Philippa Kaur

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    in Space & Astronomy

    Some fast radio bursts come from the spiral arms of other galaxies

    Five brief, bright blasts of radio waves from deep space now have precise addresses.

    The fast radio bursts, or FRBs, come from the spiral arms of their host galaxies, researchers report in a study to appear in the Astrophysical Journal. The proximity of the FRBs to sites of star formation bolsters the case for run-of-the-mill young stars as the origin of these elusive, energetic eruptions.

    “This is the first such population study of its kind and provides a unique piece to the puzzle of FRB origins,” says Wen-fai Fong, an astronomer at Northwestern University in Evanston, Ill.

    FRBs typically last a few milliseconds and are never seen again. Because the bursts are so brief, it’s difficult to nail down their precise origins on the sky. Although astronomers have detected about 1,000 FRBs since the first was reported in 2007, only 15 or so have been traced to a specific galaxy.

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    The first burst to be traced to its source came from a small, blobby dwarf galaxy with a lot of active star formation (SN: 1/4/17). That FRB sends off repeated blasts from a single source, which is an unusual feature, and helped astronomers localize its host galaxy.

    “After that, a lot of people thought, well, maybe all FRB hosts are like this,” says astronomer Alexandra Mannings of the University of California, Santa Cruz. But then a second repeating burst was tracked back to a spiral galaxy like the Milky Way (SN: 1/6/20). And a one-off burst was localized to a massive disk-shaped galaxy, also the size of the Milky Way. Others followed.

    Mannings, Fong and colleagues thought they could learn more about the FRBs’ sources by localizing their origins even more precisely. Different parts of spiral galaxies tend to host different types of stars. The bright spiral arms tend to mark sites where new stars are being born, while the older and dimmer stars have had time to drift away from the arms into the rest of the galaxy. So figuring out which galactic neighborhoods FRBs call home can reveal a lot about what kind of objects they come from.

    Using the Hubble Space Telescope, the researchers took high-resolution images of eight galaxies that were already known to host FRBs, then overlaid the FRBs’ positions onto the images. The five FRBs that came from clearly defined spiral galaxies all lay on or close to the galaxies’ spiral arms, which had not been visible in images from ground-based telescopes. The other three host galaxies had inconclusive shapes, Fong says.

    The FRB locales have a fair amount of star formation, but they’re not the brightest and most active parts of their galaxies, Fong says. That suggests FRBs originate with ordinary young stars — not the youngest, most massive stars that occupy the brightest knots in the spiral arms, but not the oldest and dimmest stars that have drifted away from their homes, either.

    That finding is consistent with the idea that FRBs come from highly magnetized stellar corpses called magnetars, Mannings says (SN: 6/4/20). There are a couple of ways to produce magnetars from ordinary stars. There’s the slow way, which involves waiting billions of years for a pair of neutron stars to collide (SN: 12/1/20). Or there’s the fast way, which follows the death of a single massive star. It seems like FRBs might come from an in-between process, like the death of a not-so-massive star, Mannings says.

    “The fact that FRBs are found to be pretty close to, if not on, the spiral arm, near to these star forming regions, that can give us a better idea of what the timeline is like for the progenitor,” whatever created the FRB, Mannings says. “And if it is a magnetar, it lets us know that it’s not through the delayed channel, like a neutron star merger.”

    The finding doesn’t entirely solve the mystery of where FRBs come from, says astrophysicist Emily Petroff of the University of Amsterdam, who was not involved in the new work. But it does help to get a broader picture of their host galaxies.

    “FRBs keep throwing a lot of surprises at us, in terms of what they look like, where they’re found, how they repeat,” Petroff says. “This is maybe providing more evidence that FRBs are more related to just sort of general neutron stars.” The next step, of course, is to find more FRBs. More

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    in Humans

    The human genome has finally been completely sequenced after 20 years

    By Michael Marshall

    The full sequence of the human genome is finally hereKTSDESIGN/SCIENCE PHOTO LIBRARY
    We have finally sequenced the complete human genome. No, for real this time.
    When scientists first announced that they had read all of a person’s DNA 20 years ago, they were still missing some bits. Now, with the benefit of far better methods for reading DNA, it has finally been possible to read the whole thing from end to end.
    “Having been part of the original Human Genome Project in 2001, and especially focused on the difficult regions, it’s really … More

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    in Humans

    Ancient jawbone reveals a 2500-kilometre journey from Sudan to Rome

    By Garry Shaw

    Catacombs of Saints Marcellinus and PeterD. Gliksman/INRAP
    Ancient human remains found in a catacomb in Rome belonged to a migrant from northern Africa who grew up along the Nile valley before travelling to the heart of the Roman Empire more than 1700 years ago.
    The remains, consisting of only a jawbone fragment with three teeth attached, were found in the Catacombs of Saints Marcellinus and Peter, south-east Rome. They were uncovered in a chamber during a rescue excavation, conducted before a support pillar could be installed.
    Kevin Salesse at the Free … More

