Am frühen Sonntagabend erreichte unsere Meldestelle mehrere E-Mail´s mit Foto-Anhängen über ein "buntes Objekt tief am Himmel", "Glitzerndes Ding", "Scheint greller als die Sterne", nur eine kleine Auswahl an Beschreibungen zu dem knapp über dem Horizont stehenden Fixstern Sirius am Osthimmel.
Wir wollten dann von mehreren Beobachtern/Meldern Fotos zugesandt bekommen, nach dem sie uns teilweise mitteilten solche angefertigt zu haben. Festzuhalten ist, das wir erst nach klarer Klärung der Beobachtungs-Richtung davon ausgehen, es sich um Sirius gehandelt hat und die Beobachtung des "Objektes" immer noch möglich war. Nachfolgende Aufnahmen welche leider alle verwackelt sind, zeigen schön die Spektralfarben welche durch unsere Atmosphäre verursacht werden.
Beobachter-Foto (auch wenn es hier fast wie eine Feuerkugel/Bolide aussieht, auch hier wurde über eine halbe Stunde beobachtet)
Beobachter-Foto, (auch dieses Kunstwerk einer Zoom-Aufnahme aus freier Hand zeigt die Verwacklungs-Spur von Sirius)
Nachfolgend ein Blick auf die aktuelle Astro-Karte von 14.01.2018:
Foto zu Vergleichszwecken über Odenwald (rote Punkte sind Antikollisionlichter von Windrädern)
Update: 15.01.2018 / 7.30 MEZ
Weitere Meldungen welche auf Grund von Sirius uns erreichten kamen aus: Laudenbach, Wald-Michelbach, Bruchsal, Baden-Baden, Lorsch.
Artist's concept of a top-down view of the K2-138 system discovered by citizen scientists, showing the orbits and relative sizes of the five known planets. Orbital periods of the five planets, shown to scale, fall close to a series of 3:2 mean motion resonances. This indicates that the planets orbiting K2-138, which likely formed much farther away from the star, migrated inward slowly and smoothly.
In its search for exoplanets—planets outside of our solar system—NASA's Kepler telescope trails behind Earth, measuring the brightness of stars that may potentially host planets. The instrument identifies potential planets around other stars by looking for dips in the brightness of the stars that occur when planets cross in front of, or transit, them. Typically, computer programs flag the stars with these brightness dips, then astronomers look at each one and decide whether or not they truly could host a planet candidate.
Over the three years of the K2 mission, 287,309 stars have been observed, and tens of thousands more roll in every few months. So how do astronomers sift through all that data?
Enter the Exoplanet Explorers citizen scientist project, developed by UC Santa Cruz astronomer Ian Crossfield and Caltech staff scientist Jessie Christiansen. Exoplanet Explorers is hosted on Zooniverse, an online platform for crowdsourcing research.
"People anywhere can log on and learn what real signals from exoplanets look like, and then look through actual data collected from the Kepler telescope to vote on whether or not to classify a given signal as a transit, or just noise," says Christiansen. "We have each potential transit signal looked at by a minimum of 10 people, and each needs a minimum of 90 percent of 'yes' votes to be considered for further characterization."
In early April, just two weeks after the initial prototype of Exoplanet Explorers was set up on Zooniverse, it was featured in a three-day event on the ABC Australia television series Stargazing Live. In the first 48 hours after the project was introduced, Exoplanet Explorers received over 2 million classifications from more than 10,000 users. Included in that search was a brand-new dataset from the K2 mission—the reincarnation of the primary Kepler mission, ended three years ago. K2 has a whole new field of view and crop of stars around which to search for planets. No professional astronomer had yet looked through this dataset, called C12.
Back in California, Crossfield and Christiansen joined NASA astronomer Geert Barentsen, who was in Australia, in examining results as they came in. Using the depth of the transit curve and the periodicity with which it appears, they made estimates for how large the potential planet is and how close it orbits to its star. On the second night of the show, the researchers discussed the demographics of the planet candidates found so far—44 Jupiter-sized planets, 72 Neptune-sized, 44 Earth-sized, and 53 so-called Super Earth's, which are larger than Earth but smaller than Neptune.
"We wanted to find a new classification that would be exciting to announce on the final night, so we were originally combing through the planet candidates to find a planet in the habitable zone—the region around a star where liquid water could exist," says Christiansen. "But those can take a while to validate, to make sure that it really is a real planet and not a false alarm. So, we decided to look for a multi-planet system because it's very hard to get an accidental false signal of several planets."
After this decision, Barentsen left to get a cup of tea. By the time he returned, Christiansen had sorted the crowdsourced data to find a star with multiple transits and discovered a star with four planets orbiting it. Three of the four planets had 100 percent "yes" votes from over 10 people, and the remaining one had 92 percent "yes" votes. This is the first multi-planet system of exoplanets discovered entirely by crowdsourcing.
