пятница, 10 августа 2018 г.

Malachite cut and polished | #Geology #GeologyPage…

Malachite cut and polished | #Geology #GeologyPage #Mineral

Locality: Nizhnetagilskii Massif, Nizhnii Tagil, Sverdlovskaya Oblast, Urals Region, Russia, Asia

Dimensions: 10.5 × 5.8 × 2.7 cm

Photo Copyright © Crystal Classics

Geology Page



Ammonite Fossil | #Geology #GeologyPage #Fossil #Ammonite Age:…

Ammonite Fossil | #Geology #GeologyPage #Fossil #Ammonite

Age: Devonian

Location: Atlas Mountains, Morocco

Measuring 10 ½ x 8 1/2in

Photo Copyright © Bonhams

Geology Page



HiPOD (10 August 2018): Source of Flow to the East of Olympus…

HiPOD (10 August 2018): Source of Flow to the East of Olympus Mons

   – Here we see part of a linear depression with branching segments in Amazonian volcanic plains east of Olympus Mons. The flow source from this feature that exhibit volcanic and/or fluvial characteristics. (276 km above the surface, less than 5 km across.)

NASA/JPL/University of Arizona


Vital Vaccination Typhoid fever is an infection caused by…

Vital Vaccination

Typhoid fever is an infection caused by Salmonella typhi bacteria, spread by eating or drinking contaminated food and water. Nowadays typhoid can be mostly prevented by the use of vaccines thanks to pioneering immunologist Almroth Wright – born on this day. A professor at the Army Medical School, Wright was the first scientist to produce a typhoid vaccine, which was later used to inoculate soldiers during the Boer War. He also invented his own technique for testing bodily fluids for bacterial infections, known as the ‘teat and capillary glass tube’.

Wright held controversial views against women’s suffrage, vigorously expressed in his book, ‘The Unexpurgated Case Against Woman Suffrage’, and his opposition to both women’s suffrage and their involvement in science was due to a wilful belief of women having ‘intellectual defects’. Nevertheless, Wright’s scientific achievements are undeniably profound, and he is celebrated today as the UK’s first academic immunologist.

Almroth Wright: Icon of Immunology was recently featured in the MRC LMS Heroes of Health article series

Written by Ellie McLaughlin

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Moel Ty Uchaf Stone Circle, nr Llandrillo, Wales, 10.8.18. This…

Moel Ty Uchaf Stone Circle, nr Llandrillo, Wales, 10.8.18.

This is the very first time I’ve visited this circle and I got drenched in the rain. It is a very distinctive monument with closely placed orthostats. I will return in nice weather at some point although I do like the wet and moody images!

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‘The Corbridge Lion’, Corbridge Roman Town, Corbridge, Newcastle…

‘The Corbridge Lion’, Corbridge Roman Town, Corbridge, Newcastle upon Tyne, 2.8.18.

This famous centrepiece stone sculpture underwent a series of uses during its time in Roman Corbridge. Originally intended for a striking mausoleum, it was reworked and the lion’s mouth adapted and reshaped to insert a pipe for use as a fountain head.

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Students digging into data archive spot mysterious X-ray source

Flaring source in NGC 6540
Copyright: ESA/XMM-Newton; A. De Carlo (INAF)

An enigmatic X-ray source revealed as part of a data-mining project for high-school students shows unexplored avenues hidden in the vast archive of ESA’s XMM-Newton X-ray Observatory.

When XMM-Newton was launched in 1999, most students who are finishing high school today were not even born. Yet ESA’s almost two-decade old X-ray observatory has many surprises to be explored by the next generation of scientists.

A taste of new discoveries was unveiled in a recent collaboration between scientists at the National Institute of Astrophysics (INAF) in Milan, Italy, and a group of twelfth-grade students from a secondary school in nearby Saronno.

The fruitful interaction was part of the Exploring the X-ray Transient and variable Sky project, EXTraS, an international research study of variable sources from the first 15 years of XMM-Newton observations.

“We recently published the EXTraS catalogue, which includes all the X-ray sources – about half a million – whose brightness changes over time as observed by XMM-Newton, and lists several observed parameters for each source,” says Andrea De Luca, one of the scientists who coordinated the student project.

“The next step was to delve into this vast dataset and find potentially interesting sources, and we thought this would be an exciting challenge for a student internship.”

Flaring source in NGC 6540

Copyright ESA/XMM-Newton; A. De Carlo (INAF)

High-school students
Copyright INAF

Scientists at INAF in Milan have been cooperating with local schools for a few years, hosting several groups of students at the institute for a couple of weeks and embedding them in the activities of the various research groups.

“For this particular project, the students received an introduction about astronomy and the exotic sources we study with X-ray telescopes, as well as a tutorial on the database and how to use it,” explains Ruben Salvaterra, another scientist involved in the programme.

“Once they were ready to explore the data archive, they proved very effective and resourceful.”

The six students analysed about 200 X-ray sources, looking at their light curve – a graph showing the object’s variability over time – and checking the scientific literature to verify whether they had been studied already.

Eventually, they identified a handful of sources exhibiting interesting properties – a powerful flare, for example – that had not been previously reported by other studies.

