Monstrous cyclones are churning over Jupiter's poles, until now a largely unexplored region that is more turbulent than scientists expected.

NASA's Juno spacecraft spotted the chaotic weather at the top and bottom of Jupiter once it began skimming the cloud tops last year, surprising researchers who assumed the giant gas planet would be relatively boring and uniform down low.

"What we're finding is anything but that is the truth. It's very different, very complex," Juno's chief scientist Scott Bolton of the Southwest Research Institute said Thursday.

With dozens of cyclones hundreds of miles across — alongside unidentifiable weather systems stretching thousands of miles — the poles look nothing like Jupiter's equatorial region, instantly recognizable by its stripes and Great Red Spot, a raging hurricane-like storm.

"That's the Jupiter we've all known and grown to love," Bolton said. "And when you look from the pole, it looks totally different ... I don't think anybody would have guessed this is Jupiter."

He calls these first major findings — published Thursday — "Earth-shattering. Or should I say, Jupiter-shattering."

Turning counter-clockwise in the northern hemisphere just like on Earth, the cyclones are clearly clustered near the poles. The diameters of some of these confirmed cyclones stretch up to 1,700 miles (2,800 kilometers). Even bigger, though shapeless weather systems are present in both polar regions. At the same time, the two poles don't really resemble each other, which is puzzling, according to Bolton.

Scientists are eager to see, over time, whether these super cyclones are stable or dynamic. "Are they going to stay the same way for years and years like the Great Red Spot ... Of course, only time will tell," Bolton said.

Just as intriguing will be how fast these super cyclones are moving.

Launched in 2011 and orbiting Jupiter since last summer, Juno is providing the best close-up views ever of our solar system's largest planet, peering beneath the clouds for a true portrait. It's made five close passes over Jupiter so far for science collection, the most recent last week; they occur about every two months given Juno's extremely oblong orbit. The next one will be in July, with investigators targeting the Great Red Spot.

Juno is moving so fast during these chummy encounters that it takes only two hours to get from the north pole to the south.

Besides polar cyclones, Juno has spotted white ice caps on Jupiter — frozen bits of ammonia and water. Bolton refers to them as Jovian snowfall — or maybe hail.

Juno also has detected an overwhelming abundance of ammonia deep down in Jupiter's atmosphere, and a surprisingly strong magnetic field in places — roughly 10 times greater than Earth's. It's also led scientists to believe Jupiter may have a "fuzzy" core — as Bolton puts it — big but partially dissolved.

Then there are the eerie sounds of plasma waves at Jupiter — "nature's music," according to Bolton. During the teleconference, he played two minutes of the spacecraft's recording from February, adjusted for the human ear and full of percussion sounds as well as high-pitched beeps and squeals, and even flute-like notes.

Results were published in Science and Geophysical Research Letters.

Jupiter's poles appear dramatically different from neighboring Saturn's, according to the scientists, with nothing like the hexagon-shaped cloud system over Saturn's north pole.

Researchers hope to compare Juno's observations with those of NASA's Cassini spacecraft, in its final months orbiting Saturn.

Juno's findings are "really going to force us to rethink not only how Jupiter works, but how do we explore Saturn, Uranus and Neptune," Bolton said.

Quelle: abc


Nasa's Juno probe captures dramatic first close-up images of Jupiter

Excitement greets pictures of giant, chaotic weather systems plus new measurements that will help build unprecedented map of planet’s interior

Jupiter’s south pole, as seen by the Juno spacecraft from an altitude of 32,000 miles (52,000 kilometers). The oval features are cyclones, up to 600 miles (1,000 kilometers) in diameter. Multiple images taken with the JunoCam instrument on three separate orbits were combined to show all areas in daylight, enhanced colour, and stereographic projection.
 Jupiter’s south pole, as seen by the Juno spacecraft from an altitude of 32,000 miles (52,000 kilometers). The oval features are cyclones, up to 600 miles (1,000 kilometers) in diameter. Photograph: NASA/JPL-Caltech/SwRI/MSSS/Betsy Asher Hall/Gervasio Robles

The first close-up observations from Nasa’s Juno spacecraft have captured towering clouds, swirling cyclones and dramatic flows of ammonia that drive giant weather systems on the largest planet in the solar system.

The $1.1bn probe swung into orbit around Jupiter in July last year on a mission to peer through the thick clouds that shroud the planet and learn how the alien world, and ultimately all of the planets in the solar system, formed around the nascent sun 4.5bn years ago.