After the discovery was announced on Stargazing Live, Christiansen and her colleagues continued to study and characterize the system, dubbed K2-138. They statistically validated the set of planet signals as being "extremely likely," according to Christiansen, to be signals from true planets. They also found that the planets are orbiting in an interesting mathematical relationship called a resonance, in which each planet takes almost exactly 50 percent longer to orbit the star than the next planet further in. The researchers also found a fifth planet on the same chain of resonances, and hints of a sixth planet as well. A paper describing the system has been accepted for publication in The Astronomical Journal.
This is the only system with a chain of unbroken resonances in this configuration, and may provide clues to theorists looking to unlock the mysteries of planet formation and migration.
"The clockwork-like orbital architecture of this planetary system is keenly reminiscent of the Galilean satellites of Jupiter," says Konstantin Batygin, assistant professor of planetary science and Van Nuys Page Scholar, who was not involved with the study. "Orbital commensurabilities among planets are fundamentally fragile, so the present-day configuration of the K2-138 planets clearly points to a rather gentle and laminar formation environment of these distant worlds."
"Some current theories suggest that planets form by a chaotic scattering of rock and gas and other material in the early stages of the planetary system's life. However, these theories are unlikely to result in such a closely packed, orderly system as K2-138," says Christiansen. "What's exciting is that we found this unusual system with the help of the general public."
The paper is titled "The K2-138 system: A Near-Resonant Chain of Five Sub-Neptune Planets Discovered by Citizen Scientists." In addition to Christiansen, Crossfield, and Barentsen; other coauthors include Chris Lintott, Campbell Allen, Adam McMaster, Grant Miller, Martin Veldthuis of the University of Oxford; Thomas Barclay of NASA Goddard and the University of Maryland; Brooke Simmons of UC San Diego; Caltech postdoctoral scholar Erik Petigura; Joshua Schlieder of NASA Goddard; Courtney Dressing of UC Berkeley; Andrew Vanderburg of Harvard; Sarah Allen and Zach Wolfenbarger of the Adler Planetarium; Brian Cox of the University of Manchester; Julia Zemiro of the Australian Broadcasting Corporation; Caltech Professor of Astronomy Andrew Howard; John Livingston of the University of Tokyo; Evan Sinukoff of the Australian Broadcasting Corporation and the University of Hawai'i at Manoa; Timothy Catron of Arizona State University; Andrew Grey, Joshua Kusch, Ivan Terentev, and Martin Vales of Zooniverse as part of the University of Oxford; and Martti Kristiansen of the Technical University of Denmark. Funding was provided by the NASA Science Mission Directorate, Google, the Alfred P. Sloan Foundation, NASA, the National Science Foundation, the U.S. Department of Energy, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England.
Mountain View, CA –The SETI Institute and the Mars Institute announced today the discovery of small pits in a large crater near the North Pole of the Moon, which may be entrances to an underground network of lava tubes. The pits were identified through analysis of imaging data from NASA’s Lunar Reconnaissance Orbiter (LRO). If water ice is present, these potential lava tube entrances or “skylights” might allow future explorers easier access to subsurface ice, and therefore water, than if they had to excavate the gritty ice-rich “regolith” (surface rubble) at the actual lunar poles.
The new pits were identified on the northeastern floor of Philolaus Crater, a large, 43 mile (70 km)-diameter impact crater located at 72.1oN, 32.4oW, about 340 miles (550 km) from the North Pole of the Moon, on the lunar near side. The pits appear as small rimless depressions, typically 50 to 100 feet across (15 to 30 meters), with completely shadowed interiors. The pits are located along sections of winding channels, known on the Moon as “sinuous rilles,” that crisscross the floor of Philolaus Crater. Lunar sinuous rilles are generally thought to be collapsed, or partially collapsed, lava tubes, underground tunnels that were once streams of flowing lava.
“The highest resolution images available for Philolaus Crater do not allow the pits to be identified as lava tube skylights with 100 percent certainty, but we are looking at good candidates considering simultaneously their size, shape, lighting conditions and geologic setting” says Pascal Lee, planetary scientist at the SETI Institute and the Mars Institute who made the new finding at NASA’s Ames Research Center in Silicon Valley.
For many years, astronomers had a simple view of our Milky Way's central hub, or bulge, as a quiescent place composed of old stars, the earliest homesteaders of our galaxy.
However, because the inner Milky Way is such a crowded environment, it has always been a challenge to disentangle stellar motions to probe the bulge in detail.
Now, a new analysis of about 10,000 normal Sun-like stars in the bulge reveals that our galaxy's hub is a dynamic environment of stars of various ages zipping around at different speeds, like travelers bustling about a busy airport. This conclusion is based on nine years' worth of archival data from NASA's Hubble Space Telescope.
The Hubble study of this complicated, chaotic heart of our Milky Way may provide new clues to the evolution of our galaxy, said researchers.
The research team, led by Will Clarkson of the University of Michigan-Dearborn, found that the motions of bulge stars are different, depending on a star's chemical composition. Stars richer in elements heavier than hydrogen and helium have less disordered motions, but are orbiting around the galactic center faster than older stars that are deficient in heavier elements.
