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Thursday, June 30, 2016

It’s Not Easy Being Green – What Colors Tell Us About Galaxy Evolution

Scientists may have answered why green galaxies are rare in our universe and why their colour could reveal a troubled past. Their research is presented today (Thursday 30 June) at the National Astronomy Meeting at the University of Nottingham.

The international team, led from Durham University's Institute for Computational Cosmology (ICC), used new computer modelling of the universe to investigate the colours that galaxies have and what those colours might tell us about how galaxies evolve. Using the state of the art EAGLE simulations, the researchers modelled how both the ages of stars in galaxies and what those stars are made from translate into the colour of light that they produce.

Composite image of blue, green and red galaxies: L-R Virtual images of blue, green and red galaxies produced by the EAGLE simulations. The green galaxy is caught in the act of transforming from blue to red as its gas supply runs out.
 Credit: James Trayford/EAGLE/Durham University. 

The team said their simulations showed that colours of galaxies can also help diagnose how they evolve.

While red and blue galaxies are relatively common, rare green galaxies are likely to be at an important stage in their evolution, when they are rapidly turning from blue – when new stars and planets are being born – to red as stars begin to burn themselves out.

Lead researcher James Trayford, PhD student in the ICC, said: “Galaxies emit a healthy blue glow while new stars and planets are being born. However, if the formation of stars is halted galaxies turn red as stars begin to age and die.

“In the real universe we see many blue and red galaxies, but these intermediate ‘green’ galaxies are more rare.

Image of blue galaxy from EAGLE simulation
Credit: James Trayford/EAGLE/Durham University

“This suggests that the few green galaxies we catch are likely to be at a critical stage in their evolution; rapidly turning from blue to red.”

Because stars form from dense gas, a powerful process is needed to rapidly destroy their gas supply and cause such dramatic changes in colour, the research found.

James added: “In a recent study we followed simulated galaxies as they changed colour, and investigated what processes caused them to change.

Image of green galaxy from EAGLE simulation.

Credit: James Trayford/EAGLE/Durham University

“We typically find that smaller green galaxies are being violently tossed around by the gravitational pull of a massive neighbour, causing their gas supply to be stripped away.

“Meanwhile, bigger green galaxies may self-destruct as immense explosions triggered by supermassive black holes at their centres can blow dense gas away.”

Image of red galaxy from EAGLE simulation
Credit: James Trayford/EAGLE/Durham University

However, the research found that there was some hope for green galaxies as a lucky few might absorb a fresh supply of gas from their surroundings. This can revive the formation of stars and planets, and restore galaxies to a healthy blue state.

James said: “By using simulations to study how galaxy colours change, we can speed up the process of galaxy evolution from the billions of years it takes in the real Universe to just a matter of days in a computer.

“This means we don’t just see galaxy colours frozen in time, we can watch them evolve. Another advantage is that we can remove unwanted factors that may change the colours we see, such as pesky dust clouds that can prevent light escaping from galaxies.

“As the EAGLE simulations we use represent a new level of realism, we can have greater confidence in applying these results to the real universe.” 


Contacts and sources:
Dr Robert Massey
Royal Astronomical Society

James Trayford
Institute for Computational Cosmology
Durham University

A 6,000 Year Old Telescope Without A Lens - Prehistoric Tombs Enhanced Astronomical Viewing

Astronomers are exploring what might be described as the first astronomical observing tool, potentially used by prehistoric humans 6,000 years ago. They suggest that the long, narrow entrance passages to ancient stone, or 'megalithic', tombs may have enhanced what early human cultures could see in the night sky, an effect that could have been interpreted as the ancestors granting special power to the initiated. The team present their study at the National Astronomy Meeting, being held this week in Nottingham.

Photographs of the megalithic cluster of Carregal do Sal: a) Dolmen da Orca, a typical dolmenic structure in western Iberia; b) view of the passage and entrance while standing within the dolmens' chamber: the 'window of visibility'; c) Orca de Santo Tisco, a dolmen with a much smaller passage or corridor. 
Credit: F. Silva

The team's idea is to investigate how a simple aperture, for example an opening or doorway, affects the observation of slightly fainter stars. They focus this study on passage graves, which are a type of megalithic tomb composed of a chamber of large interlocking stones and a long narrow entrance. These spaces are thought to have been sacred, and the sites may have been used for rites of passage, where the initiate would spend the night inside the tomb, with no natural light apart from that shining down the narrow entrance lined with the remains of the tribe's ancestors.

These structures could therefore have been the first astronomical tools to support the watching of the skies, millennia before telescopes were invented. Kieran Simcox, a student at Nottingham Trent University, and leading the project, comments: "It is quite a surprise that no one has thoroughly investigated how for example the colour of the night sky impacts on what can be seen with the naked eye."

The view towards the east from the Carregal do Sal megalithic cluster, at dawn at the end of April around 4,000 BCE, as reconstructed using a Digital Elevation Model and Stellarium. Aldebaran, the last star to rise before the sun, is rising directly above Serra da Estrela, the "mountain range of the star". 
Credit: F. Silva

The project targets how the human eye, without the aid of any telescopic device, can see stars given sky brightness and colour. The team intend to apply these ideas to the case of passage graves, such as the 6,000 year old Seven-Stone Antas in central Portugal. Dr Fabio Silva, of the University of Wales Trinity Saint David, explains that, "the orientations of the tombs may be in alignment with Aldebaran, the brightest star in the constellation of Taurus. To accurately time the first appearance of this star in the season, it is vital to be able to detect stars during twilight."

The first sighting in the year of a star after its long absence from the night sky might have been used as a seasonal marker, and could indicate for example the start of a migration to summer grazing grounds. The timing of this could have been seen as secret knowledge or foresight, only obtained after a night spent in contact with the ancestors in the depths of a passage grave, since the star may not have been observable from outside. However, the team suggest it could actually have been the result of the ability of the human eye to spot stars in such twilight conditions, given the small entrance passages of the tombs.

The yearly National Astronomy Meetings have always had some aspects of cultural astronomy present in their schedules. This is the third year running where a designated session is included, exploring the connection between the sky, societies, cultures and people throughout time. The session organiser over the past three years, Dr Daniel Brown of Nottingham Trent University, says: "It highlights the cultural agenda within astronomy, also recognised by the inclusion of aspects of ancient astronomy within the GCSE astronomy curriculum."


Contacts and sources:
Dr Robert Massey, RAS 

Mr Kieran Simcox, Nottingham Trent University
Dr Daniel Brown, Nottingham Trent University

Dr Fabio Silva, Sophia Centre for the Study of Cosmology in Culture
University of Wales Trinity Saint David

Fire Discovery Sheds New Light on 'Hobbit' Demise

Crucial new evidence has revealed modern humans (Homo sapiens) were likely using fire at Liang Bua 41,000 years ago, narrowing the time gap between the last hobbits (Homo floresiensis) and the first modern humans at this site on the Indonesian island of Flores.

The research, led by the University of Wollongong Australia (UOW) and Indonesia's National Research Centre for Archaeology and published in the Journal of Archaeological Science today (June 30, 2016), is among the earliest evidence of modern humans in Southeast Asia.

In 2003, an international team of researchers, including those from the University of Wollongong Australia, uncovered the remains of a previously unknown species of small-statured hominins at Liang Bua, a limestone cave on the Indonesian island of Flores. Homo floresiensis, affectionately dubbed 'the hobbit' for her tiny one-metre stature, would rewrite history books, capture imaginations around the world and go on to be dubbed 'the scientific find of the century'.
Credit:  University of Wollongong

Lead author Dr Mike Morley, a research fellow and geoarchaeologist at UOW's Centre for Archaeological Science (CAS), said the find is "extremely important" in the quest to discover why and how the hobbit disappeared, around 50,000 years ago.

The story of the hobbit starts in 2003, when an international team of researchers, including those from UOW, uncovered the remains of a previously unknown species of small-statured hominins at Liang Bua. Homo floresiensis, affectionately dubbed 'the hobbit' for her tiny one-metre stature, would rewrite history books, capture imaginations around the world and go on to be dubbed 'the scientific find of the century'.

After revised dating estimates of the original hobbit skeleton -- published in Nature in March -- placed the bones between 190,000 and 60,000 years old (it was previously believed to have survived on Flores until as recently as 12,000 years ago), and the most recent stone tools at 50,000 years old, a gap in the chronology of the sediment sequence opened up -- researchers had no idea what happened at the site between 46,000 and 20,000 years ago.

