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Mars-sized rogue planet found drifting through the Milky Way

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Oct. 29 (UPI) — Astronomers have discovered a planetary free agent floating through the Milky Way, unbound to the gravity of any nearby stars. The discovery, detailed Thursday in Astrophysical Journal Letters, suggests the Milky Way may be teeming with rogue planets.

The new exoplanet, the smallest free-floating planet astronomers have found, is too small to be directly observed.

Researchers were able to spot the rogue world — which is somewhere between the size of Mars and Earth — with the assistance of a microlensing event.

“If a massive object — a star or a planet — passes between an Earth-based observer and a distant source star, its gravity may deflect and focus light from the source,” lead study author Przemek Mroz, a postdoctoral scholar at the California Institute of Technology, said in a news release. “The observer will measure a short brightening of the source star.”

“Chances of observing microlensing are extremely slim because three objects — source, lens, and observer — must be nearly perfectly aligned,” Mroz said. “If we observed only one source star, we would have to wait almost a million years to see the source being microlensed.”

To increase their odds of locating microlensing events, researchers rely on surveys. In this instance, astronomers utilized data collected by the OGLE survey, featuring a Chilean telescope and led by a team of astronomers at Warsaw University in Poland.

Every night, the OGLE survey’s 1.3-meter Warsaw Telescope scans the Milky Way center, home to hundreds of millions of stars, looking for changes in stellar brightness.

Thankfully, microlensing detection doesn’t depend on the lensing object’s brightness. It’s the lensing object’s mass that matters. The more massive the lensing object, the longer the microlensing event lasts. The microlensing event caused by the recently discovered rogue planet lasted just a few hours.

Researchers were able to calculate the mass of the rogue planet by measuring the light curve and duration of the microlensing event.

“When we first spotted this event, it was clear that it must have been caused by an extremely tiny object,” said study co-author Radoslaw Poleski, researcher at the Astronomical Observatory of the University of Warsaw.

Researchers were able to determine that the lensing object was likely less massive than Earth and about the same size as Mars. Astronomers were also able to determine that the object was without a host star.

“If the lens were orbiting a star, we would detect its presence in the light curve of the event,” said Poleski. “We can rule out the planet having a star within about 8 astronomical units — the astronomical unit is the distance between the Earth and the sun.”

Since OGLE found the first rogue exoplanet several years ago, the survey has discovered several planetary free agents floating through the Milky Way, but the latest — dubbed OGLE-2016-BLG-1928 — is the smallest rogue planet scientists have found.

“Our discovery demonstrates that low-mass free-floating planets can be detected and characterized using ground-based telescopes,” said Andrzej Udalski, principle investigator on the OGLE project.

Astronomers estimate rogue worlds were initially formed around stars inside protoplanetary disks, but were ejected by gravitational interactions with other young planets. By studying the size distribution of rogue planets, scientists expect to gain a greater understanding of planetary formation and evolution.



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Longer-lingering droplets are less efficient carriers of COVID-19 virus

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Oct. 27 (UPI) — New research — published Tuesday in the journal Physics of Fluids — suggests bigger, short-lived aerosol droplets pose a much greater risk of spreading COVID-19 than aerosol microdroplets, which are tiny particles that linger longest in the air.

To better understand the behavior and virus-carrying potential of different types of aerosol droplets, researchers had volunteers breathe, speak and cough into a laser beam, which recorded the size and distribution of the array of aerosolized particles.

Researchers used a Rayleigh jet nozzle chip to generate the same distribution of droplets.

The jet released aerosol droplets composed of 1 percent glycerol and 99 percent ethanol into a chamber. A sheet of laser light running across the middle of the chamber allowed researchers to track the movements of different sized droplets as they moved through the chamber.

Researchers relied on computer models to analyze the disease transmission risk posed by different droplet sizes.

“What we used are simple models for the evaporation and sedimentation, or falling down, of the droplets,” lead study author Daniel Bonn told UPI in an email.

“Together with the measured drop size distribution, this allows us to model the concentration of aerosols in a given room as a function of the time since for instance a patient coughed,” said Bonn, a physicist and the director of the University of Amsterdam’s Van der Waals-Zeeman Institute.

Though microdroplets produced by breathing and talking can remain airborne for longer, they carry much less virus than larger droplets produced by coughs.

“The large drops that are the reason for social distancing are roughly a hundred times larger in diameter than the aerosols, and so contain a million times more virus,” Bonn said.

The models developed by Bonn and his colleagues showed the smallest, longest-lingering particles are relatively inefficient carriers of COVID-19.

That doesn’t mean airborne transmission can’t happen — however, the findings suggest the vast majority of airborne transmission isn’t happening at grocery stores, airports, or larger, well-ventilated public spaces.

According to Bonn and his colleagues, microdroplet transmission is most likely happening in poorly ventilated spaces where groups of people are spending long periods of time in close proximity.

“Avoid small ill-ventilated spaces with too many people in it, take care of good building ventilation, open doors and windows and so on,” Bonn said. “Identify and possibly isolate super-shedders.”

Scientists continue to gain new insights into the behavior to virus-carrying aerosols, including the effects of air flow and humidity on droplet movements, but a comprehensive understanding of the role different droplets play in COVID-19 transmission remains elusive.

