понедельник, 19 ноября 2018 г.

Seismic study reveals huge amount of water dragged into Earth’s interior

Slow-motion collisions of tectonic plates under the ocean drag about three times more water down into the deep Earth than previously estimated, according to a first-of-its-kind seismic study that spans the Mariana Trench.

Seismic study reveals huge amount of water dragged into Earth's interior
Credit: © vmakt/Fotolia

The observations from the deepest ocean trench in the world have important implications for the global water cycle, according to researchers in Arts & Sciences at Washington University in St. Louis.

“People knew that subduction zones could bring down water, but they didn’t know how much water,” said Chen Cai, who recently completed his doctoral studies at Washington University. Cai is the first author of the study published in the journal Nature.

“This research shows that subduction zones move far more water into Earth’s deep interior — many miles below the surface — than previously thought,” said Candace Major, a program director in the National Science Foundation’s Division of Ocean Sciences, which funded the study. “The results highlight the important role of subduction zones in Earth’s water cycle.”

“Previous estimates vary widely in the amount of water that is subducted deeper than 60 miles,” said Doug Wiens, the Robert S. Brookings Distinguished Professor in Earth and Planetary Sciences in Arts & Sciences and Cai’s research advisor for the study. “The main source of uncertainty in these calculations was the initial water content of the subducting uppermost mantle.”

To conduct this study, researchers listened to more than one year’s worth of Earth’s rumblings — from ambient noise to actual earthquakes — using a network of 19 passive, ocean-bottom seismographs deployed across the Mariana Trench, along with seven island-based seismographs. The trench is where the western Pacific Ocean plate slides beneath the Mariana plate and sinks deep into the Earth’s mantle as the plates slowly converge.

The new seismic observations paint a more nuanced picture of the Pacific plate bending into the trench — resolving its three-dimensional structure and tracking the relative speeds of types of rock that have different capabilities for holding water.

Rock can grab and hold onto water in a variety of ways.

Ocean water atop the plate runs down into the Earth’s crust and upper mantle along the fault lines that lace the area where plates collide and bend. Then it gets trapped. Under certain temperature and pressure conditions, chemical reactions force the water into a non-liquid form as hydrous minerals — wet rocks — locking the water into the rock in the geologic plate. All the while, the plate continues to crawl ever deeper into the Earth’s mantle, bringing the water along with it.

Previous studies at subduction zones like the Mariana Trench have noted that the subducting plate could hold water. But they could not determine how much water it held and how deep it went.

“Previous conventions were based on active source studies, which can only show the top 3-4 miles into the incoming plate,” Cai said.

He was referring to a type of seismic study that uses sound waves created with the blast of an air gun from aboard an ocean research vessel to create an image of the subsurface rock structure.

“They could not be very precise about how thick it is, or how hydrated it is,” Cai said. “Our study tried to constrain that. If water can penetrate deeper into the plate, it can stay there and be brought down to deeper depths.”

The seismic images that Cai and Wiens obtained show that the area of hydrated rock at the Mariana Trench extends almost 20 miles beneath the seafloor — much deeper than previously thought.

The amount of water that can be held in this block of hydrated rock is considerable.

For the Mariana Trench region alone, four times more water subducts than previously calculated. These features can be extrapolated to predict the conditions under other ocean trenches worldwide.

“If other old, cold subducting slabs contain similarly thick layers of hydrous mantle, then estimates of the global water flux into the mantle at depths greater than 60 miles must be increased by a factor of about three,” Wiens said.

And for water in the Earth, what goes down must come up. Sea levels have remained relatively stable over geologic time, varying by less than 1,000 ft. This means that all of the water that is going down into the Earth at subduction zones must be coming back up somehow, and not continuously piling up inside the Earth.

Scientists believe that most of the water that goes down at the trench comes back from the Earth into the atmosphere as water vapor when volcanoes erupt hundreds of miles away. But with the revised estimates of water from the new study, the amount of water going into the earth seems to greatly exceed the amount of water coming out.

“The estimates of water coming back out through the volcanic arc are probably very uncertain,” said Wiens, who hopes that this study will encourage other researchers to reconsider their models for how water moves back out of the Earth. “This study will probably cause some re-evaluation.”

Moving beyond the Mariana Trench, Wiens along with a team of other scientists has recently deployed a similar seismic network offshore in Alaska to consider how water is moved down into the Earth there.

“Does the amount of water vary substantially from one subduction zone to another, based on the kind of faulting that you have when the plate bends?” Wiens asked. “There’s been suggestions of that in Alaska and in Central America. But nobody has looked at the deeper structure yet like we were able to do in the Mariana Trench.”

Author: Talia Ogliore | Source: Washington University in St. Louis [November 14, 2018]



Historian tells new story about England’s venerated ‘Domesday book’

Nearly a thousand years ago, a famous king created a famous book, later given the title “Domesday” (pronounced “doomsday”).

Historian tells new story about England's venerated 'Domesday book'
“Great Domesday Book” (above, in two volumes) and “Little Domesday Book” (below, in three volumes)
[Credit: The National Archives (UK)]

At least that’s been the common story: William the Conqueror, 20 years after his 1066 invasion of England from Normandy, ordered a massive survey of his new realm. One year later, he got a book with the results—a record of the nation’s wealth and resources, everything from property to sheep to servants.