“We were all jumping up and down with excitement when the images came down,” said Fran Bagenal, a planetary space physicist at the University of Colorado, who joined the Juno mission more than a decade ago. “You’ve got to be patient, but the rewards are fantastic.”

Once every 53 days the Juno spacecraft swings close to Jupiter, speeding over its clouds. In just two hours, the spacecraft travels from a perch over Jupiter’s north pole through its closest approach (perijove), then passes over the south pole on its way back out.
 Once every 53 days the Juno spacecraft swings close to Jupiter, speeding over its clouds. In just two hours, the spacecraft travels from a perch over Jupiter’s north pole through its closest approach (perijove), then passes over the south pole on its way back out. Photograph: Credits: NASA/SWRI/MSSS/Gerald Eichstädt/Seán Doran

The spacecraft survived an almost six-year, 2.8bn km voyage across the depths of space to reach its destination, where it ducked beneath Jupiter’s intense radiation belts, turned on its suite of instruments, and swept into an orbit that loops over the planet’s north and south poles.

From 5,000km above the brown-orange blanket that covers the planet, Juno’s camera snapped pictures of tall, white storm clouds standing high above the rest. Some were so high, they stood out even on the nightside of the planet, betrayed by the feeble light of the sun glinting off them.

Yet more images revealed flashes of lightning that illuminate the Jovian sky. “The weather is dramatic,” said Bagenal. “What we thought we knew about Jupiter, we underestimated. It’s more variable, there are more features, there is much more detail the closer you look.”

Described as a “planet on steroids” by Scott Bolton, the mission’s principal investigator at the Southwest Research Institute in San Antonio, Jupiter is an enormous gas giant made from hydrogen and helium. Compared with Jupiter and the sun, the rest of the solar system is an afterthought. All of the other planets, the asteroids and comets, would fit within Jupiter, a planet 11 times wider than Earth.

Writing in two papers in the journal Science today, the Juno team describe fresh images and measurements of the planet’s atmosphere, magnetic field and the brilliant non-stop lightshows that constitute the aurorae at Jupiter’s poles.

An image of the North polar region of Jupiter.
 An image of the North polar region of Jupiter. Photograph: MSSS/SwRI/JPL-Caltech/NASA

Its sensors peering down as it swooped around the planet, Juno spotted chaotic scenes with bright oval-shaped features swirling in the clouds. Time-lapse images revealed them to be enormous cyclones, rotating counter-clockwise in the northern hemisphere. The storms reached up to 1,400km wide, more than ten times the size of the largest cyclones on Earth. Deep inside the atmosphere, the scientists found evidence for what they called an “equatorial plume” – a massive and unexpected overturning of gas driven by a steady upward stream of ammonia from around the planet’s equator. It seems to mirror the Hadley cell convection currents on Earth, where warm air rises at the equator and falls again about 30 degrees to the north and south. But “It looks like a band that goes all the way round the middle of Jupiter,” said Bagenal. The question is where does it go down?”


Another instrument on Juno measured the magnetic field of the planet and found it to be twice as strong as scientists expected, at about ten times greater than the field that surrounds Earth. During observations of the planet’s intense aurorae, Juno detected streams of electrons hurtling down into Jupiter’s upper atmosphere, where they potentially power the spectacular light shows.

Over the coming months, Juno will build up an unprecedented map of the planet’s interior before its instruments succumb to the harsh radiation and the spacecraft plunges into the clouds at the end of its mission. Along for the ride are three Lego crew members: the Roman god Jupiter, his wife Juno, and a telescope-wielding Galileo, who discovered four of Jupiter’s 53 moons.

One mystery scientists are keen to clear up is whether Jupiter has a solid core. With more data from the orbiting Juno, it is a puzzle they hope to answer. “We’re having to put together this 3D puzzle,” Bagenal said. “And surprise, surprise, it isn’t like Earth.”

Quelle: theguardian


Update: 28.05.2017




Early science results from NASA’s Juno mission to Jupiter portray the largest planet in our solar system as a complex, gigantic, turbulent world.
Credit: NASA/JPL-CalTech/USGS.

WASHINGTON, DC — Early science results from NASA’s Juno mission to Jupiter portray the largest planet in our solar system as a complex, gigantic, turbulent world, with Earth-sized polar cyclones, plunging storm systems that travel deep into the heart of the gas giant, and a mammoth, lumpy magnetic field that may indicate it was generated closer to the planet’s surface than previously thought.

