into a hot plasma, in which electrons are stripped from their host atoms. Termed the hot inner flow, it shrinks in size over weeks and months as it is eaten by the black hole. Together with colleagues, Ingram published a paper in 2009 suggesting that the QPO is driven by the Lens-Thirring precession of this hot flow. This is because the smaller the inner flow becomes, the closer to the black hole it would approach and so the faster its Lens-Thirring precession cycle would be. The question was: how to prove it?

"We have spent a lot of time trying to find smoking gun evidence for this behaviour," said Ingram.

The answer is that the inner flow is releasing high-energy radiation that strikes the matter in the surrounding accretion disc, making the iron atoms in the disc shine like a fluorescent light tube. The iron releases X-rays of a single wavelength -- referred to as "a spectral line."

Because the accretion disc is rotating, the iron line has its wavelength distorted by the Doppler effect. Line emission from the approaching side of the disc is squashed -- blue shifted -- and line emission from the receding disc material is stretched -- red shifted. If the inner flow really is precessing, it will sometimes shine on the approaching disc material and sometimes on the receding material, making the line wobble back and forth over the course of a precession cycle.

Seeing this wobbling is where XMM-Newton came in. Ingram and colleagues from Amsterdam, Cambridge, Southampton and Tokyo applied for a long-duration observation that would allow them to watch the QPO repeatedly. They chose black hole H 1743-322, which was exhibiting a four-second QPO at the time. They watched it for 260,000 seconds with XMM-Newton. They also observed it for 70,000 seconds with NASA's NuSTAR X-ray observatory.

"The high-energy capability of NuSTAR was very important," Ingram said. "NuSTAR confirmed the wobbling of the iron line, and additionally saw a feature in the spectrum called a 'reflection hump' that added evidence for precession."

After a rigorous analysis process of adding all the observational data together, they saw that the iron line was wobbling in accordance with the predictions of general relativity. "We are directly measuring the motion of matter in a strong gravitational field near to a black hole," says Ingram.

This is the first time that the Lens-Thirring effect has been measured in a strong gravitational field. The technique will allow astronomers to map matter in the inner regions of accretion discs around black holes. It also hints at a powerful new tool with which to test general relativity.

Einstein's theory is largely untested in such strong gravitational fields. So if astronomers can understand the physics of the matter that is flowing into the black hole, they can use it to test the predictions of general relativity as never before - but only if the movement of the matter in the accretion disc can be completely understood.

"If you can get to the bottom of the astrophysics, then you can really test the general relativity," says Ingram. A deviation from the predictions of general relativity would be welcomed by a lot of astronomers and physicists. It would be a concrete signal that a deeper theory of gravity exists.

Larger X-ray telescopes in the future could help in the search because they are more powerful and could more efficiently collect X-rays. This would allow astronomers to investigate the QPO phenomenon in more detail. But for now, astronomers can be content with having seen Einstein's gravity at play around a black hole.

"This is a major breakthrough since the study combines information about the timing and energy of X-ray photons to settle the 30-year debate around the origin of QPOs. The photon-collecting capability of XMM-Newton was instrumental in this work," said Norbert Schartel, ESA Project Scientist for XMM-Newton.