Dr Morley and colleagues, including CAS geoarchaeologist Professor Paul Goldberg and archaeologist Thomas Sutikna, were able to fill that gap, detailing environmental changes at the site between 190,000 and 20,000 years ago and revealing something rather unexpected: physical evidence of fire places that were used between 41,000 and 24,000 years ago, most likely by modern humans for warmth and/or cooking.

Dr Mike Morley, from the University of Wollongong, Australia, with a sediment sample taken from Liang Bua. The sample contains crucial new evidence that has revealed modern humans (Homo sapiens) were likely using fire at Liang Bua 41,000 years ago, narrowing the time gap between the last hobbits (Homo floresiensis) and the first modern humans at this site on the Indonesian island of Flores. The finding is extremely important in the quest to discover why and how the hobbit disappeared.

Credit: Paul Jones | University of Wollongong

"We now know that the hobbits only survived until around 50,000 years ago at Liang Bua. We also know that modern humans arrived in Southeast Asia and Australia at least 50,000 years ago, and most likely quite a bit earlier" Dr Morley said.

"This new evidence, which is some of the earliest evidence of modern human activity in Southeast Asia, narrows the gap between the two hominin species at the site."

Given that no evidence for the use of fire by Homo floresiensis during roughly 130,000 years of presence at the site has been found, Dr Morley said modern humans are the most likely candidates for the construction of the fire places.

"Finding the fire places in such an excellent state of preservation allows insights into the behaviour of these people," he added.

Dr Morley said researchers at Liang Bua are now searching for more evidence that further closes that gap in time; evidence that could place modern humans at exactly the right place, at the right time, possibly revealing an overlap between the two species, which could have led to interaction between the two species and ultimately the hobbit's extinction.

As part of the study, Dr Morley used a technique called 'micromorphology' to examine the sediments taken from the site at a microscopic level of detail. After extracting sediment blocks from the rear of the cave (a different area from where the hobbit fossils were recovered), the samples were shipped back to UOW and wafer-thin slices, just 30microns thick (1 micron is 1000th of a millimetre), were analysed under a microscope. Spectroscopic analyses of the sediments were made by CAS archaeological chemist Dr Linda Prinsloo, and new radiocarbon dates were used to determine the age of each layer examined for the study.

The study, which also acts as further evidence of Homo sapiens dispersal through Southeast Asia and into Australia around 50,000 years ago, comes just weeks after UOW researchers, also from CAS, announced they had found 700,000 year old fossilised remains of what appear to be ancestors of the hobbit. The remarkable finds quash any remaining doubt that Homo floresiensis was a modern human afflicted with a disease causing the diminutive stature.

 

Contacts and sources: 
Elise Pitt
Dr Mike Morley
University of Wollongong Australia 

Night-Time Light Pollution Causes Spring To Come Early

Human use of artificial light is causing Spring to come at least a week early in the UK, researchers at the University of Exeter in Cornwall have found.

New research led by a team of biologists based at the University's Penryn campus highlights for the first time and at a national scale the relationship between the amount of artificial night-time light and the date of budburst in woodland trees.

Researchers believe early bud bursting will have a cascade effect on other organisms.
Credit:  University of Exeter

The study, the result of a long term collaboration with independent environmental consultants Spalding Associates, in Truro, made use of data collected by citizen scientists from across the UK, after the Woodland Trust asked them to note down when they first saw sycamore, oak, ash and beech trees in leaf as part of the charity's Nature's Calendar initiative. The research team analysed this, information, correlated with satellite images of artificial lighting.

The research, published in the journal Proceedings of the Royal Society B, found that buds were bursting by up to 7.5 days earlier in brighter areas and that the effect was larger in later budding trees.

Researchers believe early bud bursting will have a cascade effect on other organisms whose life cycles work in synchronicity with the trees. The proliferation of the winter moth for example, which feeds on fresh emerging oak leaves is likely to be affected which may in turn have some effect on birds in the food chain that rely on it for food.

The findings provide important information for those in charge of lighting levels, such as local councils, and point to the need for further research into the impact of different light quality and the specific wavelengths of light generated by different lighting types.

"Our finding that the timing of bud burst of woodland tree species may be affected by light pollution suggests that smaller plants growing below the height of street lights are even more likely to be affected," said Professor Richard ffrench-Constant of the department of the department of Biosciences based at the University's Penryn campus. "Such results highlight the need to carry out experimental investigation into the impact of artificial night-time lighting on phenology and species interactions."

Behavioural ecologist Peter McGregor, of the Centre for Applied Zoology at Cornwall College Newquay, said: "This study also shows that we can use citizen science in a meaningful way and that it has a real role to play in research that can have a meaningful impact."

Adrian Spalding of Spalding Associates in Truro is one of the leading experts on moths in Britain He believes this work is important as councils have recently been given control over decisions as to when they want to turn on or off their street lights.

"This study shows the importance of collaborative research between business and academia to address our real concerns of the effect of lighting on plants and animals and the importance of managing light levels in our urban environment in a sustainable way."



Contacts and sources:
Louise Vennells
University of Exeter 

Citation: Light pollution is associated with earlier tree budburst across the United Kingdom by Richard H. ffrench-Constant, Robin Somers-Yeates, Jonathan Bennie, Theodoros Economou, David Hodgson, Adrian Spalding and Peter K. McGregor is published in the journal Proceedings of the Royal Society B.

Powerful Defense Against Free Radicals That Cause Aging and Diseases Discovered

Free radicals cause cell damage and death, aging and disease, and scientists have sought new ways to repel them for years.

Now, a new University of Michigan study outlines the discovery of a protein that acts as a powerful protectant against free radicals. Ironically, the protein is activated by excessive free radicals. Human mutations of the gene for this protein are previously known to cause a rare, neurodegenerative 
disease.

The red dye in the cell show healthy mitochondria in a healthy cell 

Credit: University of Michigan /Haoxing Xu

Lysosomes, which comprise the cell's recycling center, are crucial for cleaning up injured and dying parts of the cells, said lead researcher Haoxing Xu, U-M associate professor of molecular, cellular and developmental biology.

When lysosomes "sense" an overload of free radicals, they activate a calcium channel on their membranes. This triggers the expression of many genes and the production of more and stronger lysosomes, which rev into overdrive to rid the damaged parts of the cells.

Free radicals are guilty in the aging process, Xu said.

"If we have chemical compounds that can directly activate this channel, we can lower the oxidative stress in aging and other diseases," he said. "The result will be that cell damage and free radical levels could be reduced, and one can possibly slow down aging."

Green dye indicates damaged mitochondria that cannot be removed due to impaired ROS sensing mechanisms.
Credit: University of Michigan /Haoxing Xu

How does the body tell itself that there are too many free radicals so that they can be reduced or removed? His study tells us how it's done, Xu said.

"Nature is really cool," said. "The janitor of the cell, the lysosome, has this radical-sensing ability."


Contacts and sources:
Laura Bailey
University of Michigan 

Citaion:  The study, "MCOLN1 is a ROS Sensor in Lysosomes that Regulates Autophagy," is published online June 30 in Nature Communications. First authors are Xiaoli Zhang, Xiping Cheng and Yu Lu, all in the Xu lab.

Lab on Paper Strips Will Let People Test for Diseases Cheaply at Home


What if testing yourself for cancer or other diseases were as easy as testing your blood sugar or taking a home pregnancy test? In a few years, it might be.

Chemists at The Ohio State University are developing paper strips that detect diseases including cancer and malaria--for a cost of 50 cents per strip.

The idea, explained Abraham Badu-Tawiah, is that people could apply a drop of blood to the paper at home and mail it to a laboratory on a regular basis--and see a doctor only if the test comes out positive. The researchers found that the tests were accurate even a month after the blood sample was taken, proving they could work for people living in remote areas.

Ohio State chemist Abraham Badu-Tawiah holds a prototype test strip for diagnosing diseases including cancer and malaria.

Photo by Pam Frost Gorder, courtesy of The Ohio State University.

The assistant professor of chemistry and biochemistry at Ohio State conceived of the papers as a way to get cheap malaria diagnoses into the hands of people in rural Africa and southeast Asia, where the disease kills hundreds of thousands of people and infects hundreds of millions every year.

But in the Journal of the American Chemical Society, he and his colleagues report that the test can be tailored to detect any disease for which the human body produces antibodies, including ovarian cancer and cancer of the large intestine.

The patent-pending technology could bring disease diagnosis to people who need it most--those who don't have regular access to a doctor or can't afford regular in-person visits, Badu-Tawiah said.

"We want to empower people. If you care at all about your health and you have reason to worry about a condition, then you don't want to wait until you get sick to go to the hospital. You could test yourself as often as you want," he said.