“We are excited to share these early discoveries, which help us better understand what makes Jupiter so fascinating,” said Diane Brown, Juno program executive at NASA Headquarters in Washington, D.C. “It was a long trip to get to Jupiter, but these first results already demonstrate it was well worth the journey.”

Juno launched on Aug. 5, 2011, entering Jupiter’s orbit on July 4, 2016. The findings from the first data-collection pass, which flew within about 2,600 miles (4,200 kilometers) of Jupiter’s swirling cloud tops on Aug. 27, are being published this week in two papers in the journal Science, as well as a 44-paper special collection in Geophysical Research Letters, a journal of the American Geophysical Union.

“We knew, going in, that Jupiter would throw us some curves,” said Scott Bolton, Juno principal investigator from the Southwest Research Institute in San Antonio. “But now that we are here we are finding that Jupiter can throw the heat, as well as knuckleballs and sliders. There is so much going on here that we didn’t expect that we have had to take a step back and begin to rethink of this as a whole new Jupiter.”

Among the findings that challenge assumptions are those provided by Juno’s imager, JunoCam. The images show both of Jupiter’s poles are covered in Earth-sized swirling storms that are densely clustered and rubbing together.

“We’re puzzled as to how they could be formed, how stable the configuration is, and why Jupiter’s north pole doesn’t look like the south pole,” said Bolton. “We’re questioning whether this is a dynamic system, and are we seeing just one stage, and over the next year, we’re going to watch it disappear, or is this a stable configuration and these storms are circulating around one another?”

Another surprise comes from Juno’s Microwave Radiometer (MWR), which samples the thermal microwave radiation from Jupiter’s atmosphere, from the top of the ammonia clouds to deep within its atmosphere. The MWR data indicates that Jupiter’s iconic belts and zones are mysterious, with the belt near the equator penetrating all the way down, while the belts and zones at other latitudes seem to evolve to other structures. The data suggest the ammonia is quite variable and co

Tags: JUNO SPACECRAFT-Jupiter-Mission Update-9 JUNO SPACECRAFT-Jupiter-Mission 


Sonntag, 28. Mai 2017 - 08:36 Uhr

Raumfahrt - Benutzt Nordkorea die Satelliten von China, um seine Raketen zu leiten?


Is North Korea using China’s satellites to guide its missiles?

Pyongyang doesn't have the funds or resources to build its own satellite navigation network.


As North Korea fires more missiles in its drive to build and test rockets to reach the US mainland, one issue largely overlooked is that satellites are among methods used to guide such weapons to their targets.

Tags: Is North Korea using China’s satellites 


Samstag, 27. Mai 2017 - 21:30 Uhr

Astronomie - Grundsteinlegungszeremonie für das Extremely Large Telescope


Beginn der Bauarbeiten von ELT-Kuppel und Teleskop


Michelle Bachelet Jeria, die Präsidentin der Republik Chile, hat an einer Zeremonie zur Grundsteinlegung des Extremely Large Telescope (ELT) der ESO teilgenommen, die am Paranal-Observatorium im Norden Chiles in der Nähe des Standorts des zukünftigen Riesenteleskops stattgefunden hat. Dieser Meilenstein ist der Startschuss für die Bauphase von Kuppel und Teleskopstruktur des weltgrößten Teleskops für das sichtbare Licht und leitet eine neue Ära in der Astronomie ein. Gleichzeitig wurde das Obseravtorium an das nationale chilenische Elektrizitätsnetz angeschlossen.

Tim de Zeeuw, der Generaldirektor der ESO, Roberto Tamai, der ELT-Programmmanager und Andreas Kaufer, der Direktor des La Silla-Paranal-Observatoriums empfingen Präsidentin Bachelet. Ebenfalls anwesend waren Aurora Williams, die Ministerin für Bergbau, Wirtschaftsminister Luis Felipe Céspedes und Andrés Rebolledo, der Energieminister. An der Zeremonie nahmen zusätzlich viele angesehene internationale und chilenische Gäste aus Politik und Industrie teil, dazu ESO-Wissenschaftler und Ingenieure sowie Vertreter lokaler und internationaler Medien [1].