“One of the sources stood out as especially intriguing,” says Andrea.

Featuring the shortest flare of all analysed objects, this source appears to be located in the globular cluster NGC 6540 – a dense grouping of stars – and had not been studied before.

After presenting their findings to the scientists in a seminar, the students went back to school. But the work for Andrea, Ruben and collaborators had only just begun.

“The source identified by the students displays brightness changes like no other known objects, so we started looking more in detail,” says Ruben.

An otherwise low-luminosity source of X-rays, XMM-Newton saw it brighten by up to 50 times its normal level in 2005, and quickly fall again after about five minutes.

Stars like our Sun shine moderately in X-rays, and occasionally undergo flares that boost their brightness like the one observed in this source. However, such events normally last much longer – up to a few hours or even days.

On the other hand, short outbursts are observed in binary star systems hosting a dense stellar remnant such as neutron star, but these outpourings of X-rays are characterised by a much higher luminosity.

“This event is challenging our understanding of X-ray outbursts: too short to be an ordinary stellar flare, but too faint to be linked to a compact object,” explains collaborator Sandro Mereghetti, lead author of the paper presenting the results.

Another possibility is that the source is a so-called chromospherically active binary, a dual system of stars with intense X-ray activity caused by processes in their chromosphere, an intermediate layer in a star’s atmosphere. But even in this case, it does not closely match the properties of any known object of this class.

The scientists suspect that this peculiar source is not unique, and that other objects with similar properties are lurking in the XMM-Newton archive but have not yet been identified because of the combination of low luminosity and short duration of the flare.

“The systematic study of variability that led to the compilation of the EXTraS catalogue, together with this first attempt at data mining, suggests that we have opened a new, unexplored window on the X-ray Universe,” adds Sandro.

The team plans to study the newly identified source in greater detail to better understand its nature, while searching for more similar objects in the archive.

“It is exciting to find hidden jewels like this source in the XMM-Newton archive, and that young students are helping us find them while learning and having fun,” concludes Norbert Schartel, XMM-Newton project scientist at ESA.

Notes for Editors

“EXTraS discovery of a peculiar flaring X-ray source in the Galactic globular cluster NGC 6540” by S. Mereghetti et al. 2018 is published in Astronomy & Astrophysics, DOI: 10.1051/0004-6361/201833086.

The students involved in this project are Razvan Patrolea, Lorenzo Apollonio, Elena Pecchini, Cinzia Torrente, Bartolomeo Bottazzi-Baldi and Martino Giobbio from Liceo scientifico G.B. Grassi in Saronno, Italy. They discovered the peculiar source during a two-week internship at INAF, Milan, in September 2017, as part of an initiative supported by the Italian Ministry of Education, University and Research.

The discovery was made as a result of the Exploring the X-ray Transient and variable Sky (EXTraS) project, a EU/FP7 project devoted to a systematic variability study of the X-ray sources in the XMM-Newton public archive.

For further information, please contact:

Andrea De Luca
INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica
Milano, Italy
INFN, Pavia, Italy
Email: andrea.deluca@inaf.it

Ruben Salvaterra
INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica
Milano, Italy
Email: ruben.salvaterra@inaf.it

Sandro Mereghetti
INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica
Milano, Italy
Email: sandro.mereghetti@inaf.it

Norbert Schartel
XMM-Newton Project Scientist
European Space Agency
Email: norbert.schartel@esa.it

Markus Bauer

ESA Science and Robotic Exploration Communication Officer

Tel: +31 71 565 6799

Mob: +31 61 594 3 954

Email: markus.bauer@esa.int

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Roman artefacts from Corbridge Roman Town, Corbridge, Newcastle…

Roman artefacts from Corbridge Roman Town, Corbridge, Newcastle upon Tyne, 2.8.18.

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2018 August 10 Spiral Galaxy NGC 6744 Image Credit &…

2018 August 10

Spiral Galaxy NGC 6744
Image Credit & Copyright: Martin Pugh

Explanation: Beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo and appears as only a faint, extended object in small telescopes. We see the disk of the nearby island universe tilted towards our line of sight. This remarkably detailed galaxy portrait covers an area about the angular size of the full moon. In it, the giant galaxy’s elongated yellowish core is dominated by the light from old, cool stars. Beyond the core, grand spiral arms are filled with young blue star clusters and speckled with pinkish star forming regions. An extended arm sweeps past a smaller satellite galaxy at the upper left. NGC 6744’s galactic companion is reminiscent of the Milky Way’s satellite galaxy the Large Magellanic Cloud.

∞ Source: apod.nasa.gov/apod/ap180810.html


Three Deity Figurines from Roman Corbridge Town, Corbridge,…

Three Deity Figurines from Roman Corbridge Town, Corbridge, Newcastle upon Tyne, 2.8.18.

These miniatures were made for personal worship or for the household shrine. 

Pictured is:

– a copper alloy image of Mercury, god of trade, holding a money bag with a cloak over his arm. (Image 1)

– a copper alloy figure of winged Victory, the guardian of the Roman empire, She stands on a globe and holds a wreath and a cornucopia.