The technology resembles today's "lab on a chip" diagnostics, but instead of plastic, the "chip" is made from sheets of plain white paper stuck together with two-sided adhesive tape and run through a typical ink jet printer.

Ohio State University chemists have invented an printable test strip that detects diseases including malaria and cancer. Once commercialized, the technology would enable people to test themselves at home and mail the strips to a laboratory.
Photo by Pam Frost Gorder, courtesy of The Ohio State University.

Instead of regular ink, however, the researchers use wax ink to trace the outline of channels and reservoirs on the paper. The wax penetrates the paper and forms a waterproof barrier to capture the blood sample and keep it between layers. One 8.5-by-11-inch sheet of paper can hold dozens of individual tests that can then be cut apart into strips, each a little larger than a postage stamp.

"To get tested, all a person would have to do is put a drop of blood on the paper strip, fold it in half, put it in an envelope and mail it," Badu-Tawiah said.

The technology works differently than other paper-based medical diagnostics like home pregnancy tests, which are coated with enzymes or gold nanoparticles to make the paper change color. Instead, the paper contains small synthetic chemical probes that carry a positive charge. It's these "ionic" probes that allow ultra-sensitive detection by a handheld mass spectrometer.

"Enzymes are picky. They have to be kept at just the right temperature and they can't be stored dry or exposed to light," Badu-Tawiah said. "But the ionic probes are hardy. They are not affected by light, temperature, humidity--even the heat in Africa can't do anything to them. So you can mail one of these strips to a hospital and know that it will be readable when it gets there."

The chemists designed ionic probes to tag specific antibodies that extract the disease biomarker from the blood and onto the paper chip. Once they are extracted, the chemicals stay unchanged until the paper is dipped in an ammonia solution at the laboratory. There, someone peels the paper layers apart and holds them in front of a mass spectrometer, which detects the presence of the probes based on their atomic characteristics--and, by extension, the presence of biomarkers in an infected person's blood.

Badu-Tawiah and postdoctoral researchers Suming Chen and Qiongqiong Wan successfully demonstrated that they could detect protein biomarkers from the most common malaria parasite, Plasmodium falciparum, which is most prevalent in Africa.

They also successfully detected the protein biomarker for ovarian cancer, known as cancer antigen 125, and the carcinoembryonic antigen, which is a marker for cancer of the large intestine, among other cancers.

Abraham Badu-Tawiah, a chemist at The Ohio State University, has invented an inexpensive, paper-based test for diseases including cancer and malaria.

Photo by Pam Frost Gorder, courtesy of The Ohio State University.

They worked with former doctoral student Yang Song in the lab of colleague Vicki Wysocki, professor of chemistry and biochemistry, to study how the probes stick to the antibodies with a high-resolution mass spectrometer. Wysocki is the Ohio Eminent Scholar of Macromolecular Structure and Function and director of the Campus Chemical Instrument Center at Ohio State.

After confirming that their tests worked, Badu-Tawiah and his team stored the strips away and re-tested them every few days to see if the signal detected by the mass spectrometer would fade over time. It didn't. The signal was just as strong after 30 days as on day one, meaning that the disease proteins were stable and detectable even after a month.

Since the antibody strips survive more than long enough to reach a lab by mail, they could open up a whole new world of medical care for people in rural communities--even in the United States, Badu-Tawiah said. Even for people living in the city, testing themselves at home would save money compared to going to the doctor.

In the US, he said, the tests would be ideal for people who have a family history of cancer or have successfully undergone cancer treatment. Instead of waiting to visit a doctor every six months to confirm that they are still in remission, they could test themselves from home more frequently.

In the case of malaria, the human and financial costs are high, especially in Africa.

Malaria is a mosquito-borne disease caused by parasites. The infection starts with flulike symptoms that can develop into kidney failure or other complications. The Centers for Disease Control and Prevention estimates that there were 214 million cases of malaria worldwide in 2015, and 438,000 people died--mostly children in Africa.

"In Africa, malaria is so common that whenever you get feverish, the first thing you think is, 'Oh, it's probably malaria,'" Badu-Tawiah said.

While the prototype test strips at Ohio State cost about 50 cents each to produce, those costs would likely go down with mass production, he said. The greatest cost of using the strips would fall to urban medical facilities, which would have to purchase mass spectrometers to read the results. Model portable instruments can cost $100,000 but less expensive handheld mass specs are under development.

Still, Badu-Tawiah pointed out, an initial investment in mass specs would be more than offset by the potential boon to Africa's economy. UNICEF estimates that malaria costs the continent $12 billion in lost worker productivity every year.

In the United States, where mass spectrometers are more common, the cost savings would come in the form of reduced insurance use and fewer out-of-pocket expenses from going to the doctor less often.

"Although this approach requires an initial investment, we believe the low-cost paper-based consumable devices will make it sustainable," Badu-Tawiah said. "We can set one small instrument at a grocery store, then sell the paper strips for just 50 cents per test. The same for Africa, and perhaps much cheaper there."

The university will license the technology to a medical diagnostics company for further development, and Badu-Tawiah hopes to be able to test the strips in a clinical setting within three years. In the meantime, he and his colleagues are working to make the tests more sensitive, so that people could eventually use them non-invasively, with saliva or urine as the test material instead of blood.



Contacts and sources: 
Abraham Badu-Tawiah
Written by Pam Frost Gorder
The Ohio State University

Ocean Circulation Incriminated in Past Abrupt Climate Changes, Linked to Ice Ages





There was a period during the last ice age when temperatures in the Northern Hemisphere went on a rollercoaster ride, plummeting and then rising again every 1,500 years or so. Those abrupt climate changes wreaked havoc on ecosystems, but their cause has been something of a mystery. New evidence published this week in the leading journal Science shows for the first time that the ocean’s overturning circulation slowed during every one of those temperature plunges – at times almost stopping.

The global ocean overturning circulation, shown here in a simplified illustration, distributes heat through the oceans. In the Atlantic Ocean, the circulation carries warm water (red arrows) northward near the surface and cold deep water (blue arrows) southward. 
The global ocean overturning circulation, shown here in a simplified illustration, distributes heat through the oceans. In the Atlantic Ocean, the circulation carries warm water (red arrows) northward near the surface and cold deep water (blue arrows) southward. Credit: NASA/JPL
Credit: NASA/JPL

"People have long supposed this link between overturning circulation and these abrupt climate events. This evidence implicates the ocean," said L. Gene Henry, the lead author of the study and a graduate student at Columbia University’s Lamont-Doherty Earth Observatory.

The impact of changes in the ocean overturning circulation on climate has become a hot topic today as global temperatures rise and melting sea ice and glaciers add freshwater to the North Atlantic. A 2015 study suggested that cooling in the North Atlantic may be due to a reduction in the overturning circulation, while a 2016 studysuggested there had not been enough freshwater to have an effect.

The new study explores what happened to ocean circulation when the earth went through a series of abrupt climate changes in the past during a time when ice covered part of North America and temperatures were much colder than today. It looks at the Atlantic meridional overturning circulation, which distributes heat as it moves warmer surface water from the tropics toward Greenland and the high northern latitudes and carries colder, deeper water from the North Atlantic southward.

Using chemical tracers in sediment that builds up on the sea floor over time, Henry and his coauthors were able to document the relative speed of the Atlantic meridional overturning circulation during each abrupt climate change during the last ice age.

The chemical tracers show that the speed of the ocean overturning circulation changed first, and that sea surface temperature changed a while later. That suggests that cooling may start with changes in the ocean circulation, influencing the northern sea surface and atmosphere, said co-author Jerry McManus, a professor at Lamont-Doherty Earth Observatory. Evidence from ice cores and deep-sea sediment has shown that the northern climate also cooled before the southern climate during these abrupt changes, creating a “bipolar seesaw,” with the north cool while the south was warm, and the south cooling as the north warmed.

A new study using sea floor sediment from the North Atlantic connects a series of abrupt climate changes during the last ice age with changes in the ocean overturning circulation. P

hoto: Margie Turrin/Lamont-Doherty Earth Observatory.

The scientists stress that more work is needed to determine whether changes in ocean circulation initiated the abrupt climate changes or were an intermediary effect initially triggered by something else. “Our study supports the view that changes in ocean circulation were at least in part responsible for causing abrupt climate changes. However, what in turn caused those changes in circulation remains a mystery,” Henry said.

Also unclear is why these abrupt climate shifts, also seen in previous ice ages, haven’t happened in the past 10,000 years. The instability appears to occur only in certain temperature ranges, and when there is a large amount of land ice that could contribute freshwater.

“We would all like to understand better how the earth’s climate operates,” McManus said. “This demonstrates the crucial role that global circulation can play. The dynamics of the deep ocean directly influence the earth’s climate.”

