In a chorus of indris, young males vie for the spotlight, riffing in alternation rather than singing in unison. Not content to be the Joey Fatone of the group, these guys strive for Justin Timberlake status.

Indris (Indri indri), the only singing lemur species, begin their songs with roars that descend into long, phrased howls. These choirs are composed of males and females, with one dominant pair. Marco Gamba of the University of Turin in Italy and his colleagues wanted to analyze variation among individual singers.

Listening to 496 indri songs recorded over 10 years in the dense forests of Madagascar, the team found that pitch varies between males and females. And indri groups typically sing in synchrony, amplifying their tunes and vocally marking their territory to other groups. When one singer starts to croon, the others join in and match rhythm.

Solos are rare, but young male singers tend to sing out of sync — probably to stand out and advertise their masculinity, Gamba and his colleagues propose June 14 in Frontiers in Neuroscience.

There are degrees of slothfulness, it turns out, even when it comes to sloths. And three-toed sloths may be the most slothful of them all: A species of the animal has a field metabolic rate that is the lowest ever recorded for any mammal in the world.

Jonathan Pauli, an ecologist at the University of Wisconsin-Madison, got interested in sloths not because they’re adorable but because “other things eat them,” he says. And he stayed interested in the animals because they are “biologically fascinating.”

Sloths are a type of arboreal folivore, a group that includes all animals that live in trees and eat only leaves. What most people lump into the category of “sloth” are really six species in two families (two-toed and three-toed) separated by millions of years of evolution. Both families live in trees in Central and South America and eat leaves, but three-toed sloths tend to have smaller ranges and more constricted diets, eating from only a few species of trees and only a limited number of them. Studies have also shown that these sloths have a very slow metabolic rate.

But how slow? To find out, Pauli and his colleagues captured 10 brown-throated three-toed sloths (Bradypus variegatus) and 12 Hoffmann’s two-toed sloths (Choloepus hoffmanni) from a study site in northeastern Costa Rica. There, the sloths live among a variety of habitat types, ranging from pristine forest to cacao agroforest to monocultures of banana and pineapple. “It’s really a quilt of different habitat types,” Pauli says, and one that allows the researchers to not only study many habitats at once but also more easily capture and track sloths than if they were in dense jungle.

The researchers injected the sloths with water labeled with isotopes of oxygen and hydrogen and released the animals, tracking them with radiotelemetry. After a week to a week and a half, the scientists again captured the sloths and took blood samples. By seeing how much of the oxygen and hydrogen isotopes remained, the scientists could calculate the sloths’ field metabolic rate — the energy that an organism uses throughout the day.

The field metabolic rate for the three-toed sloths was 31 percent lower than that of two-toed sloths and lower than that found in any mammal outside of hibernation, the researchers report May 25 in the American Naturalist.

“There seems to be kind of a cool combination of behavior and physiological characteristics that lead to these tremendous cost savings for three-toed sloths,” Pauli says. Three-toed sloths spend a lot of time in the canopy eating and sleeping, he notes. “They don’t do a lot of movement, whereas two-toed sloths are much more mobile. They’re moving around a lot more.”

But it’s more than just that. “Three-toed sloths have the capacity to fluctuate their body temperature,” he says. Unlike humans, who need to keep their temperature within a few degrees to function properly, the sloths can let theirs rise and fall with the ambient temperature, a bit like how a lizard or snake might regulate its body temperature. “Those are big cost savings to let your body change with your surroundings.”

The results of the study help explain why there aren’t more kinds of sloths and other arboreal folivores, Pauli and his colleagues argue. “Being an arboreal folivore is really tough living,” Pauli says. Leaf eaters tend to be big because they need to accommodate a large digestive system capable of processing all the leaf matter they need to survive. But to live in the trees, an animal can’t be too big. And this could be why arboreal folivory is one of the world’s rarest lifestyles. The need for all the various adaptations for that lifestyle could prevent the rapid diversification seen among other groups, such as Darwin’s finches.