The “Great Domesday Book,” as it was later named, is perhaps the most famous document in English history after the Magna Carta.

The book’s origin story, however, had not been thoroughly investigated until University of Illinois history professor Carol Symes took up the task. “What had never been resolved is how this massive text was really created,” Symes said, “and in this incredibly narrow timeframe.”

Now, after years of research, Symes makes the case in the journal Speculum that the final “Great Domesday Book” came years and perhaps decades later than the 1087 date to which it’s attributed, also the year of William’s death.

Historian tells new story about England's venerated 'Domesday book'
A booklet from the “Exeter Domesday Book” [Credit: Carol Symes,/Exeter Cathedral Library, Exeter]

It also was not the orderly bureaucratic enterprise that’s often assumed, but instead “enabled hundreds of thousands of individuals and communities to air grievances and to make their own ideas of law and justice a matter of public record,” Symes wrote.

“This is documentation of the trauma of conquest. We’re watching people pushing back, or at least letting their voices be heard because they’re fed up,” she said. In one example, the text records townspeople bitterly complaining about the leveling of houses to build a castle.

“We need to rethink what has seemed to be a rather straightforward, top-down royal project, but is revealed to be the tip of a big, monstrous iceberg that involves the agency of many historical actors and often preserves their voices. This helps to tell a very different story about one of the landmark events of England—the Norman conquest and its aftermath—that is not just a story about ‘the great man.'”

The universe of the “Domesday Book” is complicated, to say the least. The name is attached to two different bodies of text, “Great Domesday” and “Little Domesday—the first covering all of the country’s shires except three in the southeast, the second covering those three, but in more detail, suggesting it was an earlier draft.

Historian tells new story about England's venerated 'Domesday book'
Roll fragment from the abbey at Burton-upon-Trent [Credit: Carol Symes/Staffordshire Public Record Office]

There’s also “Exeter Domesday,” a collection of 103 booklets that appears to be an even earlier draft of survey results, mostly covering three shires in the southwest.

Curiously, London does not appear in any of these records, which likely is a sign its citizens either ignored the inquest or overwhelmed it with grievances, Symes said.The Exeter collection is just one of many “satellite” documents that have some connection with the survey or book but have received little scholarly attention, Symes said. For many who focus their research on “Great Domesday,” the book has been “the sun around which everything else spins.”

Among Symes’ contributions is to suggest ways that the different texts relate to each other, since that hasn’t been clear. “I think I have figured out the workings behind how this book (“Great Domesday”) was made,” she said.

Most of Symes’ research focused on the Exeter collection and another satellite document, a small fragment of parchment roll, perhaps the oldest in England, from an abbey at Burton-on-Trent in the northwest of the country. In both cases, she examined the original documents.

The Exeter documents provide numerous clues on how “Great Domesday” was assembled, but also serve as a window on the people and the process. A bishop can be seen intervening with the king’s advisers when his property is not recorded. Teenage scribes make drinking plans in the marginal notes of manuscripts.

Historian tells new story about England's venerated 'Domesday book'
Foundation charter for the abbey at Burton-upon-Trent [Credit: Staffordshire Public Record Office]

The abbey’s parchment fragment, however, is key to Symes’ contention that the final book came years and even decades later. She ties its contents to the comings and goings of a man who served at one time as its abbot, who had access to the survey data that went into “Domesday” and may even have been involved in the survey.

“It plugs a huge hole that we had in our evidence. It suggests that the process of creating the thing we call ‘Great Domesday’ actually took a lot longer than people had thought.”Symes said she was attracted to this particular book as part of her interest in medieval manuscripts, especially the complex ways in which they were “mediated—i.e., written, handled, copied, recopied, added to, edited, interpreted and heard by audiences, all in an age before the printing press. Historians need to take a text’s complex mediation into account, she said, even considering the parchment on which it was written, to fully understand and not misinterpret it.

Symes also likes messiness—finding out “how the sausage gets made.” She was attracted to Domesday, in part, “because it’s a messy document that people pretend is not messy. It’s taken to be this pristine, transparent thing when it’s not.”

One value in the Domesday research, she said, is in “realizing that the people of almost a thousand years ago were real people with real human emotions and needs. We’re putting on a different set of glasses to look at these sources, and what we see is all those people who were written out of the record. We’re getting to see and hear them again.”

The “wonderful irony,” Symes said, is that we can do that through one of the most famous books created in the Middle Ages, by a king.

Author: Craig Chamberlain | Source: University of Illinois at Urbana-Champaign [November 14, 2018]



Auroras unlock the physics of energetic processes in space

A close study of auroras has revealed new ways of understanding the physics of explosive energy releases in space, according to new UCL-led research.

Auroras unlock the physics of energetic processes in space
Auroral beads forming along an arc [Credit: ESA]

Auroras are a tell-tale sign of physical processes in space, acting like TV screens by showing what happens millions of kilometres away from Earth where our planet’s magnetic field stretches into a long tail facing away from the Sun.

For the study, published in Nature Communications, the team from UCL and the University of Reading remotely observed rapidly evolving aurora to understand the physics behind why, when and how energy is released as the source of the aurora explosively reconfigures.

