Astronomers make first calculations of magnetic activity in 'hot Jupiter' exoplanets

Gas-giant planets orbiting close to other stars have powerful magnetic fields, many times stronger than our own Jupiter, according to a new study by a team of astrophysicists. It is the first time the strength of these fields has been calculated from observations.

The team, led by Wilson Cauley of the University of Colorado, also includes associate professor Evgenya Shkolnik of Arizona State University's School of Earth and Space Exploration. The other researchers are Joe Llama of Northern Arizona University and Antonino Lanza of the Astrophysical Observatory of Catania in Italy. Their report was published July 22 in Nature Astronomy.

"Our study is the first to use observed signals to derive exoplanet magnetic field strengths," says Shkolnik. "These signals appear to come from interactions between the magnetic fields of the star and the tightly orbiting planet."

Many worlds

More than 3,000 exoplanet systems containing over 4,000 planets have been discovered since 1988. Many of these star systems include what astronomers call "hot Jupiters." These are massive gaseous planets presumed to be like the Sun's Jupiter but orbiting their stars at close distances, typically about five times the star's diameter, or roughly 20 times the Moon's distance from Earth.

Such planets travel well inside their star's magnetic field, where interactions between the planetary field and the stellar one can be continual and strong.

Previous studies, the team says, have placed upper limits on exoplanet magnetic fields, for example from radio observations or derived purely from theory.

"We combined measurements of increased stellar emission from the magnetic star-planet interactions together with physics theory to calculate the magnetic field strengths for four hot Jupiters," says lead author Cauley.

The magnetic field strengths the team found range from 20 to 120?gauss. For comparison, Jupiter's magnetic field is 4.3 gauss and Earth's field strength is only half a gauss, although that is strong enough to orient compasses worldwide.

Triggering activity

The astrophysicists used telescopes in Hawaii and France to acquire high-resolution observations of emission from ionized calcium (Ca II) in the parent stars of the four hot Jupiters. The emission comes from a star's hot, magnetically heated chromosphere, a thin layer of gas above the cooler stellar surface. The observations let the team calculate how much energy was being released in the stars' calcium emission.

Says Shkolnik, "We used the power estimates to calculate magnetic field strengths for the planets using a theory for how the planets' magnetic fields interact with the stellar magnetic fields."

Cauley explains, "Magnetic fields like to be in a state of low energy. If you twist or stretch the field like a rubber band, this increases the energy stored in the magnetic field." Hot Jupiters orbit very close to their parent stars and so the planet's magnetic field can twist and stretch the star's magnetic field.

"When this happens," Cauley says,"energy can be released as the two fields reconnect, and this heats the star's atmosphere, increasing the calcium emission."

Probing deep

Astrophysicists have suspected that hot Jupiters would, like our own Jupiter, have magnetic fields produced deep inside them. The new observations provide the first probe of the internal dynamics of these massive planets.

"This is the first estimate of the magnetic field strengths for these planets based on observations, so it's a huge jump in our knowledge," Shkolnik notes. "It's giving us a better understanding of what is happening inside these planets."

She adds that it should also help researchers who model the internal dynamos of hot Jupiters. "We knew nothing about their magnetic fields -- or any other exoplanet magnetic fields -- and now we have estimates for four actual systems."

Surprisingly powerful

The field strengths, the team says, are larger than one would expect considering only the rotation and age of the planet. The standard dynamo theory of planetary magnetic fields predicts field strengths for the sampled planets that are much smaller than what the team found.

Instead, the observations support the idea that planetary magnetic fields depend on the amount of heat moving through the planet's interior. Because they are absorbing a lot of extra energy from their host stars, hot Jupiters should have larger magnetic fields than planets of similar mass and rotation rate.

Read more at Science Daily

Astronomers map vast void in our cosmic neighborhood

Milky Way

An astronomer from the University of Hawaii Institute for Astronomy and an international team published a new study that reveals more of the vast cosmic structure surrounding our Milky Way galaxy.