Fierce combat erupted in February 2016 at the northern Iraqi village of Kudilah. A Western-backed coalition of Arab Sunni tribesmen, Kurds in the Iraqi army and Kurdish government forces advanced on Islamic State fighters who had taken over the dusty outpost.

Islamic State combatants, led by young men wearing explosive vests, fought back. The well-trained warriors scurried through battle lines until they reached their enemy. Then they blew themselves up along with a few coalition soldiers, setting the stage for an Islamic State victory. These suicide bombers are called inghamasi, meaning “those who dive in deep.”
The inghamasi’s determination and self-sacrifice inspires their comrades to fight to the death, says anthropologist Scott Atran of the University of Michigan in Ann Arbor. Outnumbered about 6-to-1, Islamic State fighters still retained control of Kudilah after two days of heavy fighting. Coalition forces retreated, unwilling to lose more soldiers.

Atran and colleagues arrived in northern Iraq a couple of weeks later. Their plan: study “the will to fight” among soldiers on both sides of the Kudilah clash, even as fighting in the area continued. Their goals: try to understand what motivates people to join brutal organizations such as the Islamic State, and describe the personal transformations that push people leading comfortable, peaceable lives to commit acts of incredible violence and self-destruction.

Atran wondered whether there were common individual traits that explain the fierce devotion held by fighters for the Islamic State (also known as ISIS, ISIL or Daesh) as well as troops trying to take down ISIS. Scientists typically treat extreme sacrifice for others as premised on a careful weighing of pros and cons by “rational actors” who behave in a way that best satisfies their own interests even if others benefit as well. But it’s hard to see how a “what’s in it for me” formula applies to inghamasi, Atran says, much less someone who operates in a more conventionally altruistic way, such as a Navy SEAL. It’s a mistake to write off ISIS fighters as lonely losers, each seeking death as a gateway to a heavenly rendezvous with a private stock of virgins, he contends.
To break out of the rational-actor rut, Atran shifted his experimental focus nearly a decade ago to examine cherished values that mobilize people to take collective action, regardless of risks or rewards. In the last several years, he has moved his studies to the field, to focus on combatants in current conflicts and their sympathizers. And he’s finding that extreme personal sacrifices made for outfits such as the Islamic State can be understood, but only by accounting for values he describes as “sacred” and by tracking the way in which individuals identify with like-minded comrades.

Collective identity
Academics who study warfare and terrorism typically don’t conduct research just kilometers from the front lines of battle. But taking the laboratory to the fight is crucial for figuring out what impels people to make the ultimate sacrifice to, for example, impose Islamic law on others, says Atran, who is affiliated with the National Center for Scientific Research in Paris.

Atran’s war zone research over the last few years, and interviews during the last decade with members of various groups engaged in militant jihad (or holy war in the name of Islamic law), give him a gritty perspective on this issue. He rejects popular assumptions that people frequently join up, fight and die for terrorist groups due to mental problems, poverty, brainwashing or savvy recruitment efforts by jihadist organizations.

Instead, he argues, young people adrift in a globalized world find their own way to ISIS, looking to don a social identity that gives their lives significance. Groups of dissatisfied young adult friends around the world — often with little knowledge of Islam but yearning for lives of profound meaning and glory — typically choose to become volunteers in the Islamic State army in Syria and Iraq, Atran contends. Many of these individuals connect via the internet and social media to form a global community of alienated youth seeking heroic sacrifice, he proposes.

Preliminary experimental evidence suggests that not only global terrorism, but also festering state and ethnic conflicts, revolutions and even human rights movements —  think of the U.S. civil rights movement in the 1960s — depend on what Atran refers to as devoted actors. These individuals, he argues, will sacrifice themselves, their families and anyone or anything else when a volatile mix of conditions are in play. First, devoted actors adopt values they regard as sacred and nonnegotiable, to be defended at all costs. Then, when they join a like-minded group of nonkin that feels like a family — a band of brothers — a collective sense of invincibility and special destiny overwhelms feelings of individuality. As members of a tightly bound group that perceives its sacred values under attack, devoted actors will kill and die for each other.