"There are many theories describing the formation of our galaxy and central bulge," said Annalisa Calamida of the Space Telescope Science Institute, Baltimore, Maryland, a member of the Hubble research team. "Some say the bulge formed when the galaxy first formed about 13 billion years ago. In this case, all bulge stars should be old and share a similar motion. But others think the bulge formed later in the galaxy's lifetime, slowly evolving after the first generations of stars were born. In this scenario, some of the stars in the bulge might be younger, with their chemical composition enriched in heavier elements expelled from the death of previous generations of stars, and they should show a different motion compared to the older stars. The stars in our study are showing characteristics of both models. Therefore, this analysis can help us in understanding the bulge’s origin."
The astronomers divided the stars by their chemical compositions and then compared the motions of each group. They determined the stars' chemical content by studying their colors and divided them in two main groups according to their heavy-element (iron) abundance. The chemically enriched stars are moving twice as fast as the other population.
"By analyzing nine years' worth of data in the archive and improving our analysis techniques, we have made a clear, robust detection of the differences in the motion for chemically deficient and chemically enriched Sun-like stars," Clarkson said. "We hope to continue our analysis, which will allow us to make a three-dimensional chart of the rich chemical and dynamical complexity of the populations in the bulge."
The astronomers based their analysis on Advanced Camera for Surveys and Wide Field Camera 3 data from two Hubble surveys: the Wide Field Camera 3 Galactic Bulge Treasury Program and the Sagittarius Window Eclipsing Extrasolar Planet Search. Sets of spectra from the European Southern Observatory's Very Large Telescope in Chile were used to help estimate the chemical compositions of stars.
Currently, only Hubble has sharp enough resolution to simultaneously measure the motions of thousands of Sun-like stars at the the galaxy bulge's distance from Earth. The center of our galaxy is about 26,000 light-years away. "Before this analysis, the motions of these stars was not known," said team member Kailash Sahu of the Space Telescope Science Institute. "You need a long time baseline to accurately measure the positions and the motions of these faint stars."
The team studied Sun-like stars because they are so abundant and easily within Hubble's reach. Previous observations looked at brighter, aging red giant stars, which are not as plentiful because they represent a brief episode in a star's lifetime. "Hubble gave us a narrow, pencil-beam view of the galaxy’s core, but we are seeing thousands more stars than those spotted in earlier studies," Calamida said. The Milky Way's bulge is roughly one-tenth the diameter of our pancake-shaped galaxy. "We next plan to extend our analysis to do additional observations along different sight-lines, which will allow us to make a three-dimensional probe of the rich complexity of the populations in the bulge," Clarkson added.
The researchers said that this work is also an important pathfinder for NASA's James Webb Space Telescope to probe the archaeology of the Milky Way. Scheduled for launch in 2019, Webb is expected to more deeply probe stellar populations in the Milky Way bulge.
The research team will present its findings Thursday, Jan. 11, at the 231st meeting of the American Astronomical Society in Washington, D.C.
The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
Quelle: HUBBLE, NASA
Spektakuläre Sonnenuntergänge sowie Wolken sind in unserer Atmosphäre immer wieder zu sehen und oft sind es nur Minuten welche ein Lichtschau am Himmel zaubern.
Nachfolgende Aufnahmen wurden bei Sonnenuntergang über Mannheim im August 2005 aufgenommen:
NASA Great Observatories Team-up to Identify Flickering Black Hole
Supermassive black holes, weighing millions of times as much as our Sun, are gatherers not hunters. Embedded in the hearts of galaxies, they will lie dormant for a long time until the next meal happens to come along.
The team of astronomers using observations from the Hubble Space Telescope, the Chandra X-ray Observatory, and as well as the W.M. Keck Observatory in Mauna Kea, Hawaii, and the Apache Point Observatory (APO) near Sunspot, New Mexico, zeroed in on a flickering black hole.
A black hole in the center of galaxy SDSS J1354+1327, located about 800 million light-years away, appears to have consumed large amounts of gas while blasting off an outflow of high-energy particles. The fresh burst of fuel might have been supplied by a bypassing galaxy. The outflow eventually switched off then turned back on about 100,000 years later. This is strong evidence that accreting black holes can switch their power output off and on again over timescales that are short compared to the 13.8-billion-year age of the universe.
Astronomers have caught a supermassive black hole in a distant galaxy snacking on gas and then "burping" — not once, but twice.
The galaxy under study, called SDSS J1354+1327 (J1354 for short), is about 800 million light-years from Earth. The team used observations from NASA's Hubble Space Telescope, the Chandra X-ray Observatory, as well as the W.M. Keck Observatory in Mauna Kea, Hawaii, and the Apache Point Observatory (APO) near Sunspot, New Mexico.
Chandra detected a bright, point-like source of X-ray emission from J1354, a telltale sign of the presence of a supermassive black hole millions or billions of times more massive than our Sun. The X-rays are produced by gas heated to millions of degrees by the enormous gravitational and magnetic forces near the black hole. Some of this gas will fall into the black hole, while a portion will be expelled in a powerful outflow of high-energy particles.
