Philippa Kaur

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    in Space & Astronomy

    A protogalaxy in the Milky Way may be our galaxy’s original nucleus

    The Milky Way left its “poor old heart” in and around the constellation Sagittarius, astronomers report. New data from the Gaia spacecraft reveal the full extent of what seems to be the galaxy’s original nucleus — the ancient stellar population that the rest of the Milky Way grew around — which came together more than 12.5 billion years ago.

    “People have long speculated that such a vast population [of old stars] should exist in the center of our Milky Way, and Gaia now shows that there they are,” says astronomer Hans-Walter Rix of the Max Planck Institute for Astronomy in Heidelberg, Germany.

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    The Milky Way’s ancient heart is a round protogalaxy that spans nearly 18,000 light-years and possesses roughly 100 million times the mass of the sun in stars, or about 0.2 percent of the Milky Way’s current stellar mass, Rix and colleagues report in a study posted September 7 at arXiv.org.

    “This study really helps to firm up our understanding of this very, very, very young stage in the Milky Way’s life,” says Vasily Belokurov, an astronomer at the University of Cambridge who was not involved in the work. “Not much is really known about this period of the Milky Way’s life,” he says. “We’ve seen glimpses of this population before,” but the new study gives “a bird’s-eye view of the whole structure.”

    Most stars in the Milky Way’s central region abound with metals, because the stars originated in a crowded metropolis that earlier stellar generations had enriched with those metals through supernova explosions. But Rix and his colleagues wanted to find the exceptions to the rule, stars so metal-poor they must have been born well before the rest of the galaxy’s stellar denizens came along — what Rix calls “a needle-in-a-haystack exercise.”

    His team turned to data from the Gaia spacecraft, which launched in 2013 on a mission to chart the Milky Way (SN: 6/13/22). The astronomers searched about 2 million stars within a broad region around the galaxy’s center, which lies in the constellation Sagittarius, looking for stars with metal-to-hydrogen ratios no more than 3 percent of the sun’s.

    The astronomers then examined how those stars move through space, retaining only the ones that don’t dart off into the vast halo of metal-poor stars engulfing the Milky Way’s disk. The end result: a sample of 18,000 ancient stars that represents the kernel around which the entire galaxy blossomed, the researchers say. By accounting for stars obscured by dust, Rix estimates that the protogalaxy is between 50 million and 200 million times as massive as the sun.

    “That’s the original core,” Rix says, and it harbors the Milky Way’s oldest stars, which he says probably have ages exceeding 12.5 billion years. The protogalaxy formed when several large clumps of stars and gas conglomerated long ago, before the Milky Way’s first disk — the so-called thick disk — arose (SN: 3/23/22).

    The protogalaxy is compact, which means little has disturbed it since its formation. Smaller galaxies have crashed into the Milky Way, augmenting its mass, but “we didn’t have any later mergers that deeply penetrated into the core and shook it up, because then the core would be larger now,” Rix says.

    The new data on the protogalaxy even capture the Milky Way’s initial spin-up — its transition from an object that didn’t rotate into one that now does. The oldest stars in the proto–Milky Way barely revolve around the galaxy’s center but dive in and out of it instead, whereas slightly younger stars show more and more movement around the galactic center. “This is the Milky Way trying to become a disk galaxy,” says Belokurov, who saw the same spin-up in research that he and a colleague reported in July.

    Today, the Milky Way is a giant galaxy that spins rapidly — each hour our solar system speeds through 900,000 kilometers of space as we race around the galaxy’s center. But the new study shows that the Milky Way got its start as a modest protogalaxy whose stars still shine today, stars that astronomers can now scrutinize for further clues to the galaxy’s birth and early evolution. More

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    in Humans

    Hunter-gatherers kept animals for food before they farmed crops

    Ancient dung hints that 12,000 years ago, a population of hunter-gatherers in what is now Syria kept animals like sheep or gazelles around – probably for food

