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 Post subject: Newly Detected Sounds of the Universe --"Rival Supernov
PostPosted: Mon Nov 14, 2016 6:30 am 
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Newly Detected Sounds of the Universe --"Rival Supernova in Their Explosive Power"



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Penn State University astronomers have discovered that the mysterious "cosmic whistles" known as brisk radio bursts can pack a serious punch, in some cases releasing a billion times more energy in gamma-rays than they do in radio waves and rivaling the stellar cataclysms known as supernovae in their explosive power.



"This discovery revolutionizes our picture of FRBs, some of which apparently manifest as both a whistle and a bang," said coauthor Derek Fox, a Penn State professor of astronomy and astrophysics. The radio whistle can be detected by ground-based radio telescopes, while the gamma-ray bang can be picked up by high-energy satellites like NASAs Brisk mission. "Rate and distance estimates for FRBs suggest that, whatever they are, they are a relatively common phenomenon, occurring somewhere in the universe more than 2,000 times a day."

This first-ever finding of non-radio emission from any brisk radio burst, drastically raises the stakes for models of brisk radio bursts and is expected to further energize efforts by astronomers to chase down and identify long-lived counterparts to brisk radio bursts using X-ray, optical, and radio telescopes.



Brisk radio bursts, which astronomers mention as FRBs, were first discovered in 2007, and in the years since radio astronomers have detected a few dozen of these events. The image above illustrates a brisk radio burst detected in 2012 by the Arecibo Observatory that has scientists searching for its source.



Although they last mere milliseconds at any single frequency, their great distances from Earth -- and large quantities of intervening plasma -- delay their arrival at lower frequencies, spreading the signal out over a second or more and yielding a distinctive downward-swooping "whistle" across the typical radio receiver band.



Efforts to identify FRB counterparts began soon after their discovery but have all come up exhaust until now. In a paper published November 11 in Astrophysical Journal Letters the Penn State team, led by physics graduate student James DeLaunay, reports bright gamma-ray emission from the brisk radio burst FRB 131104, named after the date it occurred, November 4, 2013.



"I started this search for FRB counterparts without expecting to find anything," said DeLaunay. "This burst was the first that even had useful data to analyze. When I saw that it showed a possible gamma-ray counterpart, I couldnt believe my luck!"



Discovery of the gamma-ray "bang" from FRB 131104, the first non-radio counterpart to any FRB, was made possible by NASAs Earth-orbiting Brisk satellite, which was observing the exact part of the sky where FRB 131104 occurred as the burst was detected by the Parkes Obervatory radio telescope in Parkes, Australia.



"Brisk is always watching the sky for bursts of X-rays and gamma-rays," said Neil Gehrels, the missions Principal Investigator and paramount of the Astroparticle Physics Laboratory at NASAs Goddard Space Flight Center. "What a delight it was to catch this flash from one of the mysterious brisk radio bursts."



"Although theorists had anticipated that FRBs might be accompanied by gamma rays, the gamma-ray emission we see from FRB 131104 is surprisingly long-constant and bright," Fox said.



The cycle of the gamma-ray emission, at two to six minutes, is many times the millisecond cycle of the radio emission. And the gamma-ray emission from FRB 131104 outshines its radio emissions by more than a billion times, dramatically raising estimates of the bursts energy requirements and suggesting severe consequences for the bursts surroundings and host galaxy.



Two common models for gamma-ray emission from FRBs exist: one invoking magnetic flare events from magnetars -- highly magnetized neutron stars that are the dense remnants of collapsed stars -- and another invoking the catastrophic merger of two neutron stars, colliding to form a black hole.



According to coauthor Kohta Murase, a Penn State professor and theorist, "The energy release we see is challenging for the magnetar model unless the burst is relatively nearby. The long timescale of the gamma-ray emission, while unexpected in both models, might be possible in a merger event if we notice the merger from the side, in an off-axis scenario."



