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    Aliens could send quantum messages to Earth, calculations suggest

    An intelligent alien civilization could beam quantum messages to Earth.

    Particles of light, or photons, could be transmitted over vast, interstellar distances without losing their quantum nature, researchers report June 28 in Physical Review D. That means scientists searching for extraterrestrial signals could also look for quantum messages (SN: 1/28/19).

    Scientists are currently developing Earth-based quantum communication, a technology that uses quantum particles to send information and has the potential to be more secure than standard, or classical, communication (SN: 6/15/17). Intelligent extraterrestrials, if they’re out there, may have also adopted quantum communication, says theoretical physicist Arjun Berera.

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    A major obstacle to quantum communication is decoherence, in which a quantum particle loses its quantumness as it interacts with its surroundings. “Quantum states you generally think of as very delicate, and if there’s any kind of external interaction, you kind of destroy that state,” Berera says.

    Since the average density of matter in space is much less than on Earth, particles could be expected to travel farther before succumbing to decoherence. So Berera and theoretical physicist Jaime Calderón Figueroa, both of the University of Edinburgh, calculated how far light — in particular, X-rays — could travel unscathed through interstellar space.

    X-ray photons could more than traverse the Milky Way, potentially traveling hundreds of thousands of light-years or even more, the researchers found.

    Based on the findings, Berera and Calderón Figueroa considered strategies to search for E.T.’s quantum dispatches. One potential type of communication to search for is quantum teleportation, in which the properties of a distant particle can be transferred to another (SN: 7/7/17). Since the technology requires both quantum and classical signals, scientists could look for such simultaneous signals to identify any alien quantum missives. More

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    A new look at the ‘mineral kingdom’ may transform how we search for life

    If every mineral tells a story, then geologists now have their equivalent of The Arabian Nights.

    For the first time, scientists have cataloged every different way that every known mineral can form and put all of that information in one place. This collection of mineral origin stories hints that Earth could have harbored life earlier than previously thought, quantifies the importance of water as the most transformative ingredient in geology, and may change how researchers look for signs of life and water on other planets. 

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    “This is just going to be an explosion,” says Robert Hazen, a mineralogist and astrobiologist at the Carnegie Institution for Science in Washington, D.C. “You can ask a thousand questions now that we couldn’t have answered before.”

    For over 100 years, scientists have defined minerals in terms of “what,” focusing on their structure and chemical makeup. But that can make for an incomplete picture. For example, though all diamonds are a kind of crystalline carbon, three different diamonds might tell three different stories, Hazen says. One could have formed 5 billion years ago in a distant star, another may have been born in a meteorite impact, and a third could have been baked deep below the Earth’s crust.

    Diamonds have the same carbon structure, but they can form in different ways. This particular gem originated deep within the Earth.Rob Lavinsky/ARKENSTONE

    So Hazen and his colleagues set out to define a different approach to mineral classification. This new angle focuses on the “how” by thinking about minerals as things that evolve out of the history of life, Earth and the solar system, he and his team report July 1 in a pair of studies in American Mineralogist. The researchers defined 57 main ways that the “mineral kingdom” forms, with options ranging from condensation out of the space between stars to formation in the excrement of bats. 

    The information in the catalog isn’t new, but it was previously scattered throughout thousands of scientific papers. The “audacity” of their work, Hazen says, was to go through and compile it all together for the more than 5,600 known types of minerals. That makes the catalog a one-stop shop for those who want to use minerals to understand the past.

    The compilation also allowed the team to take a step back and think about mineral evolution from a broader perspective. Patterns immediately popped out. One of the new studies shows that over half of all known mineral kinds form in ways that ought to have been possible on the newborn Earth. The implication: Of all the geologic environments that scientists have considered as potential crucibles for the beginning of life on Earth, most could have existed as early as 4.3 billion years ago (SN: 9/24/20). Life, therefore, may have formed almost as soon as Earth did, or at the very least, had more time to arise than scientists have thought. Rocks with traces of life date to only 3.4 billion years ago (SN: 7/26/21). 