Höhepunkt der Zeremonie war das Versiegeln einer Zeitkapsel, die die ESO vorbereitet hatte. Sie enthält ein Poster mit Fotografien derzeitiger ESO-Mitarbeiter und ein Exemplar des des Buchs, das die wissenschaftliche Zielsetzung des Teleskops beschreibt. Die Abdeckung der Zeitkapsel besteht aus einem gravierten Sechseck aus Zerodur®, das einem Modell eines der Hauptspiegelsegmente des ELT im Maßstab 1:5 entspricht.

In ihrer Rede betonte die Präsidentin: “Mit dem symbolischen Beginn dieser Bauarbeiten errichten wir mehr als nur ein Teleskop: Es stellt in beispielloser Art und Weise unsere wissenschaftlichen und technologischen Möglichkeiten dar und demonstiert das gewaltige Potential nternationaler Zusammenarbeit.”

Tim de Zeeuw bedankte sich bei der Präsidentin und ihrer Regierung für ihre kontinuierliche Unterstützung der ESO in Chile und den Schutz der beispiellosen Nachthimmelsqualität im Land: “Das ELT wird entdeckungen machen, die wir heute noch gar nicht vorhersehen können, und es wird mit Sicherheit unzählige Menschen auf der ganzen Welt dazu inspirieren, über Wissenschaft, technologie und unseren Platz im Univerum nachzudenken. All das zum Wohle der ESO-Mitgliedsländer, für Chile und den Rest der Welt.

Patrick Roche, der Präsident des ESO-Rats, fügt hinzu: "Dies ist ein Meilenstein in der Geschichte der ESO, das ELT wird das leistungsfähigste und ehrgeizigste Teleskop seiner Art sein. An diesem Punkt sind wir nur dank der langjährigen Anstrengungen unzähliger Menschen in den ESO-Mitgliedsländern, in Chile und anderswo angelangt. Ich möchte mich bei all diesen Leuten bedanknen und freue mich sehr, viele von ihnen heute hier zu sehen, um diesen Augenblick zu feiern."

Mit einem Hauptspiegeldurchmesser von 39 Metern wird das Extremely Large Telescope (ELT) das größte optisch-nahinfrarote Teleskop der Welt sein und den Teleskopebau in eine neue Welt führen. Das Teleskop wird von einem gewaltigen drehbaren Kuppelbau mit 85 Metern Durchmesser geschützt – vergleichbar mit der Fläche eines Fußballfelds.

Vor einem Jahr hat die ESO mit dem ACe-Konsortium bestehend aus AstaldiCimolai und der EIE Group als nominiertem Subkontraktor einen Vertrag über den Bau von Kuppel und Teleskopstruktur geschlossen (eso1617). Dabei handelte es sich um den Vertrag mit dem größten finanziellen Volumen , den die ESO jemals abgeschlossen hat, und gleichzeitig auch um den größten in der bodengebundenen Astronomie überhaupt. Mit der Grundsteinlegung hat der Bau von ELT-Kuppel und Teleskopstruktur nun auch offiziell begonnen [2].

Die Zeremonie markiert gleichzeitig die Anbindung der ESO-Standorte Cerro Paranal und Cerro Armazones an das nationale chilenische Elektrizitätsnetz. Die Anbindung wurde durch die Unterstützung der chilenischen Regierung möglich gemacht und wird von der chilenischen Grupo SAESA verwaltet. Durch die Anbindung werden Kosten reduziert und gleichzeitig Verlässlichkeit und Stabilität der Stromversorgung erhöht. Außerdem bessert sich dadurch die CO2-Bilanz des Observatoriums.

Das ELT ist nur das jüngste der vielen Projekte der ESO über mehr als ein halbes Jahrhundert hinweg, das von der kontinuierlichen Unterstützung der Regierung des Gastlands Chile profitiert. Der starke Rückhalt des Außenministeriums, des Energieministeriums (Minenenergia) und der Nationalen Energiekommission (CNE) hat sich bei der erfolgreichen Anbindung des Standorts an das Elektrizitätsnetz als äußerst wertvoll erwiesen.

Das Gelände, auf dem das ELT errichtet werden wird, wurde von der chilenischen Regierung gestiftet und ist außerdem durch eine große Konzession für die umgebenden Ländereien geschützt, die den ungestörten Betrieb des Teleskops in der Zukunft erst möglich machen – und damit dazu beiträgt, des Status Chiles als führender astronomischer Standort zu sichern.

