The lonely giant: Milky Way-sized galaxy lacking galactic neighbors

Color images of the two recently discovered satellite galaxies around M94. The images were taken with Hyper Suprime-Cam on the Subaru telescope, located at nearly 14,000 ft above sea level on the summit of Mauna Kea in Hawaii.

Long ago in a galaxy far, far away, fewer galaxies were born than expected -- and that could create new questions for galaxy physics, according to a new University of Michigan study.

The study examined the satellite galaxies of Messier 94, or M94, a galaxy similar in size to our Milky Way. Researchers have long known the Milky Way has about 10 smaller, satellite galaxies surrounding it, each with at least a million stars, and up to more than a billion, such as the Magellanic Clouds.

Now, with the powerful Subaru telescope, astronomers can peer at galaxies five or 10 times the distance from the Milky Way, such as M94. They then can use the physics of how satellite galaxies form around the Milky Way to predict how many satellite galaxies a similar-sized galaxy such as M94 may have.

When U-M astronomers examined M94, they expected to find a similar number of satellite galaxies. However, they detected just two galaxies near M94, with very few stars each. Their results, led by Adam Smercina, a National Science Foundation fellow in the U-M Department of Astronomy, are published in the journal Astrophysical Letters.

"More than just an observational oddity, we show that the current crop of galaxy formation models cannot produce such a satellite system," Smercina said. "Our results indicate that Milky Way-like galaxies most likely host a much wider diversity of satellite populations than is predicted by any current model."

Smercina also says their results have implications for the current understanding of how galaxies form -- which is in much larger halos of dark matter.

These halos of dark matter surrounding galaxies have immense gravitational force, and can pull in gas from their immediate vicinity. Large galaxies like the Milky Way generally form in halos of about the same mass. But these smaller satellite galaxies, which form in smaller 'subhalos,' are not nearly so dependable.

The production rate of high-mass stars in these satellite galaxies actually modulates their growth. If, for example, the nascent satellite galaxy forms too many high-mass stars at one time, their eventual supernova explosions might expel all its gas and halt all further growth. But astronomers are unsure at what size halo this 'scatter' in galaxy formation becomes important.

Smercina says M94 indicates that galaxy formation in intermediate-sized dark halos may be much more uncertain than previously thought.

"We think that that scatter -- the range of galaxies we expect to see -- may be a lot higher than what people currently think for dark matter halos of a certain mass," he said. "Nobody's under any illusions as to there being this huge scatter at the very lowest halo masses, but it's at these intermediate dark matter halos that the discussion is happening."

To observe the number of satellite dwarf galaxies around M94, the researchers took a composite image of the large galaxy. The image covered about 12 square degrees of the night sky -- the full moon, for comparison, appears as about one square degree. This kind of image includes layers and layers of "noise," including cosmic rays and scattered light, which make faint dwarf galaxies difficult to detect.

To make sure they weren't missing satellite galaxies, Smercina and his team engineered artificial galaxies back into the image and recovered them using the same methods as for real satellites. With this technique, the researchers confirmed that were no more than two galaxies around M94.

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Illuminating women's role in the creation of medieval manuscripts

This is dental calculus on the lower jaw a medieval woman entrapped lapis lazuli pigment.

During the European Middle Ages, literacy and written texts were largely the province of religious institutions. Richly illustrated manuscripts were created in monasteries for use by members of religious institutions and by the nobility. Some of these illuminated manuscripts were embellished with luxurious paints and pigments, including gold leaf and ultramarine, a rare and expensive blue pigment made from lapis lazuli stone.

In a study published in Science Advances, an international team of researchers led by the Max Planck Institute for the Science of Human History and the University of York shed light on the role of women in the creation of such manuscripts with a surprising discovery -- the identification of lapis lazuli pigment embedded in the calcified dental plaque of a middle-aged woman buried at a small women's monastery in Germany around 1100 AD. Their analysis suggests that the woman was likely a painter of richly illuminated religious texts.

A quiet monastery in central Germany

As part of a study analyzing dental calculus -- tooth tartar or dental plaque that fossilizes on the teeth during life -- researchers examined the remains of individuals who were buried in a medieval cemetery associated with a women's monastery at the site of Dalheim in Germany. Few records remain of the monastery and its exact founding date is not known, although a women's community may have formed there as early as the 10th century AD. The earliest known written records from the monastery date to 1244 AD. The monastery is believed to have housed approximately 14 religious women from its founding until its destruction by fire following a series of 14th century battles.

One woman in the cemetery was found to have numerous flecks of blue pigment embedded within her dental calculus. She was 45-60 years old when she died around 1000-1200 AD. She had no particular skeletal pathologies, nor evidence of trauma or infection. The only remarkable aspect to her remains was the blue particles found in her teeth. "It came as a complete surprise -- as the calculus dissolved, it released hundreds of tiny blue particles," recalls co-first author Anita Radini of the University of York. Careful analysis using a number of different spectrographic methods -- including energy dispersive X-ray spectroscopy (SEM-EDS) and micro-Raman spectroscopy -- revealed the blue pigment to be made from lapis lazuli.

A pigment as rare and expensive as gold

"We examined many scenarios for how this mineral could have become embedded in the calculus on this woman's teeth," explains Radini. "Based on the distribution of the pigment in her mouth, we concluded that the most likely scenario was that she was herself painting with the pigment and licking the end of the brush while painting," states co-first author Monica Tromp of the Max Planck Institute for the Science of Human History.

The use of ultramarine pigment made from lapis lazuli was reserved, along with gold and silver, for the most luxurious manuscripts. "Only scribes and painters of exceptional skill would have been entrusted with its use," says Alison Beach of Ohio State University, a historian on the project.

The unexpected discovery of such a valuable pigment so early and in the mouth of an 11th century woman in rural Germany is unprecedented. While Germany is known to have been an active center of book production during this period, identifying the contributions of women has been particularly difficult. As a sign of humility, many medieval scribes and painters did not sign their work, a practice that especially applied to women. The low visibility of women's labor in manuscript production has led many modern scholars to assume that women played little part in it.

The findings of this study not only challenge long-held beliefs in the field, they also uncover an individual life history. The woman's remains were originally a relatively unremarkable find from a relatively unremarkable place, or so it seemed. But by using these techniques, the researchers were able to uncover a truly remarkable life history.

"She was plugged into a vast global commercial network stretching from the mines of Afghanistan to her community in medieval Germany through the trading metropolises of Islamic Egypt and Byzantine Constantinople. The growing economy of 11th century Europe fired demand for the precious and exquisite pigment that traveled thousands of miles via merchant caravan and ships to serve this woman artist's creative ambition," explains historian and co-author Michael McCormick of Harvard University.

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Skull scans tell tale of how world's first dogs caught their prey

Computerized scan of skull of first dog species -- Hesperocyon gregarius -- with inner ear highlighted in red.

Analysis of the skulls of lions, wolves and hyenas has helped scientists uncover how prehistoric dogs hunted 40 million years ago.

A study has revealed that the first species of dog -- called Hesperocyon gregarius -- pounced on its prey in the same way that many species, including foxes and coyotes, do today.

The findings also show that the largest dog species ever to live -- known as Epicyon haydeni -- hunted in a similar way. The animals -- which lived from 16 until seven million years ago -- could grow to the size of a grizzly bear.

Comparisons between computerised scans of fossils and modern animals have shed light on the hunting methods used by prehistoric members of a group of mammals known as carnivorans. These include modern-day foxes, wolves, cougars and leopards.

Scientists at the Universities of Edinburgh and Vienna used the scans to create digital models of the inner ears of 36 types of carnivoran, including six extinct species.

The team found that the size of three bony canals in the inner ear -- the organ that controls balance and hearing -- changed over millions of years as animals adopted different hunting styles.

Faster predators -- such as cheetahs, lions and wolves -- developed large ear canals that enable them to keep their head and vision stable while ambushing or chasing prey at speed, the team says.

Their findings reveal that inner ear structure indicates whether a species descended from dog-like animals or belongs to one of four families of animals resembling cats. A distinctive angle between two parts of the inner ear is much larger in dog-like animals, the team found.

The study is based on research carried out by Julia Schwab, a current PhD student at the University of Edinburgh, during her MSc studies at the University of Vienna, Austria. It is published in the journal Scientific Reports.

Ms Schwab, based in the University of Edinburgh's School of GeoSciences, said: "For me, the inner ear is the most interesting organ in the body, as it offers amazing insights into ancient animals and how they lived. The first dog and the largest-ever dog are such fascinating specimens to study, as nothing like them exists in the world today."

From Science Daily

Astronomers find signatures of a 'messy' star that made its companion go supernova

An X-ray/infrared composite image of G299, a Type Ia supernova remnant in the Milky Way Galaxy approximately 16,000 light years away.

Many stars explode as luminous supernovae when, swollen with age, they run out of fuel for nuclear fusion. But some stars can go supernova simply because they have a close and pesky companion star that, one day, perturbs its partner so much that it explodes.