The universe is a tapestry of galaxy congregations and vast voids. In a new study being reported in The Astrophysical Journal, Brent Tully's team applies the same tools from an earlier study to map the size and shape of an extensive empty region they called the Local Void that borders the Milky Way galaxy. Using the observations of galaxy motions, they infer the distribution of mass responsible for that motion, and construct three-dimensional maps of our local Universe.

Galaxies not only move with the overall expansion of the universe, they also respond to the gravitational tug of their neighbors and regions with a lot of mass. As a consequence, relative to the overall expansion they are moving towards the densest areas and away from regions with little mass -- the voids.

Although we live in a cosmic metropolis, back in 1987 Tully and Richard Fisher noted that our Milky Way galaxy is also at the edge of an extensive empty region that they called the Local Void. The existence of the Local Void has been widely accepted, but it remained poorly studied because it lies behind the center of our galaxy and is therefore heavily obscured from our view.

Now, Tully and his team have measured the motions of 18,000 galaxies in the Cosmicflows-3 compendium of galaxy distances, constructing a cosmographic map that highlights the boundary between the collection of matter and the absence of matter that defines the edge of the Local Void. They used the same technique in 2014 to identify the full extent of our home supercluster of over one hundred thousand galaxies, giving it the name Laniakea, meaning "immense heaven" in Hawaiian.

For 30 years, astronomers have been trying to identify why the motions of the Milky Way, our nearest large galaxy neighbor Andromeda, and their smaller neighbors deviate from the overall expansion of the Universe by over 600 km/s (1.3 million mph). The new study shows that roughly half of this motion is generated "locally" from the combination of a pull from the massive nearby Virgo Cluster and our participation in the expansion of the Local Void as it becomes ever emptier.

An 11-minute video demonstrating the shape and extend of these cosmic structures is available online at:

https://vimeo.com/326346346

Interactive visualizations that allow the user to rotate, pan, and zoom maps of the mass distribution can be found at:

https://sketchfab.com/models/f0a44df256aa4faf93391887d66010e2

https://sketchfab.com/models/78885b3d303d4b6e99cfe099b43929fb

From Science Daily

Using antibiotics without a prescription is a prevalent public health problem

Antibiotics illustration.

People using antibiotics without a prescription seems to be a prevalent public health problem. Antibiotics were obtained through various means, including saving leftover prescriptions for later use, getting them from friends and family, or obtaining them from local markets "under the counter." Findings from a scoping review are published in Annals of Internal Medicine.

When people take antibiotics without a prescription, they often take unnecessary medication or choose an inappropriate drug or dose. This practice is associated with avoidable adverse events and may also increase the risk for inducing antibiotic resistance. It is important to understand how prevalent nonprescription antibiotic use is and the factors that contribute to the issue.

Researchers from Baylor College of Medicine and the Center for Innovations in Quality, Effectiveness, and Safety reviewed 31 published studies to determine the prevalence of nonprescription antibiotic use in the U.S. and to examine the factors that influence that use. The prevalence of nonprescription antibiotic use varied from 1 percent among people visiting a clinic to 66 percent among Latino migrant workers. Storage of antibiotics for future use varied from 14 percent to 48 percent and a quarter of the people in one study reported intention to use antibiotics without a prescription.

Factors that contribute to nonprescription use include lack of insurance or health care access, cost of a physician visit or prescription, embarrassment about seeking care for a sexually transmitted infection, not being able to get time off of work to visit a clinic or physician's office, and several other reasons. According to the researchers, more studies are needed to quantitate nonprescription antibiotic use and explore potentially modifiable factors that contribute to unsafe practices.

From Science Daily

More sensitive climates are more variable climates

Power plant

A decade without any global warming is more likely to happen if the climate is more sensitive to carbon dioxide emissions, new research has revealed.

A team of scientists from the University of Exeter and the Centre of Ecology and Hydrology in the UK has conducted pioneering new research into why both surges and slowdowns of warming take place.

Using sophisticated climate models the team, led by PhD student Femke Nijsse, discovered if the climate was more sensitive to CO2 concentration also displayed larger variations of warming over a decade.

When combined with information from simulations without any carbon dioxide increases, the authors were able to assess the natural variability of each climate model.

