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    Over time, Betelgeuse changed color. Now it’s also lost its rhythm

    The star Betelgeuse has always been a diva.

    Astronomers from antiquity through the present day have watched the red supergiant pulsing at the shoulder of the constellation Orion, and the star has continually put on a show, two new studies suggest. Betelgeuse may still be recovering from a deep dimming episode a few years ago, one team reports. And the star appears to have put on its reddish stage makeup just 2,000 years ago, before which it wore yellow, another team says.

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    Together, these studies could tell researchers about how stars spew their guts into space and hint at how long it will be before Betelgeuse explodes in a supernova.

    “This star always fools you,” says astronomer Edward Guinan of Villanova University in Pennsylvania, who has studied Betelgeuse for decades and was not involved in the new works. “You think you have it, and all of a sudden, it changes.”

    The “Great Dimming”

    In late 2019, Betelgeuse captured astronomers’ attention when it suddenly grew dark for several months — an event astronomers now call the Great Dimming. Months of subsequent observations led researchers to an explanation: The star had coughed out a big bubble of plasma. That material cooled, condensed into dust and blocked the star’s face from the perspective of Earth months later (SN: 11/29/20). The surface of the star also cooled down, contributing to the dimming (SN: 6/16/21).

    But what happened next was equally surprising, astrophysicist Andrea Dupree and colleagues report in a paper submitted August 2 to arXiv.org. The star’s regular pulsating brightness, it seems, went completely out of whack.

    In its non–Great Dimming life, Betelgeuse’s brightness was on a quasi-periodic dimmer switch. As the star breathed in and out — ballooning out before shrinking back down — its brightness went up and down. “For 200 years, it had a nice, 400-day oscillation in brightness,” says Dupree, of the Harvard & Smithsonian Center for Astrophysics in Cambridge, Mass. “But that’s gone now.”

    That regular drumbeat has since grown erratic. Instead of a regular thrum, the oscillations are “like an unbalanced washing machine, going ‘wonka wonka wonka,’” Dupree says.

    The wonkiness is a sign of the star struggling to recover from the loss of material in 2019, Dupree says. She calculates that Betelgeuse ejected several times the mass of the moon from its surface, leaving a large cool spot behind. The star’s surface plasma is sloshing around as it returns to equilibrium.

    If this picture is correct, it means red supergiants like Betelgeuse can spray material into interstellar space in discrete bursts, rather than a continuous stream. That’s important to know because many of the elements that make up planets and people were formed in stars undergoing what Betelgeuse is going through right now. Studying Betelgeuse’s growing pains and death throes can tell us about our own origins.

    But while this picture of Betelgeuse holds together, it is still speculative, Guinan cautions.

    One confounding factor is a new set of observations of Betelgeuse during the four-month period when it’s usually out of view. From May through August every year, Betelgeuse is too close to the sun from Earth’s perspective to be seen at night. Usually that leaves a hole in the datasets of astronomers who track its periodic behavior.

    But amateur observer Otmar Nickel of Mainz, Germany, developed a technique to measure Betelgeuse’s brightness using multiple images taken during the day. Dupree’s paper is the first to include those daytime data.

    “That’s cool,” Guinan says. “You can follow the star all year round.”

    Those extra observations might reveal recurring changes that have always been there, rather than picking up on something truly new. “Those little variations you’re seeing…could easily be present right before the Great Dimming,” Guinan says.

    Dupree’s team predicts that the dust Betelgeuse lost could become visible to some telescopes on Earth in 2023. “That would be proof” that the brightness changes were due to a single outburst, Guinan says.

    Seeing yellow

    The Great Dimming isn’t the first time humans have recorded a major change in Betelgeuse’s personality. Two millennia ago, the star was a completely different color, astrophysicist Ralph Neuhäuser and colleagues report in a paper in press in Monthly Notices of the Royal Astronomical Society.

    The team analyzed ancient descriptions of more than 200 stars whose colors should have been visible to the naked eye in the past few thousand years. Most stars observed over human history had the same color recorded in the past as they display today, the team found. But not Betelgeuse.

    The ancient Roman astronomer Gaius Julius Hyginus, who lived from about 64 B.C. to A.D. 17, and is thought to have written the Latin work De Astronomia, described the star in the right shoulder of Orion has having a similar color to Saturn ­— which is yellow. Astrologer and archivist Sima Qian, working during the Chinese Han dynasty around 100 B.C., independently described the star as yellow. Observers from other ancient cultures conspicuously left Betelgeuse out of their lists of red stars.

    “I thought, ‘Oh, how can this be?’” says Neuhäuser, of AIU Jena in Germany. “I was not expecting such a result … to find a star to change color in historical time.”

    A star’s color is a sign of its evolutionary stage (SN: 7/23/21). When stars burn through the hydrogen fuel in their cores, they puff up and expel gases into space. That expansion makes their surface temperatures drop, and they change color from blue to red in fairly short order — about 10,000 years for a giant star like Betelgeuse, which is around 14 times as massive as the sun.