By comparing X-ray images from Chandra and visible-light (optical) images from Hubble, the team determined that the black hole is located in the center of the galaxy, the expected address for such an object. The X-ray data also provide evidence that the supermassive black hole is embedded in a heavy veil of dust and gas.
The results indicate that in the past, the supermassive black hole in J1354 appears to have consumed, or accreted, large amounts of gas while blasting off an outflow of high-energy particles. The outflow eventually switched off then turned back on about 100,000 years later. This is strong evidence that accreting black holes can switch their power output off and on again over timescales that are short compared to the 13.8-billion-year age of the universe.
"We are seeing this object feast, burp, and nap, and then feast and burp once again, which theory had predicted," said Julie Comerford of the University of Colorado (CU) at Boulder's Department of Astrophysical and Space Science, who led the study. "Fortunately, we happened to observe this galaxy at a time when we could clearly see evidence for both events."
So why did the black hole have two separate meals? The answer lies in a companion galaxy that is linked to J1354 by streams of stars and gas produced by a collision between the two galaxies. The team concluded that clumps of material from the companion galaxy swirled toward the center of J1354 and then were eaten by the supermassive black hole.
The team used optical data from Hubble, Keck, and APO to show that electrons had been stripped from atoms in a cone of gas extending some 30,000 light-years south from the galaxy’s center. This stripping was likely caused by a burst of radiation from the vicinity of the black hole, indicating that a feasting event had occurred. To the north they found evidence for a shock wave, similar to a sonic boom, located about 3,000 light-years from the black hole. This suggests that a burp occurred after a different clump of gas had been consumed roughly 100,000 years later.
"This galaxy really caught us off guard," said CU Boulder doctoral student Rebecca Nevin, a study co-author who used data from APO to look at the velocities and intensities of light from the gas and stars in J1354. "We were able to show that the gas from the northern part of the galaxy was consistent with an advancing edge of a shock wave, and the gas from the south was consistent with an older outflow from the black hole."
Our Milky Way galaxy's supermassive black hole has had at least one burp. In 2010, another research team discovered a Milky Way belch using observations from the orbiting Fermi Gamma-ray Observatory to look at the galaxy edge on. Astronomers saw gas outflows dubbed "Fermi bubbles" that shine in the gamma-ray, X-ray, and radio wave portion of the electromagnetic spectrum.
"These are the kinds of bubbles we see after a black hole feeding event," said CU postdoctoral fellow Scott Barrows. "Our galaxy's supermassive black hole is now napping after a big meal, just like J1354’s black hole has in the past. So we also expect our massive black hole to feast again, just as J1354's has."
Other co-authors on the new study include postdoctoral fellow Francisco Muller-Sanchez of CU Boulder, Jenny Greene of Princeton University, David Pooley from Trinity University, Daniel Stern from NASA's Jet Propulsion Laboratory in Pasadena, California, and Fiona Harrison from the California Institute of Technology.
A paper on the subject was published in a recent issue of The Astrophysical Journal and is available online. Comerford presented the team’s findings in a January 11th, 2018 press briefing at the 231st meeting of the American Astronomical Society held in Washington D.C.
NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington, D.C. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations. The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.
Quelle: NASA, HUBBLE
Sudden particle emissions, in which our star repeatedly hurls large amounts of charged and uncharged particles into space, are still a mystery. Some of these particle flows are accompanied by violent solar flares, a sudden and local increase of the Sun’s brightness, and contain up to 10,000 times more helium-3 and up to 10 times more iron than the Sun's atmosphere. Why is this extremely rare helium isotope accelerated into space so efficiently? And why iron? How does the Sun supply these particles with the necessary energy to catapult them into space?
"The events, that took place on the backside of the Sun in April and July 2014, were particularly intense and allowed for unusually extensive insights”, says Dr. Radoslav Bučík from the MPS. Only seldomly does the Sun emit particle flows so heavily enriched in helium-3 and heavier elements into space – and often they do not originate from the “right” place. Most space probes studying the Sun do so from an observational position close to Earth. They therefore see only the side of the Sun facing the Earth. Only the spacecraft STEREO A and B, which have been orbiting our star from opposite sides since 2006, began to observe the Sun’s far side in 2011.
Shortly before the control center lost contact to STEREO B in October 2014, both probes witnessed the "hidden" particle eruptions on 30 April 2014 and 17 and 20 July 2014. The eruptions lasted up to three days each. "The amount of helium-3 and iron in them was increased as much as in just a handful of other known events," Bučík describes the measurements.
While the ion telescope SIT (Suprathermal Ion Telescope) on board the STEREO probes recorded the composition of the particle streams, the EUVI instruments (Extreme Ultraviolet Imager), parts of STEREO’s instrument package SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation), looked at their regions of origin in the atmosphere of the Sun. There, the scientists found the typical increase of extreme ultraviolet radiation, which is usually accompanied by particle events of this kind, but this time in an unfamiliar form: helical movements were clearly recognizable.
"This is the first time that we have seen a twisted radiation outburst as the source of helium-3 and iron-rich particle flows," says Bučík. The radiation is caused by hot plasma moving along the constantly swirling and changing magnetic field lines in the Sun's atmosphere. When these field lines regroup, there may be a sudden release of energy. "The helical magnetic fields seem to efficiently provide helium-3 and iron in the solar atmosphere with energy - much like a spring coil that is suddenly released," said Bučík.