The research is published this week in Nature Climate Change.

Femke Nijsse, from the University of Exeter, said: "We were surprised to see that even when we took into account that sensitive climate models warm more over the last decades of the 20th century, these sensitive models were still more likely to have short periods of cooling."

Climate sensitivity, which sits at the very heart of climate science, is the amount of global warming that takes place as atmospheric CO2 concentrations rise.

For many years, estimates have put climate sensitivity somewhere between 1.5-4.5°C of warming for a doubling of pre-industrial CO2 levels.

The study found that cooling -- or "hiatus" -- decades were more than twice as likely around the turn of the century in high sensitivity models (models that warm 4.5 ºC after doubling CO2), compared to low sensitivity models (models that warm 1.5 ºC after doubling CO2).

Co-author Dr. Mark Williamson, A Research Fellow at Exeter: "This does not mean that the presence of a global warming slowdown at the beginning of the 21st century implies we live in a highly sensitive world.

"By looking at all decades together, we get a better picture and find observations are broadly consistent with a central estimate of climate sensitivity"

Ms Nijsse added: "We still don't exactly know how much the climate system will heat up, nor do we know exactly what the range of natural variability in trends will be over the coming decades. But our study shows that these risks should not be considered as separate."

The paper also studied the chance that a decade in the 21st century could warm by as much as the entire 20th century -- a scenario that the research team call "hyperwarming."

Under a scenario where carbon dioxide emissions from fossil fuels continue to increase, the chance of hyperwarming is even more dependent on climate sensitivity than the long-term global warming trend.

Read more at Science Daily

The early days of the Milky Way revealed

Spiral galaxy illustration

The universe 13,000 million years ago was very different from the universe we know today. It is understood that stars were forming at a very rapid rate, forming the first dwarf galaxies, whose mergers gave rise to the more massive present-day galaxies, including our own. However the exact chain of the events which produced the Milky Way was not known until now.

Exact measurements of position, brightness and distance for around a million stars of our galaxy within 6,500 light years of the sun, obtained with the Gaia space telescope, have allowed a team from the IAC to reveal some of its early stages. "We have analyzed, and compared with theoretical models, the distribution of colours and magnitudes (brightnesses) of the stars in the Milky Way, splitting them into several components; the so-called stellar halo (a spherical structure which surrounds spiral galaxies) and the thick disc (stars forming the disc of our Galaxy, but occupying a certain height range)" explains Carme Gallart, a researcher at the IAC and the first author of this article, which is published today in the journal Nature Astronomy.

Previous studies had discovered that the Galactic halo showed clear signs of being made up of two distinct stellar components, one dominated by bluer stars than the other. The movement of the stars in the blue component quickly allowed us to identify it as the remains of a dwarf galaxy (Gaia-Enceladus) which impacted onto the early Milky Way. However the nature of the red population, and the epoch of the merger between Gaia-Enceladus and our Galaxy were unknown until now.

"Analyzing the data from Gaia has allowed us to obtain the distribution of the ages of the stars in both components and has shown that the two are formed by equally old stars, which are older than those of the thick disc" says IAC researcher and co-author Chris Brook. But if both components were formed at the same time, what differentiates one from the other? "The final piece of the puzzle was given by the quantity of "metals" (elements which are not hydrogen or helium) in the stars of one component or the other" explains Tomás Ruiz Lara, an IAC researcher and another of the authors of the article. "The stars in the blue component have a smaller quantity of metals than those of the red component." These findings, with the addition of the predictions of simulations which are also analyzed in the article, have allowed the researchers to complete the history of the formation of the Milky Way.

Thirteen thousand million years ago stars began to form in two different stellar systems which then merged: one was a dwarf galaxy which we call Gaia-Enceladus, and the other was the main progenitor of our Galaxy, some four times more massive and with a larger proportion of metals. Some ten thousand million years ago there was a violent collision between the more massive system and Gaia-Enceladus. As a result some of its stars, and those of Gaia-Enceladus were set into chaotic motion, and eventually formed the halo of the present Milky Way. After that there were violent bursts of star formation until 6,000 million years ago, when the gas settled into the disc of the Galaxy, and produced what we know as the "thin disc."