These latter events can happen in binary star systems, where two stars attempt to share dominion. While the exploding star gives off lots of evidence about its identity, astronomers must engage in detective work to learn about the errant companion that triggered the explosion.

On Jan. 10 at the 2019 American Astronomical Society meeting in Seattle, an international team of astronomers announced that they have identified the type of companion star that made its partner in a binary system, a carbon-oxygen white dwarf star, explode. Through repeated observations of SN 2015cp, a supernova 545 million light years away, the team detected hydrogen-rich debris that the companion star had shed prior to the explosion.

"The presence of debris means that the companion was either a red giant star or similar star that, prior to making its companion go supernova, had shed large amounts of material," said University of Washington astronomer Melissa Graham, who presented the discovery and is lead author on the accompanying paper accepted for publication in The Astrophysical Journal.

The supernova material smacked into this stellar litter at 10 percent the speed of light, causing it to glow with ultraviolet light that was detected by the Hubble Space Telescope and other observatories nearly two years after the initial explosion. By looking for evidence of debris impacts months or years after a supernova in a binary star system, the team believes that astronomers could determine whether the companion had been a messy red giant or a relatively neat and tidy star.

The team made this discovery as part of a wider study of a particular type of supernova known as a Type Ia supernova. These occur when a carbon-oxygen white dwarf star explodes suddenly due to activity of a binary companion. Carbon-oxygen white dwarfs are small, dense and -- for stars -- quite stable. They form from the collapsed cores of larger stars and, if left undisturbed, can persist for billions of years.

Type Ia supernovae have been used for cosmological studies because their consistent luminosity makes them ideal "cosmic lighthouses," according to Graham. They've been used to estimate the expansion rate of the universe and served as indirect evidence for the existence of dark energy.

Yet scientists are not certain what kinds of companion stars could trigger a Type Ia event. Plenty of evidence indicates that, for most Type Ia supernovae, the companion was likely another carbon-oxygen white dwarf, which would leave no hydrogen-rich debris in the aftermath. Yet theoretical models have shown that stars like red giants could also trigger a Type Ia supernova, which could leave hydrogen-rich debris that would be hit by the explosion. Out of the thousands of Type Ia supernovae studied to date, only a small fraction were later observed impacting hydrogen-rich material shed by a companion star. Prior observations of at least two Type Ia supernovae detected glowing debris months after the explosion. But scientists weren't sure if those events were isolated occurrences, or signs that Type Ia supernovae could have many different kinds of companion stars.

"All of the science to date that has been done using Type Ia supernovae, including research on dark energy and the expansion of the universe, rests on the assumption that we know reasonably well what these 'cosmic lighthouses' are and how they work," said Graham. "It is very important to understand how these events are triggered, and whether only a subset of Type Ia events should be used for certain cosmology studies."

The team used Hubble Space Telescope observations to look for ultraviolet emissions from 70 Type Ia supernovae approximately one to three years following the initial explosion.

"By looking years after the initial event, we were searching for signs of shocked material that contained hydrogen, which would indicate that the companion was something other than another carbon-oxygen white dwarf," said Graham.

In the case of SN 2015cp, a supernova first detected in 2015, the scientists found what they were searching for. In 2017, 686 days after the supernova exploded, Hubble picked up an ultraviolet glow of debris. This debris was far from the supernova source -- at least 100 billion kilometers, or 62 billion miles, away. For reference, Pluto's orbit takes it a maximum of 7.4 billion kilometers from our sun.

By comparing SN 2015cp to the other Type Ia supernovae in their survey, the researchers estimate that no more than 6 percent of Type Ia supernovae have such a litterbug companion. Repeated, detailed observations of other Type Ia events would help cement these estimates, Graham said.

The Hubble Space Telescope was essential for detecting the ultraviolet signature of the companion star's debris for SN 2015cp. In the fall of 2017, the researchers arranged for additional observations of SN 2015cp by the W.M. Keck Observatory in Hawaii, the Karl G. Jansky Very Large Array in New Mexico, the European Southern Observatory's Very Large Telescope and NASA's Neil Gehrels Swift Observatory, among others. These data proved crucial in confirming the presence of hydrogen and are presented in a companion paper lead by Chelsea Harris, a research associate at Michigan State University.

"The discovery and follow-up of SN 2015cp's emission really demonstrates how it takes many astronomers, and a wide variety of types of telescopes, working together to understand transient cosmic phenomena," said Graham. "It is also a perfect example of the role of serendipity in astronomical studies: If Hubble had looked at SN 2015cp just a month or two later, we wouldn't have seen anything."

Graham is also a senior fellow with the UW's DIRAC Institute and a science analyst with the Large Synoptic Survey Telescope, or LSST.

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Birth of a black hole or neutron star captured for first time

A look at The Cow (approximately 80 days after explosion) from the W.M. Keck Observatory in Maunakea, Hawaii. The Cow is nestled in the CGCG 137-068 galaxy, 200 million light years from Earth.

A Northwestern University-led international team is getting closer to understanding the mysteriously bright object that burst in the northern sky this summer.

On June 17, the ATLAS survey's twin telescopes in Hawaii found a spectacularly bright anomaly 200 million light years away in the Hercules constellation. Dubbed AT2018cow or "The Cow," the object quickly flared up, then vanished almost as quickly.

After combining several imaging sources, including hard X-rays and radiowaves, the multi-institutional team now speculates that the telescopes captured the exact moment a star collapsed to form a compact object, such as a black hole or neutron star. The stellar debris, approaching and swirling around the object's event horizon, caused the remarkably bright glow.

This rare event will help astronomers better understand the physics at play within the first moments of the creation of a black hole or neutron star. "We think that 'The Cow' is the formation of an accreting black hole or neutron star," said Northwestern's Raffaella Margutti, who led the research. "We know from theory that black holes and neutron stars form when a star dies, but we've never seen them right after they are born. Never."

Margutti will present her findings at the 233rd meeting of the American Astronomical Society at 2:15 p.m. PST on Jan. 10 in Seattle. (Reporters can join the session to watch, listen and ask questions via webcast.) The research will then be published in the Astrophysical Journal.

Margutti is an assistant professor of physics and astronomy in Northwestern's Weinberg College of Arts and Sciences and a member of CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics), an endowed research center at Northwestern focused on advancing astrophysics studies with an emphasis on interdisciplinary connections.

The curious Cow

After it was first spotted, The Cow captured immediate international interest and left astronomers scratching their heads. "We thought it must be a supernova," Margutti said. "But what we observed challenged our current notions of stellar death."

For one, the anomaly was unnaturally bright -- 10 to 100 times brighter than a typical supernova. It also flared up and disappeared much faster than other known star explosions, with particles flying at 30,000 kilometers per second (or 10 percent of the speed of light). Within just 16 days, the object had already emitted most of its power. In a universe where some phenomena last for millions and billions of years, two weeks amounts to the blink of an eye.

"We knew right away that this source went from inactive to peak luminosity within just a few days," Margutti said. "That was enough to get everybody excited because it was so unusual and, by astronomical standards, it was very close by."

Using Northwestern's access to observational facilities at the W.M. Keck Observatory in Hawaii and the MMT Observatory in Arizona, as well as remote access to the SoAR telescope in Chile, Margutti took a closer look at the object's makeup. Margutti and her team examined The Cow's chemical composition, finding clear evidence of hydrogen and helium, which excluded models of compact objects merging -- like those that produce gravitational waves.

Comprehensive strategy

Astronomers have traditionally studied stellar deaths in the optical wavelength, which uses telescopes to capture visible light. Margutti's team, on the other hand, uses a more comprehensive approach. Her team viewed the object with X-rays, hard X-rays (which are 10 times more powerful than normal X-rays), radio waves and gamma rays. This enabled them to continue studying the anomaly long after its initial visible brightness faded.

After ATLAS spotted the object, Margutti's team quickly obtained follow-up observations of The Cow with NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and INTEGRAL hard X-ray laboratories, soft X-rays at XMM-Newton and radio antennae at the Very Large Array toward The Cow.

Margutti attributes The Cow's relative nakedness to potentially unraveling this intergalactic mystery. Although stars might collapse into black holes all the time, the large amount of material around newly born black holes blocks astronomers' vision. Fortunately, about 10 times less ejecta swirled around The Cow as compared to a typical stellar explosion. The lack of material allowed astronomers to peer straight through to the object's "central engine," which revealed itself as a probable black hole or neutron star.

"A 'lightbulb' was sitting deep inside the ejecta of the explosion," Margutti said. "It would have been hard to see this in a normal stellar explosion. But The Cow had very little ejecta mass, which allowed us to view the central engine's radiation directly."

Galactic neighbor

Margutti's team also benefited from the star's relative closeness to Earth. Even though it was nestled in the distant dwarf galaxy called CGCG 137-068, astronomers consider that to be "right around the corner."

"Two hundred million light years is close for us, by the way," Margutti said. "This is the closest transient object of this kind that we have ever found."

Margutti's team at Northwestern includes graduate student Aprajita Hajela, postdoctoral fellows Giacomo Terreran, Deanne Coppejans and Kate Alexander (who is a Hubble Fellow), and first-year undergraduate student Daniel Brethauer.