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    in Humans

    Stepped platforms in Mesopotamia were the oldest known war memorial

    By Michael Marshall

    Tell Banat North in Syria was submerged in 1999
    An earthen mound in what is now Syria may be the oldest known war memorial in the world, constructed before 2300 BC. The remains of what could be foot soldiers and charioteers were buried in distinct clusters in a monument made of piled-up soil. However, it isn’t clear if they belonged to the winning or losing side, or what the conflict was about.
    The finding comes from a re-examination of remains from the White Monument, which was excavated in the 1980s and 1990s. The area was submerged in 1999 by the construction of the Tishrin Dam on the Euphrates river, and hasn’t been investigated since.
    Anne Porter at the University of Toronto in Canada was one of the leaders of the excavations. “It was a salvage project,” she says. The flooding was “a really traumatic experience” because the area was “the most fabulous site you could imagine working on”.Advertisement
    Immediately to the north of a small mountain called Jebel Bazi, Mesopotamian people built a settlement that archaeologists call the Banat/Bazi complex. It was occupied between about 2700 and 2300 BC. The site included a set of earthen mounds called Tell Banat, and slightly further north a single large mound called Tell Banat North or the White Monument.
    The White Monument got its name because it was coated in a chalky mineral called gypsum. Porter says it was built in three stages. The first was a smooth mound, which the team never managed to excavate due to the flooding. Later, people built smaller mounds on top of it, containing human bones. “Imagine upside-down ice cream cones on the outside of a pudding,” says Porter. “That’s what it must have looked like.”

    Finally, the people constructed stepped platforms around the edge of the mound. In the soil, the team found lots of fragmentary bones. Some were human. Others belonged to animals similar to donkeys – the exact species is unclear.
    Porter has now worked with a class of undergraduates to reconstruct where all the bones were placed in the earth platforms. “It was them that realised there’s a pattern here,” she says.
    One cluster held the remains of humans buried with hard pellets of compacted earth, which may have been projectile weapons. The team argues that these were foot soldiers.

    The other set tended to have a single donkey-like animal paired with an adult human and a teenager. The team suggests these were charioteers: the adult driving the chariot and the teenager jumping on and off the chariot.
    Porter suspects the monument reflects “an internal conflict” rather than an invasion. At the time, hierarchical societies were emerging, creating “a tension between a community-based kinship society and then these narrowing elites who are in control”, she says.
    Journal reference: Antiquity, DOI: 10.15184/aqy.2021.58
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    in Humans

    What is ASMR? Science with Sam explains

    If a strange tingling feeling comes over you when someone whispers, chews or taps in your ear, you might be lucky enough to experience autonomous sensory meridian response or ASMR. This strange but relaxing sensation has spawned countless videos on YouTube, but what exactly is it? Sit back, relax and let Science with Sam explain.
    More Science with Sam:
    What is a black hole? And could you survive one?
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    in Humans

    Earliest known war was a repeated conflict in Sudan 13,400 years ago

    By Krista Charles

    An archival photograph showing a double burial at Jebel SahabaWendorf Archives of the British Museum
    Individuals buried at the prehistoric cemetery Jebel Sahaba in Sudan seem to have experienced violence and trauma at several points during their lives. The discovery may help us understand the prehistory of violence before the origin of farming.
    At about 13,400 years old, Jebel Sahaba is one of the earliest sites displaying signs of mass conflict. Violence between communities seems to have become more common once people settled in one place to farm, which had begun happening by about 12,000 years ago. But evidence of organised violence among more mobile communities, like those represented by Jebel Sahaba, is unusual.
    The remains at the cemetery were exhumed in the 1960s, and once it was clear that 20 of the skeletons carried injuries, it was suggested they had belonged to people who had died during a single war. A reanalysis shows that this probably wasn’t the case.Advertisement
    Isabelle Crevecoeur at the University of Bordeaux in France and her colleagues examined the remains of 61 individuals, including the 20 already found to have injuries. They identified more than 100 healed and unhealed bone lesions that were previously undocumented and indicate that these pre-agricultural people survived several instances of violence during their lives.

    “We knew that we were going to find maybe some additional lesions, but, in this case, this systematic and really thorough analysis of the remains allowed us to add 21 individuals to the 20 that were already recognised with traumatic lesions,” says Crevecoeur.
    There were probably deliberate, sporadic and recurrent attacks between different cultural groups among these hunter-fisher-gatherers, says Crevecoeur.
    “We do not know of any other cemetery at that time which shows such a high rate of people injured and killed,” says Thomas Terberger at the University of Göttingen in Germany. “This high rate of conflict is something unique and it will be a task for the future to analyse whether this is outstanding evidence, or perhaps the reanalysis of other [similarly ancient] sites will show more evidence of such conflicts.”
    The team found that most of the lesions were related to impact marks from projectiles, and in some cases there were still bits of stone embedded in the bones of both men and women. These fragments may have come from the heads of arrows or spears.