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    That relatively recent color change suggests Betelgeuse has just reached the end of its hydrogen-burning life and became the red supergiant we know it as today while human observers were watching.

    “It’s fully consistent with astrophysical knowledge,” Neuhäuser says. “It could have been expected, but no one really checked.”

    That result means anyone waiting for Betelgeuse to go supernova will have a very long wait. If the star just became a supergiant in the last few millennia, it has more than 1 million years to go before the boom. More

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    Losing parts of our voice box may have helped humans evolve to speak

    Unlike people, 43 species of monkeys and apes are known to have so-called vocal membranes, which may prevent them from having precise voice control

    Humans

    11 August 2022

    By Clare Wilson
    Unlike in other primates, the human voice box has lost small tissue structures called vocal membranes, which may have been involved in the evolution of speechSEBASTIAN KAULITZKI/SCIENCE PHOTO LIBRARY
    The loss of small tissue structures from the voice box may have been essential for the evolution of human speech.
    In a study of 43 non-human primates, all the animals had “vocal membranes”, a small extension of the throat’s vocal cords that makes their sounds louder and higher but also more irregular and harder to control.
    As humans lack vocal membranes, this suggests they were lost when our ancestors diverged from chimpanzees to allow more precise voice control, says Tecumseh Fitch at the University of Vienna in Austria.Advertisement
    While many animals make calls to communicate, the evolution of complex human speech seems to have required anatomical changes, as well as changes in the brain. In humans, the vocal cords are flaps of tissue in the throat that vibrate as air is expelled from the lungs, allowing us to make “voiced” sounds, as opposed to breathy ones.
    We already knew that a few species of monkeys and apes have vocal membranes. To better understand the loss of these structures in humans, Fitch’s team looked at the voice box, also known as the larynx, of 43 species of apes and monkeys. This was done by carrying out magnetic resonance imaging (MRI) or computed tomography (CT) scans on dead or anaesthetised animals in the first such large-scale study of primates. The researchers found that all 43 species had this vocal cord extension.
    The team also analysed video footage that showed the voice box of an anaesthetised chimpanzee with an endoscope in its throat while the animal made grunts and growls as it was waking up. They did the same for anaesthetised rhesus macaques and squirrel monkeys that were stimulated to make noises by having an electrode put into the part of their brain that causes them to produce vocalisations.

    The researchers found that in all these animals, vibration and collision of the vocal membranes are the primary source of their calls, as their vocal cords were in motion less often.
    If humans still had vocal membranes, our speech would probably sound more rough and variable, with abrupt pitch changes, like someone with laryngitis, says Fitch.
    “A key thing that distinguishes human speech from animal sounds is our fine-grained control over the sounds we make. That is only possible if our vocal apparatus is easy for our brains to control,” says Richard Futrell at the University of California, Irvine. “If the system is complex, then it will behave in a way that is chaotic and unpredictable.”
    But Adriano Lameira at the University of Warwick in the UK says many apes and monkeys make both loud and irregular calls as well as some quieter and more controlled noises. “The alleged limiting effect [of vocal membranes] on primate vocal production seems exaggerated,” he says.
    Journal reference: Science, DOI: 10.1126/science.abm1574

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    Am I Normal? review: Deep-dive sets us straight on our need for norms

    When it comes to human physiology, behaviour and social interaction, it is time to abandon a 200-year hunt for normal people, argues Sarah Chaney in her new book

    Humans

    10 August 2022

    By Simon Ings
    Henrik Sorensen/Getty images
    Am I Normal?
    Sarah Chaney
    Wellcome Collection
    A PAIR of unusual gloves, belonging to 19th-century polymath Francis Galton, lie in University College London. Galton was the man who coined the term eugenics to describe beliefs and practices that aim to “improve” the genetic quality of a human population.
    His motto was “whenever you can, count”, so he decided to put a pin in the thumb of his left glove and a felt pad, covered by a strip of paper, across its fingers. By touching different fingers with the pin, Galton could track the things he saw without others noticing.
    One … More

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    Don't Miss: Netflix's new alternative reality drama Look Both Ways

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    Look Both Ways stars Lili Reinhart as Natalie, whose life splits into parallel realities on the eve of her graduation. She either heads to Los Angeles to pursue a career, or stays at home with her baby. On Netflix from 17 August.
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    Five Days at Memorial review: The hospital hit by Hurricane Katrina

    Based on the book by journalist Sheri Fink, this TV mini-series dramatises the shocking stories of health workers and patients whose lives are changed forever as Hurricane Katrina overwhelms a US hospital in 2005, finds Bethan Ackerley