Das ELT wird das größte "Auge" sein, das man bis dato an den Himmel richten wird und vermutlich unsere Wahrnehmung des Universums revolutionieren. Es wird sich einigen der größten astronomischen Herausforderungen unserer Zeit annehmen, darunter Tests von erdähnlichen Exoplaneten auf Spuren von Leben, die Beobachtung der frühen Stadien des Universums, um unsere Ursprünge zu erforschen, und die Natur der Dunklen Materie und der Dunklen Energie zu verstehen. Es wird neue Fragen aufwerfen, an die heutzutage noch gar nicht gedacht wird und dank neu entwickelter Technologien und ingenieurtechnischer Durchbrüche auch die Lebensqualität auf der Erde verbessern.

Sein "Erstes Licht" soll das ELT im Jahr 2024 einfangen. Die Grundsteinlegung markiert den Beginn einer neuen Ära in der Astronomie.


[1] Die Zeremonie wurde aufgrund starker Winde vom zukünftigen Teleskopstandort auf dem Cerro Armazones an die Paranal-Residencia verlegt.

[2] Die Kuppel wird insgesamt 5000 Tonnen wiegen, während die Montierung des Teleskops und die Tubusstruktur eine bewegliche Masse von mehr als 3000 Tonnen aufweisen werden. In beiden Fällen handelt es sich um die mit Abstand größten jemals für ein optisches bzw. nahinfrarotes Teleskop errichteten Strukturen, was das ELT wortwörtlich zum weltgrößten Auge auf den Himmel machen wird.


Künstlerische Darstellung des ELT in Betrieb


Diese künstlerische Darstellung zeigt das Extremely Large Telescope auf dem Cerro Armazones im Norden Chiles in Betrieb. Das Teleskop ist hier zusammen mit den eingeschalteten Lasern gezeigt, die künstliche Sterne in der Hochatmosphäre erzeugen. An der Grundsteinlegungszeremonie für das Teleskop  am 26. Mai 2017 nahm die chilenische Präsidentin Michelle Bachelet Jeria teil.


Die sechseckige Plakette zum Versiegeln der ELT-Zeitkapsel


Dieser Aufdruck befindet sich auf einem sechseckigen Stück Zerodur-Glaskeramik, mit dem man am 26. Mai 2017 anlässlich der Grundsteinlegungszeremonie für das Extremely Large Telescope der ESO eine Zeitkapsel versiegelt hat. Es entspricht einem Modell eines der Hauptspiegelsegmente des ELT im Maßstab 1:5.


Die Messinstrumente des ELT


Diese Infografik zeigt ein vereinfachtes Schema des Aufbaus des ELT mit schwerpunkt auf seinen Instrumenten erster Generation. Das ELT soll sein "Erstes Licht" im Jahr 2024 einfangen, die Instrument dann 2025.

Quelle: ESO







Samstag, 27. Mai 2017 - 07:45 Uhr

Raumfahrt - Kamera des Lunar Orbiter LRO der NASA überlebte 2014 kleinen Meteoriten-Treffer


Camera on NASA’s Lunar Orbiter Survived 2014 Meteoroid Hit

On Oct.13, 2014 something very strange happened to the camera aboard NASA’s Lunar Reconnaissance Orbiter (LRO). The Lunar Reconnaissance Orbiter Camera (LROC), which normally produces beautifully clear images of the lunar surface, produced an image that was wild and jittery. From the sudden and jagged pattern apparent in the image, the LROC team determined that the camera must have been hit by a tiny meteoroid, a small natural object in space.   


View of moon with distortion
The first wild back-and-forth line records the moment on October 13, 2014 when the left Narrow Angle Camera's radiator was struck by a meteoroid.
Credits: NASA's Goddard Space Flight Center/Arizona State University

LROC is a system of three cameras mounted on the LRO spacecraft. Two Narrow Angle Cameras (NACs) capture high resolution black and white images. The third Wide Angle Camera captures moderate resolution images using filters to provide information about the properties and color of the lunar surface. 


The NAC works by building an image one line at a time. The first line is captured, then the orbit of the spacecraft moves the camera relative to the surface, and then the next line is captured, and so on, as thousands of lines are compiled into a full image.


According to Mark Robinson, professor and principal investigator of LROC at ASU’s School of Earth and Space Exploration, the jittery appearance of the image captured is the result of a sudden and extreme cross-track oscillation of the camera. LROC researchers concluded that there must have been a brief violent movement of the left Narrow Angle Camera.