    Humans

    14 September 2022

    By Christa Lesté-Lasserre
    Dung spherulites were found in samples of archaeological sediment from Abu Hureyra in SyriaAndrew Moore (CC-BY 4.0)
    Some hunter-gatherers probably kept sheep, or possibly gazelles, outside their huts before they even started farming crops, according to traces of ancient animal dung.
    Alexia Smith at the University of Connecticut and her colleagues have found spherulites – tiny spheres of calcium found primarily in the faeces of grass-eating ruminants like cattle, sheep and antelopes – outside groups of huts belonging to humans who lived in what is now Syria more than 12,000 years ago.
    They also found charred spherulites in fireplaces. This suggests that humans lived with herbivores, like sheep, in this region approximately 2000 years earlier than previously thought and were using their dung as a fuel source, says Smith.Advertisement

    “They’re still hunters and gatherers, and they’re still relying on hunted gazelle, but now they’re starting to bring live animals to the site and keep them for however long they need them,” says Smith. “And this result is a bit surprising, because it’s earlier than agriculture, and earlier than what we see in adjacent regions.”
    Ruminants release significant quantities of spherulites in their faeces, whereas omnivores, including humans, release very small amounts, and carnivores and horses – which are herbivores but not ruminants – release even fewer, says Smith.

    Smith was originally curious about when ancient populations first started burning animal dung as fuel, which is done because it can maintain a very high heat. So, she started looking for spherulites – which are about 5 to 20 micrometres across – in the dust at a human settlement at Abu Hureyra – in modern-day Syria near the Euphrates river – which was inhabited between about 13,300 and 7800 years ago.
    In dust from as far back as 12,300 to 12,800 years ago, she found darkened spherulites suggesting that dung had been burned at high temperatures, probably as a heat source, she says. But to her surprise, she also found undarkened spherulites all around the outside of huts, suggesting these people were tending to sheep, goats, cows or gazelles just outside their front doors. The earliest evidence we have for crop farming in the region dates back to about 11,000 years ago.

    “Very quickly, I realised, ‘Oh, my goodness, we have an opportunity here to actually consider the antiquity of live animals on the site’,” she says.
    By the late Neolithic period, about 8000 years ago, though, spherulites started to disappear from around the huts, says Smith. That may be because the herds had become so large that people were tending to them on pastures further away from the settlement. “It seems like kind of the opposite of what you’d expect,” she says. “But then, it makes sense, because if you have a huge number of animals, it’s not sustainable to keep them on site.”
    This doesn’t mean the animals were domesticated, though, adds Smith. Nor does it indicate which ruminants were living outside the huts. What is more likely is that humans tethered wild animals and fed them to keep them alive as a later meat source. “At the end of the day, these animals were dinner,” she says.
    Journal reference: PLoS One, DOI: 10.1371/journal.pone.0272947
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    in Humans

    Art of the ocean: How artists have depicted the marine world

    From Jason deCaires Taylor’s underwater statues, walking to oblivion, to Carl Chun’s detailed illustration of an octopus, a new book explores how our oceans have inspired art through the centuries

    Humans

    14 September 2022

    By Alison Flood
    Jason deCaires Taylor, RubiconJason deCaires Taylor
    A WOMAN is immortalised, gazing at her phone, part of an anonymous crowd of sculptures by British artist Jason deCaires Taylor. But this is no ordinary setting: deCaires Taylor’s pH-neutral marine cement figures (above) are 14 metres underwater off the coast of Lanzarote, Spain, and will eventually be reclaimed by the sea. The work’s name, Rubicon, draws from the idea the crowd, and the world, are heading towards a point of no return as temperatures rise.
    The image of Rubicon is taken from a new book, Ocean: Exploring the marine world, which details how our oceans have been a “symbol of infinity, beauty, solitude, isolation, danger, happiness, weightlessness and longing” in art through the centuries. Featuring more than 300 images ranging from Roman mosaics to nautical cartography, Ocean also highlights how climate change has affected the seas.
    NNtonio Rod, Trachyphyllia, from Coral ColorsNNtonio RodAdvertisement
    NNtonio Rod (Antonio Rodríguez Canto) took 25,000 photos over the course of a year to make the award-winning time-lapse film Coral Colors (2016), from which the striking still Trachyphyllia (see above), featured in the book, is taken. Rod wanted his film to raise awareness of corals as they become more vulnerable to climate change-related bleaching.
    Biodiversity Heritage Library/Contributed by MBLWHOILibrary
    Ocean also features marine biologist Carl Chun’s stunning illustration of an octopus (Muusoctopus, formerly Polypus levis), drawn from a specimen collected near the Kerguelen Islands in the south of the Indian Ocean during the 19th century. The illustration (above) is included in Die Cephalopoden, Chun’s seminal 1910 work on cephalopod molluscs.
    Book publisher Phaidon Editions