    Humans

    10 August 2022

    By Bethan Ackerley
    Anna Pou (Vera Farmiga), front, and Karen Wynn (Adepero Oduye)Courtesy of Apple
    Five Days at Memorial
    Apple TV+
    ON 11 September 2005, 45 bodies were recovered from Memorial Medical Center, New Orleans. The hospital had been hit by Hurricane Katrina, then the most devastating storm in US history. Patients, staff and their families were stranded for five days by floodwaters. Conditions were apocalyptic. Deaths were expected.
    The aftermath brought uncomfortable revelations. Some bodies contained potentially dangerous levels of morphine and other drugs. The actions of Anna Pou, a doctor at the hospital, were … More

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    Egyptian mummy’s head discovered in Kent attic

    Feedback is our weekly column of bizarre stories, implausible advertising claims, confusing instructions and more

    Humans

    10 August 2022

    Josie Ford
    Hair-raising heirloom
    Tidying the stationery cupboard throws up many archaeological treasures, but nothing so exciting, or terrifying, as the discovery made by a gentleman sorting through his deceased brother’s attic in Kent the other day. He found a head.
    This Egyptian mummy’s remains, brought to England as a souvenir, must have been passed down the family line for several generations. You would think it might have come up in conversation now and again. But no: the discoverer, who has gifted the grisly object to Canterbury Museums and Galleries, says he knew nothing about it. A CT scan has established that … More

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    On Sonorous Seas review: What a dead whale can tell us

    When a beaked whale carcass washed up near her home, part of a mass stranding around the region, Mhairi Killin was inspired to launch an artistic challenge to the military’s impact in the area

    Humans

    10 August 2022

    By David Stock
    A “constellation” of data points showing where the dead whales washed upMhairi Killin
    On Sonorous Seas
    An exhibition led by Mhairi Killin in collaboration with others
    An Tobar, Isle of Mull, UKCloses 27 August
    SOMETIMES art and science come together to raise our awareness of a compelling issue. One such occasion is a multimedia exhibition called On Sonorous Seas, led by artist Mhairi Killin and prompted by her experience of a mass stranding of dead whales.
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    Secrets of an ancient Chinese recipe for bronze finally deciphered

    Metal-making practices described in a 2300-year-old text called the Kaogong Ji are more sophisticated than anyone realised

    Humans

    10 August 2022

    By Jason Arunn Murugesu
    A Chinese bronze container from the fifth century BCB Christopher / Alamy
    THE missing ingredients of an ancient Chinese recipe for bronze may have been uncovered, revealing another level of sophistication in the practice of chemistry at the time.
    Kaogong Ji, a 2300-year-old text, is the oldest technical encyclopedia in the world. The book contains instructions on how to make several objects, such as metal drums, chariots and weapons. It also contains six recipes for bronze that have long puzzled researchers.
    While bronze-making wasn’t unique to China at that time, Ruiliang Liu at the British Museum in London says the style and scale of the bronzes produced there was unrivalled.Advertisement
    “We asked ourselves, how can Asian and Chinese people manage to produce so many bronzes [at that time],” says Liu.
    Bronze is typically made by combining copper and tin. The recipe mystery centres on two ingredients called jin and xi that researchers have been unable to identify. In modern Mandarin, jin means gold, but in antiquity it is believed to have referred to copper or a copper alloy. Meanwhile, xi has long been considered to refer to tin.
    But chemical analyses of bronze vessels from that time period suggest that jin and xi can’t simply be copper and tin.
    Liu and his colleagues analysed previously compiled data on the chemical composition of knife-shaped Chinese coins produced in the same era as when the recipes were recorded. By teasing out the relationships between the metals present in the coins, the researchers suggest the objects were created using pre-made alloys.
    They discovered that the higher the lead concentration in the coins, the lower the concentration of both copper and tin. The coins with the highest concentration of copper also had the highest concentration of tin. These findings suggest that lead was being mixed into an alloy of copper and tin – a bronze alloy.
    By modelling different combinations, the team determined that an 80:15:5 copper-tin-lead alloy mixed with a 50:50 copper-lead alloy in various ratios was the best match with the chemical coin data.
    These pre-made alloys are likely to be jin and xi respectively as recorded in the Kaogong Ji, says Liu. But he adds that the recipes in the book may not reflect how bronze was usually made.
    “If anything, the recipes are too specific,” he says. “The people who actually got their hands dirty probably couldn’t read or write so they wouldn’t have been able to record the recipe. I think there is a gap in knowledge between the person who wrote the recipe and the person who did the real work.”
    Jianjun Mei at the University of Cambridge isn’t totally convinced by the findings. He says these recipes shouldn’t considered accurate records of practices used at the time. “These officials [who wrote the text] might only pay attention to the most important materials, such as copper and tin, rather than all other materials,” he says. The recipes still largely work if you take jin and xi to be copper and tin, he says.
    Bronze was used in ancient China to make large vessels for religious purposes, says Jessica Rawson at the University of Oxford. “In China, they had a huge workforce and so could afford to use a very complicated system with a lot more metal than in the West,” she says.
    Journal reference: Antiquity, DOI: 10.15184/aqy.2022.81).

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