“What is needed is a detailed understanding of the reproduction number R, that virologists, aerosol scientists and all other agree with,” Bonn said. “This will help fighting the pandemic, and that is what we need. We have provided a potentially important step towards this goal here, but much experimental, modeling and virology work remains.”



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Mountain gorillas friendly with neighbors outside of core home ranges

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Oct. 28 (UPI) — Mountain gorillas are surprisingly neighborly.

According to a new study published Wednesday in the Journal of Animal Ecology, mountain gorillas act friendly with neighboring gorillas, as long as they stay out of the “core” parts of their territory.

Mountain gorillas occupy what scientists call a “core home range” and a wider “peripheral” range. The apes organize themselves in close-knit groups — eating, sleeping and playing within each range.

Sometimes, groups of mountain gorillas split permanently. When they do, closely related gorillas can find themselves living apart after years of companionship.

The latest study showed old friends and relatives recognize one another years later. Researchers found groups of mountain gorillas that once lived together are four times more likely to be friendly with one another, even a decade after a group’s split.

Non-group members aren’t tolerated in the core home range, no matter what. But in the peripheral range, familiar neighbors mingle peacefully.

Scientists arrived at their conclusions after analyzing 16 years worth of data on the simultaneous movement and interaction patterns of 17 mountain gorilla groups in Rwanda’s Volcanoes National Park.

“Meetings of groups are fairly rare, and at first both groups are usually cautious,” Robin Morrison, a biological anthropologist with the University of Exeter’s Center for Research in Animal Behavior, said in a news release.

Upon meeting, gorillas often beat their chests to demonstrate strength. Interactions can either turn aggressive, with fighting and yelling, or they turn friendly — or what scientists call “affiliative.”

“In affiliative interactions, the initial tension passes and the groups intermingle,” Morrison said. “They may rest together, and younger gorillas will often play with youngsters from the other group.”

Humans maintain friendly relations and cooperate with large numbers of individuals outside their immediate groups. Some scientists have theorized that the evolution of this socializing pattern allowed humans to take advantage of shared resources and space without the risk of violence.

Scientists suggest their study of mountain gorillas supports such a theory.

“The pattern we found mirrors what we see in humans,” Morrison said. “We also have concepts of public spaces outside our ‘range’ where we tolerate anyone, spaces like our homes where we tolerate certain individuals, and private spaces within those homes reserved for close family or just ourselves.”

The latest findings could also aid conservation planning. Mountain gorilla numbers are actually growing, thanks to effective conservation efforts, but the species’ available habitat is shrinking. The species have less than 300 square miles of habitat remaining.

“Understanding how groups interact and share their limited space is important for estimating future population dynamics and trends in this endangered species,” said study co-author Jean Paul Hirwa, gorilla program manager at the Dian Fossey Gorilla Fund.



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Giant lizards improved their flying abilities over millions of years

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Oct. 28 (UPI) — During their 150 million-year existence, pterodactyls and other winged reptiles known as pterosaurs steadily improved their flying abilities.

According to a paper published Wednesday in the journal Nature, pterosaurs doubled their flying efficiency over the course of their evolutionary history.

Unfortunately, their improved flying couldn’t save them from the extinction event that wiped out the dinosaurs 66 million years ago.

For the study, scientists analyzed the pterosaur fossil record using a new model designed to measure the flight efficiency of modern birds. The data showed pterosaurs didn’t benefit from major evolutionary breakthrough.

Instead, the winged reptiles made small physiological improvements over the course of their existence, slowly but steadily improving their flying prowess.

“Pterosaurs were a diverse group of winged lizards, with some the size of sparrows and others with the wingspan of a light aircraft,” lead study author Chris Venditti said in a news release.

“Fans of the movie Jurassic World will have seen a dramatization of just how huge and lethal these creatures would have been. Their diet consisted mostly of other animals, from insects to smaller dinosaurs,” said Venditti, an evolutionary biologist at the University of Reading in Britain.

Numerous studies have showcased the process of natural selection across small timescales, but identifying efficiency improvements across longer timescales has proven difficult.

“Our new method has allowed us to study long-term evolution in a completely new way, and answer this question at last by comparing the creatures at different stages of their evolutionary sequence over many millions of years,” Venditti said.

Scientists analyzed the shifting skeletal structures and dimensions of 75 pterosaur species over 150 million years. Though most pterosaurs doubled their flying efficiency, researchers found one group invested their evolutionary capital in size.

Azhdarchoids, researchers found, got bigger but not better at flying. Their size advantage allowed them to overcome their pedestrian flying abilities. One group member, Quetzlcoatlus, grew as long as a giraffe.

“This is unique evidence that although these animals were competent fliers, they probably spent much of their time on the ground,” said study co-author Joanna Baker, evolutionary biologist at Reading. “Highly efficient flight probably didn’t offer them much of an advantage, and our finding that they had smaller wings for their body size is in line with fossil evidence for their reduced reliance on flight.”

Not all Jurassic species that took to the skies were able to achieve longevity.

Research published earlier this month revealed the evolutionary failures of a pair of gliding dinosaur species. Outcompeted by birds from below and pterosaurs from above, the gliding species Yi and Ambopteryx never had the chance to evolve improved flying abilities.



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