– a copper alloy figure of Cupid, god of love, holding a bunch of grapes

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Quartz Var. “Amethyst” with Prehnite | #Geology #GeologyPage…

Quartz Var. “Amethyst” with Prehnite | #Geology #GeologyPage #Mineral

Locality: Goboboseb Mountains, Brandberg, Erongo Region, Namibia, Africa

Dimensions: 10.2 × 6.9 × 5.2 cm

Photo Copyright © Crystal Classics

Geology Page



A globular cluster’s striking red eye

NGC 2108
Credit: ESA/Hubble & NASA

This Picture of the Week shows the colourful globular cluster NGC 2108. The cluster is nestled within the Large Magellanic Cloud, in the constellation of the Swordfish (Dorado). It was discovered in 1835 by the astronomer, mathematician, chemist and inventor John Herschel, son of the famous William Herschel.

The most striking feature of this globular cluster is the gleaming ruby-red spot at the centre left of the cluster. What looks like the cluster’s watchful eye is actually a carbon star. Carbon stars are almost always cool red giants, with atmospheres containing more carbon than oxygen — the opposite to our Sun. Carbon monoxide forms in the outer layer of the star through a combination of these elements, until there is no more oxygen available. Carbon atoms are then free to form a variety of other carbon compounds, such as C2, CH, CN, C3 and SiC2, which scatter blue light within the star, allowing red light to pass through undisturbed.

This image was captured by the NASA/ESA Hubble Space Telescope’s Advanced Camera for Surveys (ACS), using three different filters.

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Water Is Destroyed, Then Reborn in Ultrahot Jupiters

These simulated views of the ultrahot Jupiter WASP-121b show what the planet might look like to the human eye from five different vantage points, illuminated to different degrees by its parent star. The images were created using a computer simulation being used to help scientists understand the atmospheres of these ultra-hot planets. Credit: NASA/JPL-Caltech/Vivien Parmentier/Aix-Marseille University (AMU).  › Full image and caption

Imagine a place where the weather forecast is always the same: scorching temperatures, relentlessly sunny, and with absolutely zero chance of rain. This hellish scenario exists on the permanent daysides of a type of planet found outside our solar system dubbed an “ultrahot Jupiter.” These worlds orbit extremely close to their stars, with one side of the planet permanently facing the star.

What has puzzled scientists is why water vapor appears to be missing from the toasty worlds’ atmospheres, when it is abundant in similar but slightly cooler planets. Observations of ultrahot Jupiters by NASA’s Spitzer and Hubble space telescopes, combined with computer simulations, have served as a springboard for a new theoretical study that may have solved this mystery. 

According to the new study, ultrahot Jupiters do in fact possess the ingredients for water (hydrogen and oxygen atoms). But due to strong irradiation on the planet’s daysides, temperatures there get so intense that water molecules are completely torn apart. 

“The daysides of these worlds are furnaces that look more like a stellar atmosphere than a planetary atmosphere,” said Vivien Parmentier, an astrophysicist at Aix Marseille University in France and lead author of the new study. “In this way, ultrahot Jupiters stretch out what we think planets should look like.” 

While telescopes like Spitzer and Hubble can gather some information about the daysides of ultrahot Jupiters, the nightsides are difficult for current instruments to probe. The new paper proposes a model for what might be happening on both the illuminated and dark sides of these planets, based largely on observations and analysis of the ultrahot Jupiter known as WASP-121b, and from three recently published studies, coauthored by Parmentier, that focus on the ultrahot Jupiters WASP-103b

WASP-18b and HAT-P-7b, respectively. The new study suggests that fierce winds may blow the sundered water molecules into the planets’ nightside hemispheres. On the cooler, dark side of the planet, the atoms can recombine into molecules and condense into clouds, all before drifting back into the dayside to be splintered again. 

Water is not the only molecule that may undergo a cycle of chemical reincarnation on these planets, according to the new study. Previous detections of clouds by Hubble at the boundary between day and night, where temperatures mercifully fall, have shown that titanium oxide (popular as a sunscreen) and aluminum oxide (the basis for ruby, the gemstone) could also be molecularly reborn on the ultrahot Jupiters’ nightsides. These materials might even form clouds and rain down as liquid metals and fluidic rubies. 

Star-planet hybrids

Among the growing catalog of planets outside our solar system — known as exoplanets — ultrahot Jupiters have stood out as a distinct class for about a decade. Found in orbits far closer to their host stars than Mercury is to our Sun, the giant planets are tidally locked, meaning the same hemisphere always faces the star, just as the Moon always presents the same side to Earth. As a result, ultrahot Jupiters’ daysides broil in a perpetual high noon. Meanwhile, their opposite hemispheres are gripped by endless nights. Dayside temperatures reach between 3,600 and 5,400 degrees Fahrenheit (2,000 and 3,000 degrees Celsius), ranking ultrahot Jupiters among the hottest exoplanets on record. Nightside temperatures are around 1,800 degrees Fahrenheit cooler (1,000 degrees Celsius), cold enough for water to re-form and, along with other molecules, coalesce into clouds.

