суббота, 26 января 2019 г.

2019 January 26 The Umbra of Earth Image Credit &…

2019 January 26

The Umbra of Earth
Image Credit & Copyright: Antonio Finazzi

Explanation: The dark, inner shadow of planet Earth is called the umbra. Shaped like a cone extending into space, it has a circular cross section most easily seen during a lunar eclipse. For example, on January 21 the Full Moon slid across the northern half of Earth’s umbral shadow, entertaining moonwatchers around much of the planet. In the total phase of the eclipse, the Moon was completely within the umbra for 63 minutes. Recorded under clear, dark skies from the hills near Chiuduno, Italy this composite eclipse image uses successive pictures from totality (center) and partial phases to trace out a large part of the umbra’s curved edge. Reflecting sunlight scattered by the atmosphere into Earth’s shadow, the lunar surface appears reddened during totality. But close to the umbra’s edge, the limb of the eclipsed Moon shows a distinct blue hue. The blue eclipsed moonlight originates as rays of sunlight pass through layers high in the upper stratosphere, colored by ozone that scatters red light and transmits blue.

∞ Source: apod.nasa.gov/apod/ap190126.html

Captioned Image Spotlight (25 Jan 2019): A First Look at…

Captioned Image Spotlight (25 Jan 2019): A First Look at Dunes

This image shows us a cross-section of a dune field. Dune shape depends on several factors, including the amount of sand present and the local wind directions. This dune field displays several distinct dune morphologies.

We see both individual barchan-like dunes and more complex dune shapes. The dunes are arranged in a linear fashion at the northern extent of the field, first in areas with lots of sand, and then with relatively sand-free patches in between dune crests. HiRISE has observed dune activity in other similar fields, but this is our first image over this group of dunes.

A second image is needed to determine if these dunes are also evolving and moving.

NASA/JPL/University of Arizona

We’re Moving!We have a new landing page for our HiRISE Image of…

We’re Moving!

We have a new landing page for our HiRISE Image of the Day, and we encourage folks to bookmark it: https://www.uahirise.org/hipod/

You can also follow us on Twitter for our HiPODs: https://twitter.com/HiRISE

We will still make an occasional post on Tumblr, but our new webpage is the place to check out for a daily pic of Mars. Thank you!

A fleeting moment in time: Last breath of a dying star

An evanescent shell of glowing gas spreading into space — the planetary nebula ESO 577-24 – dominates this image. This planetary nebula is the remains of a dead giant star that has thrown off its outer layers, leaving behind a small, intensely hot dwarf star. This diminished remnant will gradually cool and fade, living out its days as the mere ghost of a once-vast red giant star.

A fleeting moment in time: Last breath of a dying star
The faint, ephemeral glow emanating from the planetary nebula ESO 577-24 persists for only a short time — around
10,000 years, a blink of an eye in astronomical terms. ESO’s Very Large Telescope captured this shell of glowing
 ionized gas — the last breath of the dying star whose simmering remains are visible at the heart of this image.
As the gaseous shell of this planetary nebula expands and grows dimmer, it will slowly disappear from sight.
This stunning planetary nebula was imaged by one of the VLT’s most versatile instruments, FORS2. The instrument
captured the bright, central star, Abell 36, as well as the surrounding planetary nebula. The red and blue portions
of this image correspond to optical emission at red and blue wavelengths, respectively. An object much closer
 to home is also visible in this image — an asteroid wandering across the field of view has left a faint track
below and to the left of the central star. And in the far distance behind the nebula a glittering host
 of background galaxies can be seen [Credit: ESO]

Red giants are stars at the end of their lives that have exhausted the hydrogen fuel in their cores and begun to contract under the crushing grip of gravity. As a red giant shrinks, the immense pressure reignites the core of the star, causing it to throw its outer layers into the void as a powerful stellar wind.
The dying star’s incandescent core emits ultraviolet radiation intense enough to ionise these ejected layers and cause them to shine. The result is what we see as a planetary nebula — a final, fleeting testament to an ancient star at the end of its life.

This dazzling planetary nebula was discovered as part of the National Geographic Society – Palomar Observatory Sky Survey in the 1950s, and was recorded in the Abell Catalogue of Planetary Nebulae in 1966.

At around 1400 light years from Earth, the ghostly glow of ESO 577-24 is only visible through a powerful telescope. As the dwarf star cools, the nebula will continue to expand into space, slowly fading from view.
This image of ESO 577-24 was created as part of the ESO Cosmic Gems Programme, an initiative that produces images of interesting, intriguing, or visually attractive objects using ESO telescopes for the purposes of education and public outreach.

The programme makes use of telescope time that cannot be used for scientific observations; nevertheless, the data collected are made available to astronomers through the ESO Science Archive.

Source: ESO [January 22, 2019]



Rover Team Beaming New Commands to Opportunity on Mars

NASA – Mars Exploration Rover B (MER-B) patch.

January 25, 2019

Engineers at NASA’s Jet Propulsion Laboratory in Pasadena, California, have begun transmitting a new set of commands to the Opportunity rover in an attempt to compel the 15-year-old Martian explorer to contact Earth. The new commands, which will be beamed to the rover during the next several weeks, address low-likelihood events that could have occurred aboard Opportunity, preventing it from transmitting.

The rover’s last communication with Earth was received June 10, 2018, as a planet-wide dust storm blanketed the solar-powered rover’s location on Mars.

“We have and will continue to use multiple techniques in our attempts to contact the rover,” said John Callas, project manager for Opportunity at JPL. “These new command strategies are in addition to the ‘sweep and beep’ commands we have been transmitting up to the rover since September.” With “sweep and beep,” instead of just listening for Opportunity, the project sends commands to the rover to respond back with a beep.

Image above: A Goldstone 111.5-foot (34-meter) beam-waveguide antenna tracks a spacecraft as it comes into view. The Goldstone Deep Space Communications Complex is located in the Mojave Desert in California. Engineers at NASA’s Jet Propulsion Laboratory in Pasadena, California, will use antennas like this one to transmit a new set of commands to the Opportunity rover in an attempt to compel the 15-year-old Martian explorer to contact Earth.Image Credits: NASA/JPL-Caltech.

The new transmission strategies are expected to go on for several weeks. They address three possible scenarios: that the rover’s primary X-band radio – which Opportunity uses to communicate with Earth – has failed; that both its primary and secondary X-band radios have failed; or that the rover’s internal clock, which provides a timeframe for its computer brain, is offset. A series of unlikely events would need to have transpired for any one of these faults to occur. The potential remedies being beamed up to address these unlikely events include a command for the rover to switch to its backup X-band radio and commands directed to reset the clock and respond via UHF.

“Over the past seven months we have attempted to contact Opportunity over 600 times,” said Callas. “While we have not heard back from the rover and the probability that we ever will is decreasing each day, we plan to continue to pursue every logical solution that could put us back in touch.”

Mars Exploration Rover (MER). Image Credits: NASA/JPL-Caltech

Time is of the essence for the Opportunity team. The “dust-clearing season” – the time of year on Mars when increased winds could clear the rover’s solar panels of dust that might be preventing it from charging its batteries – is drawing to a close. Meanwhile, Mars is heading into southern winter, which brings with it extremely low temperatures that are likely to cause irreparable harm to an unpowered rover’s batteries, internal wiring and/or computer systems.