"Only by further exploring this mechanism can we better understand other solar outbursts," says Dr. Nariaki Nitta of the Lockheed Martin Advanced Technology Center in Palo Alto, USA. The researchers’ focus is particularly on a further variety of particle events, so-called coronal mass ejections (CMEs). The energy of these particles is very high. They can lead to solar storms on Earth, which endanger, for example, satellites. In rare cases, these ejections are also very rich in iron - and then particularly dangerous because of the particles’ high mass. The researchers now want to investigate whether these iron-rich particles outbursts, too, are accelerated by helical radiation bursts.
This research project was funded by the Deutsche Forschungsgemeinschaft (DFG) and the Max Planck Society (MPG).
Teilchenausbrüche, in denen unser Stern immer wieder explosionsartig eine große Menge geladener und ungeladener Teilchen ins All schleudert, sind noch immer ein Rätsel. Einige dieser Teilchenströme gehen mit heftigen Strahlungsausbrüchen, so genannten Flares, einher und enthalten bis zu 10000-mal mehr Helium-3 und bis zu zehnmal mehr Eisen als die Atmosphäre der Sonne. Warum wird gerade diese ausgesprochen seltene Helium-Variante so effizient ins All beschleunigt? Und warum Eisen? Auf welchem Wege versorgt die Sonne diese Teilchen mit der nötigen Energie, um sie bevorzugt ins All zu katapultieren?
„Die Ereignisse, die sich im April und Juli 2014 auf der Rückseite der Sonne abspielten, waren besonders intensiv und haben uns ungewohnt umfassende Einsichten ermöglicht“, so Dr. Radoslav Bučík vom MPS. Teilchenströme, die so stark angereichert sind mit Helium-3 und schwereren Elementen, treten auf der Sonne nur selten auf – und dann nicht immer an der „richtigen“ Stelle. Die meisten Raumsonden, die die Sonne untersuchen, tun dies in der Nähe der Erde. Ihr Blick gilt deshalb der uns zugewandten Vorderseite der Sonne. Nur die Sonden STEREO A und B, die seit 2006 unseren Stern von entgegengesetzten Seiten umrunden, beobachten seit 2011 auch den uns abgewandten Teil unseres Sterns.
Kurz bevor im Oktober 2014 der Kontakt der Bodenstation STEREO B abriss, wurden beide Sonden Zeuge der „versteckten“ Teilchenausbrüche vom 30. April 2014 sowie vom 17. und 20. Juli 2014. Die Ausbrüche dauerten jeweils bis zu drei Tagen an. „Die Menge an Helium-3 und Eisen war in ihnen so stark erhöht wie in nur einer Handvoll anderer bekannter Ereignisse“, beschreibt Bučík die Messergebnisse.
Während das Ionenteleskope SIT (Suprathermal Ion Telescope) an Bord der STEREO-Sonden die Zusammensetzung der Teilchenströme aufzeichnete, blickten die EUVI-Instrumente (Extreme Ultraviolet Imager), Teile des Instrumentenpakets SECCHI (Sun Earth Connection Coronal and Heliospheric Investigation), auf ihre Ursprungsregionen in der Atmosphäre Sonne. Dort zeigte sich den Wissenschaftlern zwar der typische Anstieg energiereicher, ultravioletter Strahlung, der meist mit Teilchenausbrüchen dieser Art einhergeht, aber in ungewohnter Form: Deutlich ließen sich schraubenartige Bewegungen erkennen.
„Dies ist das erste Mal, dass wir einen solch verdrillten Strahlungsausbruch als Ursprung der helium-3- und eisenreichen Teilchenströme beobachten“, so Bučík. Die Strahlung geht in der Regel von heißem Plasma aus, das sich entlang der ständig wabernden und verändernden magnetischen Feldlinien in der Atmosphäre der Sonne bewegt. Wenn sich diese Feldlinien neu formieren kann es zu einem plötzlichen Freisetzen von Energie kommen. „Die verdrillten Magnetfelder scheinen besonders die Helium-3 und Eisen-Teilchen in der Sonnenatmosphäre effizient mit Energie zu versorgen – ganz ähnlich wie eine gespannte Sprungfeder, die plötzlich losgelassen wird“, so Bučík.
„Nur wenn wir diesen Mechanismus weiter untersuchen, können wir auch andere Ausbrüche unseres Sterns besser verstehen“, so Dr. Nariaki Nitta vom Lockheed Martin Advanced Technology Center in Palo Alto (USA). Dabei richtet sich das Augenmerk der Forscher besonders auf eine weitere Sorte von Teilchenausbrüchen, die so genannten koronalen Masseausbrüche. Die Energie der Teilchen, welche die Sonne bei diesen Ereignissen ins All schleudert, ist sehr hoch. Sie können auf der Erde zu Sonnenstürmen führen, die beispielsweise Satelliten gefährden. In seltenen Fällen, sind auch diese Ausbrüche sehr eisenreich – und dann wegen der Schwere der Teilchen besonders gefährlich. Die Forscher wollen nun der Frage nachgehen, ob diese Eisenteilchen ebenfalls durch schraubenartige Strahlungsausbrüche beschleunigt werden.