Hot Jupiters, cousins to ultrahot Jupiters with dayside temperatures below 3,600 degrees Fahrenheit (2,000 Celsius), were the first widely discovered type of exoplanet, starting back in the mid-1990s. Water has turned out to be common in their atmospheres. One hypothesis for why it appeared absent in ultrahot Jupiters has been that these planets must have formed with very high levels of carbon instead of oxygen. Yet the authors of the new study say this idea could not explain the traces of water also sometimes detected at the dayside-nightside boundary. 

To break the logjam, Parmentier and colleagues took a cue from well-established physical models of the atmospheres of stars, as well as “failed stars,” known as brown dwarfs, whose properties overlap somewhat with hot and ultrahot Jupiters. Parmentier adapted a brown dwarf model developed by Mark Marley, one of the paper’s coauthors and a research scientist at NASA’s Ames Research Center in Silicon Valley, California, to the case of ultrahot Jupiters. Treating the atmospheres of ultrahot Jupiters more like blazing stars than conventionally colder planets offered a way to make sense of the Spitzer and Hubble observations. 

“With these studies, we are bringing some of the century-old knowledge gained from studying the astrophysics of stars, to the new field of investigating exoplanetary atmospheres,” said Parmentier.

Spitzer’s observations in infrared light zeroed in on carbon monoxide in the ultrahot Jupiters’ atmospheres. The atoms in carbon monoxide form an extremely strong bond that can uniquely withstand the thermal and radiational assault on the daysides of these planets. The brightness of the hardy carbon monoxide revealed that the planets’ atmospheres burn hotter higher up than deeper down. Parmentier said verifying this temperature difference was key for vetting Hubble’s no-water result, because a uniform atmosphere can also mask the signatures of water molecules. 

“These results are just the most recent example of Spitzer being used for exoplanet science — something that was not part of its original science manifest,” said Michael Werner, project scientist for Spitzer at NASA’s Jet Propulsion Laboratory in Pasadena, California. “In addition, it’s always heartening to see what we can discover when scientists combine the power of Hubble and Spitzer, two of NASA’s Great Observatories.”

Although the new model adequately described many ultrahot Jupiters on the books, some outliers do remain, suggesting that additional aspects of these worlds’ atmospheres still need to be understood. Those exoplanets not fitting the mold could have exotic chemical compositions or unanticipated heat and circulation patterns. Prior studies have argued that there is a more significant amount of water in the dayside atmosphere of WASP-121b than what is apparent from observations, because most of the signal from the water is obscured. The new paper provides an alternative explanation for the smaller-than-expected water signal, but more studies will be required to better understand the nature of these ultrahot atmospheres.

Resolving this dilemma could be a task for NASA’s next-generation James Webb Space Telescope, slated for a 2021 launch. Parmentier and colleagues expect it will be powerful enough to glean new details about the daysides, as well as confirm that the missing dayside water and other molecules of interest have gone to the planets’ nightsides.

“We now know that ultrahot Jupiters exhibit chemical behavior that is different and more complex than their cooler cousins, the hot Jupiters,” said Parmentier. “The studies of exoplanet atmospheres is still really in its infancy and we have so much to learn.”

The new study is forthcoming in the journal Astronomy and Astrophysics.

NASA’s Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA’s Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Spacecraft operations are based at Lockheed Martin Space, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA. 

Hubble is a project of international cooperation between NASA and ESA. NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages Hubble. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations.

News Media Contact

Calla Cofield
Jet Propulsion Laboratory, Pasadena, Calif.


Written by Adam Hadhazy

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Largest haul of extrasolar planets for Japan

Forty-four planets in solar systems beyond our own have been unveiled in one go, dwarfing the usual number of confirmations from extrasolar surveys, which is typically a dozen or less. The findings will improve our models of solar systems and may help researchers investigate exoplanet atmospheres. Novel techniques developed to validate the find could hugely accelerate the confirmation of more extrasolar planet candidates.

Largest haul of extrasolar planets for Japan
Simulated image of an Earth-like exoplanet [Credit: NASA/JPL-Caltech/R. Hurt (IPAC)]

An international team of astronomers pooled data from U.S. space agency NASA’s Kepler and the European Space Agency (ESA)’s Gaia space telescopes, as well as ground-based telescopes in the U.S. Alongside John Livingston, lead author of the study and a graduate student at the University of Tokyo, the team’s combined resources led to the confirmed existence of these 44 exoplanets and described various details about them.

A portion of the findings yield some surprising characteristics: “For example, four of the planets orbit their host stars in less than 24 hours,” says Livingston. “In other words, a year on each of those planets is shorter than a day here on Earth.” These contribute to a small but growing list of “ultrashort-period” planets, so it could turn out they’re not as unusual as they might seem.

“It was also gratifying to verify so many small planets,” continues Livingston. “Sixteen were in the same size class as Earth, one in particular turning out to be extremely small — about the size of Venus — which was a nice affirmation as it’s close to the limit of what is possible to detect.”

The source observations for this study were made by Kepler, and they would not have happened were it not for a fault in 2013, which prevented accurate control of the space telescope. “Two out of the four control-reaction wheels failed, which meant Kepler couldn’t perform its original mission to stare at one specific patch of the sky,” explains Professor Motohide Tamura of the University of Tokyo. “This led to its contingent mission, ‘K2’ — our observations came from campaign 10 of this mission. We’re lucky Kepler continues to function as well as it does.”