If either these additional transmission strategies or “sweep and beep” generates a response from the rover, engineers could attempt a recovery. If Opportunity does not respond, the project team would again consult with the Mars Program Office at JPL and NASA Headquarters to determine the path forward.

Related article:

NASA’s Opportunity Rover Logs 15 Years on Mars

For more information about Opportunity and the Mars Exploration Rover program, visit: https://mars.nasa.gov/mer/home/index.html

Images (mentioned), Text, Credits: NASA/JPL/DC Agle.

Greetings, Orbiter.chArchive link

As clouds fall apart, a new star is born

Image of the massive star cluster NGC 3603, obtained with the Very Large Telescope. It probably has evolved in the same way as the one just forming in G351.77-0.54, the object depicted in this work. © Image: ESO

New observations reveal the physics behind the formation of a massive star cluster

Using the ALMA observatory in Chile, a group of astronomers led by MPIA’s Henrik Beuther has made the most detailed observation yet of the way that a giant gas cloud fragments into dense cores, which then act as the birthplaces of stars. The astronomers found that the mechanisms for fragmentation are fairly straightforward, resulting from the combination of the cloud’s pressure and gravity. More complex features, such as magnetic lines or turbulence, play a smaller role than previously thought.

Stars are born when giant clouds of gas and dust collapse. Whenever one of the collapsing regions becomes hot and dense enough for nuclear fusion to set in, a star is born. For massive stars, i.e. those stars that exhibit more than eight times the mass of the Sun, that is only part of the picture, though. The biggest stars in the Universe are not born singly. They are born from massive clouds of molecular gas, which then form a cascade of fragments, with many of the fragments giving birth to a star.

Astronomers have long wondered whether this fragmentation-mode of forming stars requires different physical mechanisms than for lower-mass stars. Proposals include turbulent gas motion, which could destabilize a region and lead to quicker collapse, or magnetic fields that could stabilize and thus delay collapse.

The different mechanisms should leave tell-tale traces in regions where multiple stars are forming. The collapse that leads to the formation of high-mass stars takes place on a hierarchy of different levels. On the largest scales, star formation involves giant molecular clouds, which consist mostly of hydrogen gas and can reach sizes between a few dozen and more than a hundred light-years across. Within those clouds are slightly denser clumps, typically a few light-years across. Each clump contains one or more dense cores, less than a fifth of a light-year in diameter. Within each core, collapse leads to the formation of either a single star or multiple stars. Together, the stars produced in the cores of a single clump will form a star cluster.

Tell-tale scales of fragmentation

The scales of this fragmentation at multiple levels depend on the mechanisms involved. The simplest model can be written down using no more than high school physics: An ideal gas has a pressure that depends on its temperature and density. In a simplified gas cloud, assumed to have constant density, that pressure must be strong enough everywhere to balance the force of gravity (given by Newton’s law of gravity) – even in the center of the cloud, where the inward gravitation-induced push of all the surrounding matter is strongest. Write this condition down, and you will find that any such constant-density cloud can only have a maximum size. If a cloud is larger than this maximum, which is called the Jeans length, the cloud will fragment and collapse.

Is the fragmentation of young massive clusters really dominated by these comparatively straightforward processes? It doesn’t need to be, and some astronomers have constructed much more complex scenarios, which include the influence of turbulent gas motion and magnetic field lines. These additional mechanisms change the conditions for cloud stability, and typically increase the scales of the different types of fragment.

Different predictions for cloud sizes offer a way of testing the simple physics scenario against its more complex competitors. That is what Henrik Beuther and his colleagues set out to do when they observed the star formation region G351.77-0.54 in the Southern constellation Scorpius (The Scorpion). Previous observations had indicated that in this region, fragmentation could be caught in the act. But none of these observations had been powerful enough to show the smallest scale of interest for answering the question of fragmentation scales: the protostellar cores, let alone their sub-structure.

ALMA takes the most detailed look yet

Beuther and his colleagues were able to do more. They used the ALMA Observatory in the Atacama Desert in Chile. ALMA combines the simultaneous observations of up to 66 radio telescopes to achieve a resolution of down to 20 milli-arcseconds, which allows astronomers to discern details more than ten times smaller than with any previous radio telescope, and at unrivalled sensitivity – a combination that has already led to a number of breakthrough observations also in other fields.

Beuther and his colleagues used ALMA to study the high-mass star-forming region G351.77-0.54 down to sub-core scales smaller than 50 astronomical units (in other words, less than 50 times the average distance between the Earth and the Sun). As Beuther says: “This is a prime example of how technology drives astronomical progress. We could not have obtained our results without the unprecedented spatial resolution and sensitivity of ALMA.”

Their results, together with earlier studies of the same cloud at larger scales, indicate that thermal gas physics is winning the day, even when it comes to very massive stars: Both the sizes of clumps within the cloud and, as the new observations show, of cores within the clumps and even of some core substructures are as predicted by Jeans length calculations, with no need for additional ingredients. Beuther comments: “In our case, the same physics provides a uniform description. Fragmentation from the largest to the smallest scales seems to be governed by the same physical processes.”

Small accretion disks: a new challenge

Simplicity is always a boon for scientific descriptions. However, the same observations also provided a discovery that will keep astronomers on their collective toes. In addition to studying fragmentation, Beuther et al. had been looking to unravel the structure of nascent stars (“protostars”) within the cloud. Astronomers expect such a protostar to be surrounded by a swirling disk of gas, called the accretion disk. From the inner disk of the rim, gas falls onto the growing star, increasing its mass. In addition, magnetic fields produced by the motion of ionized gas and the gas itself interact to produce tightly focused streams called jets, which shoot out some of the matter into space perpendicular to that disk. Submillimeter light from those regions carries tell-tale signs (“Doppler-broadening of spectral lines”) of the motion of dust, which in turn traces the motion of gas. But where Beuther and his collaborators had hoped for a clear signature from an accretion disk, instead, he found mainly the signature of jets, cutting a comparatively smooth path through the surrounding gas. Evidently, the accretion disks are even smaller than astronomers had expected – a challenge for future observations at even greater spatial resolution.

The research described here was undertaken by Henrik Beuther, Aida Ahmadi, Joseph Mottram, Hendrik Linz, Thomas K. Henning and Rolf Kuiper (also University of Tübingen) in collaboration with Luke T. Maud (Leiden University and ESO), Andrew J. Walsh (Macquarie University), Katharine G. Johnston (University of Leeds) and Steve N. Longmore (Liverpool John Moores University).


Dr. Henrik Beuther
Max Planck Institute for Astronomy, Heidelberg
Phone:+49 6221 528-447

Dr. Markus Pössel
Press & Public Relations
Max Planck Institute for Astronomy, Heidelberg
Phone:+49 6221 528-261  

Original publicantion

Beuther, H.; Ahmadi, A.; Mottram, J. C.; Linz, H.; Maud, L. T.; Henning, Th.; Kuiper, R.; Walsh, A. J.; Johnston, K. G.; Longmore, S. N.