“Somewhere in the huge volume of space into which Earth’s magnetosphere stretches, this energy release occurs via instability which is really hard to pinpoint. They cause substorms whereby charged particles surf into the Earth’s atmosphere on electromagnetic waves, releasing large amounts of energy and lighting up the aurora” explained study author Dr Jonathan Rae (UCL Space & Climate Physics).

“By studying auroras closely, we can map back to where in space the instabilities are occurring and study the physics that cause them. It’s much more efficient than trying to observe vast areas of space.”

The team scanned a large portion of the sky and found the perfect substorm located over Poker Flats in Alaska on 18 September 2012. By using new data from the MOOSE (Multi-spectral Observatory Of Sensitive EM-CCDs) camera, they tracked the aurora as it moved towards the northern pole over a four minute period.

This is a relatively long time for this type of aurora to be studied, allowing the scientists to collect a wealth of data. The information was then analysed for specific patterns that gave important physical clues to the aurora’s formation in space and time.

The aurora began as a line of ‘auroral beads’ along an arc which grew exponentially in brightness and size. These growing ripples are a hallmark of an instability in space.

By comparing these detailed characteristics from the aurora with state of the art theory, the team could narrow down the area of space where the instability most likely is.

“We’ve shown that it’s possible to only study aurora to find out where instabilities are in space, which has not been done before,” explained co-author Dr Colin Forsyth (UCL Space & Climate Physics).

“Our method allows us to predict what the instability is and where it is in space. In fact, the region we’ve identified is incredibly small in space terms – only a small fraction of the volume of the Earth – and we hope to study it in more detail using spacecraft that pass through the area.”

Until now, scientists have been able to describe aurora and high energy events that occur on the Sun and other planets within the solar system, but is the first time real physical analysis has been done.

“Importantly, our work has given scientists more physics to work with. A whole range of theoretical models can be tested and refined based on the physical characteristics we’ve captured,” added co-author Dr Clare Watt (University of Reading).

“What we’ve reported has eluded scientists since auroras were first described in the 1960s and while we use Earth as our closest laboratory, the findings will apply to other events elsewhere in the solar system. We now look forward to pinpointing this epicentre in space and finding out what makes it unstable,” concluded Dr Rae.

Source: University College London [November 15, 2018]



Trans-galactic streamers feeding most luminous galaxy in the universe

The most luminous galaxy in the universe has been caught in the act of stripping away nearly half the mass from at least three of its smaller neighbors, according to a new study published in the journal Science. The light from this galaxy, known as W2246-0526, took 12.4 billion years to reach us, so we are seeing it as it was when our universe was only about a tenth of its present age.

Trans-galactic streamers feeding most luminous galaxy in the universe
Artist impression of W2246-0526, the most luminous known galaxy, and three companion galaxies
[Credit: NRAO/AUI/NSF, S. Dagnello]

New observations with the Atacama Large Millimeter/submillimeter Array (ALMA) reveal distinct streamers of material being pulled from three smaller galaxies and flowing into the more massive galaxy, which was discovered in 2015 by NASA’s space-based Wide-field Infrared Survey Explorer (WISE). It is by no means the largest or most massive galaxy we know of, but it is unrivaled in its brightness, emitting as much infrared light as 350 trillion Suns.
The connecting tendrils between the galaxies contain about as much material as the galaxies themselves. ALMA’s amazing resolution and sensitivity allowed the researchers to detect these remarkably faint and distant trans-galactic streamers.

“We knew from previous data that there were three companion galaxies, but there was no evidence of interactions between these neighbors and the central source,” said Tanio Díaz-Santos of the Universidad Diego Portales in Santiago, Chile, lead author of the study. “We weren’t looking for cannibalistic behavior and weren’t expecting it, but this deep dive with the ALMA observatory makes it very clear.”

Trans-galactic streamers feeding most luminous galaxy in the universe
ALMA image reveals how W2246-0526 is being fed by three companion galaxies through trans-galactic streamers of gas.
The main galaxy and one of its companions are in the center. To the lower left is another companion and its large
tidal tail that connects it to the main galaxy. The upper left concentration is the third such companion galaxy
[Credit: ALMA (ESO/NAOJ/NRAO),T. Díaz-Santos et al.; S. Dagnello (NRAO/AUI/NSF)]

Galactic cannibalism is not uncommon, though this is the most distant galaxy in which such behavior has been observed and the study authors are not aware of any other direct images of a galaxy simultaneously feeding on material from multiple sources at those early cosmic times.
The researchers emphasize that the amount of gas being devoured by W2246-0526 is enough to keep it forming stars and feeding its central black hole for hundreds of millions of years.

This galaxy’s startling luminosity is not due to its individual stars. Rather, its brightness is powered by a tiny, yet fantastically energetic disk of gas that is being superheated as it spirals in on the supermassive black hole. The light from this blazingly bright accretion disk is then absorbed by the surrounding dust, which re-emits the energy as infrared light.