    “That would be a very, very profound implication — that the potential for life is baked in at the very beginning of a planet,” says Zachary Adam, a paleobiologist at the University of Wisconsin–Madison who was not involved in the new studies.

    The exact timing of when conditions ripe for life arose is based on “iffy” models, though, says Frances Westall, a geobiologist at the Center for Molecular Biophysics in Orléans, France, who was also not part of Hazen’s team. She thinks that scientists need more data before they can be sure. But, she says, “the principle is fantastic.”

    The new results also show how essential water has been to making most of the minerals on Earth. Roughly 80 percent of known mineral types need H2O to form, the team reports.

    “Water is just incredibly important,” Hazen says, adding that the estimate is conservative. “It may be closer to 90 percent.”

    Some minerals would not form in certain ways without the influence of life. Photosynthesizing bacteria helped bring about the oxygen-rich conditions needed for this azurite (left), while the opalized ammonite (right) was created by the mineral opal filling the space where an ammonite shell used to be.Rob Lavinsky/ARKENSTONE

    Taken one way, this means that if researchers see water on a planet like Mars, they can guess that it has a rich mineral ecosystem (SN: 3/16/21). But flipping this idea may be more useful: Scientists could identify what minerals are on the Red Planet and then use the new catalog to work backward and figure out what its environment was like in the past. A group of minerals, for example, might be explainable only if there had been water, or even life.

    Right now, scientists do this sort of detective work on just a few minerals at a time (SN: 5/11/20). But if researchers want to make the most of the samples collected on other planets, something more comprehensive is needed, Adam says, like the new study’s framework.

    And that’s just the beginning. “The value of this [catalog] is that it’s ongoing and potentially multigenerational,” Adam says. “We can go back to it again and again and again for different kinds of questions.” 

    “I think we have a lot more we can do,” agrees Shaunna Morrison, a mineralogist at the Carnegie Institution and coauthor of the new studies. “We’re just scratching the surface.” More

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    50 years ago, a new theory of Earth’s core began solidifying

    How the Earth got its core – Science News, July 1, 1972

    In the beginning, scientists believe there was an interstellar gas cloud of all the elements comprising the Earth. A billion or so years later, the Earth was a globe of concentric spheres with a solid iron inner core, a liquid iron outer core and a liquid silicate mantle…. The current theory is that the primeval cloud’s materials accreted … and that sometime after accretion, the iron, melted by radioactive heating, sank toward the center of the globe…. Now another concept is gaining ground: that the Earth may have accreted … with core formation and accretion occurring simultaneously.

    Update

    Most scientists now agree that the core formed as materials that make up Earth collided and glommed together and that the process was driven by heat from the smashups. The planet’s heart is primarily made of iron, nickel and some oxygen, but what other elements may dwell there and in what forms remains an open question. Recently, scientists proposed the inner core could be superionic, with liquid hydrogen flowing through an iron and silicon lattice (SN: 3/12/22, p. 12). More

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    An otherwise quiet galaxy in the early universe is spewing star stuff

    PASADENA, Calif. — A lucky celestial alignment has given astronomers a rare look at a galaxy in the early universe that is seeding its surroundings with the elements needed to forge subsequent generations of stars and galaxies.

    Seen as it was just 700 million years after the Big Bang, the distant galaxy has gas flowing over its edges. It is the earliest-known run-of-the-mill galaxy, one that could have grown into something like the Milky Way, to show such complex behavior, astronomer Hollis Akins said June 14 during a news conference at the American Astronomical Society meeting.

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    “These results also tell us that this outflow activity seems to be able to shape galaxy evolution, even in this very early part of the universe,” said Akins, an incoming graduate student at the University of Texas at Austin. He and colleagues also submitted their findings June 14 to arXiv.org.