The series of abrupt climate changes studied here occurred between 60,000 and 25,000 years ago, ending as the last ice age peaked. Each followed a general pattern in the Northern Hemisphere: The cooling happening over hundreds to 1,000 years, then the frigid temperatures persisted for a few hundred years in what is known as a stadial, McManus said. Once warming started, it happened very rapidly, with a rise of 3 to 6 degrees Celsius in average sea surface temperature and larger changes over Greenland within a span of decades.

During every cold northern stadial, the overturning circulation had slowed, so it wasn’t bringing as much heat northward from the tropics and Southern Hemisphere, the study shows. The chemical tracers also suggest that circulation slowed almost to a halt during certain stadials known as Heinrich events, when massive amounts of icebergs broke off and drifted away from the Laurentide ice sheet, which covered a large part of North America at the time. Icebergs carry freshwater that can affect ocean circulation, and computer models have suggested that adding that much freshwater to the Atlantic could shut down circulation. Exactly what influence the icebergs had during these periods will be the target of future research.

To determine how ocean circulation changed, the scientists measured three types of chemical tracers. By comparing the ratio of protactinium-231 to thorium-230, two daughter isotopes of uranium decay that remain in seawater for relatively short but consistently different periods of time before drifting into the seafloor, they could determine when circulation was strongest. Another isotope, carbon-13, captured in tiny shells, is more common in North Atlantic waters than in southern waters. When circulation was strong, protactinium was low and carbon 13 was high, because more protactinium was carried away by the current and more northern waters formed.

Axel Timmermann, a professor of oceanography at the University of Hawaii who studies abrupt climate changes and was not involved in this study, called it a “breakthrough analysis.”

“Large changes in the North Atlantic meridional overturning circulation are thought to have played a major role in generating millennial-scale global variability, known asDansgaard-Oechger events, during the last glacial period. The paper by Henry, McManus and colleagues finally provides supporting evidence for this fundamental scientific hypothesis,” Timmermann said.

The other coauthors of the paper are Bill Curry of Woods Hole Oceanographic Institution and the Bermuda Institute of Ocean Sciences; Natalie Roberts and Alex Piotrowski of the University of Cambridge; and Lloyd Keigwin of Woods Hole. The research was funded by the National Science Foundation, the Comer Science and Education Foundation, and the Lamont-Doherty Earth Observatory Climate Center.



Contacts and sources:
Gene Henry
Jerry McManus  
Kevin Krajick, Senior editor, science news
Lamont-Doherty Earth Observatory 
Columbia University

Wednesday, June 29, 2016

The Universe Is Getting Cleaner as Stars Sweep Up Cosmic Dust


The Universe is becoming gradually cleaner as more and more cosmic dust is being mopped up by the formation of stars within galaxies, an international team of astronomers has revealed.

Peering back 12 billion years using the Herschel space telescope to produce far-infrared images of the sky, the team led by researchers at Cardiff University has been able to observe the very early formation of galaxies and compare them to galaxies that have formed much more recently.

The results showed that stars were forming inside galaxies much faster in the past compared to today, and that this rapid star birth is using up more and more of the cosmic dust that is ubiquitous in the Universe.

Cosmic dust is comprised of tiny solid particles that are found everywhere in space between the stars. The dust and the gas in the universe is the raw material out of which stars and galaxies form.

A small glimpse of one region, a tenth of the full area of the Herschel ATLAS images. Everything in this image, apart from the picture of the moon, which has just been placed there to show the area of sky covered by the survey and the small square that shows the area covered by the Hubble Deep Field, consists of far-infrared emission from cosmic dust.

Credit: The Herschel ATLAS team and the European Space Agency

Though this blanket of material is key to the formation of stars and galaxies, it also acts as a sponge, absorbing almost half of the light emitted by stellar objects and making them impossible to observe with standard optical telescopes.

With the launch of the Herschel space telescope in 2009, researchers were provided with the perfect tool for probing this hidden universe. Owing to a collection of sensitive instruments, mirrors and filters, the Herschel telescope had the capacity to detect the dust through the far-infrared emission it emits, revealing the existence of stars and galaxies hidden by the dust.

Professor Steve Eales, a co-leader of the project from Cardiff University's School of Physics and Astronomy, said: "We were surprised to find that we didn't need to look far in the past to see signs of galaxy evolution. Our results show that the reason for this evolution is that galaxies used to contain more dust and gas in the past, and the universe is gradually becoming cleaner as the dust is used up."

Professor Haley Gomez, also of the School of Physics and Astronomy, presented the team's results today, 29 June, at the National Astronomy Meeting in Nottingham. After seven years of work analysing the images from the Herschel telescope, the team of over 100 astronomers have released a large catalogue of the sources of far-infrared radiation in this 'hidden universe'.

The team's survey of the sky, called the Herschel Astrophysical Terahertz Large Area Survey (Herschel ATLAS), has revealed the details of over half a million galaxies, many of which have been viewed as they were over 12 billion years ago, just shortly after the big bang.

The team are hopeful that this unprecedented catalogue of sources will be vital tools for astronomers wishing to understand the detailed history of galaxies and the wider cosmos.

Dr Elisabetta Valiante, a lead author from Cardiff University's School of Physics and Astronomy, said: "The exciting thing about our survey is that it encompasses almost all of cosmic history, from the violent star-forming systems full of dust and gas in the early universe, that are essentially galaxies in the process of formation, to the much more subdued systems we see around us today."

Dr Loretta Dunne, a co-leader of project from Cardiff University's School of Physics and Astronomy, said: "Before Herschel we only knew of a few hundred such dusty sources in the distant universe and we could only effectively 'see' them in black and white. Herschel, with its five filters, has given us the equivalent of technicolour, and the colour of the galaxy tell us about their distances and temperatures. So we now have half a million galaxies we can use to map out the hidden star formation in the universe."

The project was jointly funded by the Science and Technology Facilities Council, the European Union's 7th Framework Programme for Research and Technological Development, and the European Research Council.


Contacts and sources:
Michael Bishop
Cardiff University

What Happens When You Steam a Planet?

The media often imply that the goal of the hunt for extrasolar planets is to find a rocky planet about the size of Earth orbiting a star like the sun at a distance that would allow liquid water to persist on its surface. In other words, the goal is to find Earth 2.0. Hot, rocky planets may change their composition if rock components vaporize in steam atmospheres that escape to space.

But there are reasons to be interested in the other worlds even if they couldn't possibly harbor life. The hot, rocky planets, for example, offer rare and precious clues to the character and evolution of the early Earth.

The Kepler satellite has detected more than 100 hot, rocky planets orbiting close to their stars. If these planets formed from interstellar clouds with Earth-like abundances of volatile elements, like hydrogen, water and carbon dioxide, these planets might have steam atmospheres.

Washington University in St. Louis cosmochemists show that hot, rocky exoplanets with steam atmospheres may vaporize some of their rocky elements and then lose them to space, changing the bulk composition of the planet.

Credit: NASA

Steaming a rocky planet wouldn't just press out the wrinkles. Because the rock-forming elements dissolve in steam to different extents, steaming could, in principle, alter the planet's bulk composition, density and internal structure, especially if all or part of the rock-bearing steam atmosphere was then lost to space.

Bruce Fegley and Katharina Lodders-Fegley, respectively professor and research professor in earth and planetary sciences in Arts & Sciences at Washington University in St. Louis, published models of the chemistry of a steam atmosphere in equilibrium with a magma ocean at various temperatures and pressures in the June 20, 2016 issue of the Astrophysical Journal.

Based on their findings, they have some suggestions for planet hunters -- things they might see when they train their telescopes on the hot rocks.

Getting some steam up

The fact that planet hunters have discovered many hot rocks roughly the size of Earth is one of three lines of evidence that come together in this research, Fegley said. The other two are the solubility of silica and other rock-forming elements in steam, and the idea that the early Earth had a steam atmosphere.

The notion that rocks will dissolve in steam may seem outlandish, but it is common knowledge among geologists. "Geologists are mainly concerned with very hot water or water and steam mixtures, whereas we're looking at pure steam and temperatures hundreds of degrees hotter. But it's the same kind of idea," Fegley said.

The suspicion that the early Earth had a steam atmosphere goes back to 1974, when Gustave Arrhenius of the Scripps Institute of Oceanography argued that planetesimals that smacked into the forming Earth got hot enough to melt and release all their volatiles into the atmosphere.

The first to model the steam atmosphere of the early Earth were Yutaka Abe and Takafumi Matsui of the University of Tokyo in 1985. "They were mainly interested in the physics of the problem," Fegley said, "and whether greenhouse gases acting as a thermal blanket would keep the surface molten. I think we're the first ones to do a detailed chemistry on it."