Trans-galactic streamers feeding most luminous galaxy in the universe
Composite image of W2246-0526 and its three companion galaxies shown in the ALMA portion of the
image (orange). The blue background is an optical image of the same region from Hubble
[Credit: ALMA (ESO/NAOJ/NRAO);T. Díaz-Santos et al.; N. Lira]

This extreme infrared radiation makes this galaxy one of a rare class of quasars known as Hot, Dust-Obscured Galaxies or Hot DOGs. Only about one out of every 3,000 quasars observed by WISE belongs to this class.
Much of the dust and gas being siphoned away from the three smaller galaxies is likely being converted into new stars and feeding the larger galaxy’s central black hole. This galaxy’s gluttony, however, may lead to its self-destruction. Previous research suggests that the energy of the AGN will ultimately jettison much, if not all of the galaxy’s star-forming fuel.

An earlier work led by co-author Chao-Wei Tsai of UCLA estimates that the black hole at the center of W2246-0526 is about 4 billion times the mass of the Sun. The mass of the black hole directly influences how bright the AGN can become, but — according to this earlier research — W2246-0526 is about 3 times more luminous than what should be possible. Solving this apparent contradiction will require additional observations.

Source: National Radio Astronomy Observatory [November 15, 2018]



Devonian integrative stratigraphy and timescale of China

The Devonian (419.2-358.9 Ma) is the first geological period of the late Paleozoic, spanning about 60.3 Ma from the end of the Silurian, and its beginning is marked by the First Appearance Datum (FAD) of graptolite Uncinatograptus uniformis. During this time interval, the Earth?s climate system underwent severe perturbations, characterized by drastic dropdown of atmospheric CO2 concentration, and gradual transition from the Silurian ‘greenhouse’ Earth to the Permo-Carboniferous ‘icehouse’ Earth.

Devonian integrative stratigraphy and timescale of China
Representative fossil groups from Devonian [Credit: © Science China Press]

The complex pattern of Devonian climate change were controlled by multiple factors at different time scales, and induced 25 global events that are characterized by sea-level rise and fall, ocean anoxic/hypoxic events, and/or biological extinctions/turnovers. Establishment of high-resolution Devonian integrative stratigraphy and timescale framework is essential for the studies on the complex ocean-land-atmosphere interactions during Devonian at different temporal and spatial scales.
A review paper by Qie et al. (2018) was published recently in Science China: Earth Sciences. Based on well-studied bio- and chronostratigraphy of Devonian in South China and adjacent areas, in combination with recent achievements in carbon isotope stratigraphy, event stratigraphy and radioactive isotope ages, this paper and briefly summarize the research history and current status of Devonian chronostratigraphy of China, and for the first time introduce Devonian integrative stratigraphy framework of China.

In 1985, the global Devonian chronostratigraphy scale was formally defined and subdivided into three series, the lower, middle and upper, and contains seven global stages. Till 1996, all seven Devonian stages’ GSSPs have been formally defined and ratified. Conodont is a key taxon in the Devonian biostratigraphic research. 6 out of the 7 global stages of Devonian, except for the basal Devonian boundary, are marked by the FAD of certain conodont species.

Devonian integrative stratigraphy and timescale of China
Devonian Chronostratigraphy and biozonations in pelagic facies in China
[Credit: ©Science China Press]

By summarizing the taxonomy and biostratigraphy of conodonts in China, Wang (2018) confirmed 58 Devonian conodonts zones in pelagic facies, among which the biozones of Emsian to Famennian can be precisely correlated to the standard international conodont zones. The bases of the Emsian and the Devonian-Carboniferous boundary (DCB) has been defined by the FAD of conodont Polygnathus kitabicus and Siphonodella sulcata.
However, the acceptance of the GSSPs for the bases of the Emsian and DCB have received major criticism since the very beginning of their ratification, and in 2008, the Subcommission on Devonian Stratigraphy (SDS) and Subcommisson on Carboniferous Stratigraphy (SCCS) have decided to redefine the boundary criteria and levels, which are still ongoing investigations. In addition to conodont biostratigraphy, important progresses on biostratigraphic research of graptolite, ostracods, brachiopods, rugose corals, as well as spores and plants are emphatically introduced in this paper.

As for chemostratigraphy, carbon and strontium isotopic records from South China show similar trend with Euramerica sections, and have global correlation significances. δ13C values show major positive shifts in the Silurian-Devonian boundary, Kačák, Frasne, lower and upper Kellwasser, as well as Hangenberg events, suggesting global carbon cycle perturbation during these critical time intervals. In Longmenshan region, 87Sr/86Sr values are 0.70788-0.70868, and its long-term trend agrees with a published mean LOWESS fitted line.

Devonian integrative stratigraphy and timescale of China
Generalized Devonian carbon and strontium isotope stratigraphy, event stratigraphy in China
[Credit: ©Science China Press]

After a gradual decline from early Devonian, 87Sr/86Sr ratios reach nadir values and stay stable in middle Devonian, then start to increase in Frasnian and define a plateau throughout the Famennian. 87Sr/86Sr ratios can be used as a tool for precise stratigraphic correlation and dating. This paper also give a detail introduction about Devonian event stratigraphy, cyclostratigraphy, geological chronology, and stratigraphic correlation among main major palaeobiogeography realms in China.
At present, the main tasks for the researches on Devonian of China include: 1) establishment of continuous astronomical time scale and high-resolution radioactive isotope dating; 2) further subdivision of Chinese regional chronostratigraphy; 3) sulfur and oxygen isotopic stratigraphy of Devonian; 4) integrated stratigraphy studies on the Devonian System in other stratigraphic regions except South China region.