    The galaxy, called A1689-zD1,­ shows up in light magnified by Abell 1689, a large galaxy cluster that can bend and intensify, or gravitationally lens, light from the universe’s earliest galaxies (SN: 2/13/08; SN: 10/6/15). Compared with other observed galaxies in the early universe, A1689-zD1 doesn’t make a lot of stars — only about 30 suns each year — meaning the galaxy isn’t very bright to our telescopes. But the intervening cluster magnified A1689-zD1’s light by nearly 10 times.

    Akins and colleagues studied the lensed light with the Atacama Large Millimeter/submillimeter Array, or ALMA, a large network of radio telescopes in Chile. The team mapped the intensities of a specific spectral line of oxygen, a tracer for hot ionized gas, and a spectral line of carbon, a tracer for cold neutral gas. Hot gas shows up where the bright stars are, but the cold gas extends four times as far, which the team did not expect.

    “There has to be some mechanism [to get] carbon out into the circumgalactic medium,” the space outside of the galaxy, Akins says.

    Only a few scenarios could explain that outflowing gas. Perhaps small galaxies are merging with A1689-zD1 and flinging gas farther out where it cools, Akins said. Or maybe the heat from star formation is pushing the gas out. The latter would be a surprise considering the relatively low rate of star formation in this galaxy. While astronomers have seen outflowing gas in other early-universe galaxies, those galaxies are bustling with activity, including converting thousands of solar masses of gas into stars per year.

    Galaxy A169-zD1 (pictured, in radio waves) exists in the universe’s first 700 million years.ALMA/ESO, NAOJ and NRAO; H. Akins/Grinnell College; B. Saxton/NRAO/AUI/NSF

    The researchers again used the ALMA data to measure the motions of both the cold neutral and hot ionized gas. The hot gas showed a larger overall movement than the cold gas, which implies it’s being pushed from A1689-zD1’s center to its outer regions, Akins said at the news conference.

    Despite the galaxy’s relatively low rate of star formation, Akins and his colleagues still think the 30-solar-masses of stars a year heat the gas enough to push it out from the center of the galaxy. The observations suggest a more orderly bulk flow of gas, which implies outflows, however the researchers are analyzing the movement of the gas in more detail and cannot yet rule out alternate scenarios.

    They think when the hot gas flows out, it expands and eventually cools, Akins said, which is why they see the colder gas flowing over the galaxy’s edge. That heavy-element-rich gas enriches the circumgalactic medium and will eventually be incorporated into later generations of stars (SN: 6/17/15). Due to gravity’s pull, cool gas, often with fewer heavy elements, around the galaxy also falls toward its center so A1689-zD1 can continue making stars.

    These observations of A1689-zD1 show this flow of gas happens not only in the superbright, extreme galaxies, but even in normal ones in the early universe. “Knowing how this cycle is working helps us to understand how these galaxies are forming stars, and how they grow,” says Caltech astrophysicist Andreas Faisst, who was not involved in the study.

    Astronomers aren’t done learning about A1689-zD1, either. “It’s a great target for follow-up observations,” Faisst says. Several of Akins’s colleagues plan to do just that with the James Webb Space Telescope (SN: 10/6/21). More

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    Gravitational wave ‘radar’ could help map the invisible universe

    It sounds like the setup for a joke: If radio waves give you radar and sound gives you sonar, what do gravitational waves get you?

    The answer might be “GRADAR” — gravitational wave “radar” — a potential future technology that could use reflections of gravitational waves to map the unseen universe, say researchers in a paper accepted to Physical Review Letters. By looking for these signals, scientists may be able to find dark matter or dim, exotic stars and learn about their deep insides.

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    Astronomers routinely use gravitational waves — traveling ripples in the fabric of space and time itself, first detected in 2015 — to watch cataclysmic events that are hard to study with light alone, such as the merging of two black holes (SN: 2/11/2016).

    But physicists have also known about a seemingly useless property of gravitational waves: They can change course. Einstein’s theory of gravity says that spacetime gets warped by matter, and any wave passing through these distortions will change course. The upshot is that when something emits gravitational waves, part of the signal comes straight at Earth, but some might arrive later — like an echo — after taking longer paths that bend around a star or anything else heavy.