High-mass star formation at sub-50 au scales

2019, Astronomy & Astrophysics, 621, A122

Source DOI

Related articles 

May 14, 2016

The interplay of magnetic fields and gravitation in the gas cloud lead to the birth of new stars. 

Further information

ALMA – the Atacama Large Millimetre Array

Archive link

Seeing double could help resolve dispute about how fast the universe is expanding

The question of how quickly the universe is expanding has been bugging astronomers for almost a century. Different studies keep coming up with different answers — which has some researchers wondering if they’ve overlooked a key mechanism in the machinery that drives the cosmos.

Seeing double could help resolve dispute about how fast the universe is expanding
Image from the Hubble Space Telescope of a doubly imaged quasar [Credit: NASA Hubble Space Telescope,
Tommaso Treu/UCLA, and Birrer et al. 2019]

Now, by pioneering a new way to measure how quickly the cosmos is expanding, a team led by UCLA astronomers has taken a step toward resolving the debate. The group’s research is published in Monthly Notices of the Royal Astronomical Society.

At the heart of the dispute is the Hubble constant, a number that relates distances to the redshifts of galaxies — the amount that light is stretched as it travels to Earth through the expanding universe. Estimates for the Hubble constant range from about 67 to 73 kilometers per second per megaparsec, meaning that two points in space 1 megaparsec apart (the equivalent of 3.26 million light-years) are racing away from each other at a speed between 67 and 73 kilometers per second.

“The Hubble constant anchors the physical scale of the universe,” said Simon Birrer, a UCLA postdoctoral scholar and lead author of the study. Without a precise value for the Hubble constant, astronomers can’t accurately determine the sizes of remote galaxies, the age of the universe or the expansion history of the cosmos.

Most methods for deriving the Hubble constant have two ingredients: a distance to some source of light and that light source’s redshift. Looking for a light source that had not been used in other scientists’ calculations, Birrer and colleagues turned to quasars, fountains of radiation that are powered by gargantuan black holes. And for their research, the scientists chose one specific subset of quasars — those whose light has been bent by the gravity of an intervening galaxy, which produces two side-by-side images of the quasar on the sky.

Light from the two images takes different routes to Earth. When the quasar’s brightness fluctuates, the two images flicker one after another, rather than at the same time. The delay in time between those two flickers, along with information about the meddling galaxy’s gravitational field, can be used to trace the light’s journey and deduce the distances from Earth to both the quasar and the foreground galaxy. Knowing the redshifts of the quasar and galaxy enabled the scientists to estimate how quickly the universe is expanding.

The UCLA team, as part of the international H0liCOW collaboration, had previously applied the technique to study quadruply imaged quasars, in which four images of a quasar appear around a foreground galaxy. But quadruple images are not nearly as common — double-image quasars are thought to be about five times as abundant as the quadruple ones.

To demonstrate the technique, the UCLA-led team studied a doubly imaged quasar known as SDSS J1206+4332; they relied on data from the Hubble Space Telescope, the Gemini and W.M. Keck observatories, and from the Cosmological Monitoring of Gravitational Lenses, or COSMOGRAIL, network — a program managed by Switzerland’s Ecole Polytechnique Federale de Lausanne that is aimed at determining the Hubble constant.

Tommaso Treu, a UCLA professor of physics and astronomy and the paper’s senior author, said the researchers took images of the quasar every day for several years to precisely measure the time delay between the images. Then, to get the best estimate possible of the Hubble constant, they combined the data gathered on that quasar with data that had previously been gathered by their H0liCOW collaboration on three quadruply imaged quasars.

“The beauty of this measurement is that it’s highly complementary to and independent of others,” Treu said.

The UCLA-led team came up with an estimate for the Hubble constant of about 72.5 kilometers per second per megaparsec, a figure in line with what other scientists had determined in research that used distances to supernovas — exploding stars in remote galaxies — as the key measurement. However, both estimates are about 8 percent higher than one that relies on a faint glow from all over the sky called the cosmic microwave background, a relic from 380,000 years after the Big Bang, when light traveled freely through space for the first time.

“If there is an actual difference between those values, it means the universe is a little more complicated,” Treu said.

On the other hand, Treu said, it could also be that one measurement — or all three — are wrong.

The researchers are now looking for more quasars to improve the precision of their Hubble constant measurement. Treu said one of the most important lessons of the new paper is that doubly imaged quasars give scientists many more useful light sources for their Hubble constant calculations. For now, though, the UCLA-led team is focusing its research on 40 quadruply imaged quasars, because of their potential to provide even more useful information than doubly imaged ones.

Author: Christopher Crockett | Source: University of California – Los Angeles [January 22, 2019]



How much rainforest do birds need?

Researchers of the Department of Conservation Biology at the University of Göttingen have carried out research in Southwest Cameroon to assess which proportion of forest would be necessary in order to provide sufficient habitat for rainforest bird species. The results of the study were published in the journal Biological Conservation.

How much rainforest do birds need?
The blue-headed bee-eater is native to African rainforests
[Credit: Professor Matthias Waltert]

The Göttingen team investigated relationships between forest cover and bird species richness using data from a 4,000 km2 large rainforest landscape. The study area contains protected areas as well as smallholder agroforestry systems and industrial oil palm plantations. The study documents minimum thresholds of forest cover in farmland below which original bird communities begin to change and where they are already dominated by species which don’t depend on forest.
The data suggest that forest cover ought not to fall below 40 percent if drastic losses in original bird species are to be avoided. Importantly, the study also shows that highly specialised bird species already start to decline significantly when the percentage of forest dips to as much as 70 percent; at these forest cover levels, these birds are beginning to be replaced by “generalists,” ie birds that are at home in different habitats.

How much rainforest do birds need?
Part of the data collection took place in an industrial oil palm plantation, which was home
to only small proportions of the native bird species [Credit: Denis Kupsch]

“The threshold values we are discussing here should play a role in defining strategies for conservation in tropical forest landscapes,” says Denis Kupsch, first author of the study. This is particularly important because the pressure to use agricultural land intensively is constantly increasing in tropical regions.
“It would therefore make sense for land-use planning and legislation in the future to be geared more to such limits in order to achieve a sustainable coexistence of industrial agricultural production, smallholder agriculture and protected area management.”

According to the authors, smallholder agricultural forest systems in particular, which represent a near-natural cultivated landscape and at the same time preserve a high proportion of natural forest, could play a significant role in this.

Source: University of Göttingen [January 22, 2019]



Planetary collision that formed the moon made life possible on Earth

Most of Earth’s essential elements for life — including most of the carbon and nitrogen in you — probably came from another planet.

Planetary collision that formed the moon made life possible on Earth
A schematic depicting the formation of a Mars-sized planet (left) and its differentiation into a body with a metallic core
and an overlying silicate reservoir. The sulfur-rich core expels carbon, producing silicate with a high carbon to nitrogen
 ratio. The moon-forming collision of such a planet with the growing Earth (right) can explain Earth’s abundance o
f both water and major life-essential elements like carbon, nitrogen and sulfur, as well as the geochemical
 similarity between Earth and the moon [Credit: Rajdeep Dasgupta]

Earth most likely received the bulk of its carbon, nitrogen and other life-essential volatile elements from the planetary collision that created the moon more than 4.4 billion years ago, according to a new study by Rice University petrologists in the journal Science Advances.