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Oceans are warming even faster than previously thought

Trends in ocean heat content match those predicted by leading climate change models. Overall ocean warming is accelerating.

Berkeley -- Heat trapped by greenhouse gases is raising ocean temperatures faster than previously thought, concludes an analysis of four recent ocean heating observations. The results provide further evidence that earlier claims of a slowdown or "hiatus" in global warming over the past 15 years were unfounded.

"If you want to see where global warming is happening, look in our oceans," said Zeke Hausfather, a graduate student in the Energy and Resources Group at the University of California, Berkeley, and co-author of the paper. "Ocean heating is a very important indicator of climate change, and we have robust evidence that it is warming more rapidly than we thought."

Ocean heating is critical marker of climate change because an estimated 93 percent of the excess solar energy trapped by greenhouse gases accumulates in the world's oceans. And, unlike surface temperatures, ocean temperatures are not affected by year-to-year variations caused by climate events like El Nino or volcanic eruptions.

The new analysis, published Jan. 11 in Science, shows that trends in ocean heat content match those predicted by leading climate change models, and that overall ocean warming is accelerating.

Assuming a "business-as-usual" scenario in which no effort has been made to reduce greenhouse gas emissions, the Coupled Model Intercomparison Project 5 (CMIP5) models predict that the temperature of the top 2,000 meters of the world's oceans will rise 0.78 degrees Celsius by the end of the century. The thermal expansion caused by this bump in temperature would raise sea levels 30 centimeters, or around 12 inches, on top of the already significant sea level rise caused by melting glaciers and ice sheets. Warmer oceans also contribute to stronger storms, hurricanes and extreme precipitation.

"While 2018 will be the fourth warmest year on record on the surface, it will most certainly be the warmest year on record in the oceans, as was 2017 and 2016 before that," Hausfather said. "The global warming signal is a lot easier to detect if it is changing in the oceans than on the surface."

The four studies, published between 2014 and 2017, provide better estimates of past trends in ocean heat content by correcting for discrepancies between different types of ocean temperature measurements and by better accounting for gaps in measurements over time or location.

"The Intergovernmental Panel on Climate Change's (IPCC) Fifth Assessment Report, published in 2013, showed that leading climate change models seemed to predict a much faster increase in ocean heat content over the last 30 years than was seen in observations," Hausfather said. "That was a problem, because of all things, that is one thing we really hope the models will get right."

"The fact that these corrected records now do agree with climate models is encouraging in that is removes an area of big uncertainty that we previously had," he said.

Deep Divers

A fleet of nearly 4,000 floating robots drift throughout the world's oceans, every few days diving to a depth of 2000 meters and measuring the ocean's temperature, pH, salinity and other bits of information as they rise back up. This ocean-monitoring battalion, called Argo, has provided consistent and widespread data on ocean heat content since the mid-2000s.

Prior to Argo, ocean temperature data was sparse at best, relying on devices called expendable bathythermographs that sank to the depths only once, transmitting data on ocean temperature until settling into watery graves.

Three of the new studies included in the Science analysis calculated ocean heat content back to 1970 and before using new methods to correct for calibration errors and biases in the both the Argo and bathythermograph data. The fourth takes a completely different approach, using the fact that a warming ocean releases oxygen to the atmosphere to calculate ocean warming from changes in atmospheric oxygen concentrations, while accounting for other factors, like burning fossil fuels, that also change atmospheric oxygen levels.

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Geoscientists reconstruct 'eye-opening' 900-year Northeastern U.S. climate record

Doctoral students Daniel Miller, in the water, with Helen Habicht and Benjamin Keisling, handle two recaptured sediment traps from an unusually deep lake in central Maine, where they collected 136 sediment samples spanning the 900-year time span to reconstruct the longest and highest-resolution climate record for the Northeastern United States to date.

Deploying a new technique for the first time in the region, geoscientists at the University of Massachusetts Amherst have reconstructed the longest and highest-resolution climate record for the Northeastern United States, which reveals previously undetected past temperature cycles and extends the record 900 years into the past, well beyond the previous early date of 1850.

First author Daniel Miller, with Helen Habicht and Benjamin Keisling, conducted this study as part of their doctoral programs with advisors geosciences professors Raymond Bradley and Isla Castañeda. As Miller explains, they used a relatively new quantitative method based on the presence of chemical compounds known as branched glycerol dialkyl glycerol tetra ethers (branched GDGTs) found in lakes, soils, rivers and peat bogs around the world. The compounds can provide an independent terrestrial paleo-thermometer that accurately assesses past temperature variability.

Miller says, "This is the first effort using these compounds to reconstruct temperature in the Northeast, and the first one at this resolution." He and colleagues were able to collect a total of 136 samples spanning the 900-year time span, many more than would be available with more traditional methods and from other locations that typically yield just one sample per 30-100 years.

In their results, Miller says, "We see essentially cooling throughout most of the record until the 1900s, which matches other paleo-records for North America. We see the Medieval Warm Period in the early part and the Little Ice Age in the 1800s." An unexpected observation was 10, 50-to-60-year temperature cycles not seen before in records from Northeast U.S., he adds, "a new finding and surprising. We're trying to figure out what causes that. It may be caused by changes in the North Atlantic Oscillation or some other atmospheric patterns. We'll be looking further into it."

He adds, "We're very excited about this. I think it's a great story of how grad students who come up with a promising idea, if they have enough support from their advisors, can produce a study with really eye-opening results." Details appear in a recent issue of the European Geophysical Union's open-access online journal, Climate of the Past.

The authors point out that paleo-temperature reconstructions are essential for distinguishing human-made climate change from natural variability, but historical temperature records are not long enough to capture pre-human-impact variability. Further, using conventional pollen- and land-based sediment samples as climate proxies can reflect confounding parameters rather than temperature, such as precipitation, humidity, evapo-transpiration and vegetation changes.

Therefore, additional quantitative paleo-temperature records are needed to accurately assess past temperature variability in the Northeast United States, the researchers point out. An independent terrestrial paleo-thermometer that relies on measuring two byproducts of processes carried out in branched GDGTs in lake sediment, a method first introduced two decades ago by researchers in The Netherlands, offered a promising alternative, Miller says.

Source organisms are not known for branch GDGTs, he points out, but they are thought to be produced in part by Acidobacteria. "These are compounds likely produced by different algae and bacteria communities in the membrane, or skin," he notes. "Just like for humans, the skin regulates the organism's body temperature and these compounds change in response to temperature. So if they grow in summer, they reflect that and the compounds are different than if they were produced in winter. We record the compounds to get the temperature curves. We found there seems to be a huge bloom of these organisms in the fall. After they die, they settle into the lake bottom. We think it's mainly a fall temperature that we're detecting."

For this work, Miller and colleagues constructed large plastic sediment traps and deployed them about ten feet below the surface of a small, 106-foot-deep lake in central Maine in May, 2014. They then dove under to collect a catchment bottle from the bottom of each trap every month in June, July, August and September, and the following May 2015.

Miller says, "This lake is very deep for its small area, with very steep sides. It doesn't seem to have much mixing of water layers by surface winds. We think that has helped to preserve a bottom water layer with no oxygen year-round, known as anoxia, which helps in the preservation of annual layers in the sediments at the bottom of the lake. It's rare for a lake to have such fine, thin lines that represent annual deposition, so all you have to do is count the lines to count the years. We double-checked our results with radiocarbon dating and other methods, and it turns out that reconstructing the temperature record this way was successful."

Miller and colleagues say this project enjoyed notable support from many quarters, including the UMass Amherst Alumni Association supporting student field work and data collection in Maine; the geology department at Bates College; funding from the U.S. Geological Survey; and at UMass Amherst, sophisticated biogeochemistry laboratory equipment and the Joe Hartshorn Memorial Award from the geosciences department, and other assistance from the Northeast Climate Adaptation Science Center.

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Cosmic telescope zooms in on the beginning of time

This is a Hubble Space Telescope image of a very distant quasar (at right) that has been brightened and split into three images by the effects of the gravitational field of a foreground galaxy (left). The crosses mark the centers of each quasar image. The quasar would have gone undetected if not for the power of gravitational lensing, which boosted its brightness by a factor of 50. The gravitational field of the foreground galaxy (seen at left) warps space like a funhouse mirror, amplifying the quasar's light. Shining with the brilliance of 600 trillion suns, the quasar is fueled by a supermassive black hole at the heart of a young galaxy in the process of forming. The image shows the quasar as it looked 12.8 billion years ago - only about 1 billion years after the big bang. The quasar appears red because its blue light has been absorbed by diffuse gas in intergalactic space. By comparison, the foreground galaxy has bluer starlight light. The quasar, cataloged as J043947.08+163415.7 (J0439+1634 for short), could hold the record of being the brightest in the early universe for some time, making it a unique object for follow-up studies.