Dieses Forschungsprojekt wurde von der Deutschen Forschungsgemeinschaft (DFG) und der Max-Planck-Gesellschaft (MPG) gefördert.
Quelle: MAX-PLANCK-GESELLSCHAFT, MÜNCHEN
A new visualization provides an exceptional virtual trip — complete with a 360-degree view — to the center of our home galaxy, the Milky Way. This project, made using data from NASA's Chandra X-ray Observatory and other telescopes, allows viewers to control their own exploration of the fascinating environment of volatile massive stars and powerful gravity around the monster black hole that lies in the center of the Milky Way.
The Earth is located about 26,000 light years, or about 150,000 trillion miles, from the center of the Galaxy. While humans cannot physically travel there, scientists have been able to study this region by using data from powerful telescopes that can detect light in a variety of forms, including X-ray and infrared light.
This visualization builds on infrared data with the European Southern Observatory's Very Large Telescope of 30 massive stellar giants called Wolf-Rayet stars that orbit within about 1.5 light years of the center of our Galaxy. Powerful winds of gas streaming from the surface of these stars are carrying some of their outer layers into interstellar space.
When the outflowing gas collides with previously ejected gas from other stars, the collisions produce shock waves, similar to sonic booms, which permeate the area. These shock waves heat the gas to millions of degrees, which causes it to glow in X-rays. Extensive observations with Chandra of the central regions of the Milky Way have provided critical data about the temperature and distribution of this multimillion-degree gas.
Astronomers are interested in better understanding what role these Wolf-Rayet stars play in the cosmic neighborhood at the Milky Way's center. In particular, they would like to know how the stars interact with the Galactic center's most dominant resident: the supermassive black hole known as Sagittarius A* (abbreviated Sgr A*). Pre-eminent yet invisible, Sgr A* has the mass equivalent to some four million Suns.
The Galactic Center visualization is a 360-degree movie that immerses the viewer into a simulation of the center of our Galaxy. The viewer is at the location of Sgr A* and is able to see about 25 Wolf-Rayet stars (white, twinkling objects) orbiting Sgr A* as they continuously eject stellar winds (black to red to yellow color scale). These winds collide with each other, and then some of this material (yellow blobs) spirals towards Sgr A*. The movie shows two simulations, each of which start around 350 years in the past and span 500 years. The first simulation shows Sgr A* in a calm state, while the second contains a more violent Sgr A* that is expelling its own material, thereby turning off the accretion of clumped material (yellow blobs) that is so prominent in the first portion.
Scientists have used the visualization to examine the effects Sgr A* has on its stellar neighbors. As the strong gravity of Sgr A* pulls clumps of material inwards, tidal forces stretch the clumps as they get closer to the black hole. Sgr A* also impacts its surroundings through occasional outbursts from its vicinity that result in the expulsion of material away from the giant black hole, as shown in the later part of the movie. These outbursts can have the effect of clearing away some of the gas produced by the Wolf-Rayet winds.
The researchers, led by Christopher Russell of the Pontifical Catholic University of Chile, used the visualization to understand the presence of previously detected X-rays in the shape of a disk that extend about 0.6 light years outward from Sgr A*. Their work shows that the amount of X-rays generated by these colliding winds depends on the strength of outbursts powered by Sgr A*, and also the amount of time that has elapsed since an eruption occurred. Stronger and more recent outbursts result in weaker X-ray emission.
The information provided by the theoretical modeling and a comparison with the strength of X-ray emission observed with Chandra led Russell and his colleagues to determine that Sgr A* most likely had a relatively powerful outburst that started within the last few centuries. Moreover, their findings suggest the outburst from the supermassive black hole is still affecting the region around Sgr A* even though it ended about one hundred years ago.
The 360-degree video of the Galactic Center is ideally viewed in virtual reality (VR)goggles, such as Samsung Gear VR or Google Cardboard. The video can also be viewed on smartphones using the YouTube app. Moving the phone around pans to show a different portion of the movie, mimicking the effect in the VR goggles. Finally, most browsers on a computer also allow 360-degree videos to be shown on YouTube. To look around, either click and drag the video, or click the direction pad in the corner.
Christopher Russell presented this new visualization and the related scientific findings at the 231st meeting of the American Astronomical Society in Washington, DC. Some of the results are based on a paper by Russell et al published in 2017 in the Monthly Notices of the Royal Astronomical Society. An online version is here. The co-authors of this paper are Daniel Wang from University of Massachusetts in Amherst, Mass. and Jorge Cuadra from Pontifical Catholic University of Chile. 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.
Quelle: CHANDRA, NASA
PicSat will be launched into Earth orbit on 12 January 2018 to study the star Beta Pictoris, its exoplanet and its famous debris disk, thanks to a small telescope 5 cm in diameter. The nanosatellite has been designed and built in a record time of just three years by scientists and engineers at the Paris Observatory and the CNRS, with support from the Université PSL, the French space agency CNES, the European Research Council and the MERAC Foundation.