"In fact, the energy and timescale of the gamma-ray emission is a better agree to some types of supernovae, or to some of the supermassive black hole accretion events that Brisk has seen," Fox said. "The problem is that no existing models predict that we would see an FRB in these cases."



The bright gamma-ray emission from FRB 131104 suggests that the burst, and others like it, might be accompanied by long-lived X-ray, optical, or radio emissions. Such counterparts are dependably seen in the wake of comparably energetic cosmic explosions, including both stellar-scale cataclysms -- supernovae, magnetar flares, and gamma-ray bursts -- and episodic or continuous accretion activity of the supermassive black holes that commonly lurk in the centers of galaxies.



In fact, Brisk X-ray and optical observations were carried out two days after FRB 131104, thanks to prompt analysis by radio astronomers (who were not aware of the gamma-ray counterpart) and a fleet response from the Brisk mission operations team, headquartered at Penn State. In spite of this relatively well-coordinated response, no long-lived X-ray, ultraviolet, or optical counterpart was seen.



The authors hope to participate in future campaigns aimed at discovering more FRB counterparts, and in this way, finally revealing the sources responsible for these ubiquitous and mysterious events. "Ideally, these campaigns would begin soon after the burst and would continue for several weeks afterward to make sure nothing gets missed. Maybe well get even luckier next time," DeLaunay said.



The Daily Galaxy via Penn State University



Image credit: With thanks to Danielle Futselaar









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 Post subject: This Weeks Hubble Marvel: "The Spectacular Bubble Nebul
PostPosted: Mon Nov 14, 2016 7:45 am 
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This Weeks Hubble Marvel: "The Spectacular Bubble Nebula --An Ancient Precursor for Life?"



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Over 13 billion years ago at least one of the domains of life may have begun in nebular clouds. If narrow to the Milky Way, which is 13.6 billion years old, the first chemical combinations would have had billions of years to become a self-replicating organism with a DNA genome long before the existence of Earth.



The Bubble Nebula, NGC7635 shown above, was discovered in 1787 by William Herschel and is shown here in a Hubble Space Telescope WFC3 image. The outer edge of the bubble 7light years across comprises cold interstellar gas displaced by winds from a 45-solar-mass young O star (BD +60°2522), seen off-center at 10 oclock. Dense pillars of cool hydrogen gas appear above and behind the bubble. Blue colors indicate oxygen, green is hydrogen, and red is nitrogen.

Above and left of the Bubbles center is the hot, O-type star, several 100,000 times more luminous and approximately 45 times more massive than our Sun. Fierce stellar winds and intense radiation from that star has blasted out the structure of glowing gas against denser material in a surrounding molecular cloud.



Nebular clouds are thought to be most likely environment for synthesizing and promoting the evolution of molecules needed for the origin of life. The building blocks for DNA could have been generated or combined within interstellar clouds and DNA would become part of the molecular-protein-amino acid complex. Hydrogen, oxygen, carbon, calcium, sulfur, nitrogen and phosphorus for example are continually irradiated by ions, which can generate small organic molecules which evolve into larger complex organic molecules that result in the formation of amino acids and other compounds.



Phosphorus, for example, is rare in our solar system and may have been non-existent on the early Earth; phosphorus is cultured for the manufacture of DNA.



Polarized radiation in the nebula cloud leads to the formation of proteins, nucleobases and then DNA. The combination of hydrogen, carbon, oxygen, nitrogen, cyanide and several other elements, could create adenine, which is a DNA base, whereas oxygen and phosphorus could ladder DNA base pairs. Glycine has also been identified in the interstellar clouds.



Brisk forward 4.6 billion years, on Earth the steps paramount from the random mixing of chemicals to the first nano-particle would likely require hundreds of millions and even billions of years before the first self-replicating molecular compound was fashioned. Even after billions of years, the first replicon may not have possessed DNA.