Escaping steam

Fegley and Lodders looked particularly at magnesium, silicon and iron, the three most abundant elements in material that combine with oxygen to form rock -- both on Earth and the other terrestrial planets and probably on exoplanets orbiting stars with a composition like our sun's.

The rocky elements enter the atmosphere as hydroxides (Si(OH)4, Fe(OH)2, and Mg (OH)2). Because these oxides have different solubilities in steam, cooking a planet in steam can change its major-element chemistry.

"Potassium, for example, easily goes into steam and if it's lost, you'll lose its radioactive isotope and so change the heat production on the planet," Fegley said.

"If you dissolve more silicon than magnesium, and some of the atmosphere is lost, you can change the ratio of these elements in the planets. This might explain why the ratio of silicon to magnesium in the Earth is about 15 percent smaller than the ratio in the sun, even though the two formed from the same interstellar cloud," he said.

"If you boil off a lot of the silicon, you might end up with a much denser planet than you'd expect. We've found some pretty dense exoplanets," Fegley said. "Sometimes it's crazy high. Earth is about 5.51 g/cm3, but Corot-7b is closer to 10 g/cm3 . . . high enough that it's kind of hard to explain.

"And if you don't lose the atmosphere, when the atmosphere cools down, the rock-forming elements would precipitate out. Since silicon is the rocky element most soluble in steam, it will be the most abundant, and you'll get a silicate-rich-crust ready-made," he said.

What to look for

Although the scientists are experimenting with numerical models, they remark that their conclusions are testable by observation.

"We're hoping astrophysicists doing mass/radius diagrams to figure out the internal composition of planets will consider compositions other than Earth's," Fegley said.

"We're also hoping space-based spectrometers will be trained on the hot, rocky planets. Astrophysicists see silicon, magnesium and sodium coming off the atmospheres of hot Jupiters and hot Neptunes but not yet off of hot rocks, which are dimmer and harder to observe," Fegley said.

Intense ultraviolet light from nearby stars is likely to break up hydroxide molecules at the top of atmospheres, the scientists said. The "photoproducts" of these reactions, such as monatomic gases of aluminum, calcium, iron, magnesium and silicon, might be easier to see both because of their abundances and because their spectral lines are less likely be masked by other emissions.



Contacts and sources:
Diana Lutz
Washington University in St. Louis


Citation: Solubility Of Rock In Steam Atmospheres Of Planets The Astrophysical Journal, Volume 824, Number 2 http://dx.doi.org/10.3847/0004-637X/824/2/103

Clandestine Black Hole May Represent New Population


Astronomers have combined data from NASA’s Chandra X-ray Observatory, the Hubble Space Telescope and the National Science Foundation's Karl G. Jansky Very Large Array (VLA) to conclude that a peculiar source of radio waves thought to be a distant galaxy is actually a nearby binary star system containing a low-mass star and a black hole. This identification suggests there may be a vast number of black holes in our Galaxy that have gone unnoticed until now.

By combining data from Chandra and several other telescopes, astronomers have identified the true nature of an unusual source in the Milky Way galaxy. This discovery implies that there could be a much larger number of black holes in the Galaxy that have previously been unaccounted for. The images on the left show X-rays from Chandra and an optical image from Hubble of a large area around the source VLA J2130+12, including M15. The images on the right show the source VLA J2130+12 that is bright in radio waves, but can only be giving off a very small amount of X-rays. These pieces of information indicate the source contains a black hole with a few times the mass of the Sun.

Credit: X-ray: NASA/CXC/Univ. of Alberta/B.Tetarenko et al; Optical: NASA/STScI; Radio: NSF/AUI/NRAO/Curtin Univ./J. Miller-Jones


For about two decades, astronomers have known about an object called VLA J213002.08+120904 (VLA J2130+12 for short). Although it is close to the line of sight to the globular cluster M15, most astronomers had thought that this source of bright radio waves was probably a distant galaxy.

Thanks to recent distance measurements with an international network of radio telescopes, including the EVN (European Very Long Baseline Interferometry Network) telescopes, the NSF's Green Bank Telescope and Arecibo Observatory, astronomers realized that VLA J2130+12 is at a distance of 7,200 light years, showing that it is well within our own Milky Way galaxy and about five times closer than M15. A deep image from Chandra reveals it can only be giving off a very small amount of X-rays, while recent VLA data indicates the source remains bright in radio waves.

This new study indicates that VLA J2130+12 is a black hole a few times the mass of our Sun that is very slowly pulling in material from a companion star. At this paltry feeding rate, VLA J2130+12 was not previously flagged as a black hole since it lacks some of the telltale signs that black holes in binaries typically display.

"Usually, we find black holes when they are pulling in lots of material. Before falling into the black hole this material gets very hot and emits brightly in X-rays," said Bailey Tetarenko of the University of Alberta, Canada, who led the study. "This one is so quiet that it's practically a stealth black hole."

This is the first time a black hole binary system outside of a globular cluster has been initially discovered while it is in such a quiet state.

Hubble observations identified VLA J2130+12 with a star having only about one-tenth to one-fifth the mass of the Sun. The observed radio brightness and the limit on the X-ray brightness from Chandra allowed the researchers to rule out other possible interpretations, such as an ultra-cool dwarf star, a neutron star, or a white dwarf pulling material away from a companion star.

Because this study only covered a very small patch of sky, the implication is that there should be many of these quiet black holes around the Milky Way. The estimates are that tens of thousands to millions of these black holes could exist within our Galaxy, about three to thousands of times as many as previous studies have suggested.

"Unless we were incredibly lucky to find one source like this in a small patch of the sky, there must be many more of these black hole binaries in our Galaxy than we used to think," said co-author Arash Bahramian, also of the University of Alberta.

There are other implications of finding that VLA J2130+12 is relatively near to us.

"Some of these undiscovered black holes could be closer to the Earth than we previously thought," said Robin Arnason, a co-author from Western University, Canada "However there's no need to worry as even these black holes would still be many light years away from Earth."

Sensitive radio and X-ray surveys covering large regions of the sky will need to be performed to uncover more of this missing population.

If, like many others, this black hole was formed in the plane of the Milky Way's disk, it would have needed a large kick at birth to launch it to its current position about 3,000 light years above the plane of the Galaxy.

These results appear in a paper in The Astrophysical Journal. 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.



Contacts and sources:
Kirsten Gottschalk
International Centre for Radio Astronomy Research

Sparklers In Slow Motion



As Independence Day approaches, people across the country are getting ready to celebrate with fireworks. 
 JaxFireworks2015.jpg
Credit: Wikimedia

Sparklers are a classic crowd-pleaser, and this week Reactions looks at the chemistry of these July 4th mainstays in super slow-motion. Watch as the special chemical composition of sparklers creates a prolonged, magical experience.



Contacts and sources:
American Chemical Society
 

Tuesday, June 28, 2016

Rotating Ring of Complex Organic Molecules Discovered around Newborn Star: Chemical Diversity in Planet Forming Regions Unveiled

Researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered a rotating ring containing large organic molecules around a protostar. This observation definitively shows that organic materials formed in interstellar space are brought into the planet-forming region. 

Researchers also found that the molecular species brought into the planet-forming region vary from one protostar to another. Chemical composition is a new way to answer the long-standing question of whether or not the Solar System is a typical example of a planetary system.

(Upper panel) A schematic illustration of the infalling gas around the protostar. A disk structure with a radius of about 50 AU exists around the protostar. The disk in turn is surrounded by an envelope of gas extended over a 200 AU scale. OCS exists in the envelope gas, while methyl formate mainly exists in the boundary area between the envelope gas and the disk structure. (Lower left) Intensity distribution of methyl formate (HCOOCH3) observed with ALMA. A structure elongated along A-B can be seen centered on the position of the protostar. Methyl formate is located within 50 AU from the protostar. (Lower right) Intensity distribution of OCS (carbonyl sulfide) observed with ALMA. A structure elongated along A-B can be seen centered on the position of the protostar position, similar to the case of OCS. However the distribution of OCS (~200 AU) is more extended than that of methyl formate.

 Credit: ALMA (ESO/NAOJ/NRAO), Oya et al.

Astronomers have long known that organic molecules form in diffuse gas clouds floating between stars. It is thought that as the Solar System formed 4.6 billion years ago, some of these organic molecules were transported from interstellar space to the planet forming disk. Later, these molecules played important roles in the chemical evolution resulting in the emergence of life on the Earth.