“From the study of primitive meteorites, scientists have long known that Earth and other rocky planets in the inner solar system are volatile-depleted,” said study co-author Rajdeep Dasgupta. “But the timing and mechanism of volatile delivery has been hotly debated. Ours is the first scenario that can explain the timing and delivery in a way that is consistent with all of the geochemical evidence.”

The evidence was compiled from a combination of high-temperature, high-pressure experiments in Dasgupta’s lab, which specializes in studying geochemical reactions that take place deep within a planet under intense heat and pressure.

In a series of experiments, study lead author and graduate student Damanveer Grewal gathered evidence to test a long-standing theory that Earth’s volatiles arrived from a collision with an embryonic planet that had a sulfur-rich core.

The sulfur content of the donor planet’s core matters because of the puzzling array of experimental evidence about the carbon, nitrogen and sulfur that exist in all parts of the Earth other than the core.

“The core doesn’t interact with the rest of Earth, but everything above it, the mantle, the crust, the hydrosphere and the atmosphere, are all connected,” Grewal said. “Material cycles between them.”

One long-standing idea about how Earth received its volatiles was the “late veneer” theory that volatile-rich meteorites, leftover chunks of primordial matter from the outer solar system, arrived after Earth’s core formed. And while the isotopic signatures of Earth’s volatiles match these primordial objects, known as carbonaceous chondrites, the elemental ratio of carbon to nitrogen is off. Earth’s non-core material, which geologists call the bulk silicate Earth, has about 40 parts carbon to each part nitrogen, approximately twice the 20-1 ratio seen in carbonaceous chondrites.

Grewal’s experiments, which simulated the high pressures and temperatures during core formation, tested the idea that a sulfur-rich planetary core might exclude carbon or nitrogen, or both, leaving much larger fractions of those elements in the bulk silicate as compared to Earth. In a series of tests at a range of temperatures and pressure, Grewal examined how much carbon and nitrogen made it into the core in three scenarios: no sulfur, 10 percent sulfur and 25 percent sulfur.

“Nitrogen was largely unaffected,” he said. “It remained soluble in the alloys relative to silicates, and only began to be excluded from the core under the highest sulfur concentration.”

Carbon, by contrast, was considerably less soluble in alloys with intermediate sulfur concentrations, and sulfur-rich alloys took up about 10 times less carbon by weight than sulfur-free alloys.

Using this information, along with the known ratios and concentrations of elements both on Earth and in non-terrestrial bodies, Dasgupta, Grewal and Rice postdoctoral researcher Chenguang Sun designed a computer simulation to find the most likely scenario that produced Earth’s volatiles. Finding the answer involved varying the starting conditions, running approximately 1 billion scenarios and comparing them against the known conditions in the solar system today.

“What we found is that all the evidence — isotopic signatures, the carbon-nitrogen ratio and the overall amounts of carbon, nitrogen and sulfur in the bulk silicate Earth — are consistent with a moon-forming impact involving a volatile-bearing, Mars-sized planet with a sulfur-rich core,” Grewal said.

Dasgupta, the principal investigator on a NASA-funded effort called CLEVER Planets that is exploring how life-essential elements might come together on distant rocky planets, said better understanding the origin of Earth’s life-essential elements has implications beyond our solar system.

“This study suggests that a rocky, Earth-like planet gets more chances to acquire life-essential elements if it forms and grows from giant impacts with planets that have sampled different building blocks, perhaps from different parts of a protoplanetary disk,” Dasgupta said.

“This removes some boundary conditions,” he said. “It shows that life-essential volatiles can arrive at the surface layers of a planet, even if they were produced on planetary bodies that underwent core formation under very different conditions.”

Dasgupta said it does not appear that Earth’s bulk silicate, on its own, could have attained the life-essential volatile budgets that produced our biosphere, atmosphere and hydrosphere.

“That means we can broaden our search for pathways that lead to volatile elements coming together on a planet to support life as we know it.”

Source: Rice University [January 23, 2019]



Scientists reconstruct ancient lost plates under Andes mountains

The Andes Mountains are the longest continuous mountain range in the world, stretching about 7,000 kilometers, or 4,300 miles, along the western coast of South America.

Scientists reconstruct ancient lost plates under Andes mountains
The Andes mountain range as seen from a plane, between Santiago de Chile and Mendoza, Argentina
[Credit: Jorge Morales Piderit/WikiCommons]

The Andean margin, where two tectonic plates meet, has long been considered the textbook example of a steady, continuous subduction event, where one plate slipped under another, eventually forming the mountain range seen today.

In a paper published in the journal Nature, geologists from the University of Houston demonstrate the reconstruction of the subduction of the Nazca Ocean plate, the remnants of which are currently found down to 1,500 kilometers, or about 900 miles, below the Earth’s surface.

Their results show that the formation of the Andean mountain range was more complicated than previous models suggested.

“The Andes Mountain formation has long been a paradigm of plate tectonics,” said Jonny Wu, assistant professor of geology at UH and a co-author of the paper.

When tectonic plates move under the Earth’s crust and enter the mantle, they do not disappear. Rather, they sink toward the core, like leaves sinking to the bottom of a lake. As these plates sink, they retain some of their shape, offering glimpses of what the Earth’s surface looked like millions of years ago.

These plate remnants can be imaged, similar to the way CT scans allow doctors to see inside of a patient, using data gleaned from earthquake waves.

“We have attempted to go back in time with more accuracy than anyone has ever done before. This has resulted in more detail than previously thought possible,” Wu said. “We’ve managed to go back to the age of the dinosaurs.”

Scientists reconstruct ancient lost plates under Andes mountains
University of Houston researchers John Suppe, left, Jonny Wu and Yi-Wei Chen have reconstructed
the ancient plates under the Andes Mountains [Credit: University of Houston]

The paper describes the deepest and oldest plate remnants reconstructed to date, with plates dating back to the Cretaceous Period.

“We found indications that when the slab reached the transition zone, it created signals on the surface,” said Yi-Wei Chen, a PhD geology student in the UH College of Natural Sciences and Mathematics and first author on the paper. A transition zone is a discontinuous layer in the Earth’s mantle, one which, when a sinking plate hits it, slows the plate’s movement, causing a build-up above it.

In addition to Wu and Chen, John Suppe, Distinguished Professor of Earth and Atmospheric Sciences at UH, is a co-author on the paper.

The researchers also found evidence for the idea that, instead of a steady, continuous subduction, at times the Nazca plate was torn away from the Andean margin, which led to volcanic activity. To confirm this, they modeled volcanic activity along the Andean margin.

“We were able to test this model by looking at the pattern of over 14,000 volcanic records along the Andes,” Wu said.

The work was conducted as part of the UH Center for Tectonics and Tomography, which is directed by Suppe.

“The Center for Tectonics and Tomography brings together experts from different fields in order to relate tomography, which is the imaging of the Earth’s interior from seismology, to the study of tectonics,” Wu said. “For example, the same techniques we use to explore for these lost plates are adapted from petroleum exploration techniques.”