Observations from Gemini Observatory identify a key fingerprint of an extremely distant quasar, allowing astronomers to sample light emitted from the dawn of time. Astronomers happened upon this deep glimpse into space and time thanks to an unremarkable foreground galaxy acting as a gravitational lens, which magnified the quasar's ancient light. The Gemini observations provide critical pieces of the puzzle in confirming this object as the brightest appearing quasar so early in the history of the Universe, raising hopes that more sources like this will be found.

Before the cosmos reached its billionth birthday, some of the very first cosmic light began a long journey through the expanding Universe. One particular beam of light, from an energetic source called a quasar, serendipitously passed near an intervening galaxy, whose gravity bent and magnified the quasar's light and refocused it in our direction, allowing telescopes like Gemini North to probe the quasar in great detail.

"If it weren't for this makeshift cosmic telescope, the quasar's light would appear about 50 times dimmer," said Xiaohui Fan of the University of Arizona who led the study. "This discovery demonstrates that strongly gravitationally lensed quasars do exist despite the fact that we've been looking for over 20 years and not found any others this far back in time."

The Gemini observations provided key pieces of the puzzle by filling a critical hole in the data. The Gemini North telescope on Maunakea, Hawai'i, utilized the Gemini Near-InfraRed Spectrograph (GNIRS) to dissect a significant swath of the infrared part of the light's spectrum. The Gemini data contained the tell-tale signature of magnesium which is critical for determining how far back in time we are looking. The Gemini observations also led to a determination of the mass of the black hole powering the quasar. "When we combined the Gemini data with observations from multiple observatories on Maunakea, the Hubble Space Telescope, and other observatories around the world, we were able to paint a complete picture of the quasar and the intervening galaxy," said Feige Wang of the University of California, Santa Barbara, who is a member of the discovery team.

That picture reveals that the quasar is located extremely far back in time and space -- shortly after what is known as the Epoch of Reionization -- when the very first light emerged from the Big Bang. "This is one of the first sources to shine as the Universe emerged from the cosmic dark ages," said Jinyi Yang of the University of Arizona, another member of the discovery team. "Prior to this, no stars, quasars, or galaxies had been formed, until objects like this appeared like candles in the dark."

The foreground galaxy that enhances our view of the quasar is especially dim, which is extremely fortuitous. "If this galaxy were much brighter, we wouldn't have been able to differentiate it from the quasar," explained Fan, adding that this finding will change the way astronomers look for lensed quasars in the future and could significantly increase the number of lensed quasar discoveries. However, as Fan suggested, "We don't expect to find many quasars brighter than this one in the whole observable Universe."

The intense brilliance of the quasar, known as J0439+1634 (J0439+1634 for short), also suggests that it is fueled by a supermassive black hole at the heart of a young forming galaxy. The broad appearance of the magnesium fingerprint captured by Gemini also allowed astronomers to measure the mass of the quasar's supermassive black hole at 700 million times that of the Sun. The supermassive black hole is most likely surrounded by a sizable flattened disk of dust and gas. This torus of matter -- known as an accretion disk -- most likely continually spirals inward to feed the black hole powerhouse. Observations at submillimeter wavelengths with the James Clerk Maxwell Telescope on Maunakea suggest that the black hole is not only accreting gas but may be triggering star birth at a prodigious rate -- which appears to be up to 10,000 stars per year; by comparison, our Milky Way Galaxy makes one star per year. However, because of the boosting effect of gravitational lensing, the actual rate of star formation could be much lower.

Quasars are extremely energetic sources powered by huge black holes thought to have resided in the very first galaxies to form in the Universe. Because of their brightness and distance, quasars provide a unique glimpse into the conditions in the early Universe. This quasar has a redshift of 6.51, which translates to a distance of 12.8 billion light years, and appears to shine with a combined light of about 600 trillion Suns, boosted by the gravitational lensing magnification. The foreground galaxy which bent the quasar's light is about half that distance away, at a mere 6 billion light years from us.

Fan's team selected J0439+1634 as a very distant quasar candidate based on optical data from several sources: the Panoramic Survey Telescope and Rapid Response System1 (Pan-STARRS1; operated by the University of Hawai'i's Institute for Astronomy), the United Kingdom Infra-Red Telescope Hemisphere Survey (conducted on Maunakea, Hawai'i), and NASA's Wide-field Infrared Survey Explorer (WISE) space telescope archive.

The first follow-up spectroscopic observations, conducted at the Multi-Mirror Telescope in Arizona, confirmed the object as a high-redshift quasar. Subsequent observations with the Gemini North and Keck I telescopes in Hawai'i confirmed the MMT's finding, and led to Gemini's detection of the crucial magnesium fingerprint -- the key to nailing down the quasar's fantastic distance. However, the foreground lensing galaxy and the quasar appear so close that it is impossible to separate them with images taken from the ground due to blurring of the Earth's atmosphere. It took the exquisitely sharp images by the Hubble Space Telescope to reveal that the quasar image is split into three components by a faint lensing galaxy.

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X-ray pulse detected near event horizon as black hole devours star

This artist's impression shows hot gas orbiting in a disk around a rapidly-spinning black hole. The elongated spot depicts an X-ray-bright region in the disk, which allows the spin of the black hole to be estimated.

On Nov. 22, 2014, astronomers spotted a rare event in the night sky: A supermassive black hole at the center of a galaxy, nearly 300 million light years from Earth, ripping apart a passing star. The event, known as a tidal disruption flare, for the black hole's massive tidal pull that tears a star apart, created a burst of X-ray activity near the center of the galaxy. Since then, a host of observatories have trained their sights on the event, in hopes of learning more about how black holes feed.

Now researchers at MIT and elsewhere have pored through data from multiple telescopes' observations of the event, and discovered a curiously intense, stable, and periodic pulse, or signal, of X-rays, across all datasets. The signal appears to emanate from an area very close to the black hole's event horizon -- the point beyond which material is swallowed inescapably by the black hole. The signal appears to periodically brighten and fade every 131 seconds, and persists over at least 450 days.

The researchers believe that whatever is emitting the periodic signal must be orbiting the black hole, just outside the event horizon, near the Innermost Stable Circular Orbit, or ISCO -- the smallest orbit in which a particle can safely travel around a black hole.

Given the signal's stable proximity to the black hole, and the black hole's mass, which researchers previously estimated to be about 1 million times that of the sun, the team has calculated that the black hole is spinning at about 50 percent the speed of light.

The findings, reported today in the journal Science, are the first demonstration of a tidal disruption flare being used to estimate a black hole's spin.

The study's first author, Dheeraj Pasham, a postdoc in MIT's Kavli Institute for Astrophysics and Space Research, says that most supermassive black holes are dormant and don't usually emit much in the way of X-ray radiation. Only occasionally will they release a burst of activity, such as when stars get close enough for black holes to devour them. Now he says that, given the team's results, such tidal disruption flares can be used to estimate the spin of supermassive black holes -- a characteristic that has been, up until now, incredibly tricky to pin down.

"Events where black holes shred stars that come too close to them could help us map out the spins of several supermassive black holes that are dormant and otherwise hidden at the centers of galaxies," Pasham says. "This could ultimately help us understand how galaxies evolved over cosmic time."

Pasham's co-authors include Ronald Remillard, Jeroen Homan, Deepto Chakrabarty, Frederick Baganoff, and James Steiner of MIT; Alessia Franchini at the University of Nevada; Chris Fragile of the College of Charleston; Nicholas Stone of Columbia University; Eric Coughlin of the University of California at Berkeley; and Nishanth Pasham, of Sunnyvale, California.

A real signal

Theoretical models of tidal disruption flares show that when a black hole shreds a star apart, some of that star's material may stay outside the event horizon, circling, at least temporarily, in a stable orbit such as the ISCO, and giving off periodic flashes of X-rays before ultimately being fed by the black hole. The periodicity of the X-ray flashes thus encodes key information about the size of the ISCO, which itself is dictated by how fast the black hole is spinning.

Pasham and his colleagues thought that if they could see such regular flashes very close to a black hole that had undergone a recent tidal disruption event, these signals could give them an idea of how fast the black hole was spinning.

They focused their search on ASASSN-14li, the tidal disruption event that astronomers identified in November 2014, using the ground-based All-Sky Automated Survey for SuperNovae (ASASSN).

"This system is exciting because we think it's a poster child for tidal disruption flares," Pasham says. "This particular event seems to match many of the theoretical predictions."

The team looked through archived datasets from three observatories that collected X-ray measurements of the event since its discovery: the European Space Agency's XMM-Newton space observatory, and NASA's space-based Chandra and Swift observatories. Pasham previously developed a computer code to detect periodic patterns in astrophysical data, though not for tidal disruption events specifically. He decided to apply his code to the three datasets for ASASSN-14li, to see if any common periodic patterns would rise to the surface.

What he observed was a surprisingly strong, stable, and periodic burst of X-ray radiation that appeared to come from very close to the edge of the black hole. The signal pulsed every 131 seconds, over 450 days, and was extremely intense -- about 40 percent above the black hole's average X-ray brightness.

"At first I didn't believe it because the signal was so strong," Pasham says. "But we saw it in all three telescopes. So in the end, the signal was real."