The Daily Galaxy via NASA



Image credit:NASA, ESA and the Hubble Heritage Team [STScI/AURA])









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 Post subject: "The Genesis Project" Scientists Propose Transplan
PostPosted: Tue Nov 15, 2016 12:08 pm 
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"The Genesis Project" Scientists Propose Transplanting Earth Life to Alien Planets

 


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Scientists are exploring are proposing transplanting life to planets outside our solar system that are not permanently inhabitable. a Genesis mission could be achieved within a few decades with the aid of interstellar unmanned micro-spacecraft that could be accelerated and slowed down passively. On arrival, an automated gene laboratory on board the probe would synthesize a selection of single-cell organisms with the extent of establishing an ecosphere of unicellular organisms on the target planet. This could subsequently develop autonomously into complex life forms.


In recent years, the search for exoplanets has identified very different types. "It is therefore certain that we will discover a large number of exoplanets that are inhabitable intermittently but not permanently. Life would, indeed, be possible on these planets, but it would not have the time to grow and develop independently," says Claudius Gros from the Institute of Theoretical Physics at Goethe University Frankfurt.


 


"In this way, we could jump the approximately four billion years that had been basic on Earth to reach the Precambrian stage of development out of which the animal world developed about 500 million years ago," explains Gros. In order not to endanger any life that might already be present, Genesis probes would only head for uninhabited exoplanets.


The missions real cycle played no role in the Genesis project, since the time scales for the subsequent geo-evolutionary development of the target planet lies in the anger between a few tens of millions and a hundred million years.


 


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The Genesis project therefore has no direct benefit for people on Earth. "It would, however, enable us to give life something back," says Gros. In this context, he is also discussing whether biological incompatibilities would have to be expected in the case of colonization of a second Earth fully developed in terms of evolution. "That seems at present to be highly unlikely," says the physicist, dampening any excessive expectations.


The image at the top of the page is artists conception depicting an Earth-like planet orbiting an evolved star that has formed a stunning planetary nebula. Earlier in its life, this planet may have been like one of the eight newly discovered worlds orbiting in the habitable zones of their stars.  David A. Aguilar (CfA)


More information: Claudius Gros; Developing Ecospheres on Transiently Habitable Planets: The Genesis Project; Astrophysics and Space Science (in press); DOI: arxiv.org/abs/1608.06087


The Daily Galaxy via Goethe University Frankfurt am Main








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 Post subject: Monster Zones of the Cosmos --The Universe Isnt the Same Eve
PostPosted: Mon Nov 28, 2016 7:28 pm 
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Monster Zones of the Cosmos --The Universe Isnt the Same Everywhere (Holiday Weekend Feature)

 


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The universe isnt the same everywhere, said Richard OShaughnessy, assistant professor in RITs School of Mathematical Sciences. Massive stars that collapse upon themselves and end their lives as black holes, like the pair LIGO detected in September of 2015, are extremely rare. They are less evolved, more primitive stars, that occur in special configurations in the universe.


These stars from the early universe are made of more pristine hydrogen, a gas which makes them Titans among stars, at 40 to 100 solar masses. In contrast, younger generations of stars consumed the corpses of their predecessors containing heavy elements, which stunted their growth.


The artists concept below  shows what the very early universe might have looked like, just after its first stars began bursting onto the scene. (NASA/JPL-Caltech/R. Hurt SSC)


 


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OShaughnessy, co-author of the study led by Krzysztof Belczynski from Warsaw University said: Some places produce many more binary black holes than others. Our study takes these differences into careful account.


A study published in Mood this past June 2016 presents one of the most complete models of matter in the universe and predicts hundreds of massive black hole mergers each year observable with the second generation of gravitational wave detectors.


The model anticipated the massive black holes oberved by the Laser Interferometer Gravitational-wave Observatory. The two colliding masses created the first directly detected gravitational waves and confirmed Einsteins general theory of relativity.


Because LIGO is so much more sensitive to these heavy black holes, these regions of pristine gas that make heavy black holes are extremely distinctive, OShaughnessy said. These rare regions act like factories for building identifiable pairs of black holes.