The 44 confirmed planets and their approximate size class, orbits and surface temperatures 

[Credit: John Livingston]

The planets observed by K2 are known as transiting planets because their orbits bring them in front of their host stars, slightly reducing their brightness. However, other astrophysical phenomena can cause similar signals, so follow-up observations and detailed statistical analyses were performed to confirm the planetary nature of these signals. As part of his doctoral work, Livingston traveled to Kitt Peak observatory in the U.S. state of Arizona to obtain data from a special type of camera, known as a speckle interferometer installed on a large telescope there.

These observations, along with follow-up observations from a telescope in the state of Texas, were necessary to characterize the host stars and rule out false positives. The combination of detailed analyses of data from these ground-based telescopes, K2 and Gaia enabled the precise determination of the planets’ sizes and temperatures. The team’s findings include 27 additional candidates that are likely to be real planets, which will be the subject of future research.

Scientists hope to understand what kinds of planets might be out there, but can only draw valid conclusions if there are enough planets for robust statistical analysis. The addition of a large number of new planets, therefore, leads directly to a better theoretical understanding of solar-system formation. The planets also provide good targets for detailed individual studies to yield measurements of planetary composition, interior structure and atmospheres — in particular, the 18 planets in several multiplanet systems.

“The investigation of other solar systems can help us understand how planets and even our own solar system formed,” says Livingston. “The study of other worlds has much to teach us about our own.”

The findings are published in The Astronomical Journal.

Source: University of Tokyo [August 07, 2018]




Forests crucial for limiting climate change to 1.5 degrees

Trying to tackle climate change by replacing forests with crops for bioenergy power stations that capture carbon dioxide (CO2) could instead increase the amount of CO2 in the atmosphere, scientists say.

Forests crucial for limiting climate change to 1.5 degrees
Field of miscanthus – a tall grass used by BECCS power stations
[Credit: Anna Harper]

Biomass Energy with Carbon Capture and Storage (BECCS) power stations are designed to produce energy and store the resulting carbon dioxide (CO2) in bedrock deep underground.

But a study led by the University of Exeter suggests that converting large land areas to growing crops as biomass for BECCS would release so much CO2 that protecting and regenerating forests is a better option in many places.

“The vast majority of current IPCC scenarios for how we can limit global warming to less than 2°C include BECCS,” said lead author Dr. Anna Harper, from the University of Exeter.

“But the land required to grow biomass in these scenarios would be twice the size of India”.

This motivated the research team to look at the wider consequences of such a radical change in global land use.

The researchers used a cutting-edge computer model of global vegetation and soil and presented it with scenarios of land-use change consistent with stabilising the climate at less than 1.5oC and 2oC of global warming.

The results warn that using BECCS on such a large scale could lead to a net increase of carbon in the atmosphere, especially where the crops are assumed to replace existing forests.

Co-author Dr. Tom Powell, from the University of Exeter, explained: “In some places BECCS will be effective, but we’ve found that in many places protecting or regenerating forests is much more sensible.”

How well BECCS works depends on factors such as the choice of biomass, the fate of initial above-ground biomass and the fossil-fuel emissions offset in the energy system—so future improvements could make it a better option.

Professor Chris Huntingford, of the UK Centre for Ecology and Hydrology, said: “Our paper illustrates that the manipulation of land can help offset carbon dioxide emissions, but only if applied for certain quite specific locations.”

Dr. Harper concluded: “To meet the climate change targets from the Paris agreement, we need to both drastically reduce emissions and employ a mix of technologies to remove carbon dioxide from the atmosphere. There is no single get-out-of-jail-free card.”

The team involved in the new study included researchers from the Centre for Ecology and Hydrology and the Met Office.

Drawing together expertise to create solutions to the global changes that humans are now causing is a key focus of the University of Exeter’s new Global Systems Institute.

The paper, published in the journal Nature Communications, is entitled: “Land-use emissions play a critical role in land-based mitigation for Paris climate targets.”

Source: University of Exeter [August 07, 2018]




Iron-silica particles unlock part of the mystery of Earth’s oxygenation

The oxygenation of Earth’s atmosphere was thanks, in part, to iron and silica particles in ancient seawater, according to a new study by geomicrobiologists at the University of Alberta. But these results solve only part of this ancient mystery.

Iron-silica particles unlock part of the mystery of Earth's oxygenation
Iron-silica particles helped shield cyanobacteria like these, which played a key role in the oxygenation
of Earth’s atmosphere according to new research from UAlberta [Credit: George Owttrim]

Early organisms called cyanobacteria produced oxygen through oxygenic photosynthesis, resulting in the oxygenation of Earth’s atmosphere. But cyanobacteria needed protection from the sun’s UV radiation in order to evolve. That’s where iron and silica particles in ancient seawater come in, according to Aleksandra Mloszewska, a former PhD student who conducted this research under the supervision of Kurt Konhauser, professor in the Department of Earth and Atmospheric Sciences, and George Owttrim, professor in the Department of Biological Sciences.