His team’s studies of devoted actors may help to explain why a growing number of people from around the world are leaving their families and home nations to join ISIS. Congressional and United Nations reports suggest that by October 2015, nearly 30,000 recruits from more than 100 countries had become fighters in Syria and Iraq, primarily for the Islamic State.

“The rise of the Islamic State is a revolutionary movement of historic proportions,” Atran says. “Many of its members are devoted actors with an apocalyptic belief that they must destroy the world to save it.” That uncompromising vision feeds off the promise of a global caliphate — a joint political and Islamic entity that kills or controls nonbelievers — that will bring on the end of the world and replace it with God’s true kingdom. Volunteers to that cause have participated in more than 50 terror attacks in 20 countries since June 2014. Muslim militants carried out 450 suicide bombing attacks in 2015, with 174 attributed to the Islamic State.

Atran’s research may provide a rare tool to study soldiers’ will to fight, whether or not they’re Islamic State adherents, says psychologist and terrorism researcher John Horgan of Georgia State University in Atlanta. Too many investigators have dismissed those deemed to be terrorists “as either incomprehensible or not even worthy of understanding,” Horgan says.

At the time of the Kudilah battle, the Islamic State controlled hundreds of thousands of square kilometers in the Middle East. It had successfully defended a 3,000-kilometer-long military front stretching from Iraq to Syria against multi-national forces. It’s certainly possible to destroy the Islamic State with overwhelming military might, Atran says, but that approach would come at a price. It would leave a fragmented Sunni Muslim world, from which the Islamic State arose, as well as a global pool of passionate young men and women seeking liberation through sacrifice and martyrdom. A military takedown alone might trigger “a volcanic resurgence of rebels with a cause, even readier for doomsday,” he predicts.

Sacred apocalyptic values are best opposed by the spread of deeply held, life- and freedom-affirming values that supporters are willing to defend unconditionally, Atran argues. The Kurds have had success with this approach.

Sacred kin
In the Middle East, only Kurdish people living in northern Iraq have consistently held off Islamic State attacks. The Kurds, Atran finds, display a will to fight equal to that of captured Islamic State fighters. As important as guns and other material support are to a military operation, an indomitable will to fight may be even more crucial, he says. Both the Islamic State and the Kurdish army have achieved considerable military success without all the hardware of Western armies.

At Kudilah, Kurdish soldiers showed their mettle in a fierce clash. Several of these men later described the event to Atran. As Iraqi army units withdrew, Islamic State forces rapidly pushed forward. A small company of Kurds stood their ground. After the fight raged for several hours, Iraqi army reinforcements arrived, enabling the Kurds to live to fight another day.

Atran’s team interviewed 28 Kurdish soldiers plus 10 Kurds who provided supplies, medical care and other frontline assistance. Seven Islamic State fighters, six of them prisoners, also agreed to be interviewed. One had been freed and changed sides, working with groups opposed to the Islamic State.

Among the 38 Kurdish volunteers, 22 reported devotion to a homeland of “Kurdistan” as a sacred value that they would fight and die for, even overriding family ties and their Islamic religion, Atran reports in the June Current Anthropology. All but one of the 22 reported feeling a collective bond, or what Atran calls identity fusion, with the Kurdish people.

Captured ISIS members reported visceral, family-like bonds with their fellow fighters. All Islamic State prisoners cited an absolute commitment to an imposition of Islamic law, or Sharia, on nonbelievers.

Investigators measured identity fusion by presenting participants with touch-screen computer tablets showing a small circle labeled “me” and a large circle with a group label, such as “Kurds” or “family.” To represent their relationship to a particular group, individuals could move the circles together so that they partly or completely overlapped. Those who moved the small circle inside the large circle were regarded as fully fused with that group.
Atran adopted this test from ongoing research initiated nearly a decade ago by psychologist William Swann of the University of Texas at Austin. An international team led by social anthropologist Harvey Whitehouse of the University of Oxford, including Swann, studied Libyan men who tried to overthrow their government in 2011. The researchers found that nearly all the men reported intense, family-like bonds with fellow combatants. Revolutionary leaders granted the researchers access to 42 Libyan soldiers and 137 support personnel, including mechanics and ambulance drivers, as hostilities wound down in late 2011.