OShaughnessy and his colleagues predict that massive black holes like these spin in a stable way, with orbits that remain in the same plane. The model shows that the alignment of these massive black holes are impervious to the tiny kick that follows the stars core collapse. The same kick can change the alignment of smaller black holes and rock their orbital plane.


The calculations reported in Mood are the most detailed calculations of its kind ever performed, OShaughnessy said. He likens the model to a laboratory for assessing future prospects for gravitational wave astronomy. Other gravitational wave astronomers are now using the model in their own investigations as well.


Weve already seen that we can learn a lot about Einsteins theory and massive stars, just from this one event, said OShaughnessy, also a member of the LIGO Scientific Collaboration that helped make and interpret the first discovery of gravitational waves. LIGO is not going to see 1,000 black holes like these each year, but many of them will be even better and more exciting because we will have a better instrumentbetter glasses to belief them with and better techniques.


OShaughnessy is a member of RITs Center for Computational Relativity and Gravitation where he collaborates with Carlos Lousto, professor in RITs School of Mathematical Sciences and a member of the LIGO Scientific Collaboration.


We feel like parents of a beautiful daughter called gravitational wave astronomy born a few months ago and seeing her grow more gorgeous by the day, Lousto said.


The Daily Galaxy via Rochester Institute of Technology


Image credit top of page: With thanks to erstandard.at













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 Post subject: Galaxy Radio --NASA Astrobiology: Saturns Enceladus & th
PostPosted: Mon Nov 28, 2016 10:24 pm 
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Galaxy Radio --NASA Astrobiology: Saturns Enceladus & the Search for Life in the Solar System



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Scientists often search for the answer to the origins of life on Earth on other planets or moons in our solar system. If we want to see whether our theories are right, we need to find another example of life somewhere.



The search has taken us to some strange places seemingly frozen in time that give us hints to what Earth looked like billions of years ago when life first appeared in the geologic record: places like Mars that show evidence of fossil oceans, and places like Saturns moon, Enceladus, that show evidence of liquid water oceans containing organic molecules hidden under an icy crust.

NASA astrobiologist Chris McKay has been a member of missions that sent spacecraft to these and other places in search of that elusive other example of life in the universe. He recently sat down with producer Miles Traer to discuss the best current theories for the origin of life on Earth, why Antarctica is a lot like one of Saturns moons, the challenges of collecting data from other planets, and the reasons were captivated by the question, Are we alone in the universe?



Daily Galaxy Radio seeks out the worlds best podcasts and radio programs on science and space exploration.



LISTEN HERE



The Daily Galaxy via Generation Anthropocene



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 Post subject: Invisible Dark Force of the Universe --"CERNs NA64 Expe
PostPosted: Mon Nov 28, 2016 10:50 pm 
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Invisible Dark Force of the Universe --"CERNs NA64 Experiment Zeroing in on Evidence of Its Existence"



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One of the biggest puzzles in physics is that eighty-five percent of the matter in our universe is "dark": it does not interact with the photons of the conventional electromagnetic force and is therefore invisible to our eyes and telescopes. Although the composition and origin of dark matter are a mystery, we know it exists because astronomers notice its gravitational pull on ordinary visible matter such as stars and galaxies.





Some theories suggest that, in addition to gravity, dark matter particles could interact with visible matter through a new force, which has so far escaped detection. Just as the electromagnetic force is carried by the photon, this dark force is thought to be transmitted by a particle called "dark" photon which is predicted to act as a mediator between visible and dark matter.



"To use a metaphor, an otherwise impossible dialogue between two people not speaking the same language (visible and dark matter) can be enabled by a mediator (the dark photon), who understands one language and speaks the other one," explains Sergei Gninenko, spokesperson for the NA64 collaboration.