However, it is still unknown what kinds and quantities of organic molecules were actually supplied from interstellar space. Although radio astronomy observations during the last decade showed that saturated complex organic molecules, such as methanol (CH3OH) and methyl formate (HCOOCH3) [1], exist around Solar-type protostars, their distributions were too compact to be resolved with the radio telescopes available at the time.

With ALMA, an international team lead by Yoko Oya, a graduate student of Department of Physics, The University of Tokyo, and Nami Sakai, an associate chief scientist of RIKEN, studied the distribution of various organic molecules around a Solar-type protostar IRAS 16293-2422A at a high spatial resolution. They discovered a ring structure of complex organic molecules around the protostar. The radius of the ring is 50 times wider than the Earth’s orbit. This size is comparable to the size of the Solar System, and the ring structure most likely represents the boundary region between infalling gas and a rotating disk structure around the protostar.

The observations clearly showed the distribution of large organic molecules methyl formate (HCOOCH3) and carbonyl sulfide (OCS). Apparently the distribution of methyl formate is confined in a more compact area around the protostar than the OCS distribution, which mainly traces the infalling gas. “When we measured the motion of the gas containing methyl formate by using the Doppler effect,” said Oya “we found a clear rotation motion specific to the ring structure.” In this way, they identified the rotating ring structure of methyl formate, although it is not resolved spatially. A similar ring structure is also found for methanol.

These saturated organic molecules are formed in interstellar space and are preserved on the surfaces of dust grains. Around the outer boundary of the disk structure, they evaporate due to shock generated by collisions of the disk and infalling material, and/or due to heating by the light from the baby star. This result is the first direct evidence that interstellar organic materials are indeed fed into the rotating disk structure that eventually forms a planetary system.

In 2014, the team found a similar ring structure of SO (sulfur monoxide) around another Solar-type protostar L1527. In this source, unsaturated complex organic molecules such as CCH and cyclic-C3H2 are very abundant in the infalling gas, while SO preferentially exists in the boundary between the infalling gas and the disk structure. 

Although the physical structure in L1527 is similar to that found in IRAS 16293-2422A, the chemical composition is much different. Saturated complex organic molecules are almost completely absent in L1527. The present result, taken together with previous results on L1527, clearly demonstrates for the first time that the materials delivered to a planetary system differ from star to star. A new perspective on chemical composition is thus indispensable for a thorough understanding of the origin of the Solar System and the origin of life on the Earth.

Note.

[1] Organic molecules without multiple bonds between atoms are collectively called saturated molecules. On the other hand, molecules with multiple bonds ar

Contacts and sources:
National Astronomical Observatory of Japan

Citation:   “Infalling-Rotating Motion and Associated Chemical Change in the Envelope of IRAS 16293-2422 Source A Studied with ALMA”, Yoko Oya (The University of Tokyo), Nami Sakai (RIKEN), Ana López-Sepulcre (The University of Tokyo), Yoshimasa Watanabe (The University of Tokyo), Cecilia Ceccarelli (Universite Grenoble Alpes/CNRS), Bertrand Lefloch (Universite Grenoble Alpes/CNRS), Cécile Favre (Universite Grenoble Alpes/CNRS), Satoshi Yamamoto (The University of Tokyo)Astrophysical Journal issued on 20 June 2016,

Minor Galaxy Mergers Are Major Drivers of Star Formation



Around half of the star formation in the local Universe arises from minor mergers between galaxies, according to data from the Sloan Digital Sky Survey. The patch of sky called Stripe 82 is observed repeatedly to produce high-quality images of spiral galaxies. Disruptions to the shapes of these galaxies, caused by interactions with their smallest neighbors, pointed to increased star formation in a study being presented at the National Astronomy Meeting at the University of Nottingham.

A NASA/ESA Hubble Space Telescope view of the spiral galaxy NGC 7714, which has been dramatically distorted in shape by a close interaction with another nearby galaxy. Minor, but frequent, disturbances such as this cause a burst of star formation, accounting for around half of all new stars being formed in the local Universe.'

Credit:  NASA/ESA Hubble Space Telescope

Gravity, the ubiquitous attractive force that pervades our Universe, is a significant driver of galaxy formation. Gravity makes galaxies collide, and these collisions can affect various properties – merging drives strong star formation in the galaxies in question, increases the masses of their constituent black holes and can significantly alter the internal structure of the galaxies.

Our classical paradigm has often assumed that mergers between equal mass progenitors (‘major’ mergers) have the most transformative impact on galaxies. However, such events are rare. Much more common are mergers between massive galaxies and small satellites (‘minor’ mergers). This is because small galaxies far outnumber their more massive counterparts – the attractive nature of gravity then ensures that these massive galaxies are constantly being bombarded by satellites.

While major mergers are more spectacular and easier to study because they tend to be brighter, studying minor mergers requires large surveys which offer ‘deep’ i.e. long exposure imaging which is able to detect the faint tidal features that are the signatures of minor mergers.

Recently, circumstantial evidence is accumulating that suggests that minor mergers are indeed important drivers of galaxy evolution e.g. the observed size growth of galaxies over the last 10-12 billion years is likely due to repeated minor mergers. This study is the first to use a deep survey to quantify what fraction of the star formation in the nearby Universe is likely to be driven by the minor-merger process. “The results are striking”, according to Dr Sugata Kaviraj of the University of Hertfordshire, the scientist behind this work. “Just over half of the cosmic star formation budget is directly driven by minor mergers. In other words, if this process did not take place then galaxies in today’s Universe would be at least a factor of two less massive.”

Without a good comprehension of the minor-merger process, therefore, our understanding of galaxy evolution will remain incomplete. This paper is a precursor to work that can be done using future instrumentation like the Large Synoptic Survey Telescope which will, for the first time, provide deep imaging over around half the sky, enabling the first statistically robust studies of minor merging over at least 50% of cosmic time.


Contacts and sources:
Dr Robert Massey
Royal Astronomical Society

Dr Sugata Kaviraj
University of Hertfordshire

Listen Like an Astroseismologist: 13 Billion Year Old Music, The Resonant Songs of the Earliest Stars



Astrophysicists from the University of Birmingham have captured the sounds of some of the oldest stars in our galaxy, the Milky Way, according to research published this month in the journal Monthly Notices of the Royal Astronomical Society

.

The research team, from the University of Birmingham's School of Physics and Astronomy, has reported the detection of resonant acoustic oscillations of stars in 'M4', one of the oldest known clusters of stars in the Galaxy, some 13 billion years old.

An image of the globular star cluster M4, made with the MPG/ESO 2.2-m telescope at the La Silla Observatory in Chile. The yellow circles mark the positions of the stars observed in the new study. Click the image for an animation and audio from each star.
 Credit: ESO / University of Birmingham

Using data from the NASA Kepler/K2 mission, the team has studied the resonant oscillations of stars using a technique called asteroseismology. These oscillations lead to miniscule changes or pulses in brightness, and are caused by sound trapped inside the stars. By measuring the tones in this 'stellar music', it is possible to determine the mass and age of individual stars. (You can listen to the sound of each star here.)

This discovery opens the door to using asteroseismology to study the very early history of our Galaxy.

Dr Andrea Miglio, from the University of Birmingham's School of Physics and Astronomy, who led the study, said: 'We were thrilled to be able to listen to some of the stellar relics of the early universe. The stars we have studied really are living fossils from the time of the formation of our Galaxy, and we now hope be able to unlock the secrets of how spiral galaxies, like our own, formed and evolved.'

Dr Guy Davies, from the University of Birmingham's School of Physics and Astronomy, and co-author on the study, said: 'The age scale of stars has so far been restricted to relatively young stars, limiting our ability to probe the early history of our Galaxy. In this research we have been able to prove that asteroseismology can give precise and accurate ages for the oldest stars in the Galaxy '

Professor Bill Chaplin, from the University of Birmingham's School of Physics and Astronomy and leader of the international collaboration on asteroseismology, said: 'Just as archaeologists can reveal the past by excavating the earth, so we can use sound inside the stars to perform Galactic archaeology.'



Contacts and sources:
Luke Harrison
Prof Andrea Miglio
University of Birmingham

Citation:  The work appears in "Detection of solar-like oscillations in relics of the Milky Way: asteroseismology of K giants in M4 using data from the NASA K2 mission", A. Miglio, W. J. Chaplin, K. Brogaard, M. N. Lund, B. Mosser, G. R. Davies, R. Handberg, A. P. Milone, A. F. Marino, D. Bossini, Y. P. Elsworth, F. Grundahl, T. Arentoft, L. R. Bedin, T. L. Campante, J. Jessen-Hansen, C. D. Jones, J. S. Kuszlewicz, L. Malavolta, V. Nascimbeni and E. L. Sandquist, Monthly Notices of the Royal Astronomical Society, in press.