On the overlapping circles test, 45 percent of fighters reported being more strongly bonded to their battalions of three to five comrades than to their families, the researchers reported in 2014 in the Proceedings of the National Academy of Sciences. A smaller portion of support personnel, 28 percent, identified more with revolutionary battalions than with their families. That’s consistent with the idea that frontline fighters most often bond tightly to their units, upping their readiness to give their lives for comrades.

Libyan soldiers who felt intense connections to their battalions probably qualified as devoted actors, says psychologist Hammad Sheikh of the New School for Social Research in New York City, who was not involved in Whitehouse’s study. The soldiers’ commitment to the revolution’s goals probably transcended even family loyalties, Sheikh suspects. He bases that opinion on Atran’s findings. Whitehouse’s team did not try to identify devoted actors among Libyan fighters.

People willing to sacrifice everything in defense of the Islamic State’s sacred values also exist outside of the war zone. Among 260 Moroccans who lived in either of two city neighborhoods known as pro-ISIS hotbeds, testing indicated that about 30 percent were devoted actors. They described the imposition of Sharia as a nonnegotiable necessity, Sheikh and his colleagues, including Atran, report in a second paper in the June Current Anthropology.

On the overlapping circles test, devoted actors in Morocco depicted especially close bonds with family-like groups of friends, ranging from Islamic State supporters to soccer buddies.
Western weakness
Such dedication to collective values may be tougher to come by in Western nations. Online testing of 644 people in Spain identified only 12 percent as devoted actors willing to sacrifice all for democracy, even after being reminded of threats by ISIS and Al Qaeda. Frequent corruption scandals have left many Spaniards disillusioned with democracy, Sheikh says. Whether a similarly weak devotion to democratic values applies to citizens of other European countries or the United States remains to be tested.

Field research suggests that collective commitments to democratic values may be weaker in the West. When devoted actors among Islamic State fighters, Kurds and members of a Kurdish-speaking religious community known as Yazidis were given a hypothetical choice between abandoning their sacred values if others in their group do, or leaving the group to fight on for their sacred values, they nearly always opted to fight on for their values, Atran says.

Devoted actors in Spain, however, typically say they’d follow their group if it rejected democratic values. People in France and Spain tested by Atran’s team also rate their own society’s “spiritual force,” or the strength of collective beliefs and commitments, as much weaker than that of ISIS.

Among U.S., British and former Soviet soldiers, there have long been indications from interviews, field reports and personal letters of a stronger willingness to die for close comrades in war than in defense of broader values, Atran says. Historical evidence, however, suggests that certain relentless fighters, including Nazi troops during World War II and Viet Cong soldiers in the Vietnam War, were devoted actors inspired by beliefs in a higher cause, he says, adding that the same may have been true for soldiers on both sides of the U.S. Civil War.
Sacrificial appeal
Atran and his colleagues now have their own cause: describing more fully how some people go from holding extreme beliefs on the sidelines to becoming devoted actors at the front lines of extreme movements.

It would help, says political psychologist Clark McCauley of Bryn Mawr College in Pennsylvania, if researchers could clarify what counts as a sacred value and why some sacred values outweigh others. Identity fusion is also a tricky concept to pin down, McCauley says. Further research needs to determine whether a person who moves a “me” circle inside a circle representing a fighting unit still feels a sense of individuality or totally buys into a collective identity, he suggests.

Only by venturing into war zones can researchers begin to understand the will to fight on all sides, from the perspectives of the fighters themselves, Atran argues. It’s daunting work. He has seen ISIS fighters advancing on an Iraqi army outpost, then detonating their explosive vests in the ultimate show of commitment to their cause. He has spoken to Kurdish veterans missing arms or legs and men who had joined the Kurdish army back in the 1950s, all of them now fighting at the front to defend their homeland.

A young Yazidi fighter told Atran that he used vacation time from college to train for a week with Kurdish Marxists in Syria to defend his Kurdish religious community against the Islamic State. Fighting with a few comrades in August 2014, the student-soldier fended off ISIS attackers long enough for reinforcements to arrive. He helped save thousands of Yazidis from slaughter. The young man then returned to his studies. He wanted to be an archaeologist.