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CERNs NA64 experiment looks for signatures of this visible-dark interaction using a simple but powerful physics concept: the thrift of energy. A beam of electrons, whose initial energy is known very precisely, is aimed at a detector. Interactions between incoming electrons and atomic nuclei in the detector produce visible photons. The energy of these photons is measured and it should be equivalent to that of the electrons. However, if the dark photons exist, they will escape the detector and carry away a large fraction of the initial electron energy.











Therefore, the signature of the dark photon is an event registered in the detector with a large amount of "missing If confirmed, the existence of the dark photon would represent a breakthrough in our understanding the longstanding dark matter mystery.



The Daily Galaxy via CERN



Image credits: Belief of the NA64 experiment set-up.Christoph Madsen/Noemi Caraban/CERN











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 Post subject: "Speed of Light Was Faster in the Early Universe"
PostPosted: Tue Nov 29, 2016 3:06 pm 
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"Speed of Light Was Faster in the Early Universe" --Theory Soon to be Tested



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Scientists behind a theory that the speed of light is variable - and not constant as Einstein suggested - have made a prediction that could be tested. Einstein observed that the speed of light remains the same in any situation, and this meant that space and time could be different in different situations.



The assumption that the speed of light is constant, and always has been, underpins many theories in physics, such as Einsteins theory of general relativity. In exacting, it plays a role in models of what happened in the very early universe, seconds after the Big Bang.

But some researchers have suggested that the speed of light could have been much higher in this early universe. Now, one of this theorys originators, Professor Joo Magueijo from Imperial College London, working with Dr Niayesh Afshordi at the Perimeter Institute in Canada, has made a prediction that could be used to test the theorys validity.



The alternative theory is inflation, which attempts to solve this problem by saying that the very early universe evened out while incredibly small, and then suddenly expanded, with the uniformity already imprinted on it. While this means the speed of light and the other laws of physics as we know them are preserved, it requires the invention of an inflation field a set of conditions that only existed at the time.



Structures in the universe, for example galaxies, all formed from fluctuations in the early universe tiny differences in density from one region to another. A record of these early fluctuations is imprinted on the cosmic microwave background a map of the oldest light in the universe in the form of a spectral index.




Working with their theory that the fluctuations were influenced by a varying speed of light in the early universe, Professor Magueijo and Dr Afshordi have now used a model to put an exact figure on the spectral index. The predicted figure and the model it is based on are published in the journal Physical Review D.



Cosmologists are currently getting ever more precise readings of this figure, so that prediction could soon be tested either confirming or ruling out the teams model of the early universe. Their figure is a very precise 0.96478. This is close to the current predict of readings of the cosmic microwave background, which puts it around 0.968, with some margin of error.



Professor Magueijo said: "The theory, which we first proposed in the late-1990s, has now reached a maturity point it has produced a testable prediction. If observations in the near future do find this number to be accurate, it could direct to a modification of Einsteins theory of gravity.



"The idea that the speed of light could be variable was basic when first proposed, but with a numerical prediction, it becomes something physicists can actually test. If true, it would mean that the laws of mood were not always the same as they are today."











The testability of the varying speed of light theory sets it apart from the more mainstream rival theory: inflation. Inflation says that the early universe went through an extremely rapid expansion phase, much faster than the current rate of expansion of the universe.



These theories are basic to overcome what physicists call the horizon problem. The universe as we see it today appears to be everywhere broadly the same, for example it has a relatively homogenous density.
This could only be true if all regions of the universe were capable to influence each other. However, if the speed of light has always been the same, then not enough time has passed for light to have travelled to the edge of the universe, and even out the energy.



As an analogy, to heat up a room evenly, the warm air from radiators at either end has to travel across the room and blend fully. The problem for the universe is that the room the oberved size of the universe appears to be too large for this to have happened in the time since it was formed.
The varying speed of light theory suggests that the speed of light was much higher in the early universe, allowing the distant edges to be connected as the universe expanded. The speed of light would have then dropped in a predictable way as the density of the universe changed. This variability led the team to the prediction published today.