Based on the properties of the signal, and the mass and size of the black hole, the team estimated that the black hole is spinning at least at 50 percent the speed of light.

"That's not super fast -- there are other black holes with spins estimated to be near 99 percent the speed of light," Pasham says. "But this is the first time we're able to use tidal disruption flares to constrain the spins of supermassive black holes."

Illuminating the invisible

Once Pasham discovered the periodic signal, it was up to the theorists on the team to find an explanation for what may have generated it. The team came up with various scenarios, but the one that seems the most likely to generate such a strong, regular X-ray flare involves not just a black hole shredding a passing star, but also a smaller type of star, known as a white dwarf, orbiting close to the black hole.

Such a white dwarf may have been circling the supermassive black hole, at ISCO -- the innermost stable circular orbit -- for some time. Alone, it would not have been enough to emit any sort of detectable radiation. For all intents and purposes, the white dwarf would have been invisible to telescopes as it circled the relatively inactive, spinning black hole.

Sometime around Nov. 22, 2014, a second star passed close enough to the system that the black hole tore it apart in a tidal disruption flare that emitted an enormous amount of X-ray radiation, in the form of hot, shredded stellar material. As the black hole pulled this material inward, some of the stellar debris fell into the black hole, while some remained just outside, in the innermost stable orbit -- the very same orbit in which the white dwarf circled. As the white dwarf came in contact with this hot stellar material, it likely dragged it along as a luminous overcoat of sorts, illuminating the white dwarf in an intense amount of X-rays each time it circled the black hole, every 131 seconds.

The scientists admit that such a scenario would be incredibly rare and would only last for several hundred years at most -- a blink of an eye in cosmic scales. The chances of detecting such a scenario would be exceedingly slim.

"The problem with this scenario is that, if you have a black hole with a mass that's 1 million times that of the sun, and a white dwarf is circling it, then at some point over just a few hundred years, the white dwarf will plunge into the black hole," Pasham says. "We would've been extremely lucky to find such a system. But at least in terms of the properties of the system, this scenario seems to work."

The results' overarching significance is that they show it is possible to constrain the spin of a black hole, from tidal disruption events, according to Pasham. Going forward, he hopes to identify similar stable patterns in other star-shredding events, from black holes that reside further back in space and time.

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Thousands of stars turning into crystals

White dwarf star in the process of solidifying.

The first direct evidence of white dwarf stars solidifying into crystals has been discovered by astronomers at the University of Warwick, and our skies are filled with them.

Observations have revealed that dead remnants of stars like our Sun, called white dwarfs, have a core of solid oxygen and carbon due to a phase transition during their lifecycle similar to water turning into ice but at much higher temperatures. This could make them potentially billions of years older than previously thought.

The discovery, led by Dr Pier-Emmanuel Tremblay from the University of Warwick's Department of Physics, has been published in Nature and is largely based on observations taken with the European Space Agency's Gaia satellite.

White dwarf stars are some of the oldest stellar objects in the universe. They are incredibly useful to astronomers as their predictable lifecycle allows them to be used as cosmic clocks to estimate the age of groups of neighboring stars to a high degree of accuracy. They are the remaining cores of red giants after these huge stars have died and shed their outer layers and are constantly cooling as they release their stored up heat over the course of billions of years.

The astronomers selected 15,000 white dwarf candidates within around 300 light years of Earth from observations made by the Gaia satellite and analysed data on the stars' luminosities and colours.

They identified a pile-up, an excess in the number of stars at specific colours and luminosities that do not correspond to any single mass or age. When compared to evolutionary models of stars, the pile-up strongly coincides to the phase in their development in which latent heat is predicted to be released in large amounts, resulting in a slowing down of their cooling process. It is estimated that in some cases these stars have slowed down their aging by as much as 2 billion years, or 15 percent of the age of our galaxy.

Dr Tremblay said: "This is the first direct evidence that white dwarfs crystallise, or transition from liquid to solid. It was predicted fifty years ago that we should observe a pile-up in the number of white dwarfs at certain luminosities and colours due to crystallisation and only now this has been observed.

"All white dwarfs will crystallise at some point in their evolution, although more massive white dwarfs go through the process sooner. This means that billions of white dwarfs in our galaxy have already completed the process and are essentially crystal spheres in the sky. The Sun itself will become a crystal white dwarf in about 10 billion years."

Crystallisation is the process of a material becoming a solid state, in which its atoms form an ordered structure. Under the extreme pressures in white dwarf cores, atoms are packed so densely that their electrons become unbound, leaving a conducting electron gas governed by quantum physics, and positively charged nuclei in a fluid form. When the core cools down to about 10 million degrees, enough energy has been released that the fluid begins to solidify, forming a metallic core at its heart with a mantle enhanced in carbon.

Dr Tremblay adds: "Not only do we have evidence of heat release upon solidification, but considerably more energy release is needed to explain the observations. We believe this is due to the oxygen crystallising first and then sinking to the core, a process similar to sedimentation on a river bed on Earth. This will push the carbon upwards, and that separation will release gravitational energy.

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15-meter-long ancient whale Basilosaurus isis was top marine predator

Fig 1. Skeletons of Basilosaurus isis (A; CGM 42195) and Dorudon atrox (B; CGM 42183 and UM 97512, 100146, 101215, 101222) from Wadi Al Hitan, Egypt, as exhibited at the University of Michigan. Both are adult, fully grown, and illustrated at the same scale (scale bar equals 1 meter). CGM 42195 shows a cast of a 15 meter long B. isis specimen.

The stomach contents of ancient whale Basilosaurus isis suggest it was an apex predator, according to a study published January 9, 2019 in the open-access journal PLOS ONE by Manja Voss from the Museum für Naturkunde Berlin, Germany, and colleagues.

The authors uncovered an adult B. isis specimen in 2010 in the Wadi Al Hitan ("Valley of Whales") site in Cairo, Egypt. This site was once a shallow sea during the late Eocene period and is remarkable for its wealth of marine fossils. While excavating this main B. isis specimen, the authors also revealed the remains of sharks, large bony fish, and, most numerously, bones from Dorudon atrox, a smaller species of ancient whale. The Basilosaurus skeleton was distinct from other skeletons in the cluster, containing pointed B. isis incisors and sharp cheek teeth as well as bones. Most of the fish, and Dorudon whale remains showed signs of breakage and bite marks, were fragmented, and tended to be clustered within the body cavity of the B. isis specimen.

One hypothesis to explain the clustering of these remains was that D. atrox had scavenged the B. isis carcass and fish. However, the D. atrox were juveniles, capable only of drinking mother's milk. Bite marks on prey skulls also indicated predation rather than scavenging, since predators commonly target the head. The authors therefore position B. isis as a top predator which ate its prey live, rather than by scavenging. They propose that the remains of fish and juvenile D. atrox in the cluster are remnants of previous B. isis meals, while the teeth of sharks indicate postmortem scavenging.

Voss and colleagues draw a comparison with the modern-day killer whale (Orcinus orca), another toothed whale apex predator which often feeds on smaller whales and frequently hunts humpback whale calves during humpback calving season. The authors hypothesize that the Wadi Al Hitan site was a whale calving site for prey whale Dorudon, making it a hunting site for top predator B. isis during the late Eocene.

From Science Daily

Research explains public resistance to vaccination

Social imitation dynamics of vaccination can exhibit hysteresis. This figure illustrates a hysteresis loop in relation to outbreaks of measles and other childhood diseases in Europe and North America.

Why is it so challenging to increase the number of people who get vaccinated? How does popular resistance to vaccination remain strong even as preventable diseases make a comeback?

A new study from Dartmouth College shows that past problems with vaccines can cause a phenomenon known as hysteresis, creating a negative history that stiffens public resolve against vaccination. The finding explains why it is so hard to increase uptake even when overwhelming evidence indicates that vaccines are safe and beneficial.

A hysteresis loop causes the impact of a force to be observed even after the force itself has been eliminated. It's why unemployment rates can sometimes remain high in a recovering economy. It's why physical objects resist returning to their original state after being acted on by an outside force. And, according to the Dartmouth research, it's why the public resists vaccination campaigns for ailments like the common flu.

"Given all the benefits of vaccination, it's been a struggle to understand why vaccination rates can remain stubbornly low," said Feng Fu, an assistant professor of mathematics at Dartmouth College. "History matters, and we now know that hysteresis is part of the answer."

The research, published in the journal Proceedings of the Royal Society B, is the first study to demonstrate that hysteresis can impact public health.

"Once people question the safety or effectiveness of a vaccine, it can be very difficult to get them to move beyond those negative associations. Hysteresis is a powerful force that is difficult to break at a societal level," said Fu, who led the research team.

Low vaccine compliance is a public health issue that can cause the loss of "herd immunity" and lead to the spread of infectious diseases. In parts of Europe and North America, childhood diseases like measles, mumps and pertussis have returned as a result of insufficient vaccination coverage.

Previous studies have combined behavior models with epidemiology to understand the challenge of voluntary vaccination, but have been unable to completely explain the persistence of low vaccine compliance. The Dartmouth research specifically studies how past problems associated with vaccinations can impact present and future vaccination decisions.