Source: Science China Press [November 15, 2018]



New study reveals connection between climate, life and the movement of continents

A new study by The University of Texas at Austin has demonstrated a possible link between life on Earth and the movement of continents. The findings show that sediment, which is often composed of pieces of dead organisms, could play a key role in determining the speed of continental drift. In addition to challenging existing ideas about how plates interact, the findings are important because they describe potential feedback mechanisms between tectonic movement, climate and life on Earth.

New study reveals connection between climate, life and the movement of continents
High mountain ranges such as the Andes are formed near subduction zones where one plate is forced under another.
Eroding mountains and subducting seafloor could be elements of a self-regulating mechanism modulating
the speed of continental movement [Credit: Nicolas Prieto on Unsplash]

The study, published in Earth and Planetary Science Letters, describes how sediment moving under or subducting beneath tectonic plates could regulate the movement of the plates and may even play a role in the rapid rise of mountain ranges and growth of continental crust.

The research was led by Whitney Behr, a research fellow at the Jackson School and professor at ETH Zurich in Switzerland, and co-authored by Thorsten Becker, a professor at the UT Jackson School of Geosciences and research scientist at its Institute for Geophysics (UTIG).

Sediment is created when wind, water and ice erode existing rock or when the shells and skeletons of microscopic organisms like plankton accumulate on the seafloor. Sediment entering subduction zones has long been known to influence geological activity such as the frequency of earthquakes, but until now it was thought to have little influence on continental movement. That’s because the speed of subduction was believed to be dependent on the strength of the subducting plate as it bends and slides into the viscous mantle, the semi molten layer of rock beneath Earth’s crust. Continental movement is driven by one plate sinking under another so, in this scenario, the strength of the portion of the plate being pulled into Earth’s mantle (and the energy required to bend it) would be the primary control for the speed of the plate movement, with sediment having little effect.

However, prior research involving UTIG scientists had shown the subducting plates may be weaker and more sensitive to other influences than previously thought. This led researchers to look for other mechanisms that might impact plate velocity. They estimated how different types of rock might affect the plate interface – the boundary where subducting plates meet. Subsequent modelling showed that rock made of sediment can create a lubricating effect between plates, accelerating subduction and increasing plate velocity.

New study reveals connection between climate, life and the movement of continents
Planktonic foraminifera, such as these collected in the Gulf of Mexico, form the base of many marine and aquatic food
chains. Upon death, their skeletons settle on the seafloor to form sedimentary rock such as limestone and chalk.
Pressed together in sufficient quantities, such sedimentary rock could have a lubricating effect
on the movement of continental plates [Credit: Randolph Femmer, USGS]

This mechanism could set in motion a complex feedback loop. As plate velocity increases, there would be less time for sediment to accumulate, so the amount of subducting sediment would be reduced. This leads to slower subduction, which may allow for mountains to grow at plate boundaries as the force of the two plates running into each other causes uplift. In turn, erosion of those mountains by wind, water and other forces can produce more sediments which feed back into the subduction zone and restart the cycle by increasing the speed of subduction.

“The feedback mechanisms serve to regulate subduction speeds such that they don’t ‘runaway’ with extremely fast velocities,” said Behr.

Behr and Becker’s new model also offers a compelling explanation for variations found in plate speed, such as India’s dramatic northward acceleration some 70 million years ago. The authors propose that as India moved through equatorial seas teeming with life, an abundance of sedimentary rock formed by organic matter settling on the seafloor created a lubricating effect in the subducting plate. India’s march north accelerated from a stately 5 centimeters per year (about 2 inches) to an eye-watering 16 centimeters per year (about 6 inches). As the continent accelerated the amount of sediment being subducted decreased and India slowed before finally colliding with Asia.

Behr and Becker suggest these feedback mechanisms would have been very different in the early Earth before the formation of continents and the emergence of life. Although their model does not examine the origins of these feedback mechanisms, it does raise compelling questions about the interaction between continental movement and life on Earth.

“What is becoming clear is that the geological history of the incoming plate matters,” said Becker, who also holds the Shell Distinguished Chair in Geophysics at UT. “We will have to study in more detail how those possible feedback processes may work.”

Source: University of Texas at Austin [November 15, 2018]



2018 November 19 Gibbous Moon beyond Swedish Mountain Image…

2018 November 19

Gibbous Moon beyond Swedish Mountain
Image Credit & Copyright: Göran Strand

Explanation: This is a gibbous Moon. More Earthlings are familiar with a full moon, when the entire face of Luna is lit by the Sun, and a crescent moon, when only a sliver of the Moon’s face is lit. When more than half of the Moon is illuminated, though, but still short of full illumination, the phase is called gibbous. Rarely seen in television and movies, gibbous moons are quite common in the actual night sky. The featured image was taken in Jämtland, Sweden near the end of last month. That gibbous moon turned, in a few days, into a crescent moon, and then a new moon, then back to a crescent, and a few days ago back to gibbous. And this same gibbous moon is visible again tonight, leading up to the Full Beaver Moon that occurs Friday night. Setting up to capture a picturesque gibbous moonscape, the photographer was quite surprised to find an airplane, surely well in the foreground, appearing to fly past it.