    “These results enrich our understanding of the contexts in which violence emerges among foragers,” says Luke Glowacki at Harvard University. “They provide additional evidence for an emerging consensus that foragers, just like agricultural peoples, had interpersonal violence in the form of raids and ambushes.”
    Journal reference: Scientific Reports, DOI: 10.1038/s41598-021-89386-y
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    in Humans

    Can't be bothered? Why some of us are more motivated than others

    Some people seem to possess unlimited get-up-and-go, while others can barely muster enough drive to leave the couch. Here’s what science tells us about motivation – and how to cultivate it

    Health

    26 May 2021

    By Amelia Tait

    Antonio Sortino
    I’VE had three weeks to write the words you are about to read, but they were written at the last possible minute. Why? I wasn’t busy exercising – I haven’t done that in months. My time wasn’t spent at my book club or calligraphy class, because I’m not involved in anything of the sort. Nor did I procrastinate by mastering the ultimate sourdough loaf – just the thought of it makes me want to lie down. Quite simply, I waited until the last minute because I couldn’t be arsed.
    My condition is what’s known colloquially among my generation as “The CBAs” – the “can’t be arseds”. In my case, it is chronic. I can’t be arsed to go on a run. I can’t be arsed to cook. I can’t be arsed to reply to my emails.
    I’m not alone. According to a December 2020 survey by the Pew Research Center, 42 per cent of people in the US aged between 18 and 49 say they have struggled to find the motivation to work since the beginning of the covid-19 pandemic. That still leaves half of the population who are fine, who get up and get on. Then there are those people who wake at 6 am and run 10 kilometres before work. People who write their memoirs. People who wash their curtains.
    What are their secrets? Why do some people have so much drive and others, like me, so little? And is it possible for me to become a go-getter? To find out, I mustered the motivation to ask a few of the scientists who might know.
    Motivation is what drives much … More

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    in Humans

    The Menopause Manifesto review: A guide to counteract medical misogyny

    By Helen Thomson

    I AM only 37 and I have experienced the menopause multiple times. Drugs for IVF and endometriosis paused my hormonal cycles on five separate occasions, placing me in what doctors call “artificial menopause”.
    But there was nothing artificial about the symptoms – the hot flushes that burned deep inside my core at 2 am were a particular shock. So when I came across The Menopause Manifesto, written by gynaecologist Jen Gunter, I jumped at the chance to learn more about what was in store when the real thing hits.
    Despite the universal nature of menopause for half the planet’s population, few of us are fully informed about the symptoms, physical changes, medical concerns or treatment options.
    According to Gunter, this information vacuum is largely down to medical misogyny. Indeed, medicine’s long history of neglecting women means that menopause concerns are still too often dismissed as fabricated, unimportant or just “part of being a woman”.
    Gunter’s ambition is to change this conversation, which is worthy in all the right ways. Menopause shouldn’t be a fringe part of women’s healthcare: aside from quality of life issues, social impact and physical symptoms, there is its link to cardiovascular disease. This is responsible for 1 in 3 female deaths each year – more than die from breast cancer.
    So it turns out that my 2 am “hot blooms” (as I find they would have been called in the 18th century) are the least of it. Women can also expect abnormal bleeding, temporary cognitive changes, vaginal dryness, pain during sex, decreased libido and joint pain. Not to mention the increased risk of osteoporosis, dementia, metabolic syndrome (a combination of diabetes, high blood pressure and obesity), type 2 diabetes and urinary tract infections. Sound like something you should know about?
    “We don’t define men as they age by an obvious physical change in their reproductive function”
    Gunter’s teaching of the history and biology around menopause is second to none. Her opinions on the societal lens through which we view the menopause are just as interesting. She highlights the fact that it is misogynistic to tie a description for a third of a woman’s life to the function of her uterus and ovaries. We don’t define men as they age by an obvious physical change in their reproductive function, she points out. Yes, the menopause is a marker for increased risk of heart disease for women, but so, too, she says, is erectile dysfunction for men. Imagine a world with men in what she calls the “erectopause”.
    Running throughout the book is a wealth of information on the physiological processes at play during a woman’s life. While it could do with a little pruning, it can’t fail to leave you feeling completely wised up, without veering into a biology lesson.
    As a gynaecologist, Gunter also has the authority to provide vital information on treatments, from traditional hormone replacement therapies (HRT) to alternative medicines. She also shows us where we may be led astray by celebrity endorsements of natural remedies, and by “compound” therapies – treatments that resemble traditional HRT, but which remain largely unregulated and untested, she says.
    There is information on drugs like fezolinetant, too, which look promising for hot flushes. My copy has many page corners turned over – things I plan to ask my doctor, now and later.
    “I am here to scare you about osteoporosis,” Gunter says in one chapter. It isn’t the only scary thing she reveals about this future time in my life, but at least I am now better prepared, have the confidence to know what to ask, and feel able to have a more grown-up conversation.
    Gunter promises to give women strength, value, agency and knowledge to help them through this transition in their life. She has unquestionably achieved that. More