It is no bigger than three apples stacked upon each other, or rather three cubes, each 10 centimetres in size. It is not heavier than a cat (3.5 kg). It uses about 5 Watt of power, equivalent to that of an economical light bulb. Its telescope is only five centimetres in diameter, much like that of a young amateur astronomer. And yet, this nanosatellite seeks to improve our knowledge of the Beta Pictoris star system, a real “star” in the sky of the Southern Hemisphere.
Beta Pictoris lies merely 63.4 light years from the Earth. It is a very bright star, which makes it an easy target for study. This is quite fortunate, because with only 23 million years of age this star is very young astronomically speaking, and it has been a very popular object of study for scientists ever since the discovery in the 1980s of a massive disk of dust, gas and debris surrounding it. This disk, left-over from the gas cloud from which the star itself formed, is a rather rare object and astronomers worldwide have been scrutinizing it ever since. Indeed, better understanding Beta Pictoris means elucidating the formation of giant planets and planetary systems in general. In 2009, a French team led by Anne-Marie Lagrange1 found a giant gas planet, dubbed Beta-Pictoris b, seven times more massive than Jupiter, orbiting the star at 1.5 billion kilometres, similar to the distance planet Saturn orbits the Sun.
Seen from the Earth, the exoplanet Beta Pictoris b could be passing in front of its star between now and the summer of this year. By observing this transit phenomenon, which repeats itself every 18 years, astronomers could derive the exact size of the exoplanet, the extent of its atmosphere, as well as its chemical composition. However, the transit of the exoplanet will only last a few hours. To be able to observe the phenomenon, the exact timing of which is now known, the star has to be monitored continuously. This can only be done from Space, where there is no interruption due to the cycle of day and night, or the passage of clouds.
To attempt to observe the transit from Space, only a small, light nanosatellite could be developed in a short enough period of time. PicSat has been designed and built in only three years. This has been possible thanks
to the use of existing cubic modular structures, a CubeSat structure, which is a standardised format developed in the US, initially for educational use.
For the French CNRS, as well as for the Paris Observatory, this is the first satellite designed and built entirely in-house. PicSat is born from an idea by Sylvestre Lacour, astrophysicist at the CNRS, in collaboration with Alain le Lecavelier des Etangs from the Institut d'Astrophysique de Paris (CNRS/Sorbonne Université), who has been working on the Beta Pictoris system for many years. Sylvestre Lacour made the project come true in his laboratory, Lesia (Observatoire de Paris - PSL/CNRS/Sorbonne Université/Université Paris-Diderot) with a small team of scientists and engineers. It is a completely new approach to space instrumentation that has now taken off for French space research. The technological developments for PicSat have been supported in the framework of the C2ERES Space centre of the Université PSL, also at the site of the Paris Observatory in Meudon, France. The project has been made possible thanks to the financial support of the European Research Council (ERC), as well as that of the French CNRS, the Labex ESEP2 and the Swiss MERAC Foundation as part of its program to support young researchers in the field of Astrophysics.
On Friday 12 January 2018 at 4h58am local Paris time, the Indian PSLV launcher will lift off and place PicSat in a polar orbit at an altitude of 505 km, together with about thirty other satellites. PicSat will be operated from Lesia in Meudon. However, the satellite will be visible from Meudon for only about 30 minutes every day, when it passes over Paris. Therefore, PicSat uses radio amateur bands for its communication, for which authorisation has been obtained thanks to the help of the French Réseau des Émetteurs Français (REF, or the Network of French Emitters). Anybody who owns a minimum radio receiving equipment can listen to and receive PicSat’s transmissions. The PicSat team invites radio amateurs from all over the world to collaborate in following the satellite, receiving its data and relaying them to the PicSat data base via the Internet. Those interested can register on the PicSat website at PicSat.obspm.fr to follow the updates and, if they so wish, become part of the radio network.
The nominal PicSat mission will last for one year. When the start of a planetary or other transit is observed, the 3.6-meter telescope from the European Southern Observatory in La Sille, Chile, will also be immediately put into action to observe Beta Pictoris using the powerful HARPS instrument. These data combined will allow an even better understanding of the phenomenon.
In China, a Cold War-era strategy to ward off foreign enemies has made for some dangerous modern-day conditions.
In China, a Cold War-era strategy to ward off foreign enemies has made for some dangerous modern-day conditions.
On Friday morning in China, a rocket blasted off from the Xichang Satellite Launch Center in the Sichuan province with a pair of navigation satellites bound for orbit around Earth. As the rocket climbed higher and higher, the four strap-on boosters that launched with it began to fall away. This is supposed to happen; the boosters provide extra lift in the minutes after launch, and when they burn through their fuel, they separate and fall back down to Earth.
The satellites made it safely into orbit. But back on the ground, there were flames.