∞ Source: apod.nasa.gov/apod/ap181119.html

Astronomers Find Possible Elusive Star Behind Supernova

Artist’s Illustration of SN 2017ein

Credits: NASA, ESA, and J. Olmsted (STScI)

SN 2017ein in NGC 3938

Credits: NASA, ESA, S. Van Dyk (Caltech), and W. Li (University of California)

Astronomers may have finally uncovered the long-sought progenitor to a specific type of exploding star by sifting through NASA Hubble Space Telescope archival data. The supernova, called a Type Ic, is thought to detonate after its massive star has shed or been stripped of its outer layers of hydrogen and helium.

These stars could be among the most massive known — at least 30 times heftier than our Sun. Even after shedding some of their material late in life, they are expected to be big and bright. So it was a mystery why astronomers had not been able to nab one of these stars in pre-explosion images.

Finally, in 2017, astronomers got lucky. A nearby star ended its life as a Type Ic supernova. Two teams of astronomers pored through the archive of Hubble images to uncover the putative precursor star in pre-explosion photos taken in 2007. The supernova, catalogued as SN 2017ein, appeared near the center of the nearby spiral galaxy NGC 3938, located roughly 65 million light-years away.

This potential discovery could yield insight into stellar evolution, including how the masses of stars are distributed when they are born in batches.

“Finding a bona fide progenitor of a supernova Ic is a big prize of progenitor searching,” said Schuyler Van Dyk of the California Institute of Technology (Caltech) in Pasadena, lead researcher of one of the teams. “We now have for the first time a clearly detected candidate object.” His team’s paper was published in June in The Astrophysical Journal.

A paper by a second team, which appeared in the Oct. 21, 2018, issue of the Monthly Notices of the Royal Astronomical Society, is consistent with the earlier team’s conclusions.

“We were fortunate that the supernova was nearby and very bright, about 5 to 10 times brighter than other Type Ic supernovas, which may have made the progenitor easier to find,” said Charles Kilpatrick of the University of California, Santa Cruz, leader of the second team. “Astronomers have observed many Type Ic supernovas, but they are all too far away for Hubble to resolve. You need one of these massive, bright stars in a nearby galaxy to go off. It looks like most Type Ic supernovas are less massive and therefore less bright, and that’s the reason we haven’t been able to find them.”

An analysis of the object’s colors shows that it is blue and extremely hot. Based on that assessment, both teams suggest two possibilities for the source’s identity. The progenitor could be a single hefty star between 45 and 55 times more massive than our Sun. Another idea is that it could have been a massive binary-star system in which one of the stars weighs between 60 and 80 solar masses and the other roughly 48 suns. In this latter scenario, the stars are orbiting closely and interact with each other. The more massive star is stripped of its hydrogen and helium layers by the close companion, and eventually explodes as a supernova.

The possibility of a massive double-star system is a surprise. “This is not what we would expect from current models, which call for lower-mass interacting binary progenitor systems,” Van Dyk said.

Expectations on the identity of the progenitors of Type Ic supernovas have been a puzzle. Astronomers have known that the supernovas were deficient in hydrogen and helium, and initially proposed that some hefty stars shed this material in a strong wind (a stream of charged particles) before they exploded. When they didn’t find the progenitors stars, which should have been extremely massive and bright, they suggested a second method to produce the exploding stars that involves a pair of close-orbiting, lower-mass binary stars. In this scenario, the heftier star is stripped of its hydrogen and helium by its companion. But the “stripped” star is still massive enough to eventually explode as a Type Ic supernova. “Disentangling these two scenarios for producing Type Ic supernovas impacts our understanding of stellar evolution and star formation, including how the masses of stars are distributed when they are born, and how many stars form in interacting binary systems,” explained Ori Fox of the Space Telescope Science Institute (STScI) in Baltimore, Maryland, a member of Van Dyk’s team. “And those are questions that not just astronomers studying supernovas want to know, but all astronomers are after.”

Type Ic supernovas are just one class of exploding star. They account for about 20 percent of massive stars that explode from the collapse of their cores.

The teams caution that they won’t be able to confirm the source’s identity until the supernova fades in about two years. The astronomers hope to use either Hubble or the upcoming NASA James Webb Space Telescope to see whether the candidate progenitor star has disappeared or has significantly dimmed. They also will be able to separate the supernova’s light from that of stars in its environment to calculate a more accurate measurement of the object’s brightness and mass.

SN 2017ein was discovered in May 2017 by Tenagra Observatories in Arizona. But it took the sharp resolution of Hubble to pinpoint the exact location of the possible source. Van Dyk’s team imaged the young supernova in June 2017 with Hubble’s Wide Field Camera 3. The astronomers used that image to pinpoint the candidate progenitor star nestled in one of the host galaxy’s spiral arms in archival Hubble photos taken in December 2007 by the Wide Field Planetary Camera 2.

Kilpatrick’s group also observed the supernova in June 2017 in infrared images from one of the 10-meter telescopes at the W. M. Keck Observatory in Hawaii. The team then analyzed the same archival Hubble photos as Van Dyk’s team to uncover the possible source.