Critical geometry of a thermal big bang by Niayesh Afshordi and Joo Magueijo is published in Physical Review D.

The Daily Galaxy via Imperial College London









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 Post subject: Last Weeks Most Popular --From NASAs StarTrek Propulsion Sys
PostPosted: Tue Nov 29, 2016 5:20 pm 
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Last Weeks Most Popular --From NASAs StarTrek Propulsion System to Invisible Dark Force of the Cosmos






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 Post subject: NASAs Operation IceBridge" --Antarcticas Melting Polar
PostPosted: Wed Nov 30, 2016 7:20 am 
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NASAs Operation IceBridge" --Antarcticas Melting Polar Ice Threatens Planets Water Levels



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Antarctica is heading into austral summer, a period of rapid sea ice melt in the Southern Ocean. But this year, NASAs Operation Icebridge reports that the sea ice loss has been particularly brisk and the Antarctic sea ice extent is currently at the lowest level for this time of year ever recorded in the satellite record, which began in 1979.



Operation IceBridge is particularly well suited to measure changes in polar ice: it carries probably the most innovative and precise package of instruments ever flown over Antarctica, Newman said.

"This campaign was possibly the best Antarctic campaign IceBridge has ever had, said John Sonntag, IceBridge mission scientist at NASAs Goddard Space Flight Center in Greenbelt, Maryland. "We flew as many flights as we did in our best prior campaigns down here, and we certainly got more science return out of each flight than we have before, due to steadily improving instrumentation and also to some exceptionally good weather in the Weddell Sea that favored our sea ice flights."



"We flew over the Bellingshausen Sea many times during this campaign and saw that areas that are typically covered by sea ice were just open water this year, said Nathan Kurtz, IceBridges project scientist and a sea ice researcher at NASA Goddard. "It is a reminder that it is distinctive that we continue the time series of IceBridge measurements in the area so that we can measure both changes in sea ice extent and in sea ice thickness to assess the future trajectory of the ice pack and its impact on the climate.












IceBridge expanded its reach this year, covering a vast swath of Antarctica from the Ruppert Coast in West Antarctica to Recovery Glacier in the eastern half of the continent, plus the Weddell and Bellingshausen seas. Additionally, IceBridge flew twice over the South Pole, an area rarely measured since satellites dont overfly it.



During its six weeks of operations from its base in Punta Arenas, in the southernmost tip of Chile, IceBridge carried out 24 flights over Antarctica. In total, IceBridges airborne laboratory and team flew 308 hours.



"We are very satisfied that we flew all of our baseline flights and most of our high-priority ones, said Joe MacGregor, IceBridge deputy project scientist and glaciologist at Goddard. "We flew to places we had never surveyed comprehensively before or had only flown once, like the Abbott Ice Shelf, and revisited some of our classic targets, like the ever-changing Pine Island and Thwaites glaciers.



One of this years missions flew over a massive rift in the Antarctic Peninsulas Larsen C Ice Shelf. Ice shelves are the floating parts of ice streams and glaciers, and they buttress the grounded ice behind them; when ice shelves collapse, the ice behind accelerates toward the ocean, where it then adds to sea level rise. Larsen C neighbors a smaller ice shelf that disintegrated in 2002 after developing a rift similar to the one now growing in Larsen C.



The IceBridge scientists measured the Larsen C fracture to be about 70 miles long, more than 300 feet wide and about a third of a mile deep. The crack completely cuts through the ice shelf but it does not go all the way across it once it does, it will produce an iceberg roughly the size of the state of Delaware.



"Its a large rift on an ice shelf whose future we are curious about. Inevitably, when you see it in satellite imagery or from a plane, you wonder what is going to happen when it breaks off, MacGregor said. "However, large icebergs calve from ice shelves regularly and they normally do not direct to ice-shelf collapse. The growth of this rift likely indicates that the section of the ice shelf downstream of the rift is no longer holding back any grounded ice.