"This study shows why it is so hard to reverse low or declining vaccine levels," said Xingru Chen, a graduate student at Dartmouth and the first author of the research paper. "The sheer force of factual, logical arguments around public health issues is just not enough to overcome hysteresis and human behavior."

According to the research, the hysteresis loop can be caused by questions related to the risk and effectiveness of vaccines. Negative experiences or perceptions related to vaccination impact the trend of uptake over time -- known to the researchers as a "vaccination trajectory" that gets stuck in the hysteresis loop.

Hysteresis prevents an increase in vaccination levels even after the negative objections have been cleared, making society increasingly vulnerable to disease outbreaks.

"When it comes to vaccination levels, the past predicts the future. Unfortunately, this means that a lot of people are going to needlessly suffer unless we find a way to break the negative impact of the hysteresis loop," said Fu.

The study refers to the example of whole-cell pertussis vaccine in England and Wales in the period from 1978 through 1992. It took that 15-year span for uptake of the "whooping cough" vaccine to recover from 30 percent to 91 percent. According to the research team, such a recovery should only take about a year under ideal circumstances.

The research also notes the slow increase in measles vaccination in the face of resurgent outbreaks. In some countries, like France, measles has become an endemic disease despite the availability of an effective vaccine.

According to the study: "The coverage of measles vaccination has only gradually climbed up, but still remains insufficient, for more than a decade following the infamous MMR vaccination and autism controversy."

"Vaccination levels in a population can drop quickly, but, because of hysteresis, the recovery in that same population can take many years," said Chen.

For the common flu, the study suggests that a vaccine would have to have an effectiveness of above 50 percent in order to achieve high levels of vaccination, a difficult level to reach because of the speed with which the illness mutates.

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Nature's magnifying glass reveals unexpected intermediate mass exoplanets

Planet OGLE-2012-BLG-0950Lb was detected through gravitational microlensing, a phenomenon that acts as nature's magnifying glass.

Astronomers have found a new exoplanet that could alter the standing theory of planet formation. With a mass that's between that of Neptune and Saturn, and its location beyond the "snow line" of its host star, an alien world of this scale was supposed to be rare.

Aparna Bhattacharya, a postdoctoral researcher from the University of Maryland and NASA's Goddard Space Flight Center (GSFC), led the team that made the discovery, which was announced today during a press conference at the 233rd Meeting of the American Astronomical Society in Seattle.

Using the Near-Infrared Camera, second generation (NIRC2) instrument on the 10-meter Keck II telescope of the W. M. Keck Observatory on Maunakea, Hawaii and the Wide Field Camera 3 (WFC3) instrument on the Hubble Space Telescope, the researchers took simultaneous high-resolution images of the exoplanet, named OGLE-2012-BLG-0950Lb, allowing them to determine its mass.

"We were surprised to see the mass come out right in the middle of the predicted intermediate giant planet mass gap," said Bhattacharya. "It's like finding an oasis in the middle of the exoplanet desert!"

"I was very pleased with how quickly Aparna completed the analysis," said co-author David Bennett, a senior research scientist at the University of Maryland and GSFC. "She had to develop some new methods to analyze this data -- a type of analysis that had never been done before."

In an uncanny timing of events, another team of astronomers (which included Bhattacharya and Bennett) published a statistical analysis at almost the same time showing that such sub-Saturn mass planets are not rare after all.

"We were just finishing up the analysis when the mass measurements of OGLE-2012- BLG-0950Lb came in," said lead author Daisuke Suzuki of Japan's Institute of Space and Astronautical Science. "This planet confirmed our interpretation of the statistical study."

The teams' results on OGLE-2012-BLG-0950Lb are published in the December issue of The Astronomical Journal and the statistical study was published in the December 20th issue of the Astrophysical Journal Letters.

OGLE-2012-BLG-0950Lb was among the sub-Saturn planets in the statistical study; all were detected through microlensing, the only method currently sensitive enough to detect planets with less than Saturn's mass in Jupiter-like orbits.

Microlensing leverages a consequence of Einstein's theory of general relativity: the bending and magnification of light near a massive object like a star, producing a natural lens on the sky. In the case of OGLE-2012-BLG-0950Lb, the light from a distant background star was magnified by OGLE-2012-BLG-0950L (the exoplanet's host star) over the course of two months as it passed close to perfect alignment in the sky with the background star.

By carefully analyzing the light during the alignment, an unexpected dimming with a duration of about a day was observed, revealing the presence of OGLE-2012-BLG-0950Lb via its own influence on the lensing.

METHODOLOGY

OGLE-2012-BLG-0950Lb was first detected by the microlensing survey telescopes of the Optical Gravitational Lensing Experiment (OGLE) and the Microlensing Observations in Astrophysics (MOA) collaborations.

Bhattacharya's team then conducted follow-up observations using Keck Observatory's powerful adaptive optics system in combination with NIRC2.

"The Keck observations allowed us to determine that the sub-Saturn or super-Neptune size planet has a mass of 39 times that of the Earth, and that its host star is 0.58 times the mass of the Sun," said Bennett. "They measured the separation of the foreground planetary system from the background star. This allowed us to work out the complete geometry of the microlensing event. Without this data, we only knew the star-planet mass ratio, not the individual masses."

For the statistical study, Suzuki's team and MOA analyzed the properties of 30 sub-Saturn planets found by microlensing and compared them to predictions from the core accretion theory.

CHALLENGING THE THEORY

What is unique about the microlensing method is its sensitivity to sub-Saturn planets like OGLE-2012-BLG-0950Lb that orbit beyond the "snow line" of their host stars.

The snow line, or frost line, is the distance in a young solar system, (a.k.a. a protoplanetary disk) at which it is cold enough for water to condense into ice. At and beyond the snow line there is a dramatic increase in the amount of solid material needed for planet formation. According to the core accretion theory, the solids are thought to build up into planetary cores first through chemical and then gravitational processes.

"A key process of the core accretion theory is called "runaway gas accretion," said Bennett. "Giant planets are thought to start their formation process by collecting a core mass of about 10 times the Earth mass in rock and ice. At this stage, a slow accretion of hydrogen and helium gas begins until the mass has doubled. Then, the accretion of hydrogen and helium is expected to speed up exponentially in this runaway gas accretion process. This process stops when the supply is exhausted. If the supply of gas is stopped before runaway accretion stops, we get "failed Jupiter" planets with masses of 10-20 Earth-masses (like Neptune)."

The runaway gas accretion scenario of the core accretion theory predicts that planets like OGLE-2012- BLG-0950Lb are expected to be rare. At 39 times the mass of the Earth, planets this size are thought to be continuing through a stage of rapid growth, ending in a much more massive planet. This new result suggests that the runaway growth scenario may need revision.

Suzuki's team compared the distribution of planet-star mass ratios found by microlensing to distributions predicted by the core accretion theory.

They found that the core accretion theory's runaway gas accretion process predicts about 10 times fewer intermediate mass giant planets like OGLE-2012- BLG-0950Lb than are seen in the microlensing results.

This discrepancy implies that gas giant formation may involve processes that have been overlooked by existing core accretion models, or that the planet forming environment varies considerably as a function of host star mass.

NEXT STEPS

This discovery has not only called into question an established theory, it was made using a new technique that will be a key part of NASA's next big planet finding mission, the Wide Field Infra-Red Survey Telescope (WFIRST), which is scheduled to launch into orbit in the mid-2020s.

"This is exactly the method that WFIRST will use to measure the masses of the planets that it discovers with its exoplanet microlensing survey. Until WFIRST comes online, we need to develop this method with observations from our Keck Key Strategic Mission Support (KSMS) program as well as observations from Hubble," said Bennett.

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Insomnia has many faces

Researchers at the Netherlands Institute for Neuroscience revealed that there are five types of insomnia. This finding was published on Monday January 7 by The Lancet Psychiatry. A commentary in the journal stated that the finding could be a new page in the history of insomnia, promoting discoveries on mechanisms and interventions.

Insomnia is a major problem

One out of ten people suffer from chronic insomnia: it's the second-most prevalent and burdensome mental disorder. Findings on underlying brain mechanisms have been inconsistent. Treatment that is effective for some, gives no relief to others. Insomnia has remained an enigma. Thanks to volunteers of the internet-platform slaapregister.nl there is now hope for faster discoveries.

Insomnia has many faces

With the help of thousands of volunteers, Drs. Tessa Blanken and her colleagues at the Netherlands Institute for Neuroscience now revealed why it has been so difficult to find consistent brain mechanisms and treatment effects. "While we have always considered insomnia to be one disorder, it actually represents five different disorders. Underlying brain mechanisms may be very different. For comparison: progress in our understanding of dementia was propelled once we realized that there are different kinds, such as Alzheimer-, vascular-, and frontal-temporal dementia."