    Scientists have always thought these later signals, called “gravitational glints,” should be too weak to detect. But physicists Craig Copi and Glenn Starkman of Case Western Reserve University in Cleveland, Ohio, took a leap: Working off Einstein’s theory, they calculated how strong the signal would be when waves scatter through the gravitational field inside a star itself.

    “The shocking thing is that you seem to get a much larger result than you would have expected,” Copi says. “It’s something we’re still trying to understand, where that comes from — whether it’s believable, even, because it just seems too good to be true.”

    If gravitational glints can be so strong, astronomers could possibly use them to trace the insides of stars, the team says. Researchers could even look for massive bodies in space that would otherwise be impossible to detect, like globs of dark matter or lone neutron stars on the other side of the observable universe.“That would be a very exciting probe,” says Maya Fishbach, an astrophysicist at Northwestern University in Evanston, Ill., who was not involved in the study.

    There are still reasons to be cautious, though. If this phenomenon stands up to more detailed scrutiny, Fishbach says, scientists would have to understand it better before they could use it — and that will probably be difficult.

    “It’s a very hard calculation,” Copi says.

    But similar challenges have been overcome before. “The whole story of gravitational wave detection has been like that,” Fishbach says. It was a struggle to do all the math needed to understand their measurements, she says, but now the field is taking off (SN: 1/21/21). “This is the time to really be creative with gravitational waves.” More

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    Seven newfound dwarf galaxies sit on just one side of a larger galaxy

    PASADENA, Calif. — The faint dwarf galaxies in a nearby galaxy group seem to have missed the memo. Instead of being dispersed evenly around the group’s most massive galaxy, which is what happens in our own galaxy group, these newly found dwarfs cluster in one region. And astronomers don’t know why.

    “This satellite distribution is just weird,” astronomer Eric Bell said June 13 at the American Astronomical Society meeting.

    Bell, of the University of Michigan in Ann Arbor, and colleagues used the Subaru telescope in Hawaii to hunt for faint clumps of stars, indicating dwarf galaxies, around the galaxy M81. This Milky Way–like galaxy is the most prominent member in a relatively nearby group of galaxies, all about 12 million light-years from Earth. The team found one definite dwarf galaxy and six possible fainter ones.

    Most of the known satellite galaxies (circled in red) in the M81 galaxy group, along with seven newfound candidates (yellow), seem to cluster toward one side of the galaxy M81 (center).Sloan Digital Sky Survey

    “The part that’s just bananas,” Bell said, is that the newfound satellite galaxies all sit on one side of M81.

    Computer simulations of galaxy evolution suggest that the largest galaxies have many faint, small galaxies sprinkled uniformly throughout the outer part of the dominant galaxy’s diffuse cloudlike halo. Observations in our galaxy group back this up: The dozens of dwarf galaxies known to orbit in the Milky Way’s outskirts are distributed evenly around the galaxy, as are most of the dwarf galaxies seen around our nearest large neighbor, the Andromeda Galaxy (SN: 3/11/15; SN: 8/19/15).

    But in the M81 group, the seven newly identified star clumps appear to surround a smaller member of that group, NGC 3077, which is about one-tenth the mass of M81. “The fact that the bigger thing doesn’t have more satellites,” Bell says, “nobody expects that.” More

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    Neutrinos hint the sun has more carbon and nitrogen than previously thought

    After two decades of debate, scientists are getting closer to figuring out exactly what the sun — and thus the whole universe — is made of.

    The sun is mostly composed of hydrogen and helium. There are also heavier elements such as oxygen and carbon, but just how much is controversial. New observations of ghostly subatomic particles known as neutrinos suggest that the sun has an ample supply of “metals,” the term astronomers use for all elements heavier than hydrogen and helium, researchers report May 31 at arXiv.org.

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    The results “are fully compatible with [a] high metallicity” for the sun, says Livia Ludhova, a physicist at Research Center Jülich in Germany.