All Puffed Up with Gas: Little Planets with Big Atmospheres Posing as Large Planets

Hazes and clouds high up in the atmospheres of exoplanets may make them appear bigger than they really are, according to new research by astronomers at the Space Research Institute (IWF) of the Austrian Academy of Sciences. The team, led by researcher Dr Helmut Lammer, publish their results in a letter to Monthly Notices of the Royal Astronomical Society.

An artist’s illustration of a hot Neptune-sized world moving behind its host star.

Credit: NASA / JPL-Caltech.  

Since the first confirmed discovery in 1993, astronomers have found more than 3,000 planets in orbit around stars other than our Sun. A key goal now is to characterise known worlds by mass, size and composition, to better understand the evolution of planetary systems, and the prospects for ‘Earthlike’ planets that might support life.

In 2014 Lammer and his team used the European Space Agency (ESA) CoRoT space telescope to study the upper atmosphere of two low-mass planets that are regularly seen to pass in front of (transit) the star they orbit. The two planets orbit their star in 5 and 12 days, appear to be around 4 and 5 times the diameter of the Earth, and have respective masses of less than 6, and 28 times Earth. The outer, more massive planet, CoRoT-24c, is similar in mass to Neptune. In contrast, the inner planet, CoRoT-24b, is less than a quarter as massive, but is similar in size, so seems to have a very low density.

With such short orbits, both worlds are close to and will experience dramatic heating from the star. The team modelled this and found that the lower mass planet would see its atmosphere evaporate within 100 million years, if it really is as big as suggested. But the star is billions of years old, so the planet should have lost its atmosphere long ago.

A diagram of a the hot low-mass extended atmosphere with cloud deck and haze, around the exoplanet CoRoT-24b (left), compared to the cooler, more massive, and compact CoRoT-24c (right).

Credit: IWF/Lammer.  

The solution seems to be that the planet is only about half as big as thought. Lammer argues that an extended, very thin, atmosphere, surrounds a relatively compact planet, but has high altitude features that confuse observations. He explains: “The radius is based on what we see when the planet makes its transit. This is probably distorted by clouds and haze high in the atmosphere, in a region where atmospheric pressure is otherwise very low.”

Co-author Luca Fosseti adds that this effect needs to be considered by future exoplanet missions, like the ESA CHaracterising ExOPlanets Satellite (CHEOPS) mission due to launch in December 2017. Results for some worlds found by the NASA Keplerobservatory may also need to be re-evaluated.

“Our results show that CHEOPS scientists need to be cautious about their first measurements”, says Fossati.

“Since Kepler has also discovered several similar low-density and low-mass planets, it is very likely that the size measured for many of them also differ from the true value, so there could be a bias in the results.”

If the Austrian team are right, this has dramatic implications, for example in the studies of planet populations and how the mass of planets relate to their size.




Contacts and sources:
Dr Helmut Lammer
Dr Luca Fossati
Space Research Institute (IWF) of the Austrian Academy of Sciences

Dr Robert Massey
Royal Astronomical Society

The new work appears in "Identifying the "true" radius of the hot sub-Neptune CoRoT-24b by mass loss modelling", H. Lammer, N.V. Erkaev, L. Fossati, I. Juvan, P. Odert, E. Cubillos, E. Guenther, K.G. Kislyakova, T. Lüftinger, M. Güdel, Monthly Notices of the Royal Astronomical Society, in press.

Whistling Wormholes Causing Unstable Conditions, Caribbean Singing A Flat Octaves Below Audible



National Oceanography Centre scientists have discovered the Caribbean Sea works like a whistle.

This finding will enable scientists to predict some sea level changes many months in advance, and may be an important factor in regulating how the Gulf Stream varies.

This research, published today in Geophysical Research Letters, has found the Caribbean Current flow is unstable, which causes it to shed eddies, or swirling currents of water hundreds of kilometres in diameter. This is similar to the way in which a jet of air sheds eddies when it hits the lip of a whistle. 

Rossby waves are planetary waves that determine basic meteorological conditions at latitudes outside of the tropics.

Credit: University of Oregon

 Vorticity is generated in the atmospheric and ocean fluids by the rotation of the earth since these fluids can't co-rotate with the earth because of internal currents and friction and various energy losses. Vorticity is a measure of spin.
In a whistle the radiating sound comes from a resonating pressure wave created by the eddies, causing mass to be exchanged with the air around it. In the case of the current the eddies create a resonant Rossby wave in the ocean basin, which because it is not completely closed, allows water mass to be exchanged with the rest of the ocean. The net result is a sloshing of water into and out of the basin with a period of 120 days, corresponding to a note of A flat, many octaves below the audible range.

The sloshing water is big enough to be detected by its gravitational influence on the GRACE satellites.
Caribbean 


Furthermore, the Rossby wave resonance relies on a peculiar effect known as a Rossby wormhole - the wave propagates to the west across the basin where it seems to disappear, only to reappear in the east Advanced computer models of the ocean, run at the NOC, predicted this should happen. This prediction was later confirmed using a range of observations, including satellite gravity, satellite sea level measurements, coastal tide gauges and a bottom pressure recorder which is part of the global tsunami warning network.

Professor Chris Hughes, who led the research, said “It was a real surprise to find this oscillation. We were looking at ocean bottom pressure data from round the world as part of an NOC contribution to the global sea level database, which we host, and found this region. It behaved quite differently from the rest of the tropics, which are typically very quiet. With hindsight we found theoreticians had predicted this kind of behaviour, but had never thought to apply their models to the Caribbean Sea – ironically this seems to be the only place where conditions are suitable.”

The oscillation is always present, sometimes with higher and sometimes with lower amplitude. Since the waves van be seen as they propagate across the Caribbean Sea, scientists can predict when the wave will arrive at the coast and cause the sea level to rise or fall at least 120 days in advance.

The work was funded by the Natural Environment Research Council (NERC) as part of a project on Weighing the Ocean and forms part of the NOC’s ongoing research into global ocean dynamics and sea level.



Contacts and sources:
National Oceanography Centre

Citation: A Rossby Whistle: A resonant basin mode observed in the Caribbean Sea; A Rossby Whistle: A resonant basin mode observed in the Caribbean Sea; Chris W. Hughes, Joanne Williams, Angela Hibbert, Carmen Boening, James Oram; Geophysical Research Letters; DOI: 10.1002/2016GL069573  http://bit.ly/28WQVkT

Spectacular Survey of the Distant Universe Shows Galaxies Billions of Years Before the Earth Was Born

Astronomers today (28 June) released spectacular new infrared images of the distant Universe, providing the deepest view ever obtained over a large area of sky. The team, led by Prof Omar Almaini, present their results at the National Astronomy Meeting at the University of Nottingham.

The final data release from the Ultra-Deep Survey (UDS) maps an area four times the size of the full Moon to unprecedented depth. Over 250,000 galaxies have been detected, including several hundred observed within the first billion years after the Big Bang. Astronomers around the world will use the new images to study the early stages of galaxy formation and evolution.

An image of a small section (0.4%) of the UDS field. Most of the objects in the image are very distant galaxies, observed as they were over 9 billion years ago. In the full image, 250,000 galaxies have been detected over an area of sky four times the size of the full Moon.
 Credit: Omar Almaini, University of Nottingham.

The release of the final UDS images represents the culmination of a project that began taking data in 2005. The scientists used the United Kingdom Infrared Telescope (UKIRT) on Hawaii to observe the same patch of sky repeatedly, building up more than 1000 hours of exposure time. Observing in the infrared is vital for studying very distant objects, as ordinary starlight is "redshifted" to longer wavelengths due to the cosmological expansion of the Universe.

Because of the finite speed of light, the most distant galaxies are also observed very far back in time.

"With the UDS we can study distant galaxies in large numbers, and observe how they evolved at different stages in the history of the Universe. We see most of the galaxies in our image as they were billions of years before the Earth was formed", said Almaini.

The UDS is the deepest of 5 projects, collectively known as the UKIRT Infrared Deep Sky Survey (UKIDSS).

Earlier releases of data from the UDS have already produced a wide range of scientific advances, including studies of the earliest galaxies in the first billion years after the Big Bang, measurements of the build-up of galaxies through cosmic time, and studies of the large-scale distribution of galaxies to weigh the mysterious ‘dark matter’ that pervades the cosmos. The added depth from the new release is expected to produce many new breakthroughs.