As with every field season, IceBridge collaborated with other science teams: this year, IceBridge flew under one of ESAs (the European Space Agency) CryoSat-2 satellites tracks and coordinated with a team from the British Antarctic Survey that was also conducting aerial surveys of the frozen continent.



"The British group began their campaign after we did, but targeted some of the areas we flew with a similar instrument suite. Once we process our data and they process theirs, well be capable to compare our measurements and blend them to form a better picture of Antarctica, MacGregor said. "We also flew over their on-continent bases, providing them with images of nearby areas as they prepare their operations for this field season.



During her stay in Punta Arenas, Newman met with Chilean researchers and students to discuss future opportunities with Chile.



We love working with our Chilean colleagues: from the northern Atacama leave for astrobiology research to its southernmost city, Punta Arenas, to study Antarctic land and sea ice, Newman said. Given this strong partnership, were looking forward to exciting future collaborations.



In addition to the NASA deputy administrator, IceBridge also welcomed U.S. Ambassador to Chile Carol Perez. Other guest participation included visitors from the State Department and U.S. Embassy in Chile; six U.S. teachers currently living and teaching in Chile; a Facebook representative; a visual artist; two photographers; and several journalists from various media outlets.



IceBridge researchers and Maggie Kane, a high school science teacher from Colorado who was embedded in the Antarctic campaign through the Arctic Research Consortium of the United States PolarTREC program, participated in 70 chats directly from the plane with classrooms in the U.S., Canada, Mexico and Chile, reaching over 1,800 students. Kane also gave several talks on IceBridges research to Chilean students in Punta Arenas and Santiago.



The mission of Operation IceBridge is to collect data on changing polar land and sea ice and maintain continuity of measurements between NASAs Ice, Cloud and Land Elevation Satellite (ICESat) missions.



The original ICESat mission ended in 2009, and its successor, ICESat-2, is scheduled for launch in 2018. Operation IceBridge, which began in 2009, is currently funded until 2019. The planned overlap with ICESat-2 will help scientists validate the satellites measurements.



The Daily Galaxy via NASAs Operation IceBridge









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 Post subject: New NASA Alien Planet K2-3d Discovered --"Scientists Ho
PostPosted: Wed Nov 30, 2016 2:21 pm 
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New NASA Alien Planet K2-3d Discovered --"Scientists Hope Detect Extraterrestrial Life Via Molecules in Its Atmosphere"

 


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A group of researchers from the National Astronomical Obervatory of Japan (NAOJ), the University of Tokyo, and the Astrobiology Center among others has oberved the transit of a potentially Earth-like extrasolar planet known as K2-3d using the MuSCAT instrument on the Okayama Astrophysical Observatory 188-cm telescope.


A transit is a phenomenon in which a planet passes in front of its parent star, blocking a small amount of light from the star, like a shadow of the planet. While transits have previously been observed for thousands of other extrasolar planets, K2-3d is distinctive because there is a possibility that it might harbor extraterrestrial life.


By observing its transit precisely using the next generation of telescopes, such as TMT, scientists expect to be capable to search the atmosphere of the planet for molecules related to life, such as oxygen.


With only the previous space telescope observations, however, researchers cant calculate the orbital period of the planet precisely, which makes predicting the exact times of future transits more difficult. This research group has succeeded in measuring the orbital period of the planet with a high precision of about 18 seconds.


This greatly improved the forecast accuracy for future transit times. Now researchers will know exactly when to notice for the transits using the next generation of telescopes. This research result is an distinctive step towards the search for extraterrestrial life in the future.


K2-3d is an extrasolar planet about 150 light-years away that was discovered by the NASA K2 mission (the Kepler telescopes "second light") (Note 1). K2-3ds size is 1.5 times the size of the Earth. The planet orbits its host star, which is half the size of the Sun, with a period of about 45 days.