“You learn more in five minutes in the field than in five years of analysis from afar,” Atran says.

Despite careful planning, Atran’s team sometimes gets distressingly close to warring parties while conducting research in Iraq. It’s an unavoidable risk but not a deal breaker for the researchers. “There’s something so compelling,” he says, “about trying to figure out humans in extreme circumstances such as war.”
This article appears in the July 9, 2016, issue of Science News under the headline “Deadly devotion: New studies explore why ordinary people turn terrorist.”

Grasses have top-notch border control to conserve water in their leaves. Now, scientists have identified the genetic switch that makes them such masters at taking in carbon dioxide without losing water. The find might eventually help scientists create more drought-resistant crop plants, the researchers report in the March 17 Science.

Adjustable pores called stomata on the undersides of leaves help plants take in CO2 while minimizing water loss. Like pupils responding to sunlight, plants open and close their stomata in response to changing light, humidity and temperature. Grass stomata can open wider and respond more quickly than those in other plants, which helps grasses photosynthesize more efficiently.
This ability might help explain why grasses grow successfully in so many places on Earth, says Brent Helliker, a plant ecologist at the University of Pennsylvania who wasn’t part of the new study. For instance, grasses are particularly well equipped to deal with the rapidly changing weather and strong winds that can hit plains and prairies.

In most plant stomata, two kidney bean–shaped cells, one on each side of the pore, swell or deflate like balloons to control the size of the opening. But in grass, each of these cells is shaped like a dumbbell instead. And each dumbbell is linked to two other cells called subsidiary cells.
Scientists have long suspected that grasses’ subsidiary cells might give the dumbbells, known as guard cells, an assist by making it easier for them to open and close. But that’s been hard to test in a controlled way.
When a stoma opens, “it’s elbowing its way into the neighbor cells,” says study coauthor Dominique Bergmann, a biologist at Stanford University. “If the neighbors don’t want to move, you’re stuck.” But subsidiary cells have some squish. As guard cells inflate, their neighboring subsidiary cells deflate.
Bergmann and her colleagues mutated a gene called MUTE in purple false brome (Brachypodium distachyon) so that the grass didn’t make the MUTE protein. Without MUTE, plants didn’t make subsidiary cells. And without the helping hand, the plants were less efficient than usual at opening and closing their stomata.

Grasses aren’t the only plants that have the MUTE gene, Bergmann says. But in other plants, the gene provides instructions to help make guard cells, not subsidiary cells. At some point in grasses’ evolution, the MUTE gene took on a function that differs from the rest of the plant kingdom.

Although the new work confirms that subsidiary cells and guard cells work together to make grass stomata more responsive, more research is still needed to understand exactly how subsidiary cells lend a hand. “It would be really nice to show that there’s actually an exchange of ions between the two cell types,” says Michael Blatt, a plant physiologist at the University of Glasgow in Scotland. Sharing ions could incentivize water to flow from one cell type to the other, controlling which one is more inflated.

More responsive stomata may have helped grasses survive during periods when Earth’s climate was warm and dry. “Grasses got lucky,” says study coauthor Michael Raissig, also at Stanford. As Earth’s climate continues to change, Raissig says, these genetic innovations might be exploited to help other plants make it through, too.

Dengue is a bit of a homebody. By mapping the spread of the virus across Bangkok, scientists found that infections were most likely to occur within a few minutes’ walk of the home of the first person infected.

Pinpointing where dengue is likely to be transmitted can better focus efforts to stop the spread of the disease, the researchers report in the March 24 Science.

“We often think of transmission and infection as occurring in this ubiquitous, pervasive and amorphous way,” says study coauthor Derek Cummings. But there is a pattern to how dengue spreads. This study, he adds, shows that scientists are “starting to have the tools and methods to really track how infectious diseases move across a population.”
Dengue is a viral disease transmitted by Aedes aegypti mosquitoes and can cause fever and muscle pain so excruciating that it’s also known as “breakbone fever.” In some cases, it can be deadly, resulting in more than 20,000 deaths per year.
Cummings and colleagues looked at both the genetics and locations of about 18,000 cases of dengue from 1994 to 2010 in Thailand, most from the capital Bangkok. If two cases of dengue evolved from the same parent strain of the virus within a season, or about six months, researchers considered the pair to belong to the same transmission chain, which connects dengue infections that spread from one person to the next. About 160 chains occur in Bangkok in a season.