    More on these topics: More

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    in Humans

    Future Stories review: Has thinking about the future got even harder?

    In unstable times we need to think clearly about the future. There is a lot to learn from David Christian’s Future Stories: A user’s guide to the future, an ambitious book with a Big History approach

    Humans

    14 September 2022

    By Elle Hunt
    Facing the scenarios ahead is vital – while we can still do somethingBrian Jackson/Alamy
    Future Stories
    David Christian (Penguin Random House)
    NOW more than ever, it feels like the future is uncertain: the times, they are unprecedented. Adam Tooze, an economic historian at Columbia University in New York City, recently described the global outlook as a “polycrisis”, remarkable not only for the number of risks currently active, but also their volatility.
    As well as the pandemic, we have the invasion of Ukraine, inflation, pressures on food and energy markets and upheavals in … More

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    in Humans

    Flush review: Stop letting human faeces go down the toilet

    Bryn Nelson’s extraordinary book asks why we let a vital natural resource, human faeces, get flushed away when we could be using it to heal guts, improve soil and understand our past

    Humans

    14 September 2022

    By Chelsea Whyte
    Clinical-looking modern toilets may help fuel unhelpful notions that faecal matter is disgustingShutterstock/Oasisamuel
    Flush
    Bryn Nelson (Hachette)
    ASK me to name the world’s best invention, and I will always give the same answer: the toilet. Its ability to whisk waste away to a safe place where potential pathogens and odours can do no harm isn’t to be sniffed at. But an unusual book has convinced me that toilets make it too easy to waste our waste.
    Bryn Nelson’s Flush: The remarkable science of an unlikely treasure explains the many ways … More

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    in Humans

    Don't Miss: Andor, prequel to the Star Wars spin-off Rogue One

    New Scientist’s weekly round-up of the best books, films, TV series, games and more that you shouldn’t miss

    Humans

    14 September 2022

    Cassian Andor (Diego Luna) in Lucasfilm’s AndorLucasfilm Ltd
    Watch
    Andor takes Star Wars fans back to before the events of Rogue One, and finds Cassian Andor (Diego Luna, pictured above) doing all he can to avoid getting involved with a seemingly doomed rebellion. On Disney+ from 21 September.
    Read
    Stars in Your Hand, by Kimberly Arcand and Megan Watzke, shows how to make models of the cosmos using a 3D printer and 3D computer imaging. Luckily, it includes easy instructions for creating stars and more. On sale from 20 September.
    … More

  • 138 Shares139 Views

    in Humans

    Simple puzzles are revealing why humans are the only talking apes

    Cognitive scientist Gillian Forrester is challenging chimps and gorillas to solve puzzles in an attempt to address the long-standing mystery of how humans evolved the ability to speak