One of those four discarded boosters had landed near a town in the Guangxi region and exploded. Video captured by onlookers and shared on social media shows the booster falling from the sky and striking the ground behind buildings. Screams are heard as flames erupt when it makes contact. Other footage shows bystanders approaching the flaming wreckage in a grassy area. Flames billow out from one end of the booster, and the ground is littered with chunks of debris.
The incident, which was first reported by Andrew Jones at GB Times, is actually not uncommon in China. Three of the country’s four launch facilities—Xichang in the Sichuan province, Jiuquan in the Gobi desert in Mongolia, and Taiyuan in the Shanxi province—are located deep inland, hundreds of miles from open water. For China to send satellites and other payloads into space from these spots, rockets must fly over land. The setup contrasts that of the U.S. and other nations that host rocket launches, where facilities are located near the coastline and rockets travel over oceans as they ascend.
China started developing a fleet of expendable “Long March” rockets in the mid-1960s. The program is named for a historic trek across the country by Chinese communists in the 1930s, which led to the emergence of Mao Zedong as their leader until his death in 1976. Several iterations of the rocket have been developed since the maiden launch in 1970, including the Long March 3B that flew on Friday. China designates some areas around their launch facilities as zones for discarded debris, like strap-on boosters. Most of these zones are rural regions. The photo at the top of this story, for example, shows some hardware that fell in a field in the Jiangxi province in December 2016.
Xichang is located in a remote area, but remote doesn’t mean empty. “It’s in the middle of nowhere, and yet, around the launch site, there are villages, there worker’s dorms,” said Joan Johnson-Freese, a national-security affairs professor at the U.S. Naval War College who has studied space security for 20 years.
There were no reports of injuries Friday. Boosters are supposed to exhaust their toxic propellant before they detach, but exposure to them on the ground could still pose some health risks to people who come near, Jones writes. China calculates where launch leftovers might fall and tries to warn nearby residents, but remnants can—and have—struck both people and buildings. In 2015, part of a booster of a Long March 4C rocket struck a house in Shanxi after a launch from the Taiyuan facility, cutting a sizable hole into the roof. In 1996, a Long March rocket carrying a U.S.-manufactured satellite crashed into a hillside 22 seconds after liftoff at Xichang. Xinhua, China’s state-run news agency, reported that the accident killed six people and injured 57, but some suspect the toll was much higher.
“That, in fact, might be a realistic number for the casualties among the technical personnel involved in preparing the mission,” wrote Anatoly Zak, a space journalist, of the official tally, in Air & Space magazine in 2013. “We may never know how many local villagers died, although the numbers could easily have run into the hundreds, which would make the accident the worst disaster in launch history.”
So if launching rockets over land can be so dangerous, why did China build its facilities so far inland?
China built three launch facilities between the 1950s and 1970s, during the Cold War. In 1958, the Jiuquan facility opened as part of Mao’s ambitious plan to match the ballistic-missile capabilities of the Soviet Union and the United States, and the Chinese leader insisted they be as far away from its international borders as possible, out of reach of the enemy, said Johnson-Freese.
No one could have anticipated that a decision to protect a burgeoning rocket industry would someday end up complicating it instead.
The 1996 accident drew widespread criticism from other countries about China’s safety measures for rocket launches, Johnson-Freese said. “They got such international condemnation for this prior accident that they started to pay attention and say, okay, how do Western countries do this? What are the safety standards that we should use?” In the years since, “Chinese safety standards have evolved significantly,” she said.
These days, China picks locations for launch sites based on science, not geopolitics. In 2009, China began construction on its fourth launch site, the Wenchang Space Launch Center. Wenchang is located on the island province of Hainan—right off the coast of the South China Sea. Officials chose the site because it sits just 19 degrees north of the equator, a prime spot for launches because rockets traveling in the same direction of the Earth’s spin get a boost in velocity there. When rockets can launch faster, their operators save money on fuel. Rocket hardware is transported there by ship rather than train, and any falling debris would hit water. Wenchang opened in 2014 and has hosted three successful launches.
The booster incident on Friday is not quite a setback for its Long March program—the payload, two satellites to support the country’s BeiDou navigation system—got where they needed. But the fiery spectacle is not reassuring. The risk of fallen debris in populated areas will only increase as China ramps up launch activities.
The country has steadily increased its annual number of launches into low-Earth orbit in the last 20 years, and has reached more than 15 each year since 2010, according to a comprehensive database maintained by Gunter Krebs, a spaceflight historian in Germany. The China Aerospace Science and Technology Corporation, the country’s main contractor for space development, seeks to test the Long March 9, a super heavy-lift launch vehicle, by 2030. The Long March 9 will be similar in power to the Saturn V, the U.S. rocket that launched Apollo astronauts to the moon, and the Falcon Heavy, the SpaceX rocket preparing for its maiden launch this month. China wants to achieve full reusability for all their launch vehicles by 2035.
The biggest test for the Long March program will come much earlier than that. China has targeted late 2018 to launch Chang’e 4—a combination of a lander and a rover—to the far side of the moon. The mission, if successful, would be a first for humankind. Here’s hoping fiery debris from the launch don’t distract from the moment.
Quelle: The Atlantic