The researchers found that 60 percent of dengue cases within a 200-meter radius in Bangkok were closely related. These infections with a particular dengue strain belonged to the same transmission chain, says Cummings, an epidemiologist at the University of Florida in Gainesville. In contrast, only three percent of cases separated by a greater distance, between one to five kilometers, were from the same transmission chain.
The new study’s combination of genetic and location information provides more details on the ecology of dengue than previous research, says Caroline Buckee, an infectious disease epidemiologist at the Harvard School of Public Health. “It would be great to see this kind of approach become a standard for studies of dengue transmission and epidemiology.”

When the researchers mapped the locations of cases within the same transmission chain, they found that the home of the person originally infected by a mosquito bite, the first link in the chain, is a good indicator of where new cases of dengue will occur.

Thailand’s Ministry of Public Health responds to dengue infections by spraying to kill mosquitoes. “Now, we have some quantitative details to start targeting control technologies,” Cummings says, to better focus spraying in high-priority areas.

The data may also be helpful for a vaccine. Though there is a dengue vaccine licensed for use in Thailand, Cummings says, researchers don’t know yet whether the vaccine will need to be updated with more strains of the virus over time, like the flu shot. Understanding the diversity of dengue strains and how they spread across Bangkok in a season may help researchers address this vaccine concern, he adds.

“Once we can understand these detailed patterns of how things spread, then we might be able to refine how we respond to the pathogen,” Cummings says.

The pill is a sledgehammer approach to contraception…. A second-generation of [drugs] is being designed to do the job without upsetting a woman’s normal cycle of ovulation and menstruation…. A contraceptive administered to the man can be given only for a short time without actually affecting the development of sperm … and, therefore, is not being considered for actual clinical use. —Science News, April 15, 1967

Update
Contraceptives have come a long way since 1967. Women can choose low-dose pills, hormonal rings, implants and intrauterine devices — effective methods that can be less disruptive to normal menstrual cycles. Men have far fewer options, but that may eventually change. A long-acting gel injected into 16 adult male rhesus monkeys’ reproductive tracts completely prevented pregnancy in their partners over one to two breeding periods. The gel works like a vasectomy but is less invasive and can be reversed more easily, researchers report February 7 in Basic and Clinical Andrology.

A misfit gang of superconducting materials may be losing their outsider status.

Certain copper-based compounds superconduct, or transmit electricity without resistance, at unusually high temperatures. It was thought that the standard theory of superconductivity, known as Bardeen-Cooper-Schrieffer theory, couldn’t explain these oddballs. But new evidence suggests that the standard theory applies despite the materials’ quirks, researchers report in the Dec. 8 Physical Review Letters.

All known superconductors must be chilled to work. Most must be cooled to temperatures that hover above absolute zero (–273.15° Celsius). But some copper-based superconductors work at temperatures above the boiling point of liquid nitrogen (around –196° C). Finding a superconductor that functions at even higher temperatures — above room temperature — could provide massive energy savings and new technologies (SN: 12/26/15, p. 25). So scientists are intent upon understanding the physics behind known high-temperature superconductors.
When placed in a magnetic field, many superconductors display swirling vortices of electric current — a hallmark of the standard superconductivity theory. But for the copper-based superconductors, known as cuprates, scientists couldn’t find whirls that matched the theory’s predictions, suggesting that a different theory was needed to explain how the materials superconduct. “This was one of the remaining mysteries,” says physicist Christoph Renner of the University of Geneva. Now, Renner and colleagues have found vortices that agree with the theory in a high-temperature copper-based superconductor, studying a compound of yttrium, barium, copper and oxygen.