    Elements heavier than hydrogen and helium are crucial for creating rock-iron planets like Earth and sustaining life-forms like humans. By far the most abundant of these elements in the universe is oxygen, followed by carbon, neon and nitrogen.

    But astronomers don’t know exactly how much of these elements exist relative to hydrogen, the most common element in the cosmos. That’s because astronomers typically use the sun as a reference point to gauge elemental abundances in other stars and galaxies, and two techniques imply very different chemical compositions for our star.

    One technique exploits vibrations inside the sun to deduce its internal structure and favors a high metal content. The second technique determines the sun’s composition from how atoms on its surface absorb certain wavelengths of light. Two decades ago, a use of this second technique suggested that oxygen, carbon, neon and nitrogen levels in the sun were 26 to 42 percent lower than an earlier determination found, creating the current conflict.

    Another technique has now emerged that could decide the long-standing debate: using solar neutrinos.

    These particles arise from nuclear reactions in the sun’s core that turn hydrogen into helium. About 1 percent of the sun’s energy comes from reactions involving carbon, nitrogen and oxygen, which convert hydrogen into helium but do not get used up in the process. So the more carbon, nitrogen and oxygen the sun actually has, the more neutrinos this CNO cycle should emit.

    In 2020, scientists announced that Borexino, an underground detector in Italy, had spotted these CNO neutrinos (SN: 6/24/20). Now Ludhova and her colleagues have recorded enough neutrinos to calculate that carbon and nitrogen atoms together are about 0.06 percent as abundant as hydrogen atoms in the sun — the first use of neutrinos to determine the sun’s makeup.

    And though that number sounds small, it’s even higher than the one favored by astronomers who support a high-metal sun. And it’s 70 percent greater than the number a low-metal sun should have.

    “This is a great result,” says Marc Pinsonneault, an astronomer at Ohio State University in Columbus who has long advocated for a high-metal sun. “They’ve been able to demonstrate robustly that the current low-metallicity solution is inconsistent with the data.”

    Still, because of uncertainties in both the observed and predicted neutrino numbers, Borexino can’t fully rule out a low-metal sun, Ludhova says.

    The new work is “a significant improvement,” says Gaël Buldgen, an astrophysicist at Geneva University in Switzerland who favors a low-metal sun. But the predicted numbers of CNO neutrinos come from models of the sun that he criticizes as too simplified. Those models neglect the sun’s spin, which could induce mixing of chemical elements over its life and change the amount of carbon, nitrogen and oxygen near the sun’s center, thereby changing the predicted number of CNO neutrinos, Buldgen says.

    Additional neutrino observations are needed for a final verdict, Ludhova says. Borexino shut down in 2021, but future experiments could fill the void.

    The stakes are high. “We’re arguing about what the universe is made of,” Pinsonneault says, because “the sun is the benchmark for all of our studies.”

    So if the sun has much more carbon, nitrogen and oxygen than currently thought, so does the whole universe. “That changes our understanding about how the chemical elements are made. It changes our understanding of how stars evolve and how they live and die,” Pinsonneault says. And, he adds, it’s a reminder that even the best-studied star — our sun — still has secrets. More

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    A celestial loner might be the first known rogue black hole

    A solitary celestial object — more massive than the sun, yet far smaller — is wandering the galaxy a few thousand light-years from Earth. It might be the first isolated stellar-mass black hole to be detected in the Milky Way. Or it might be one of the heaviest neutron stars known.

    The interstellar wanderer first revealed itself in 2011, when its gravity briefly magnified the light from a more distant star. But at the time, its true nature eluded researchers. Now, two teams of astronomers have analyzed Hubble Space Telescope images to unmask the traveler’s identity — and have come to somewhat different conclusions.

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    The mysterious rogue is a black hole roughly seven times as massive as the sun, one team reports in a study in press in the Astrophysical Journal. Or it’s a bit lighter — a mere two to four times the weight of our nearest star — and therefore either an unusually lightweight black hole or a curiously hefty neutron star, another group reports in a study in press in the Astrophysical Journal Letters.  