There were no spacecraft events like solar panel movements or antenna tracking that might have caused spacecraft jitter during this period. “Even if there had been, the resulting jitter would have affected both cameras identically,” says Robinson. “The only logical explanation is that the NAC was hit by a meteoroid.”


Camera sitting on a bench
The Narrow Angle Camera sits on a bench in the clean room at Malin Space Science Systems. The radiator (right) extends off the electronics end and keeps the sensor cool while imaging the moon. Computer modeling shows the meteoroid impacted somewhere on the radiator.
Credits: Malin Space Science Systems/Arizona State University

How big was the meteoroid?


During LROC’s development, a detailed computer model was made to insure the NAC would not fail during the severe vibrations caused by the launch of the spacecraft. The computer model was tested before launch by attaching the NAC to a vibration table that simulated launch. The camera passed the test with flying colors, proving its stability. 


Using this detailed computer model, the LROC team ran simulations to see if they could reproduce the distortions seen on the Oct. 13 image and determine the size of the meteoroid that hit the camera. They estimate the impacting meteoroid would have been about half the size of a pinhead (0.8 millimeter), assuming a velocity of about 4.3 miles (7 kilometers) per second and a density of an ordinary chondrite meteorite (2.7 grams/cm3).


“The meteoroid was traveling much faster than a speeding bullet,” says Robinson. “In this case, LROC did not dodge a speeding bullet, but rather survived a speeding bullet!”


How rare is it that the effects of an event like this were captured on camera? Very rare, according to Robinson. LROC typically only captures images during daylight and then only about 10 percent of the day, so for the camera to be hit by a meteor during the time that it was also capturing images is statistically unlikely.


“LROC was struck and survived to keep exploring the moon,” says Robinson, “thanks to Malin Space Science Systems’ robust camera design.”


“Since the impact presented no technical problems for the health and safety of the instrument, the team is only now announcing this event as a fascinating example of how engineering data can be used, in ways not previously anticipated, to understand what is happing to the spacecraft over 236,000 miles (380,000 kilometers) from the Earth," said John Keller, LRO project scientist from NASA’s Goddard Space Flight Center in Greenbelt, Maryland.


Launched on June 18, 2009, LRO has collected a treasure trove of data with its seven powerful instruments, making an invaluable contribution to our knowledge about the moon. 


“A meteoroid impact on the LROC NAC reminds us that LRO is constantly exposed to the hazards of space,” says Noah Petro, deputy project scientist from NASA Goddard. “And as we continue to explore the moon, it reminds us of the precious nature of the data being returned.”


LRO is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland, as a project under NASA's Discovery Program. The Discovery Program is managed by NASA's Marshall Spaceflight Center in Huntsville, Alabama, for the Science Mission Directorate at NASA Headquarters in Washington.


The Lunar Reconnaissance Orbiter Camera was developed at Malin Space Science Systems in San Diego, California and Arizona State University in Tempe.

Quelle: NASA




Tags: Lunar Orbiter LRO 


Samstag, 27. Mai 2017 - 07:40 Uhr

Astronomie - ‘Tiny clocks’ crystallize understanding of meteorite crashes




This rocky outcrop at Sudbury is where the crystals of baddeleyite came from -- crystals that are now being used in a new technology to help date when meteorite strikes took place. Photo by Des Moser/Western University

Almost two billion years ago, a 10-kilometre-wide chunk of space slammed down into rock near what is now the city of Sudbury. Now, scientists from Western University and the University of Portsmouth are marrying details of that meteorite impact with technology that measures surrounding crystal fragments as a way to date other ancient meteorite strikes.

The pioneering technique is helping add context and insight into the age of meteor impacts. And ultimately, it provides new clues into the beginnings of life on this planet and others, said Desmond (Des) Moser, associate professor in the Departments of Earth Sciences and Geography at Western.

“The underlying theme is, when did life begin? We know that it couldn’t happen as long as the surface was being periodically vaporized by meteorite strikes during the solar system’s early years and youth — so if we can figure out when those strikes stopped, we can then understand a bit more about how we got here, and when.”

In this instance, researchers have been able to use new imaging techniques to measure the atomic nanostructure of ancient crystals at impact locations, using the 150-kilometre-wide crater at Sudbury as a test site.

Shock waves from that meteorite impact deformed the minerals that made up the rock beneath the crater, including small, tough crystals that contain trace amounts of radioactive uranium and lead. “These can be used as tiny clocks that are the basis for our geologic time scale,” Moser said. “But because these crystals are a banged-up mess, conventional methods won’t help in extracting age data from them.”