Read more at Science Daily

New species of pocket shark identified

A team of researchers, including two from Tulane University, has identified a new species of pocket shark, following careful study of a pocket shark that made international headlines in 2015 after it was brought to the Royal D. Suttkus Fish Collection at the Tulane University Biodiversity Research Institute.

The 5½-inch male kitefin shark has been identified as the American Pocket Shark, or Mollisquama mississippiensis, based on five features not seen in the only other known specimen of this kind. That specimen was captured in the Eastern Pacific Ocean in 1979 and is now housed at the Zoological Museum in St. Petersburg, Russia.

The details of the new species, which was caught in the Gulf of Mexico in February 2010, are described in an article published in the animal taxonomy journal Zootaxa. The authors include Mark Grace of the NMFS Mississippi Laboratories of the National Oceanic and Atmospheric Administration (NOAA) and Henry Bart and Michael Doosey of the Tulane University Biodiversity Research. Other researchers involved in the study are John S. Denton and Gavin Taylor of the Florida Program for Shark Research at the University of Florida, and John Maisey of the Department of Vertebrate Paleontology at the American Museum of Natural History in New York.

"In the history of fisheries science, only two pocket sharks have ever been captured or reported," Grace said. "Both are separate species, each from separate oceans. Both are exceedingly rare."

Bart added, "The fact that only one pocket shark has ever been reported from the Gulf of Mexico, and that it is a new species, underscores how little we know about the Gulf -- especially its deeper waters -- and how many additional new species from these waters await discovery."

Researchers said there were notable differences between the original Pacific Ocean specimen and the newer specimen from the Gulf of Mexico. Those differences include fewer vertebrae and numerous light-producing photophores that cover much of the body. The two species both have two small pockets that produce luminous fluid (one on each side near the gills).

The pocket shark was collected in February 2010 in the eastern Gulf of Mexico by the NOAA ship Pisces, during a mission to study sperm whale feeding. Much to his surprise, Grace discovered the shark in 2013 while examining specimens that were collected during the NOAA survey. Grace asked Tulane to archive the specimen in its Fish Collection. Soon after, Grace and Tulane postdoctoral researcher Doosey undertook a study to determine what species it was.

Identifying the shark involved examining and photographing external features of the specimen with a dissecting microscope, studying radiographic (x-ray) images and high resolution CT scans. The most sophisticated images of internal features of the shark were produced at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, which uses the most intense source of synchrotron-generated light in the world to produce x-rays 100 billion times brighter than the x-rays used in hospitals.

Read more at Science Daily

Airborne lidar system poised to improve accuracy of climate change models

Researchers have developed a laser-based system that can be used for airborne measurement of important atmospheric gases with unprecedented accuracy and resolution. The ability to collect this data will help scientists better understand how these atmospheric gases affect the climate and could help improve climate change predictions.

In the Optical Society journal Applied Optics, researchers from Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) -- Germany's national center for aerospace, energy and transportation research -- describe how their lidar instrument was used aboard an aircraft to acquire the first simultaneous measurements of the vertical structure of water vapor and ozone in the tropopause region of the atmosphere. The researchers say that the new system might even be useful for monitoring atmospheric gases from space.

The tropopause separates the surface-based troposphere layer where weather takes place from the overlying stratosphere that contains the ozone layer that protects life on Earth from harmful radiation. Scientists want to study water vapor and ozone in the tropopause because the distribution of these atmospheric gases in this layer plays a crucial role in the Earth's climate.

"The ability to detect the vertical structure of water vapor and ozone is critical for understanding the exchange of these atmospheric gases between the troposphere and the stratosphere," said Andreas Fix, who led the research team. "These measurements could help us identify errors and uncertainties in climate models that would help improve predictions of the future climate, which is one of the central challenges for our society and economy."

Gaining a 3D perspective

Atmospheric gases can be assessed with instruments flown into the atmosphere or with data acquired from satellites. However, these methods haven't been able to provide a full picture of atmospheric gas distribution because they either lack the vertical component or don't provide high enough resolution. Although instruments carried with balloons -- known as balloon sondes -- can provide highly resolved vertical profiles they don't offer detailed temporal resolution and can only be used at selected sites.