    Neutron stars and stellar-mass black holes form when massive stars — at least several times the heft of the sun — collapse under their own gravity at the end of their lives. Astronomers believe that about a billion neutron stars and roughly 100 million stellar-mass black holes lurk in our galaxy (SN: 8/18/17). But these objects aren’t easy to spot. Neutron stars are so tiny — about the size of a city — that they don’t produce much light. And black holes emit no light at all.

    To detect these kinds of objects, scientists typically observe how they affect their surroundings. “The only way that we can find them is if they influence something else,” says Kailash Sahu, an astronomer at the Space Telescope Science Institute in Baltimore.

    To date, scientists have detected nearly two dozen stellar-mass black holes. (These relatively lightweight black holes are puny compared to the supermassive behemoths that sit at the center of most galaxies, including our own (SN: 1/18/21).) To do so, researchers have watched how these objects interact with their nearby celestial neighbors. When a black hole is locked in a gravitational dance with another star, it rips away matter from its partner. As that material falls onto the black hole, it emits X-rays, which telescopes orbiting the Earth can detect.

    But finding black holes in binary systems doesn’t paint a whole picture of the black hole kingdom. Because these objects are continually accreting matter, it’s challenging to determine the mass at which they formed. And since birthweight is a key characteristic of a black hole, that’s a significant drawback to looking at binary systems, Sahu says. “If we want to understand the properties of black holes, it’s best to find isolated ones.”

    For more than a decade, researchers have been scanning the heavens for solitary black holes. The searches have hinged on Einstein’s theory of general relativity, which states that any massive object, even an unseen one, bends space in its vicinity (SN: 2/3/21). That bending causes light from background stars to be magnified and distorted, a phenomenon known as gravitational microlensing. By measuring changes in the brightness and apparent position of stars, scientists can calculate the mass of the intervening object that’s acting like a lens — a technique that’s rounded up a few extrasolar planets as well (SN: 7/24/17).

    In 2011, researchers announced that they had spotted a star that suddenly had gotten more than 200 times brighter. But those initial observations, made using telescopes in Chile and New Zealand, were unable to reveal whether the star’s apparent position was also changing. And that information is key to pinning down the mass of the intervening object. If it’s a heavyweight, its gravity would distort space so much that the star would appear to move. But even a “big” shift in the star’s position would have been extremely small and hard to detect. And unfortunately fine details in astronomical images captured by ground-based telescopes tend to be blurred out because of our planet’s turbulent atmosphere (SN: 7/29/20).

    To circumvent this Earthly limitation, two independent teams of astronomers turned to the Hubble Space Telescope. This observatory can capture extremely detailed images since it orbits above most of Earth’s atmosphere.  

    Both groups found that the star’s location shifted over the course of several years. One of the teams, led by Sahu, concluded that the star’s apparent dance was caused by an object roughly seven times as hefty as the sun. A star of that mass would have been blazingly bright in the Hubble images, but the researchers saw nothing. Something that heavy and dark must be a black hole, the team reports.

    But another group of researchers, led by astronomer Casey Lam at the University of California, Berkeley, found different results. Lam and her colleagues calculated that the mass of the lensing object was lower, only about two to four times the mass of the sun. It could therefore be either a neutron star or a black hole, the group concluded.

    Whatever it is, it’s an intriguing object, says astronomer Jessica Lu, a member of Lam’s team also at UC Berkeley. That’s because it’s a bit of an oddball in terms of mass. It’s either one of the most massive neutron stars discovered to date, or it’s one of the least massive black holes known, Lu says. “It falls within this strange region we call the mass gap.”

    Despite the disagreement, these are thrilling results, says Will M. Farr, an astrophysicist at Stony Brook University in New York not involved in either study. “To be working at the instrumental limit at the real forefront of what’s measurable is very exciting.” More