The research team characterized the effect of UV stress on cyanobacteria and the degree of radiation through the seawater medium through a combination of microbiological, spectroscopic, geochemical and modelling techniques. Their results show that the presence of high silica and iron concentrations in early sea water allowed for the formation of iron-silica precipitates that remained suspended in the ocean for extended periods of time.

“In effect, the iron-silica particles acted as an ancient ‘sunscreen’ for the cyanobacteria, protecting them from the lethal effects of direct UV exposure,” said Konhauser, the senior author from UAlberta. “This was critical on the early Earth before a sufficiently thick ozone layer was established that could enable marine plankton to spread across the globe, as is the case today.”

More missing pieces

But, the researchers explain, the iron-silica rich precipitates tell only part of the story.

“The accumulation of atmospheric oxygen from cyanobacterial facilitated the evolution of oxygen-based respiration and multicellular organisms,” says Owttrim. But the reason for the large amount of time that it took for free oxygen to accumulate permanently in the atmosphere after the initial evolution of cyanobacteria remains a mystery.

While iron-silica precipitates would have allowed early cyanobacteria to survive, UV radiation would still have prevented their widespread growth.

“It is likely that early cyanobacteria would not have been as productive as they are today because of the effects of UV stress. Until the accumulation of sufficient cyanobacteria-derived oxygen allowed a more permanent means of protection to develop, such as an ozone layer, UV stress may have played an even more important role in shaping the structure of the earliest ecosystems,” explained Mloszewska.

These new findings are helping researchers to understand not only how early cyanobacteria were affected by the high level of radiation on the early Earth but also the environmental dynamics that affected the oxygenation history of our atmosphere.

“These findings could also be used as a case study to help us understand the potential for the emergence of life on other planets that are affected by elevated UV radiation levels, for example Earth-sized rocky planets within the habitable zones of nearby M-dwarf star systems like TRAPPIST-1, Proxima Centauri, LHS 1140 and Ross 128 among others,” said Mloszewska.

The paper is published in Nature Communications.

Author: Katie Willis | Source: University of Alberta [August 07, 2018]




The Umov Effect: Space dust clouds and the mysteries of the universe

FEFU scientists are developing a methodology to calculate the ratio of dust and gas in comas and tails of comets. This will help learn more about the history of the Solar System and its development, as well as understand the processes that took part on different stages of universal evolution.

The Umov Effect: Space dust clouds and the mysteries of the universe
This is Comet17P/Holmes seen by the Hubble Space Telescope [Credit: NASA, ESA, H. Weaver, A. Dyer]

A team of scientists from the Far Eastern Federal University (FEFU) under the supervision of the astrophysicist Evgenij Zubko, Ph.D., a lead scientist of the School of Natural Sciences at FEFU is trying to solve a fundamental problem of modern astrophysics which is to assess the reflectivity of cosmic dust particles, their ability to scatter sunlight (or, more generally, star light). To do so, the scientists study the optic characteristics of dust particles in the comae and tails of comets.

The methodology under development is based on the Umov effect – an inverse correlation between the reflectivity of a body and the degree of linear polarization of light scattered by it. The brighter is an object, the lower polarization it produces. This relation was first formulated by the Russian physicist Nikolay Umov in 1905.

According to Evgenij Zubko, previously the Umov effect was studied only for surfaces, such as regolite (Moon surface) and the surfaces of asteroids. The explanation of this effect given in 1960-1970s, excluded its application to single dust particles that comprise the regolite. However, the team concluded that the Umov effect is almost equally applicable to individual particles and surfaces in general.

Previously the researchers concluded that the Umov effect holds in a homogenous sparse cloud of space dust. In the article published in the Monthly Notices of the Royal Astronomical Society the scientists suggested that this physical effect could be also applicable to clouds consisting of two types of dust particles which is characteristic of comae and tails of comets. The Umov effect is also expected to be observed in a three-component clouds of cosmic dust that is more typical for protoplanetary disks.

The Umov Effect: Space dust clouds and the mysteries of the universe
This is Comet Garradd and the Coat Hanger [Credit: Rogelio Bernal Andreo]

After studying the degree of linear polarization acquired by sunlight when it is scattered by cometary dust particles, scientists are able to give reliable estimation of the particles’ albedo or reflectivity. This characteristic is an extremely important for retrieval the total volume of dust expelled from a comet. The latter parameter allows the scientists to improve the existing methods of estimation of the dust-to-gas volume ratio in cometary comae. This is one of the most important characteristic of a cometary evolution – for example, it could indicate the place in the Solar System in which the comet was formed.

“Knowing the ratio between the volumes of ejected dust and gas, we can better understand the evolutionary stages passed by different comets and the circumstances of the Solar-System formation. However, while it is easy to calculate the volume of gas in a comet, in case of dust particles this is much more complicated,” said Evgenij Zubko. “When we measure the sunlight reflected by the coma, we need to understand the number of dust particles that contribute to the sunlight scattering. Their albedo or reflectivity is the key data we require to answer this question. However, different dust particles also behave differently, and the difference in the reflectivity of dark and bright particles in comets may exceed ten times. This is a common issue nowadays that also arises in other areas of astrophysics, such as the evaluation of matter volumes in protoplanetary disks around other stars.