To solve these problems, the researchers developed a lidar system that uses laser light to measure both ozone and water vapor at the same time. Their approach, called differential absorption lidar (DIAL), uses two slightly different UV wavelengths to measure each gas. The UV radiation at one wavelength is mostly absorbed by the gas molecules while most of the other wavelength is reflected. Measuring the ratio of the UV signals returning from the atmosphere allows calculation of a detailed gas profile.

The gas profiles created using the new lidar system exhibit a vertical resolution of around 250 meters and a horizontal resolution of about 10 kilometers below the aircraft's flight track.

"This vertical capability is a significant advancement in studying exchange processes at the tropopause," said Fix. "It helps overcome significant shortcomings in resolving the fine-scale distribution that have made it difficult to understand processes responsible for exchange at the tropopause."

Achieving energy efficiency

To perform this method aboard a plane, the researchers used a highly efficient optical parametric oscillator (OPO) they previously developed to convert the laser output to the UV wavelengths needed to measure water vapor and ozone. "The conversion needs to be very energy efficient to generate UV radiation with adequate pulse energies and high average power from the limited energy available on board an aircraft," explained Fix.

Tests of the new lidar system showed that its accuracy matched well with that of balloon sondes. In 2017, the researchers flew the new system aboard the wave-driven isentropic exchange (WISE) mission, which involved multiple long-range flights over the North Atlantic and Northern Europe. They found that the instrument worked remarkably well, remained stable during use and could measure characteristic ozone and water vapor distributions at the tropopause.

Read more at Science Daily

Heart disease biomarker linked to paleo diet

People who follow the paleo diet have twice the amount of a key blood biomarker linked closely to heart disease, the world's first major study examining the impact of the diet on gut bacteria has found.

Researchers from Edith Cowan University (ECU) compared 44 people on the diet with 47 following a traditional Australian diet.

The research, published in the European Journal of Nutrition, measured the amount of trimethylamine-n-oxide (TMAO) in participants' blood.

High levels of TMAO, an organic compound produced in the gut, are associated with an increased risk of heart disease, which kills one Australian every 12 minutes.

Impact on gut health

The controversial Paleo (or 'caveman') diet advocates eating meat, vegetables, nuts and limited fruit, and excludes grains, legumes, dairy, salt, refined sugar and processed oils.

Lead researcher Dr Angela Genoni said that with the diet's growing popularity, it was important to understand the impact it could have on overall health.

"Many Paleo diet proponents claim the diet is beneficial to gut health, but this research suggests that when it comes to the production of TMAO in the gut, the Paleo diet could be having an adverse impact in terms of heart health," she said.

"We also found that populations of beneficial bacterial species were lower in the Paleolithic groups, associated with the reduced carbohydrate intake, which may have consequences for other chronic diseases over the long term."

Reduced intake of whole grains to blame

She said the reason TMAO was so elevated in people on the Paleo diet appeared to be the lack of whole grains in their diet.

"We found the lack of whole grains were associated with TMAO levels, which may provide a link between the reduced risks of cardiovascular disease we see in populations with high intakes of whole grains," she said.

The researchers also found higher concentrations of the bacteria that produces TMAO in the Paleo group.

"The Paleo diet excludes all grains and we know that whole grains are a fantastic source of resistant starch and many other fermentable fibres that are vital to the health of your gut microbiome," Dr Genoni said.

"Because TMAO is produced in the gut, a lack of whole grains might change the populations of bacteria enough to enable higher production of this compound.

"Additionally, the Paleo diet includes greater servings per day of red meat, which provides the precursor compounds to produce TMAO, and Paleo followers consumed twice the recommended level of saturated fats, which is cause for concern.

Read more at Science Daily

Warning to those wanting to spice up their lives

Think twice before adding that extra kick of chili sauce or chopped jalapeno to your meal. New research involving the University of South Australia shows a spicy diet could be linked to dementia.