Five insomnia types

Surprisingly, the five insomnia types did not differ at all on sleep complaints like difficulty falling asleep versus early morning awakening. Some earlier attempts to define subtypes focused on these sleep complaints, and may therefore have been unsuccessful. Blanken and colleagues identified subtypes by looking beyond sleep complaints. They assessed dozens of questionnaires on personality traits that are known to be rooted in brain structure and function. Insomnia subtypes could be discovered by looking at trait profiles. Type 1 scores high on many distressing traits such as neuroticism and feeling down or tense. Types 2 and 3 experienced less distress and were distinguished by their high versus low sensitivity to reward. Type 4 and 5 experienced even less distress and differed by the way their sleep responded to stressful life events. These induced severe and long-lasting insomnia in type 4, while the sleep of type 5 was unaffected by these events.

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Giant singers from neighboring oceans share song parts over time

Humpback whales.

Singing humpback whales from different ocean basins seem to be picking up musical ideas from afar, and incorporating these new phrases and themes into the latest song, according to a newly published study in Royal Society Open Science that's helping scientists better understand how whales learn and change their musical compositions.

The new research shows that two humpback whale populations in different ocean basins (the South Atlantic and Indian Oceans) in the Southern Hemisphere sing similar song types, but the amount of similarity differs across years. This suggests that males from these two populations come into contact at some point in the year to hear and learn songs from each other.

The study titled "Culturally transmitted song exchange between humpback whales (Megaptera novaeangliae) in the southeast Atlantic and southwest Indian Ocean basins" appears in the latest edition of the Royal Society Open Science journal. The authors are: Melinda L. Rekdahl, Carissa D. King, Tim Collins, and Howard Rosenbaum of WCS (Wildlife Conservation Society); Ellen C. Garland of the University of St. Andrews; Gabriella A. Carvajal of WCS and Stony Brook University; and Yvette Razafindrakoto of COSAP and Madagascar National Parks.

"Song sharing between populations tends to happen more in the Northern Hemisphere where there are fewer physical barriers to movement of individuals between populations on the breeding grounds, where they do the majority of their singing. In some populations in the Southern Hemisphere song sharing appears to be more complex, with little song similarity within years but entire songs can spread to neighboring populations leading to song similarity across years," said Dr. Melinda Rekdahl, marine conservation scientist for WCS's Ocean Giants Program and lead author of the study. "Our study shows that this is not always the case in Southern Hemisphere populations, with similarities between both ocean basin songs occurring within years to different degrees over a 5-year period."

The study authors examined humpback whale song recordings from both sides of the African continent -- from animals off the coasts of Gabon and Madagascar respectively -- and transcribed more than 1,500 individual sounds that were recorded between 2001-2005. Song similarity was quantified using statistical methods.

Male humpback whales are one of the animal kingdom's most noteworthy singers, and individual animals sing complex compositions consisting of moans, cries, and other vocalizations called "song units." Song units are composed into larger phrases, which are repeated to form "themes." Different themes are produced in a sequence to form a song cycle that are then repeated for hours, or even days. For the most part, all males within the same population sing the same song type, and this population-wide song similarity is maintained despite continual evolution or change to the song leading to seasonal "hit songs." Some song learning can occur between populations that are in close proximity and may be able to hear the other population's song.

Over time, the researchers detected shared phrases and themes in both populations, with some years exhibiting more similarities than others. In the beginning of the study, whale populations in both locations shared five "themes." One of the shared themes, however, had differences. Gabon's version of Theme 1, the researchers found, consisted of a descending "cry-woop," whereas the Madagascar singers split Theme 1 into two parts: a descending cry followed by a separate woop or "trumpet."

Other differences soon emerged over time. By 2003, the song sung by whales in Gabon became more elaborate than their counterparts in Madagascar. In 2004, both population song types shared the same themes, with the whales in Gabon's waters singing three additional themes. Interestingly, both whale groups had dropped the same two themes from the previous year's song types. By 2005, songs being sung on both sides of Africa were largely similar, with individuals in both locations singing songs with the same themes and order. However, there were exceptions, including one whale that revived two discontinued themes from the previous year.

The study's results stands in contrast to other research in which a song in one part of an ocean basin replaces or "revolutionizes" another population's song preference. In this instance, the gradual changes and degrees of similarity shared by humpbacks on both sides of Africa was more gradual and subtle.

"Studies such as this one are an important means of understanding connectivity between different whale populations and how they move between different seascapes," said Dr. Howard Rosenbaum, Director of WCS's Ocean Giants Program and one of the co-authors of the new paper. "Insights on how different populations interact with one another and the factors that drive the movements of these animals can lead to more effective plans for conservation."

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Physics can show us the inside of tumors

Dark red indicates the most rigid areas, towards the interior of the tumor. The edge is less rigid (yellow-green).

A team of physicists at the Institut Lumière Matière (CNRS/Université Claude Bernard Lyon 1), in collaboration with the Cancer Research Center of Lyon (CNRS/INSERM/ Université Claude Bernard Lyon 1//Centre Léon Bérard/Hospices civils de Lyon), has demonstrated the potential, for oncology, of an imaging technique based only on the physical properties of tumors. It can differentiate populations of malignant cells and monitor how effective an anticancer treatment is. These results, published in Physical Review Letters on January 8, 2019, should help in the design of new therapeutic molecules and in the personalization of treatments.

Despite a good understanding of the biology of cancer, 90% of experimental drugs fail during clinical trials. It is also increasingly suspected that the mechanical properties of tumors influence disease progression, and treatment efficacy. Although we can evaluate tumor elasticity globally, it is more difficult to measure local rigidity deep down and to see whether the core of the tumor resists the penetration of therapeutic liquids. To probe these physical properties, the researchers have used a noncontact imaging technique that does not require the use of contrast agents -- therefore that does not disturb tissue function -- that exploits natural infinitesimal vibrations of matter.

To recapitulate the behavior of colorectal tumors in vitro, the researchers created organoids, spheres with diameter 0.3 mm formed by the aggregation of tumor cells. They focused a red laser beam onto these objects. The infinitesimal vibrations of the sample, generated by thermal agitation, modify very slightly the color of the light beam that exits the sample. By analyzing this light, a map of the mechanical properties of the model tumors is created: the more rigid the area scanned by the laser, the faster the vibrations and, in a manner comparable to the Doppler effect (the mechanism that makes a siren sound increasingly shrill as it gets closer), the greater the color change.

From organoids composed of two cell lines with different malignancies, the researchers have shown that they could distinguish the two cell types from their mechanical properties. Such information is crucial because it may allow diagnosis from biopsy analysis to be refined and offer better assessment of tumor grade. Local variations in mechanical properties after a drug treatment have also been monitored using this technique: the center of the tumor remains rigid longer than the edge, demonstrating the treatment's efficacy gradient. So local measurement of mechanical properties could confirm the total destruction of the tumor and help in choosing as low a treatment dose and duration as possible.

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Space microbes aren't so alien after all

The International Space Station photographed by Expedition 56 crew members from a Soyuz spacecraft after undocking.

Microbes stranded in the International Space Station (ISS) are just trying to survive, man.

A new Northwestern University study has found that -- despite its seemingly harsh conditions -- the ISS is not causing bacteria to mutate into dangerous, antibiotic-resistant superbugs.

While the team found that the bacteria isolated from the ISS did contain different genes than their Earthling counterparts, those genes did not make the bacteria more detrimental to human health. The bacteria are instead simply responding, and perhaps evolving, to survive in a stressful environment.

"There has been a lot of speculation about radiation, microgravity and the lack of ventilation and how that might affect living organisms, including bacteria," said Northwestern's Erica Hartmann, who led the study. "These are stressful, harsh conditions. Does the environment select for superbugs because they have an advantage? The answer appears to be 'no.'"

The study was published today (Jan. 8) in the journal mSystems. Hartmann is an assistant professor of environmental engineering in Northwestern's McCormick School of Engineering.

As the conversation about sending travelers to Mars gets more serious, there has been an increasing interest in understanding how microbes behave in enclosed environments.

"People will be in little capsules where they cannot open windows, go outside or circulate the air for long periods of time," said Hartmann. "We're genuinely concerned about how this could affect microbes."

The ISS houses thousands of different microbes, which have traveled into space either on astronauts or in cargo. The National Center for Biotechnology Information maintains a publicly available database, containing the genomic analyses of many of bacteria isolated from the ISS. Hartmann's team used that data to compare the strains of Staphylococcus aureus and Bacillus cereus on the ISS to those on Earth.

Found on human skin, S. aureus contains the tough-to-treat MRSA strain. B. cereus lives in soil and has fewer implications for human health.

"Bacteria that live on skin are very happy there," Hartmann said. "Your skin is warm and has certain oils and organic chemicals that bacteria really like. When you shed those bacteria, they find themselves living in a very different environment. A building's surface is cold and barren, which is extremely stressful for certain bacteria."

To adapt to living on surfaces, the bacteria containing advantageous genes are selected for or they mutate. For those living on the ISS, these genes potentially helped the bacteria respond to stress, so they could eat, grow and function in a harsh environment.

"Based on genomic analysis, it looks like bacteria are adapting to live -- not evolving to cause disease," said Ryan Blaustein, a postdoctoral fellow in Hartmann's laboratory and the study's first author. "We didn't see anything special about antibiotic resistance or virulence in the space station's bacteria."