We strive to understand the value of this albedo and use additional methods to do so – in particular, polarimetry to measure the degree of linear polarization and, thus, retrieve the reflectivity of cometary dust particles based on the Umov effect.”

There is still a lot to be discovered in the course of this work. “We are literally chasing a ghost,” says the scientist. He also pointed out that to achieve a breakthrough in this area of studies, groups of astrophysicists from different parts of the world had to extensively collaborate.

The analysis methodology based on the Umov effect may be further used in other areas besides the studies of comets. It may serve as a key to understanding the processes of formation and evolution of other planetary systems and therefore the Solar System as well.

According to Evgenij Zubko, the value of the Umov effect for the science in general is as high as the importance of the spectral analysis method developed by Gustav Kirchhoff. While the spectral analysis helps us understand the chemical composition of distant bodies based on the light reflected from them, the Umov effect allows to evaluate their size even if they appear like a point to an observer.

Source: Far Eastern Federal Univeristy [August 08, 2018]




For the first time, scientists are putting extinct mammals on the map

Researchers from Aarhus University and University of Gothenburg have produced the most comprehensive family tree and atlas of mammals to date, connecting all living and recently extinct mammal species — nearly 6,000 in total — and overturning many previous ideas about global patterns of biodiversity.

For the first time, scientists are putting extinct mammals on the map
The thylacine, or Tasmanian tiger, is a marsupial predator that was last seen alive in the 1930s
[Credit: American Museum of Natural History, New York]

While others have tried to map the ranges of all mammals or figure out their family tree, previous studies always left out one crucial group of mammals: species driven to extinction by humans.

“This is the first time we’ve been able to comprehensively include extinct species like the Tasmanian tiger or the woolly mammoth as well as account for human-induced regional range losses among extant species in such a large database, and it’s really changing our beliefs about what is ‘natural’ or not,” said biologist Søren Faurby of the University of Gothenburg in Sweden, who co-led the assembly of the database and the study, which was resently published in the scientific magazine Ecology.

Scientist often use maps of mammal species ranges to investigate patterns of biodiversity or to predict how climate change will affect species. But these maps are incomplete because they don’t show species’ natural ranges, only where they occur today. Many species have had their ranges drastically reduced by humans, for instance, through overhunting and habitat destruction.

“Brown bears may be emblematic of Alaska or Russia today but their range used to stretch all the way from Mexico to Northern Africa before widespread hunting by humans. If we want to predict how a warming climate will affect these bears, we can’t leave out these natural areas of their range,” said Faurby.

For the first time, scientists are putting extinct mammals on the map
The maps show the diversity of Australian big herbivorous marsupials (a mammalian infraclass) as is today, and as it
would be today, had most of the species not been extinct. The phylogenetic tree to the right shows the evolutionary
relationships among a sample of extant and extinct species, while the circles illustrate the size of each species
as well as their status: EP = Extinct in prehistory, CR = Critically Endangered, NT = Near Threatened,
LC = Least Concern [Credit: Soeren Faurby, University of Gothenburg]

Tasmanian tigers and mammoths back on the map

It is also important to include species that have been totally exterminated.

“If we are studying global patterns of biodiversity, we really need to start considering species like the Tasmanian tiger that was hunted to extinction less than 100 years ago, a mere eye blink in geological time,” said paleontologist and co-leader Matt Davis of Aarhus University in Denmark.

We associate large mammals like elephants and lions with Africa today, but for most of the last 30 million years, big animals roamed all over the Earth. It was only relatively recently that humans drove many of these large mammals extinct, leaving a world depauperate of giants.

“Even a species like the woolly mammoth, that we think of as prehistoric, lived up to the time the Great Pyramid was being built,” Davis said.

Old maps and new algorithms

Assembling a database that included every species of mammal was no easy task. It took the research team, headquartered at Aarhus University, months just to stitch together existing datasets and fill in missing holes in the data.

They then poured over old maps and checked museum records to see where species natural ranges might be without the interference of modern humans.

For the first time, scientists are putting extinct mammals on the map
The blue color shows the range of brown bear today. The red color shows, where you would
also find brown bears today, had they not been driven away by human activity
[Credit: Soeren Faurby, University of Gothenburg]

Adding extinct species to the mammal family tree and making modern ranges for them was even harder. The scientists combined DNA evidence and data from fossil dig sites around the world with a powerful new computer algorithm to predict where extinct species fit in with mammals that are alive today.

New baselines for restoration

“This comprehensive database has already provided much needed evidence to inform restoration baselines and to provide re-assessments of several hotly debated ideas in biology, but this is just the beginning” said Jens-Christian Svenning, professor at Aarhus University and leader of the Aarhus team.

He expects that other researchers, conservationists, and educators will also find the easy to use and publicly available database valuable.

“We are already using the database to quantify and map human-induced biodiversity deficits and assess restoration potential across the globe.

Source: Aarhus University [August 08, 2018]




Finding the Happy Medium of Black Holes

Black Hole Ilustration
Credit: X-ray: NASA/CXC/ICE/M.Mezcua et al.; 

Infrared: NASA/JPL-Caltech; 

Illustration: NASA/CXC/A.Hobart

This image shows data from a massive observing campaign that includes NASA’s Chandra X-ray Observatory. These Chandra data have provided strong evidence for the existence of so-called intermediate-mass black holes (IMBHs). Combined with a separate study also using Chandra data, these results may allow astronomers to better understand how the very largest black holes in the early Universe formed, as described in our latest press release.