Source: University of Houston [January 23, 2019]



Results of the 2018 Tremithos Neolithic Survey

The Department of Antiquities of the Republic of Cyprus has announced that the Tremithos Neolithic Survey under the direction of Dr Sarah Stewart (Trent University Archaeological Research Centre) completed in May 2018 the surface survey of the Tremithos River Valley. The pedestrian survey focused on the area along the coast east and west of the Tremithos River Delta and north of the Kiti Dam to the Larnaca-Limassol Highway. All diagnostic finds were catalogued and photographed and submitted to the Larnaka District Museum.

Results of the 2018 Tremithos Neolithic Survey
Credit: Department of Antiquities, Republic of Cyprus

A pedestrian surface survey of the coastal region from just east of the Pouzis River, west through the Tremithos delta, and east of the delta towards Pervolia, just west of Cape Kiti was undertaken. The beach floor, any associated sections and the terraces above the beach were examined. Numerous chert nodules, cores and flakes, often water worn, and manufactured from a wide variety of chert raw materials were found.  On the terraces above the beach, the fields were generally stubble wheat fields cultivated with no-till plowing, from which early material is rarely moved to the surface. Thus, it is increasingly difficult to find earlier prehistoric sites through pedestrian survey in tilled fields. The fact that relatively fresh lithics were found in the area where the terrace meets the beach, suggests that there is in situ cultural material below the surface. The best potential for finding these sites will be through test excavations.
The survey area with the highest potential for in-situ early archaeological material is located just east of the promontory at Limnes, with high potential for both Roman and Epipalaeolithic material, the latter including two microlithic multi-directional cores and numerous retouched flakes from a variety of chert. This is the most promising location along this coastal region for a potential Epipalaeolithic site, based on the recovered lithics and the fact that there is evidence of a small stream that would have flowed into the sea. The stream is currently buried under approximately one meter of well-developed soil at the stream outlet, which is marked by water worn cobbles.

Results of the 2018 Tremithos Neolithic Survey
Location map of the Tremithos (T.) drainage basin. D.: Dhiarizos catchment; V.: Vassilikos catchment; G. or mid-Hol.: Gialias catchment configuration during early to mid-Holocene (after Devillers, 2005). The white stars show the
location of major archaeological sites mentioned in this paper (Erimi, Sotira, Tenta and Khirokitia)
[Credit: M. Ghilardi et al. Environmental Archaeology, 2014]

Other areas along the coast with prehistoric potential include the Careta Beach, located about half way between the Limnes promontory and the Tremithos River mouth. Clear stratigraphy was identified in the beach sections which included a series of palaeosols, with the upper the primary artifact bearing deposit with a quantity of pottery (Roman) and lithics. There was one small stream outlet that is either contemporary with, or cuts into, the artifact bearing strata. These sections are associated with stubble wheat fields in the terraces above, and thus have a high probability for in situ archaeological material.

On the east bank of the Tremithos River mouth early diagnostic material was found during the 2015 surface survey. Unfortunately this area is heavily disturbed by the recent road construction and soil levelling and may represent just a small remnant of the original eastern bank of a Tremithos meander. No additional potentially early material was found.

The east terraces above the banks of the Pouzis River between the sea and the highway, are under wheat cultivation, but with a combination of stubble no till fields and directly adjacent deeply tilled zones in which several chert cores and numerous retouched flakes with a distinctive Epipalaeolithic typology were located.

Very little archaeological material in the area between the Kiti Dam and the Larnaca to Limassol highway was found. These finds were isolated to some undiagnostic ceramic sherds (mostly apparently modern) and a few isolated lithic finds, again mostly undiagnostic, and probably from the Dhoukani threshing sledge industry. This area of the Tremithos, north of the dam, would be subject to flooding, alluvial deposition and erosion and most early material would likely now be deeply buried or washed downstream.

Source: Department of Antiquities, Republic of Cyprus [January 23, 2019]



This galaxy is no match for a hungry cluster

A new study led by Yale University astronomers tells the story of a galaxy that ran out of gas. It’s a story as old as the universe itself: A galaxy is born, brimming with new stars, its spiral arms stretching and curving. But then it runs into trouble, veering too close to the center of a nearby galaxy cluster. The surrounding cluster begins to siphon off the galaxy’s star-making gas, until it loses its spiral arms and becomes a dead relic.

This galaxy is no match for a hungry cluster
The spiral galaxy D100, on the far right of this Hubble Space Telescope image, is being stripped of its gas as it plunges
toward the center of the giant Coma galaxy cluster [Credit: NASA, ESA, M. Sun (University of Alabama),
and W. Cramer and J. Kenney (Yale University)]

That’s what happened to a galaxy called D100 in the massive, Coma galaxy cluster, starting roughly 300 million years ago. Images from NASA’s Hubble Space Telescope allowed researchers to see the phenomenon in unprecedented detail.

“This galaxy stands out as a particularly extreme example of processes common in massive clusters, where a galaxy goes from being a healthy spiral full of star formation to a ‘red and dead’ galaxy. The spiral arms disappear and the galaxy is left with no gas and only old stars,” said William Cramer, a graduate student in Yale’s Department of Astronomy who led the new research. “This phenomenon has been known about for several decades, but Hubble provides the best imagery of galaxies undergoing this process.”

The process, called “ram pressure stripping,” occurs when a galaxy falls toward the dense center of a massive cluster of thousands of galaxies. During its plunge, the galaxy plows through intra-cluster material that is even more dense. This material pushes gas and dust — star-making fuel — away from the galaxy. Once the galaxy loses all of its gas, it meets an untimely death because it can no longer create new stars.

In the Coma cluster, this violent gas-loss process occurs in many galaxies. But D100 is unique, note the scientists. Its long, thin tail, for example, extends nearly 200,000 light years — about the length of two Milky Way galaxies. In addition, the tail is narrow, only 7,000 light years wide.

“The dust tail is remarkably well-defined, straight, and smooth, and has clear edges,” said Yale astronomer Jeffrey Kenney, a co-author of the study. “This is a surprise because a tail like this is not seen in most computer simulations. Most galaxies undergoing this process are more of a mess. The clean edges and filamentary structures of the dust tail suggest that magnetic fields play a prominent role in shaping the tail. Computer simulations show that magnetic fields form filaments in the tail’s gas. With no magnetic fields, the gas tail is more clumpy than filamentary.”

The Subaru Telescope in Hawaii uncovered the long, glowing hydrogen tail in 2007 during a survey of Coma cluster galaxies. But astronomers needed Hubble observations to confirm the hot gas was a signature of star formation. “Without the depth and resolution of Hubble, it’s hard to say if the glowing hydrogen gas emission is coming from stars in the tail or if it’s just from the gas being heated,” Cramer said.

The researchers’ main goal was to study star formation in the tail, which was fueled by D100’s ongoing gas loss. However, Hubble did not find as many stars as the team expected, based on the amount of glowing hydrogen gas contained in the tail. The brightest clump of young stars in the middle of the tail contains at least 200,000 stars.