Vortices in superconductors can be probed with a scanning tunneling microscope. As the microscope tip moves over a vortex, the instrument records a change in the electrical current. Renner and colleagues realized that, in their copper compound, there were two contributions to the current that the probe was measuring, one from superconducting electrons and one from nonsuperconducting ones. The nonsuperconducting contribution was present across the entire surface of the material and masked the signature of the vortices.

Subtracting the nonsuperconducting portion revealed the vortices, which behaved in agreement with the standard superconductivity theory. “That, I think, is quite astonishing; it’s quite a feat,” says Mikael Fogelström of Chalmers University of Technology in Gothenburg, Sweden, who was not involved with the research.
The result lifts some of the fog surrounding cuprates, which have so far resisted theoretical explanation. But plenty of questions still surround the materials, Fogelström says. “It leaves many things still open, but it sort of gives a new picture.”

Proxima Centauri has a temper. Earth’s nearest planet-hosting neighbor released a gigantic flare in March 2017, a new analysis of observations of the star shows. And that’s bad news for the potential for life on the star’s planet, Proxima b.

The star got 1,000 times brighter over 10 seconds before dimming again. That can best be explained by an enormous stellar flare, astronomer Meredith MacGregor of the Carnegie Institution for Science in Washington, D.C., and colleagues report February 26 in Astrophysical Journal Letters.
Because Proxima b is so much closer to its star than Earth is to the sun, the flare would have blasted Proxima b with 4,000 times more radiation than Earth typically gets from the sun’s flares. “If there are flares like this at all frequently, then [the exoplanet] is likely not in the best shape,” MacGregor says.

Proxima b was one of the most sought-after sites for finding life outside the solar system. Just four light-years away, it has a mass about the same as Earth’s and probably has temperatures suitable for liquid water (SN: 12/24/16, p. 20). But its star is an M dwarf, a class of small dim stars notoriously prone to flares that could rip away their planets’ atmospheres (SN: 6/24/17, p. 18).
MacGregor and her colleagues reanalyzed data from a recent study led by astronomer Guillem Anglada of the Institute of Astrophysics of Andalusia in Granada, Spain. Anglada and his colleagues had observed Proxima Centauri with the Atacama Large Millimeter Array telescopes in Chile. The team saw extra light that it interpreted as a ring of dust analogous to the solar system’s Kuiper Belt, scattering the light in all directions, the team reported November 15 in Astrophysical Journal Letters.
But Anglada and his colleagues had averaged the amount of light over 10 hours of observations. That smeared out any short-term changes in the star’s brightness — such as a bright flare.

When MacGregor’s team reanalyzed the data, they found that all the excess light came from the same two-minute period on March 24. A massive flare explains all the extra light, she says — none of it was masquerading as a glittering dust ring.

Anglada says he and his colleagues are aware of the March 24 flare and are currently revising their original claim. But he says the flare can’t account for all the extra light, so the dust ring theory might still survive.

Physicist Stephen Hawking, a black hole whisperer who divined secrets of the universe’s most inscrutable objects, died March 14 at age 76. In addition to his scientific research, Hawking, a professor at the University of Cambridge, was known for his popular science books, including the best-selling A Brief History of Time, which captivated readers with lucid explanations of the universe’s birth and the physical laws that rule the cosmos.

In one of his best-known discoveries, Hawking determined that black holes are not truly black. Instead, they emit a faint haze of particles, known as Hawking radiation (SN: 5/31/14, p. 16). This discovery, which arose at the interface of gravity and quantum mechanics, had remarkable consequences. It suggested that black holes are not eternal, but eventually evaporate. That led to a conundrum known as the black hole information paradox (SN: 10/3/15, p. 10): When a black hole disappears, what happens to the information that fell into it? Physicists are still puzzling over that question.

In the face of physical disabilities due to amyotrophic lateral sclerosis, which profoundly limited his mobility and ability to communicate, Hawking became one of science’s most well-known figures, and survived far beyond the timeline initially expected given his condition.

Science News has covered Hawking’s work extensively over the past decades, including his four laws of black hole mechanics, his work on miniature black holes and, most recently, Hawking’s search for a solution to the black hole paradox.