The COSMOS (“cosmic evolution survey”) Legacy Survey has assembled data from some of the world’s most powerful telescopes spanning the electromagnetic spectrum. This image contains Chandra data from this survey, equivalent to about 4.6 million seconds of observing time. The colors in this image represent different levels of X-ray energy detected by Chandra. Here the lowest-energy X-rays are red, the medium band is green, and the highest-energy X-rays observed by Chandra are blue. Most of the colored dots in this image are black holes. Data from the Spitzer Space Telescope are shown in grey. The inset shows an artist’s impression of a growing black hole in the center of a galaxy. A disk of material surrounding the black hole and a jet of outflowing material are also depicted.

Two new separate studies using the Chandra COSMOS-Legacy survey data and other Chandra data have independently collected samples of IMBHs, an elusive category of black holes in between stellar mass black holes and the supermassive black holes found in the central regions of massive galaxies.

One team of researchers identified 40 growing black holes in dwarf galaxies. Twelve of them are located at distances more than five billion light years from Earth and the most distant is 10.9 billion light years away, the most distant growing black hole in a dwarf galaxy ever seen. Most of these sources are likely IMBHs with masses that are about 10,000 to 100,000 times that of the Sun.

A second team found a separate, important sample of possible IMBHs in galaxies that are closer to Earth. In this sample, the most distant IMBH candidate is about 2.8 billion light years from Earth and about 90% of the IMBH candidates they discovered are no more than 1.3 billion light years away.

They detected 305 galaxies in their survey with black hole masses less than 300,000 solar masses. Observations with Chandra and with ESA’s XMM-Newton of a small part of this sample show that about half of the 305 IMBH candidates are likely to be valid IMBHs. The masses for the ten sources detected with X-ray observations were determined to be between 40,000 and 300,000 times the mass of the Sun.

IMBHs may be able to explain how the very biggest black holes, the supermassive ones, were able to form so quickly after the Big Bang. One leading explanation is that supermassive black holes grow over time from smaller black holes “seeds” containing about a hundred times the Sun’s mass. Some of these seeds should merge to form IMBHs. Another explanation is that they form very quickly from the collapse of a giant cloud of gas with a mass equal to hundreds of thousands of times that of the Sun. There is yet to be a consensus among astronomers on the role IMBHs may play.

A paper describing the COSMOS-Legacy result by Mar Mezcua (Institute for Space Sciences, Spain) and colleagues was published in the August issue of the Monthly Notices of the Royal Astronomical Society and is available online. The paper by Igor Chilingarian (Harvard-Smithsonian Center for Astrophysics) on the closer IMBH sample is being published in the August 10th issue of The Astrophysical Journal and is available online.

NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

Fast Facts for COSMOS Legacy Survey:

Category: Black Holes, Cosmology/Deep Fields/X-ray Background
Constellation: Sextans
Observation Date: 68 pointings between Nov 2012 and March 2014
Observation Time: 1277 hours (53 days 5 hours)
Obs. ID: 15207-15262, 15590, 15591, 15598, 15600, 15604-15606, 15649, 15653, 15655, 16544, 16562
Instrument: ACIS
References: Mezcua, M. et al., 2018, MNRAS, 478, 2576; arXiv:1802.01567; [Non-COSMOS study: Chilingarian, I. et al., 2018, ApJ, 873, 1; arXiv:1805.01467]
Distance Estimate: About 410 million to 11.0 billion light years

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Facebook hopes to launch an internet satellite in early 2019

Facebook logo.

August 9, 2018

Facebook has cooperated on internet satellite initiatives (with less-than-ideal results), but there’s been precious little word of plans to make its own satellite beyond high-level promises. Now, however, there’s something tangible. Both publicly disclosed FCC emails and a direct confirmation to Wired have revealed that Facebook aims to launch an internally developed satellite, Athena, sometime in early 2019. A spokesperson didn’t share details, but the shell organization Facebook used to keep filings hidden (PointView Tech LLC) talked about offering broadband to “unserved and underserved” areas with a low Earth orbit satellite on a “limited duration” mission.

Facebook to Launch Athena, a Satellite-Based ISP

This is likely just an experiment rather than a full-fledged deployment. Low Earth orbit satellite internet would require a large cloud of satellites to provide significant coverage, similar to SpaceX’s planned Starlink network. However, it shows that the company isn’t done building its own high-altitude hardware now that it has stopped work on its internet drone.

Whatever Athena shapes up to be, Facebook’s motives likely remain the same. As with Alphabet’s Loon internet balloons, there’s a strong commercial incentive to connect underserved regions. Even if Facebook doesn’t charge a thing for access, it could benefit by adding millions of new users who’d view ads and use services (including through Instagram and WhatsApp). It would also look good to investors, as Facebook would keep its audience growing at a time when there’s seemingly no more room to grow.

Facebook: https://www.facebook.com/

Image, Text, Credits: Yahoo/Orbiter.ch Aerospace/Roland Berga.

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