The Hubble data shows that the gas-stripping process began on the outskirts of D100 and is moving in towards the center. Based on the images, the gas has been cleared out all the way down to the galaxy’s central region.

Another image reveals D100’s eventual fate. It’s an image of galaxy D99, which underwent the same violent gas loss that D100 is now undergoing. All of D99’s gas was siphoned between 500 million and 1 billion years ago, and its spiral structure has mostly faded away.

“D100 will look like D99 in a few hundred million years,” Kenney said.

The Coma cluster is located 330 million light years from Earth.

The study appears in The Astrophysical Journal.

Author: Jim Shelton | Source: Yale University [January 24, 2019]



Shattuckite, Malachite | #Geology #GeologyPage…

Shattuckite, Malachite | #Geology #GeologyPage #Mineral

Locality: Katanga Copper Crescent, Katanga, Congo – Kinshasa

Size: 28mm x 18mm x 21mm

Photo Copyright © Quebul Fine Minerals

Geology Page



Silver specimen with dendritic structure | #Geology #GeologyPage…

Silver specimen with dendritic structure | #Geology #GeologyPage #Mineral

Locality: Tamdrost Mine, Tamdrost, Bou Azzer District, Tazenakht, Ouarzazate Province, Draa-Tafilalet Region, Morocco

Size: 28mm x 13mm x 11mm

Photo Copyright © Quebul Fine Minerals

Geology Page



South Stack Formation, Anglesey | #Geology #GeologyPage…

South Stack Formation, Anglesey | #Geology #GeologyPage #Wales

The South Stack Formation is a sequence of late Neoproterozoic metasedimentary rocks exposed in northwestern Anglesey, North Wales. The outcrop of this formation at South Stack was chosen as one of the top 100 geosites in the United Kingdom by the Geological Society of London, for its display of small-scale folding.

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Cargo Ship Takes out Trash; Crew Works on Cygnus Preps and Science Hardware

ISS – Expedition 58 Mission patch.

January 25, 2019

A Russian cargo ship left the International Space Station this morning and was deorbited for a destructive demise over the Pacific Ocean. The Expedition 58 crew now turns its attention to the departure of a U.S. space freighter next month.

The Progress 70 (70P) resupply ship ended its six-and-a-half month stay at the station when it undocked from Pirs docking compartment today at 7:55 a.m. EST. It descended into Earth’s atmosphere less than four hours later loaded with trash and discarded gear and burned up safely over the southern Pacific.

Image above: Jan. 25, 2019: International Space Station Configuration. Three spaceships are parked at the space station including the Northrop Grumman Cygnus resupply ship and Russia’s Progress 71 resupply ship and Soyuz MS-11 crew ship. Image Credit: NASA.

Northrop Grumman’s Cygnus commercial cargo vessel is next up, scheduled to depart the Unity module in early February. Astronauts Anne McClain and David Saint-Jacques have been reviewing Cygnus departure procedures and carefully packing the spaceship throughout the week.

McClain and Saint-Jacques spent Friday working on a variety of science hardware and life support gear aboard the orbital lab. The duo first set up gear to measure airflow inside Japan’s Kibo laboratory module. Next, they serviced a pair of science freezers nicknamed MELFI and GLACIER that store research samples at ultra-cold temperatures.

International Space Station (ISS). Animation Credit: NASA

NASA’s McClain also replaced hardware in the Actiwatch Spectrum, a wearable device that analyzes an astronaut’s sleep quality, sleep onset, hyperactivity and other daily routines. Saint-Jacques from the Canadian Space Agency activated a new 3D printer known as the Refabricator that uses recycled plastics.

Commander Oleg Kononenko from Roscosmos monitored this morning’s 70P undocking and photographed the departing spacecraft. The station veteran also checked on Russian laptop computers and participated in a study that explores how cosmonauts adapt to complex space tasks.

Related links:

Expedition 58: https://www.nasa.gov/mission_pages/station/expeditions/expedition58/index.html

Pirs docking compartment: https://www.nasa.gov/mission_pages/station/structure/elements/pirs-docking-compartment

Unity module: https://www.nasa.gov/mission_pages/station/structure/elements/unity

Kibo laboratory module: https://www.nasa.gov/mission_pages/station/structure/elements/japan-kibo-laboratory

MELFI: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=56

GLACIER: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=342

Actiwatch Spectrum: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Facility.html?#id=838

Refabricator: https://www.nasa.gov/mission_pages/station/research/experiments/explorer/Investigation.html?#id=7321

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

Image (mentioned), Animation (mentioned), Text, Credits: NASA/Mark Garcia.

Best regards, Orbiter.chArchive link

Meteor Activity Outlook for January 26- February 1, 2019

Peter Slansky was photographing the lunar eclipse from Plose Mountain, Southern Tyrolia, Italy, when this bright meteor occurred at 6:18 CET. He was using a Canon 20Da at ISO 800 and 15 sec. exposure time with a Sigma Zoom 3.5/10-20 mm at f = 20 mm and F = 4.5. © Peter Slansky

During this period the moon will reach its last quarter phase on Sunday January 27th. At this time the moon will be located 90 degrees west of the sun and will rise near midnight local standard time (LST) as seen from mid-northern latitudes. As the week progresses the waning crescent moon will rise later in the morning, allowing a longer window to watch meteor activity under dark skies. Hourly meteor rates for evening observers this week is near 3 as seen from mid-northern latitudes (45N) and 4 as seen from tropical southern locations (25S). For morning observers the estimated total hourly rates should be near 7 as seen from mid-northern latitudes and 10 from the southern tropics. The actual rates will also depend on factors such as personal light and motion perception, local weather conditions, alertness and experience in watching meteor activity. Morning rates are  slightly reduced due to moonlight. Note that the hourly rates listed below are estimates as viewed from dark sky sites away from urban light sources. Observers viewing from urban areas will see less activity as only the brighter meteors will be visible from such locations.

The radiant (the area of the sky where meteors appear to shoot from) positions and rates listed below are exact for Saturday night/Sunday morning January 26/27. These positions do not change greatly day to day so the listed coordinates may be used during this entire period. Most star atlases (available at science stores and planetariums) will provide maps with grid lines of the celestial coordinates so that you may find out exactly where these positions are located in the sky. A planisphere or computer planetarium program is also useful in showing the sky at any time of night on any date of the year. Activity from each radiant is best seen when it is positioned highest in the sky, either due north or south along the meridian, depending on your latitude. It must be remembered that meteor activity is rarely seen at the radiant position. Rather they shoot outwards from the radiant so it is best to center your field of view so that the radiant lies near the edge and not the center. Viewing there will allow you to easily trace the path of each meteor back to the radiant (if it is a shower member) or in another direction if it is a sporadic. Meteor activity is not seen from radiants that are located far below the horizon. The positions below are listed in a west to east manner in order of right ascension (celestial longitude). The positions listed first are located further west therefore are accessible earlier in the night while those listed further down the list rise later in the night.

Radiant Positions at 7:00pm Local Standard Time

Radiant Positions at 12:00am Local Standard Time

Radiant Positions at 5:00am Local Standard Time

These sources of meteoric activity are expected to be active this week.