The collage below summarizes the research. Using the Okayama 188-cm Reflector Telescope and the observational instrument MuSCAT (See real photo on the bottom left.), researchers succeeded in observing the extrasolar planet K2-3d, which is about the same size and temperature as the Earth, pass in front of its host, the primary star blocking some of the light coming from the star (See artistic visualization at the top.), making it appear to dim (See real data on the bottom right.)


 


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Compared to the Earth, the planet orbits close to its host star (about 1/5 of the Earth-Sun distance). But, because the temperature of the host star is lower than that of the Sun, calculations show that this is the right distance for the planet to have a relatively warm climate like the Earths. There is a possibility that liquid water could exist on the surface of the planet, raising the tantalizing possibility of extraterrestrial life.


K2-3ds orbit is aligned so that as seen from Earth, it transits (passes in front of) its host star. This causes, brief, periodic decreases in the stars brightness, as the planet blocks some of the stars light. This alignment enables researchers to probe the atmospheric composition of these planets by precise measurement of the amount of blocked starlight at different wavelengths.


About 30 potentially habitable planets that also have transiting orbits were discovered by the NASA Kepler mission, but most of these planets orbit fainter, more distant stars. Because it is closer to Earth and its host star is brighter, K2-3d is a more interesting candidate for detailed follow-up studies (See Figure 2).


The brightness decrease of the host star caused by the transit of K2-3d is small, only 0.07%. However, it is expected that the next generation of large telescopes (Note 2) will be capable to measure how this brightness decrease varies with wavelength, enabling investigations of the composition of the planets atmosphere.


If extraterrestrial life exists on K2-3d, scientists hope to be capable to detect molecules related to it, such as oxygen, in the atmosphere.


The orbital period of K2-3d is about 45 days. Since the K2 missions survey period is only 80 days for each area of sky, researchers could only measure two transits in the K2 data. This isnt sufficient to measure the planets orbital period precisely, so when researchers attempt to predict the times of future transits, creating something called a "transit ephemeris," there are uncertainties in the predicted times.


These uncertainties grow larger as they try to predict farther into the future. Therefore, early additional transit observations and adjustments to the ephemeris were required before researchers lost track of the transit.


Because of the importance of K2-3d, the Spitzer Space Telescope observed two transits soon after the planets discovery, bringing the total to four transit measurements. However, the addition of even a single transit measurement farther in the future can help to yield a significantly improved ephemeris.


Using the Okayama 188-cm Reflector Telescope and the latest observational instrument MuSCAT, the team observed a transit of K2-3d for the first time with a ground based telescope. Though a 0.07% brightness decrease is near the limit of what can be observed with ground based telescopes, MuSCATs ability to notice three wavelength bands simultaneously enhanced its ability to detect the transit.


By reanalyzing the data from K2 and Spitzer in combination with this new observation, researchers have greatly improved the precision of the ephemeris, determining the orbital period of the planet to within about 18 seconds (1/30 of the original uncertainty).


This improved transit ephemeris (Figure 3) ensures that when the next generation of large telescopes come online, they will know exactly when to notice for transits. Thus these research results help pave the way for future extraterrestrial life surveys.


The NASA K2 mission will continue until at least February 2018, and is expected to discover more potentially habitable planets like K2-3d. Furthermore, K2s successor, the Transiting Exoplanet Survey Satellite (TESS), will be launched in December 2017. TESS will survey the whole sky for two years, and is expected to detect hundreds of small planets like K2-3d near our Solar System.


The next generation of large telescopes includes the James Webb Space Telescope (JWST), which NASA will launch in 2018, and the Thirty Meter Telescope (TMT), which is being pursued through international collaboration including Japan.


To characterize a Second Earth using the next generation of large telescopes, it will be distinctive to measure the ephemerides and characteristics of planets with additional transit obervations using medium sized ground-based telescopes. The team will continue using MuSCAT for research related to the future search for extraterrestrial life.


The Daily Galaxy via National Institutes of Casual Sciences


Image Credit: NAOJ










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