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 in Washington, D.C.

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Donna Weaver / Ray Villard
Space Telescope Science Institute, Baltimore, Maryland
410-338-4493 / 410-338-4514

dweaver@stsci.edu / villard@stsci.edu

Schuyler Van Dyk
Caltech/IPAC, Pasadena, California


Charles Kilpatrick
University of California, Santa Cruz, California


Archive link

Petrified Wood | #Geology #GeologyPage #Fossil Locality: Cerro…

Petrified Wood | #Geology #GeologyPage #Fossil

Locality: Cerro Cuadrado, Patagonia, Argentina

Size: 7.2 × 6.6 × 2.5 cm

Photo Copyright © Viamineralia /e-rocks.com

Geology Page



Stolzite & Raspite | #Geology #GeologyPage…

Stolzite & Raspite | #Geology #GeologyPage #Mineral

Locality: Broken Hill, New South Wales, Australia

Size: 8 × 5.5 × 4 cm

Largest Crystal: 0.20cm

Photo Copyright © FERRERO’S MINERALS /e-rocks.com

Geology Page



Harrison’s Cave | #Geology #GeologyPage…

Harrison’s Cave | #Geology #GeologyPage #Cave

Harrison’s Cave is a tourist attraction in the country of Barbados, The caves were first mentioned in historical documents in 1795. For almost 200 years they were forgotten. In the early 1970s, Ole Sorensen, along with Tony Mason, re-discovered them.the cave was not made by man but by nature and earth.

The caves are naturally formed by water erosion through the limestone rock. The calcium-rich water that runs through the caves have formed the unusual stalactites and stalagmites formations.

Geology Page



Russian Cargo Craft Docks to Station and Delivers Goods

ROSCOSMOS – Russian Vehicles patch.

November 18, 2018

Image above: The Russian Progress 60 cargo craft is seen shortly after undocking from the Space Station, Dec. 19, 2005. The unpiloted Russian Progress 71 cargo ship is scheduled to launch Friday, Nov. 16, to the orbiting laboratory, bringing food, fuel and supplies to the crew. Image Credit: NASA.

Traveling about 252 miles over Algeria, the unpiloted Russian Progress 71 cargo ship docked at 2:28 p.m. EST to the aft port of the Zvezda Service Module on the Russian segment of the International Space Station.

Progress MS-10 docking to the ISS

In addition to the arrival of Progress today, a Northrop Grumman Cygnus spacecraft is on its way to the space station with about 7,400 pounds of cargo after launching at 4:01 a.m. Saturday from NASA’s Wallops Flight Facility on Virginia’s Eastern Shore.

Image above: Nov. 18, 2018: International Space Station Configuration. Three spaceships are docked at the space station including the Progress 70 and Progress 71 resupply ships and the Soyuz MS-09 crew ship. Image Credit: NASA.

The Cygnus spacecraft is scheduled to arrive at the orbital laboratory Monday, Nov. 19. Expedition 57 astronauts Serena Auñón-Chancellor of NASA and Alexander Gerst of ESA (European Space Agency) will use the space station’s robotic arm to grapple Cygnus about 5:20 a.m. Watch installation coverage beginning at 4 a.m. on NASA Television and the agency’s website: http://www.nasa.gov/live

Related links:

Expedition 57: https://www.nasa.gov/mission_pages/station/expeditions/expedition57/index.html

NASA TV: http://www.nasa.gov/live

ROSCOSMOS Press Release: https://www.roscosmos.ru/25740/

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Images (mentioned), Video, Text, Credits: NASA/Marck Garcia/NASA TV/SciNews.

Best regards, Orbiter.chArchive link

Space Station Science Highlights: Week of November 12, 2018

ISS – Expedition 57 Mission patch.

Nov. 18, 2018

Last week, the Expedition 57 crew members aboard the International Space Station conducted scientific investigations and prepared for the arrival of Northrop Grumman’s Cygnus vehicle, which launched early Saturday morning. The resupply vehicle delivered 7,400 pounds of food, fuel and supplies to the station two days later.

Learn about some of the science launching aboard the Northrop Grumman Commercial Resupply-10 mission here: 3D Printing, Virtual Reality, Simulated Stardust and More Headed to Orbiting Lab: https://orbiterchspacenews.blogspot.com/2018/11/3d-printing-virtual-reality-simulated.html

Here’s a look at some of the science conducted last week aboard the orbiting lab:

Final operations conducted in crystallography investigation

A crew member performed the final microscopy operations by placing samples under the microscope for observation, and providing photographic documentation for BioServe Protein Crystallography (BPC-1) last week.

Animation above: ESA astronaut Alexander Gerst conducts an (Optical Coherence Tomography) OCT examination. Animation Credit: NASA.

BPC-1 seeks to demonstrate the feasibility of conducting protein crystal growth in real time aboard the space station. Crew members can observe crystal formation and adjust for follow-on experiments. This approach optimizes a scientist’s ability to grow crystals in microgravity without having to wait for samples to return to Earth and re-launch.

Free-flying AI soars through Columbus

Astronauts on future lengthy missions deep into space face hard work and long hours, and long communication delays back to Earth that could slow down their work pace. Soon, though, they may be able to call for assistance from artificial intelligence (AI). Pilot Study with the Crew Interactive Mobile Companion (CIMON) observes the effects of AI for crew support in terms of helping the crew and the crew’s acceptance of using AI during long-term flight.