The center of the large Anthelion (ANT) radiant is currently located at 09:20 (140) +15. This position lies on the Leo/Cancer border, 12 degrees northwest of the 1st magnitude star known as Regulus (alpha Leonis). Due to the large size of this radiant, Anthelion activity may also appear from Cancer, and northwestern Hydra, as well as western Leo. This radiant is best placed near 0100 local standard time (LST), when it lies on the meridian and is located highest in the sky. Rates at this time should be near 2 per hour as seen from the northern hemisphere and 1 per hour from south of the equator. With an entry velocity of 30 km/sec., the average Anthelion meteor would be of slow velocity.

The alpha Antliids (AAN) should be active from a radiant located near 10:10 (153) -08. This position actually lies in northwestern Crater, 8 degrees north of the 3rd magnitude star known as nu Hydrae. I’m not certain how this stream was named as it the radiant lies a good 20 degrees north of the Antlia border. Perhaps when activity was first noticed from this source the radiant was incorrectly determined? This radiant is best placed near 0200 LST, when it lies on the meridian and is located highest in the sky. Rates are expected to be less than 1 per hour no matter your location. With an entry velocity of 45 km/sec., the average meteor from this source would be of medium velocity.

The February Epsilon Virginids (FEV) were discovered by Kathryn Steakly & Dr. Peter Jenniskens using data from CAMS and SonotaCo. This shower is active from January 29-February 9, with maximum activity occurring on February 3rd. The radiant is currently located at 13:04 (196) +13, which places it in northern Virgo, just 2 degrees north of the 3rd magnitude star known as Vindemiatrix (Epsilon Virginis). These meteors would be best seen near 0400 LST when the radiant lies highest above the horizon. Rates at maximum would be expected to be near 1 per hour during the last dark hour before dawn but the bright moon will make it difficult to view this activity. These meteors are equally well seen from either hemisphere. These meteors encounter the atmosphere at 64 km/sec., which would produce mostly swift meteors.

The last of the eta Corvids (ECV) are expected this weekend from a radiant located at 13:08 (197) -19, which places the radiant in southern Virgo, 4 degrees north of the 3rd magnitude star known as gamma Hydrae. These meteors are best seen near 0400 LST when the radiant lies highest above the horizon. Expected hourly rates would be less than 1 per hour no matter your location. At 68 km/sec. these meteors would be fast.

As seen from the mid-northern hemisphere (45N) one would expect to see approximately 5 sporadic meteors per hour during the last hour before dawn as seen from rural observing sites. Evening rates would be near 2 per hour. As seen from the tropical southern latitudes (25S), morning rates would also be near 9 per hour as seen from rural observing sites and 3 per hour during the evening hours. Locations between these two extremes would see activity between the listed figures. Morning rates are reduced during this period due to moonlight.


RA (RA in Deg.) DEC Km/Sec Local Standard Time North-South
Anthelion (ANT) 09:20 (140) +15 30 01:00 2 – 1 II
alpha Antliids (AAN) Feb 01 10:10 (153) -08 45 02:00 <1 – <1 IV
February Epsilon Virginids (FEV) Feb 03 13:04 (196) +13 64 04:00 <1 – <1 IV
eta Corvids (ECV) Jan 22 13:08 (197) -19 68 05:00 <1 – <1 IV

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Crocodiles have complex past

A new study throws into question the notion that today’s crocodiles and alligators have a simple evolutionary past.

Crocodiles have complex past
Nile crocodile [Credit: Leigh Bedford/WikiCommons]

Previous research has pointed to crocodiles and alligators starting with a land-based ancestor some 200 million years ago and then moving to fresh water, becoming the semi-aquatic ambush predators they are today.

But a new analysis, published online in the journal Scientific Reports, offers a different story. Modern crocodiles and alligators came from a variety of surroundings beginning in the early Jurassic Period, and various species occupied a host of ecosystems over time, including land, estuarine, freshwater and marine.

As University of Iowa researcher and study co-author Christopher Brochu says, “Crocodiles are not living fossils. Transitions between land, sea, and freshwater were more frequent than we thought, and the transitions were not always land-to-freshwater or freshwater-to-marine.”

Brochu and colleagues from Stony Brook University pieced together crocodile and alligator ancestry by analyzing a large family tree showing the evolutionary history of living and extinct crocodylomorphs (modern crocodiles and alligators and their extinct relatives). The team was then able to predict the ancestral habitat for several divergence points on the evolutionary tree.

This suggests a complex evolutionary history not only of habitat, but of form. Those living at sea had paddles instead of limbs, and those on land often had hoof-like claws and long legs. These did not all evolve from ancestors that looked like modern crocodiles, as has long been assumed.

Source: University of Iowa [January 24, 2019]



A reptile platypus from the early Triassic

No animal alive today looks quite like a duckbilled platypus, but about 250 million years ago something very similar swam the shallow seas in what is now China, finding prey by touch with a cartilaginous bill. The newly discovered marine reptile Eretmorhipis carrolldongi from the lower Triassic period is described in the journal Scientific Reports.

A reptile platypus from the early Triassic
Artist’s impression of Eretmorhipis carrolldongi. Related to the dolphin-like ichthyosaurs, Eretmorhipis evolved
in a world devastated by the mass extinction event at the end of the Permian era. Its small eyes and bill
suggest that like the duckbilled platypus, it hunted by touch [Credit: Gianluca Danini]

Apart from its platypus-like bill, Eretmorhipis was about 70 centimeters long with a long rigid body, small head and tiny eyes, and four flippers for swimming and steering. Bony plates ran down the animal’s back.
Eretmorhipis was previously known only from partial fossils without a head, said Professor Ryosuke Motani, a paleontologist at the University of California, Davis Department of Earth and Planetary Sciences and coauthor on the paper.

“This is a very strange animal,” Motani said. “When I started thinking about the biology I was really puzzled.”

A reptile platypus from the early Triassic
Complete fossil and line drawing of Eretmorhipis carrolldongi. Related to the dolphin-like ichthyosaurs,
Eretmorhipis evolved in a world devastated by the mass extinction event at the end of the Permian era
[Credit: L. Cheng et al., 2018]

The two new fossils show the animal’s skull had bones that would have supported a bill of cartilage. Like the modern platypus, there is a large hole in the bones in the middle of the bill. In the platypus, the bill is filled with receptors that allow it to hunt by touch in muddy streams.
In the early Triassic, the area was covered by a shallow sea, about a meter deep, over a carbonate platform extending for hundreds of miles. Eretmorhipis fossils were found at what were deeper holes, or lagoons, in the platform. There are no fossils to show what Eretmorhipis ate, but it likely fed on shrimp, worms and other small invertebrates, Motani said.

Its long, bony body means that Eretmorhipis was probably a poor swimmer, Motani said.

A reptile platypus from the early Triassic
Comparison of the skulls of the duckbilled platypus (Ornithorhynchus anatinus), left, and Eretmorhipis carrolldongi
on the right. Blue shading indicates cartilage. In the platypus, the bill is sensitive to touch allowing
the animal to hunt in low light conditions [Credit: L. Cheng et al., 2018]

“It wouldn’t survive in the modern world, but it didn’t have any rivals at the time,” he said.
Related to the dolphin-like ichthyosaurs, Eretmorhipis evolved in a world devastated by the mass extinction event at the end of the Permian era. The fossil provides more evidence of rapid evolution occurring during the early Triassic, Motani said.