"We are particularly keen to understand the dramatic transformation that many massive galaxies underwent around 10 billion years ago", said Dr William Hartley, a postdoctoral researcher at University College London. “At that time many galaxies appear to have abruptly stopped forming stars, and they also changed shape to form spheroidal-looking galaxies. We still don’t fully understand why this happens. With our new UDS images we expect to find large numbers of these galaxies, caught in the act of transformation, so we can study them in detail to solve this important puzzle.”



Contacts and sources:

Will Dreaming Robot Find Habitable Alien Worlds: Meet RobERt a Diviner of Clouds

Machine-learning techniques that mimic human recognition and dreaming processes are being deployed in the search for habitable worlds beyond our solar system. 

A deep belief neural network, called RobERt (Robotic Exoplanet Recognition), has been developed by astronomers at UCL to sift through detections of light emanating from distant planetary systems and retrieve spectral information about the gases present in the exoplanet atmospheres. RobERt will be presented at the National Astronomy Meeting (NAM) 2016 in Nottingham by Dr Ingo Waldmann on Tuesday 28th June.

A neural network’s dream of Earth. Similar to RobERt dreaming of exoplanet spectra, this neural network (Gatys et al. 2015) was trained to dream in the style of a Monet painting. 
Credit: Waldmann/UCL/Gatys 

“Different types of molecules absorb and emit light at specific wavelengths, embedding a unique pattern of lines within the electromagnetic spectrum,” explained Dr Waldmann, who leads RobERt’s development team. “We can take light that has been filtered through an exoplanet’s atmosphere or reflected from its cloud-tops, split it like a rainbow and then pick out the ‘fingerprint’ of features associated with the different molecules or gases. Human brains are really good at finding these patterns in spectra and label them from experience, but it’s a really time consuming job and there will be huge amounts of data.

We built RobERt to independently learn from examples and to build on his own experiences. This way, like a seasoned astronomer or a detective, RobERt has a pretty good feeling for what molecules are inside a spectrum and which are the most promising data for more detailed analysis. But what usually takes days or weeks takes RobERt mere seconds.”

Deep belief neural networks, or DBNs, were developed more than a decade ago and are commonly used for speech recognition, Internet searches and tracking customer behaviour. RobERt’s DBN has three layers of unit processors, or ‘neurons’. Information is fed into a bottom layer of 500 neurons, which make an initial filter of the data and pass a subset up to the second layer. Here, 200 neurons refine the selection and pass data up to a third layer of 50 neurons to make the final identification of the gases most likely to be present.

To prepare RobERt for his challenge, Waldmann and colleagues at UCL created a total of 85,750 simulated spectra, covering five different types of exoplanet ranging from GJ1214b, a potential “ocean planet”, to WASP-12, a hot Jupiter orbiting very close to its star. Each spectrum in the training set contained the fingerprint of a single gas species. RobERt’s learning progress was tested at intervals during the training with ‘control’ spectra. At the end of the training phase, RobERt had a recognition accuracy of 99.7%.

“RobERt has learned to take into account factors such as noise, restricted wavelength ranges and mixtures of gases,” said Waldmann. “He can pick out components such as water and methane in a mixed atmosphere with a high probability, even when the input comes from the limited wavebands that most space instruments provide and when it contains overlapping features.”

RobERt’s DBN can also be reversed so that instead of analysing data fed into the system, he can enter a ‘dreaming state’ in which he can generate full spectra based on his experiences.

“Robots really do dream. We can ask RobERt to dream up what he thinks a water spectrum will look like, and he’s proved very accurate,” said Waldmann. “This dreaming ability has been very useful when trying to identify features in incomplete data. RobERt can use his dream state to fill in the gaps. The James Webb Space Telescope, due for launch in 2018, will tell as more about the atmospheres of exoplanets, and new facilities like Twinkle or ARIEL will be coming online over the next decade that are specifically tailored to characterising the atmospheres of exoplanets. The amount of data these missions will provide will be breathtaking. RobERt will play an invaluable role in helping us to analyse data from these missions and find out what these distant worlds are really like.”

Contacts and sources:
Dr Robert Massey
Royal Astronomical Society

Dr Ingo Waldmann, Department of Physics and Astronomy,
University College London


Citation:  Waldmann, I.P., Dreaming of Atmospheres, The Astrophysical Journal, 820:107 (8pp), 1 April 2016

Mars Atmosphere Was Once Oxygen Rich Say Researchers, "More Earth-Like Than Previously Believed"


The discovery of manganese oxides in Martian rocks might tell us that the Red Planet was once more Earth-like than previously believed. A new paper in Geophysical Research Letters reveals that NASA's Curiosity rover observed high levels of manganese oxides in Martian rocks, which could indicate that higher levels of atmospheric oxygen once existed on our neighboring planet. This hint of more oxygen in Mars' early atmosphere adds to other Curiosity findings--such as evidence of ancient lakes--revealing how Earth-like our neighboring planet once was.

"The only ways on Earth that we know how to make these manganese materials involve atmospheric oxygen or microbes," said Nina Lanza, a planetary scientist at Los Alamos National Laboratory and lead author on the study published in the American Geophysical Union's journal. "Now we're seeing manganese-oxides on Mars and wondering how the heck these could have formed."

The Curiosity rover examines the Kimberley formation in Gale crater, Mars. In front of the rover are two holes from the rover's sample-collection drill and several dark-toned features that have been cleared of dust (see inset images). These flat features are erosion-resistant fracture fills that are composed of manganese oxides, which require abundant liquid water and strongly oxidizing conditions to form. The discovery of these materials suggests that the Martian atmosphere might once have contained higher abundances of free oxygen than in the present day.
Credit:  MSSS/JPL/NASA (PIA18390)

Lanza uses the Los Alamos-developed ChemCam instrument that sits atop Curiosity to "zap" rocks on Mars and analyze their chemical make-up. This work stems from Los Alamos National Laboratory's experience building and operating more than 500 spacecraft instruments for national defense, giving the Laboratory the expertise needed to develop discovery-driven instruments like ChemCam. In less than four years since landing on Mars, ChemCam has analyzed roughly 1,500 rock and soil samples.

Microbes seem a far-fetched explanation for the manganese oxides at this point, said Lanza, but the idea that the Martian atmosphere contained more oxygen in the past than it does now seems possible. "These high-manganese materials can't form without lots of liquid water and strongly oxidizing conditions," said Lanza "Here on Earth, we had lots of water but no widespread deposits of manganese oxides until after the oxygen levels in our atmosphere rose due to photosynthesizing microbes."

In the Earth's geological record, the appearance of high concentrations of manganese is an important marker of a major shift in our atmosphere's composition, from relatively low oxygen abundances to the oxygen-rich atmosphere we see today. The presence of the same types of materials on Mars suggests that something similar happened there. If that's the case, how was that oxygen-rich environment formed?

"One potential way that oxygen could have gotten into the Martian atmosphere is from the breakdown of water when Mars was losing its magnetic field," said Lanza. "It's thought that at this time in Mars' history, water was much more abundant." Yet without a protective magnetic field to shield the surface from ionizing radiation, that radiation started splitting water molecules into hydrogen and oxygen. Because of Mars' relatively low gravity, it wasn't able to hold onto the very light hydrogen atoms, but the heavier oxygen atoms remained behind. Much of this oxygen went into the rocks, leading to the rusty red dust that covers the surface today. While Mars' famous red iron oxides require only a mildly oxidizing environment to form, manganese oxides require a strongly oxidizing environment. These results suggest that past conditions were far more oxidizing (oxygen-rich) than previously thought.

"It's hard to confirm whether this scenario for Martian atmospheric oxygen actually occurred," Lanza added. "But it's important to note that this idea represents a departure in our understanding for how planetary atmospheres might become oxygenated." So far, abundant atmospheric oxygen has been treated as a so-called biosignature, or a sign of existing life.

The next step in this work is for scientists to better understand the signatures of non-biogenic versus biogenic manganese, which is directly produced by microbes. If it's possible to distinguish between manganese oxides produced by life and those produced in a non-biological setting, that knowledge can be directly applied to Martian manganese observations to better understand their origin.

The high-manganese materials were found in mineral-filled cracks in sandstones in the Kimberley region of Gale crater, which the Curiosity rover has been exploring for the last four years. But that's not the only place on Mars that abundant manganese has been found. The Opportunity rover, which has been exploring Mars since 2004, also recently discovered high-manganese deposits in its landing site thousands of miles from Curiosity, which supports the idea that the conditions needed to form these materials were present well beyond Gale crater.




Contacts and sources:
Laura Mullane
Los Alamos National Laboratory


Citation: Oxidation of manganese in an ancient aquifer, Kimberley formation, Gale crater, Mars
http://dx.doi.org/10.1002/2016GL069109