A spherical device a bit larger than a basketball, CIMON can see, hear, speak, understand and move autonomously. It is intended to assist with routine crew activities such as moving hardware, and for complex science tasks such as recording measurements and other data. Ultimately, it can serve as a mobile camera to provide crew members with video-assisted instructions and document procedures for either live or retrospective analysis.

Image above: ESA astronaut Alexander Gerst with CIMON, an artificial intelligence helper aboard the station. Image Credit: NASA.

Last week, crew members prepared CIMON for demonstrations. They adjusted his microphone, checked the camera view and charged the batteries. By Thursday, Cimon was able to demonstrate free flying and navigation in the station’s Columbus Module.

New investigation set to begin in LMM

Proteins are important biological molecules that can be crystallized to provide better views of their structure, which helps scientists understand how they work. The Effect of Macromolecular Transport on Microgravity Protein Crystallization (LMM Biophysics 4) studies why microgravity-grown crystals are often higher in quality than those grown on Earth by examining the movement of single protein molecules in microgravity.

Space to Ground: Honoring a Legend: 11/16/2018

Last week, a crew member removed an LMM Biophysics-4 sample from the Minus Eighty-degree Laboratory Freezer (MELFI) and installed it into the Light Microscopy Module (LMM) for the start of the Growth Rate Dispersion as a Predictive Indicator for Biological Crystal Samples Where Quality Can be Improved with Microgravity Growth (LMM Biophysics-6) investigation.

Other work was done on these investigations:

– The Plasma Kristall-4 investigation (PK-4) conducts research in the field of “Complex Plasmas”: low temperature gaseous mixtures composed of ionized gas, neutral gas, and micron-sized particles: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1192

– Food Acceptability examines changes in how food appeals to crew members during their time aboard the station. Acceptability of food – whether crew members like and actually eat something – may directly affect crew caloric intake and associated nutritional benefits: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7562

– Meteor is a visible spectroscopy instrument used to observe meteors in Earth orbit: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1174

– The Veg-03 investigation expands on previous validation tests of the new Veggie hardware, which crew members used to grow cabbage, lettuce and other fresh vegetables in space: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=1159

– The Life Sciences Glovebox (LSG) is a sealed work area that accommodates life science and technology investigations in a workbench-type environment. Due to its larger size, two crew members can work in the LSG simultaneously: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=7676

Image above: Sunrise over Peru Coast, just over Ecuador line (longitude 0), seen by EarthCam on ISS, speed: 27’597 Km/h, altitude: 407,95 Km, image captured by Roland Berga (on Earth in Switzerland) from International Space Station (ISS) using ISS-HD Live application with EarthCam’s from ISS on November 18, 2018 at 12:23 UTC. Image Credits: Orbiter.ch Aerospace/Roland Berga.

Related links:

Expedition 57: https://www.nasa.gov/mission_pages/station/expeditions/expedition57/index.html

BioServe Protein Crystallography (BPC-1): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7729

Crew Interactive Mobile Companion (CIMON): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7639

LMM Biophysics 4: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7741

Light Microscopy Module (LMM): https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=531

LMM Biophysics-6: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7743

Veggie: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=374

Space Station Research and Technology: https://www.nasa.gov/mission_pages/station/research/index.html

International Space Station (ISS): https://www.nasa.gov/mission_pages/station/main/index.html

Animation (mentioned), Images (mentioned), Video (NASA), Text, Credits: NASA/Michael Johnson/Vic Cooley, Lead Increment Scientist Expeditions 57/58/Orbiter.ch Aerospace/Roland Berga.

Best regards, Orbiter.chArchive link

Hang Son Doong “The World’s Largest Caves” | #Geology…

Hang Son Doong “The World’s Largest Caves” | #Geology #GeologyPage #Cave #Vietnam

Hang Sơn Đoòng also known as Sơn Đoòng cave is a solutional cave in Phong Nha-Kẻ Bàng National Park, Bố Trạch District, Quảng Bình Province, Vietnam. As of 2009 it has the largest known cave passage cross-section in the world, and is located near the Laos–Vietnam border.

Read more & More Photos: http://www.geologypage.com/2016/05/hang-son-doong-the-worlds-largest-caves.html


Spinel | #Geology #GeologyPage #Mineral Locality: Mogok…

Spinel | #Geology #GeologyPage #Mineral

Locality: Mogok Township, Pyin-Oo-Lwin District, Mandalay, Myanmar (former Burma)

Size: 3.1 × 2.9 × 2.9 cm

Photo Copyright © Viamineralia /e-rocks.com

Geology Page



HiPOD (18 November 2018): Channels in Syria Planum   – The…

HiPOD (18 November 2018): Channels in Syria Planum

   – The objective of this observation is to determine the nature of a curved channel with levees. (Alt: 255 km. Black and white is less than 5 km across; enhanced color is less than 1 km.)

NASA/JPL/University of Arizona


Полет на параплане с обрыва на мысу Куяльницкого лимана, соленого озера. Экстремальный развлекательный полет проводится для любителей. ...