A 15-year study of 4582 Chinese adults aged over 55 found evidence of faster cognitive decline in those who consistently ate more than 50 grams of chili a day. Memory decline was even more significant if the chili lovers were slim.

The study, led by Dr Zumin Shi from Qatar University, showed that those who consumed in excess of 50 grams of chili a day had almost double the risk of memory decline and poor cognition.

"Chili consumption was found to be beneficial for body weight and blood pressure in our previous studies. However, in this study, we found adverse effects on cognition among older adults," Dr Zumin says.

UniSA epidemiologist Dr Ming Li, one of five researchers involved in the study, says chili intake included both fresh and dried chili peppers but not sweet capsicum or black pepper.

"Chili is one of the most commonly used spices in the world and particularly popular in Asia compared to European countries," Dr Li says. "In certain regions of China, such as Sichuan and Hunan, almost one in three adults consume spicy food every day."

Capsaicin is the active component in chili which reportedly speeds up metabolism, fat loss and inhibits vascular disorders but this is the first longitudinal study to investigate the association between chili intake and cognitive function.

Those who ate a lot of chili had a lower income and body mass index (BMI) and were more physically active compared to non-consumers. Researchers say people of normal body weight may be more sensitive to chili intake than overweight people, hence the impact on memory and weight. Education levels may also play a role in cognitive decline and this link requires further research.

From Science Daily

Flying the final approach to Tranquility Base, the moon

As the Apollo 11 Lunar Module approached the Moon's surface for the first manned landing, commander Neil Armstrong switched off the autopilot and flew the spacecraft manuallly to a landing.

A new video, created at Arizona State University's School of Earth and Space Exploration, shows what Armstrong saw out his window as the lander descended -- and you'll see for yourself why he took over control.

A team led by Mark Robinson, principal investigator for the Lunar Reconnaissance Orbiter Camera (LROC) and professor in the School, recreated the view in a striking video. They used the crew's voice recording, the timings, a video taken on film, and images taken from lunar orbit by the LRO Camera over the last 10 years.

Said Robinson, "The only visual record of the actual Apollo 11 landing is from a 16mm time-lapse movie camera, running at 6 frames a second and mounted in Buzz Aldrin's window." Edwin "Buzz" Aldrin was designated as the LM pilot, although for the actual landing his role was to announce the LM's altitude and rates of descent and forward motion. He stood on the right side of the cabin.

"Due to the small size of the lander windows and the angle at which the movie camera was mounted, what mission commander Neil Armstrong saw as he flew the LM to the landing was not recorded," Robinson explained. Armstrong's place was on the cabin's left side.

The LROC team reconstructed the last three minutes of the landing trajectory (latitude, longitude, orientation, velocity, altitude) using lunar landmark navigation and altitude callouts from the crew's voice recording.

Robinson said, "From this trajectory information, and high resolution LROC Narrow-Angle Camera images and topography, we simulated what Armstrong saw in those final minutes as he guided the LM down to the surface of the Moon."

Video: https://youtu.be/ScFJBcLfasQ

As the video begins, Armstrong could see the autopilot was aiming to land on the rocky flank of West Crater (625 feet wide). This caused him to take over manual control and fly horizontally, searching for a safe landing spot. At the time, only Armstrong saw the hazard, and he was too busy flying the LM to discuss the situation with mission control.

After flying over the hazards presented by the bouldery flank of West Crater, Armstrong spotted a safe landing site about 1,600 feet ahead where he carefully descended to the surface. Just before landing, the LM flew over what was later called Little West Crater (135 feet wide). After landing Armstrong visited and photographed this crater during his extravehicular activity.

"Of course, during the landing he was able to lean forward and back and turn his head to gain a view that was better than the simple, fixed viewpoint presented here," said Robinson. "However, our simulated movie lets you relive those dramatic moments."

Robinson points out that because LROC's images were taken almost 50 years after the actual landing, the video shows the lander's descent stage on the surface. (It was used as a launch pad when the astronauts blasted off for their return to Earth.) And the video shows where they disturbed the lunar soil as they walked: look for dark thread-like paths.

Read more at Science Daily