    Humans

    13 September 2022

    By Alison George
    Nabil Nezzar
    IT LIES at the centre of human experience, and yet how our incredible capacity for complex language arose is a mystery. We are still far from understanding why we are the only living ape with such a skill.
    Answering these questions is difficult, not least because speech doesn’t leave its trace in the fossil record. However, we can look to our ape relatives for clues, as cognitive scientist Gillian Forrester at Birkbeck, University of London, is doing. She has developed puzzle mazes for chimpanzees, gorillas, orangutans and children that shed light on one idea of how language evolved. She tells New Scientist how her findings are challenging our understanding of the brain and painting a clearer picture of how language began.
    Alison George: What inspired you to study the evolution of language?
    Gillian Forrester: I’ve always been intrigued by the efforts to teach chimpanzees to speak, which were going on while I was growing up in the 1980s. They were a massive failure when it came to chimps learning to combine words into more complex phrases.
    This got me intrigued about the common factors between human language and other animal communication systems, and how and why a language system emerged in humans but not for other great apes.
    How do we start to answer that question?
    We don’t have our ancient ancestors to look at to see how things changed over evolutionary time because they are all extinct, and cognition doesn’t fossilise. So all we can do is make suppositions based on their artefacts, such as tools and things they were buried with, to give us an indication of their communication skills. … More

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    in Space & Astronomy

    Passing through the Milky Way’s arms may have helped form Earth’s solid ground

    Earth’s journey through the Milky Way might have helped create the planet’s first continents.

    Comets may have bombarded Earth every time the early solar system traveled through our galaxy’s spiral arms, a new study suggests. Those recurring barrages in turn helped trigger the formation of our planet’s continental crust, researchers propose August 23 in Geology.

    Previous theories have suggested that such impacts might have played a role in forming Earth’s landmasses. But there has been little research explaining how those impacts occurred, until now, the team says.

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    It’s an intriguing hypothesis, other scientists say, but it’s not the last word when it comes to explaining how Earth got its landmasses.

    To peer back in time, geochronologist Chris Kirkland and his colleagues turned to geologic structures known as cratons (SN: 12/3/10). These relics of Earth’s ancient continental crust are some of the planet’s oldest rocks. Using material from cratons in Australia and Greenland that are billions of years old, the team measured the chemistry of more than 2,000 bits of rock. The analysis let the researchers determine the exact ages of the rocks, and whether they had formed anew from molten material deep within the Earth or from earlier generations of existing crust.

    When Kirkland and his colleagues looked for patterns in their measurements, the team found that new crust seemed to form in spurts at roughly regular intervals. “Every 200 million years, we see a pattern of more crust production,” says Kirkland, of Curtin University in Perth, Australia.

    That timing rang a bell: It’s also the frequency at which the Earth passes through the spiral arms of the Milky Way (SN: 12/30/15). The solar system loops around the center of the galaxy a bit faster than the spiral arms move, periodically passing through and overtaking them. Perhaps cosmic encounters with more stars, gas and dust within the spiral arms affected the young planet, the team suggests.

    The idea makes sense, the researchers say, since the higher density of material in the spiral arms would have led to more gravitational tugs on the reservoir of comets at our solar system’s periphery (SN: 8/18/22). Some of those encounters would have sent comets zooming into the inner solar system, and a fraction of those icy denizens would have collided with Earth, Kirkland and his team propose.

    Earth was probably covered mostly by oceans billions of years ago, and the energy delivered by all those comets would have fractured the planet’s existing oceanic crust — the relatively dense rock present since even earlier in Earth’s history — and excavated copious amounts of material while launching shock waves into the planet. That mayhem would have primed the way for parts of Earth’s mantle to melt, Kirkland says. The resulting magma would have naturally separated into a denser part — the precursor to more oceanic crust — and a lighter, more buoyant liquid that eventually turned into continental crust, the researchers suggest.

    That’s one hypothesis, but it’s far from a slam dunk, says Jesse Reimink, a geoscientist at Penn State who was not involved in the research. For starters, comet and meteorite impacts are notoriously tough to trace, especially that far back in time, he says. “There’s very few diagnostics of impacts.” And it’s not well-known whether such impacts, if they occurred in the first place, would have resulted in the release of magma, he says.

    In the future, Kirkland and his colleagues hope to analyze moon rocks to look for the same pattern of crust formation (SN: 7/15/19). Our nearest celestial neighbor would have been walloped by about the same amount of stuff that hit Earth, Kirkland says. “You’d predict it’d also be subject to these periodic impact events.” More