Although this is good news for astronauts and potential space tourists, Hartmann and Blaustein are careful to point out that unhealthy people can still spread illness on space stations and space shuttles.

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Medical scanner helps to unlock the mysteries of a giant prehistoric marine reptile

Thinktank ichthyosaur skull: CT-scanning copyright.

A nearly metre-long skull of a giant fossil marine ichthyosaur found in a farmer's field more than 60 years ago has been studied for the first time.

Using cutting-edge computerised tomography (CT) scanning technology, the research reveals new information including details of the rarely preserved braincase.

The almost 200 million year old fossil, which was found in 1955 at Fell Mill Farm in Warwickshire, had never formally been studied prior to this research.

Now, thanks to data collected from CT scans, the research team were able to digitally reconstruct the entire skull in 3D. It is the first time a digital reconstruction of a skull and mandible of a large marine reptile has ever been made available for research purposes and to the public.

Although thousands of ichthyosaur fossils have been unearthed in the UK, this specimen is particularly important and unusual because it is three-dimensionally preserved and contains bones of the skull that are rarely exposed.

In 2014, as part of a project at Thinktank Science Museum, Birmingham, palaeontologists Dean Lomax, from The University of Manchester, and Nigel Larkin began to study the skull and its incomplete skeleton for the first time and were soon convinced of its importance.

Dean, the lead author and one of the world's leading ichthyosaur experts, explains: "The first time I saw this specimen I was puzzled by its excellent preservation.

Ichthyosaurs of this age (Early Jurassic) are usually 'pancaked', meaning that they are squished so that the original structure of the skull is either not preserved or is distorted or damaged. So to have a skull and portions of the skeleton of an ichthyosaur of this age preserved in three dimensions, and without any surrounding rock obscuring it, is something quite special."

The ichthyosaur was originally identified as a common species called Ichthyosaurus communis, but after studying it closer, Dean was convinced it was a rarer species. Based on various features of the skull, he identified it as an example of an ichthyosaur called Protoichthyosaurus prostaxalis. With a skull almost twice as long as any other specimen of Protoichthyosaurus, this is the largest specimen so far known of the species.

Co-author Nigel Larkin added: "Initially, the aim of the project was to clean and conserve the skull and partially dismantle it to rebuild it more accurately, ready for redisplay at the Thinktank Museum. But we soon realised that the individual bones of the skull were exceptionally well preserved in three dimensions, better than in any other ichthyosaur skull we'd seen. Furthermore, that they would respond well to CT scanning, enabling us to capture their shape digitally and to see their internal details. This presented an opportunity that couldn't be missed"

The skull isn't quite complete, but several bones of the braincase -- which are rarely preserved in ichthyosaurs -- are present. To unlock information contained in the skull, these bones were micro-CT scanned at Cambridge University in 2015 by expert palaeontologist and co-author, Dr Laura Porro of University College London (UCL).

The fossil only preserved bones from the left side of the braincase; however, using CT scans these elements were digitally mirrored and 3D printed at life size to complete the braincase. Finally, the entire skull was CT scanned at the Royal Veterinary College (RVC) using a scanner typically reserved for horses and other large animals.

Dr Porro added: "CT scanning allows us to look inside fossils -- in this case, we could see long canals within the skull bones that originally contained blood vessels and nerves. Scans also revealed the curation history of the specimen since its discovery in the '50s. There were several areas reconstructed in plaster and clay, and one bone was so expertly modelled that only the scans revealed part of it was a fake. Finally there is the potential to digitally reconstruct the skull in 3D. This is hard (and risky) to do with the original, fragile and very heavy fossil bones; plus, we can now make the 3D reconstruction freely available to other scientists and for education."

The use of modern technologies, such as medical scanners, have revolutionised the way in which palaeontologists are able to study and describe fossils.

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TESS discovers its third new planet, with longest orbit yet

NASA’s TESS mission, which will survey the entire sky over the next two years, has already discovered three new exoplanets around nearby stars.

NASA's Transiting Exoplanet Survey Satellite, TESS, has discovered a third small planet outside our solar system, scientists announced this week at the annual American Astronomical Society meeting in Seattle.

The new planet, named HD 21749b, orbits a bright, nearby dwarf star about 53 light years away, in the constellation Reticulum, and appears to have the longest orbital period of the three planets so far identified by TESS. HD 21749b journeys around its star in a relatively leisurely 36 days, compared to the two other planets -- Pi Mensae b, a "super-Earth" with a 6.3-day orbit, and LHS 3844b, a rocky world that speeds around its star in just 11 hours. All three planets were discovered in the first three months of TESS observations.

The surface of the new planet is likely around 300 degrees Fahrenheit -- relatively cool, given its proximity to its star, which is almost as bright as the sun.

"It's the coolest small planet that we know of around a star this bright," says Diana Dragomir, a postdoc in MIT's Kavli Institute for Astrophysics and Space Research, who led the new discovery. "We know a lot about atmospheres of hot planets, but because it's very hard to find small planets that orbit farther from their stars, and are therefore cooler, we haven't been able to learn much about these smaller, cooler planets. But here we were lucky, and caught this one, and can now study it in more detail."

The planet is about three times the size of Earth, which puts it in the category of a "sub-Neptune." Surprisingly, it is also a whopping 23 times as massive as Earth. But it is unlikely that the planet is rocky and therefore habitable; it's more likely made of gas, of a kind that is much more dense than the atmospheres of either Neptune or Uranus.

"We think this planet wouldn't be as gaseous as Neptune or Uranus, which are mostly hydrogen and really puffy," Dragomir says. "The planet likely has a density of water, or a thick atmosphere."

Serendipitously, the researchers have also detected evidence of a second planet, though not yet confirmed, in the same planetary system, with a shorter, 7.8-day orbit. If it is confirmed as a planet, it could be the first Earth-sized planet discovered by TESS.

In addition to presenting their results at the AAS meeting, the researchers have submitted a paper to Astrophysical Journal Letters.

"Something there"

Since it launched in April 2018, TESS, an MIT-led mission, has been monitoring the sky, sector by sector, for momentary dips in the light of about 200,000 nearby stars. Such dips likely represent a planet passing in front of that star.

The satellite trains its four onboard cameras on each sector for 27 days, taking in light from the stars in that particular segment before shifting to view the next one. Over its two-year mission, TESS will survey nearly the entire sky by monitoring and piecing together overlapping slices of the night sky. The satellite will spend the first year surveying the sky in the Southern Hemisphere, before swiveling around to take in the Northern Hemisphere sky.

The mission has released to the public all the data TESS has collected so far from the first three of the 13 sectors that it will monitor in the southern sky. For their new analysis, the researchers looked through this data, collected between July 25 and Oct. 14.

Within the sector 1 data, Dragomir identified a single transit, or dip, in the light from the star HD 21749. As the satellite only collects data from a sector for 27 days, it's difficult to identify planets with orbits longer than that time period; by the time a planet passes around again, the satellite may have shifted to view another slice of the sky.

To complicate matters, the star itself is relatively active, and Dragomir wasn't sure if the single transit she spotted was a result of a passing planet or a blip in stellar activity. So she consulted a second dataset, collected by the High Accuracy Radial velocity Planet Searcher, or HARPS, a high-precision spectrograph installed on a large ground-based telescope in Chile, which identifies exoplanets by their gravitational tug on their host stars.

"They had looked at this star system a decade ago and never announced anything because they weren't sure if they were looking at a planet versus the activity of the star," Dragomir says. "But we had this one transit, and knew something was there."

Stellar detectives

When the researchers looked through the HARPS data, they discovered a repeating signal emanating from HD 21749 every 36 days. From this, they estimated that, if they indeed had seen a transit in the TESS data from sector 1, then another transit should appear 36 days later, in data from sector 3. When that data became publicly available, a momentary glitch created a gap in the data just at the time when Dragomir expected the second transit to occur.

"Because there was an interruption in data around that time, we initially didn't see a second transit, and were pretty disappointed," Dragomir recalls. "But we re-extracted the data and zoomed in to look more carefully, and found what looked like the end of a transit."

She and her colleagues compared the pattern to the first full transit they had originally discovered, and found a near perfect match -- an indication that the planet passed again in front of its star, in a 36-day orbit.

"There was quite some detective work involved, and the right people were there at the right time," Dragomir says. "But we were lucky and we caught the signals, and they were really clear."

They also used data from the Planet Finder Spectrograph, an instrument installed on the Magellan Telescope in Chile, to further validate their findings and constrain the planet's mass and orbit.

Once TESS has completed its two-year monitoring of the entire sky, the science team has committed to delivering information on 50 small planets less than four times the size of Earth to the astronomy community for further follow-up, either with ground-based telescopes or the future James Webb Space Telescope.

"We've confirmed three planets so far, and there are so many more that are just waiting for telescope and people time to be confirmed," Dragomir says. "So it's going really well, and TESS is already helping us to learn about the diversity of these small planets."

Read more at Science Daily