Author: Andy Fell | Source: University of California – Davis [January 24, 2019]



Large volcanic eruption in Scotland may have contributed to prehistoric global warming

Around 56 million years ago, global temperatures spiked. Researchers at Uppsala University and in the UK now show that a major explosive eruption from the Red Hills on the Isle of Skye may have been a contributing factor to the massive climate disturbance. Their findings have been published in the journal Scientific Reports.

Large volcanic eruption in Scotland may have contributed to prehistoric global warming
False colour electron-microscope image of a resorbed apatite crystal (green) in pitchstone glass (blue). The composition
of the pitchstone glass and the characteristic mineral textures are identical in the studied pitchstone sites of the Sgùrr
of Eigg and Òigh-sgeir, although over 30km apart, indicating a common origin, and thus a large and
geographically widespread volcanic eruption [Credit: Valentin Troll]

Large explosive volcanic eruptions can have lasting effects on climate and have been held responsible for severe climate effects in Earth’s history. One such event occurred around 56 million years ago when global temperatures increased by 5-8 °C. This event has been named the Paleocene-Eocene Thermal Maximum (PETM). The warm period was associated with volcanic activity in the North Atlantic region, especially in Greenland, the British Isles and the present day North Sea region. However, until now, no large-scale explosive eruptions had been confirmed in current-day Scotland.
A team of researchers at Uppsala University, Sweden, the Universities of Durham and St Andrews in the UK, and the Scottish Environmental Research Centre in Glasgow, now seem to have found a missing piece of the puzzle. By studying volcanic rocks called pitchstones from islands more than 30 kilometres apart in the Inner Hebrides off the west coast of Scotland, the researchers have found plausible evidence of a major eruption from what is today the Isle of Skye.

The researchers used several different methods to compare the pitchstones recovered from the two sites (Sgùrr of Eigg and Òigh-sgeir) including isotope geochemistry. Samples from the two pitchstone outcrops display identical textures and compositions in all analyses, confirming that the two outcrops represent deposits of a single, massive and explosive volcanic eruption.

The researcher’s geochemical data identify the Red Hills on Skye, around 40 kilometres to the North, as the most likely vent area for this large eruption. Using this vent location, a reconstruction estimates the eruption to have been similar in magnitude to the infamous Krakatoa eruption of 1883, one of the deadliest and most destructive volcanic events in recorded history.

Earth scientists have long thought that the Scottish sector of the North Atlantic Volcanic province did not see any large explosive eruptions at the time of the PETM. This notion is now contradicted by the findings of the current study and the researchers conclude that large explosive volcanic events in the Scottish sector of the North Atlantic Volcanic Province were likely a major contributing factor to the climate disturbance of the PETM.

Source: Uppsala University [January 24, 2019]



Clues of heart disease found in 16th-century mummies from Greenland

What secrets lie in the hearts of our ancestors? Signs of cardiovascular disease, for one, as a team of cardiovascular-imaging experts from Brigham and Women’s Hospital (BWH) recently helped discover.

Clues of heart disease found in 16th-century mummies from Greenland
Harvard research assistant Emily Venable ’17 examines mummified remains that would later undergo CT scans,
 revealing evidence of plaque in the arteries [Credit: Rose Lincoln/Harvard University]

Through a collaboration with Harvard’s Peabody Museum of Archaeology & Ethnology and an international team of researchers and anthropologists, BWH faculty and staff performed CT scans on five mummies from 16th-century Greenland in the Shapiro Cardiovascular Center early last year. The team was looking for evidence of plaque in the arteries—also known as atherosclerosis—to see if the leading cause of death in the U.S. today was also prevalent centuries ago.

Sure enough, high-resolution scans of the mummified remains—belonging to four young adults and one child from an Inuit community—revealed the telltale hardened calcium deposits in various blood vessels in the chest.

“It’s always fascinating to look at humans who lived hundreds of years ago and see if learning about the past could teach us more about the present and future,” said Ron Blankstein, associate director of the Brigham’s Cardiovascular Imaging Program, director of cardiac computed tomography, and a preventive cardiology specialist.

Blankstein was among the experts who scanned the mummies and interpreted the images in 2018, an event featured on National Geographic’s “Explorer” series. The effort was part of a broader project, led by a group of external researchers, to scan mummies from hunter-gatherer and preindustrial civilizations around the world to search for signs of heart disease.

Searching the past

From Egypt to Mongolia and now Greenland, mummies throughout the ages have shown evidence of atherosclerosis. The Greenland mummies were of particular interest due to their diet, which would have primarily consisted of fish and sea mammals.

While increased fish consumption is commonly touted as heart-healthy—which may make the findings of atherosclerosis seem surprising—Blankstein emphasized that scientists still have much to learn about its relationship to cardiovascular health. For example, although it is known that consuming fish rich in omega-3 fats has benefits, some types of fish can also be high in cholesterol and, in the current era, contain toxins like mercury or polychlorinated biphenyls (PCBs) that may pose risk, he said.
Lifestyle factors, such as exposure to cooking smoke in their dwellings, may have also contributed to the mummified individuals developing cardiovascular disease during their lifetimes, Blankstein said. Given that and the small sample sizes of these mummy scans, he noted that the team’s findings shouldn’t be taken too much to heart.

“The question of whether fish is good or bad for you is still open-ended, and it would be unrealistic to think that we could provide a definitive answer by scanning a small number of mummies for plaque,” Blankstein said. “Our team found it fascinating that there was evidence of atherosclerosis despite the mummies’ estimated young ages, but this also doesn’t mean cardiovascular disease is inevitable. In fact, the majority of cardiovascular disease events that we see in patients is preventable with appropriate diet, weight control, and lifestyle changes, such as regular exercise; at times, medication can also be used to treat various risk factors.”

A different kind of patient

Scanning the mummies wasn’t too different from work the cardiovascular imaging team normally does. In fact, they were a little easier to scan than living patients; normally, the CT scanner must account for the movement of a beating heart.

Clues of heart disease found in 16th-century mummies from Greenland
High-resolution scans were done on the mummified remains. Credit: Brigham and Women’s Hospital
[Credit: Harvard University]

Interpreting the images required a different perspective, however, Blankstein explained.

“This is not the same as scanning a human. All of the organs are decomposed—in fact, you don’t see much of the heart at all,” he said. “The major plaque we saw was not necessarily in the arteries of the heart but in some other blood vessels in the chest, such as the aorta or some arteries of the neck.”

In addition to satisfying the team’s intellectual curiosity, Blankstein said he hopes the findings will inspire people to learn more about atherosclerosis and how to reduce their risk.

“It was certainly an exciting and interesting experience, and I hope we can use it to promote awareness of this mostly preventable disease,” he said.

Author: Jessica Zimmerman | Source: Harvard University [January 24, 2019]




    Солнечное затмение 14 декабря 2020 года  — полное  солнечное затмение  142  сароса , которое лучше всего будет видно в юго-восточной час...