An international team using specialized instruments at Western’s Zircon and Accessory Phase Laboratory (ZAPLab) and a new instrument called the atom probe, at CAMECA Laboratories in the US, have made that job easier. With the probe, researchers are able to slice and lift out tiny pieces of crystal baddeleyite which is common in terrestrial, Martian and lunar rocks and meteorites.

Then Moser’s team – including researcher Lee White and co-supervisor James Darling of the University of Portsmouth – measured the deformation in the crystals after sharpening and polishing the pieces into extremely fine needles, then evaporated and identified the atoms and their isotopes layer by layer. The result is a 3D model of the atoms and their positions.

“Using the atom probe to go from the rock to the crystal to its atomic level is like zooming in with the ultimate Google Earth,” Moser says. This atomic-scale approach holds great potential in establishing a more accurate chronology of the formation and evolution of planetary crusts.

The team’s findings are published in the journal Nature Communications.

Quelle: MR


Samstag, 27. Mai 2017 - 07:35 Uhr

Astronomie - Riesiger sterbender Stern kollabiert gerade in Schwarzen Loch



It appears the path to becoming a black hole is more complex than astronomers thought. Rather than exploding into a supernova before collapsing into a black hole, as expected, one giant star skipped the pyrotechnics and went straight to the collapse. 


This so-called "massive fail," spotted in a nearby galaxy, could explain why so few massive stars have been observed going supernova, researchers conducting a new study explained. As many as 30 percent of these massive stars may instead quietly collapse into a black hole.


"The typical view is that a star can form a black hole only after it goes supernova," Christopher Kochanek, co-author on the paper and an astronomer at Ohio State University, said in a statement. "If a star can fall short of a supernova and still make a black hole, that would help to explain why we don't see supernovae from the most massive stars."

The dying star was about 25 times as massive as Earth's sun and located in NGC 6946, a spiral galaxy 22 million light-years from Earth. (Astronomers nickname this galaxy the "Fireworks Galaxy" because so many supernovas happen there, including recently discovered SN 2017eaw.)

One star in this galaxy, called N6946-BH1, began to brighten weakly in 2009. It vanished altogether in 2015, and the researchers, who had been monitoring the sky with the Large Binocular Telescope in Arizona, could not see signs of a supernova in that zone. So astronomers aimed two more powerful space telescopes — Hubble and Spitzer — toward the area to see if the star had faded a little, or was hidden behind a dust cloud. 

These two Hubble Space Telescope images show the giant star N6946-BH1 before (left) and after it disappeared by collapsing into a black hole. The left image shows the star as it appeared in 2007. The right image shows the same region in 2015, with the star missing.
These two Hubble Space Telescope images show the giant star N6946-BH1 before (left) and after it disappeared by collapsing into a black hole. The left image shows the star as it appeared in 2007. The right image shows the same region in 2015, with the star missing.
Credit: NASA, ESA, and C. Kochanek (OSU) 

With searches coming up empty, astronomers eliminated other possibilities and concluded that N6946-BH1 had turned directly into a black hole.

"N6946-BH1 is the only likely failed supernova that we found in the first seven years of our survey," Scott Adams, a former Ohio State University student who earned his doctorate as a co-author of this work, said in the statement. "During this period, six normal supernovae have occurred within the galaxies we've been monitoring, suggesting that 10 to 30 percent of massive stars die as failed supernovae."

"This is just the fraction that would explain the very problem that motivated us to start the survey, that is, that there are fewer observed supernovae than should be occurring if all massive stars die that way," he added.

In this illustration of a red giant's failed supernova, the star's envelope is ejected and expands to surround the newly formed black hole.
In this illustration of a red giant's failed supernova, the star's envelope is ejected and expands to surround the newly formed black hole.
Credit: P. Jeffries (STScl)/NASA/ESA 

Another co-author, Ohio State astronomer Krzysztof Stanek, suggested that stars collapsing directly into black holes may actually make more sense than a supernova collapsing into a black hole. That's because the supernova blows off much of a star's outer layers, leaving little mass behind to create a massive black hole, he said in the statement.

The results from the new study have been accepted to publish in the Monthly Notices of the Royal Astronomical Society.

Quelle: SC

Tags: Schwarzes Loch Black Hole Astronomie 


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