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Ancient Stars Could Make Elements With More Than 260 Nucleons

Elements heavier than iron, like gold or platinum, were created when massive stars died or through colliding neutron stars. Some of our heavy elements on Earth resulted from an even heavier element decaying through fission. Astronomers studied several stars and found elements that must have been formed through the death of previous generations of stars and the fission of their matter. Some of these elements would have been more than an atomic mass of 260.

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Did the Last Great Galactic Merger Create the Milky Way's Bar?

About 8-11 billion years ago, a dwarf galaxy merged with the Milky Way, adding 50 billion solar masses of stars, gas, and dark matter. The object is known as the “Gaia Sausage” because of the extended stream of stars found using ESA’s Gaia mission. Astronomers think the Milky Way’s central bar formed roughly the same time as the merger. A new paper suggests that merging with the Gaia Sausage triggers the formation of the Milky Way’s bar and the build-up of its disk.

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Dark Matter Could Help Solve the Final Parsec Problem of Black Holes

One outstanding mystery in astrophysics is known as the “final parsec problem.” Simulations predict that binary black holes should stall out in the last stages of their merger. Since we’re detecting the gravitational waves from these mergers, we know it happens, but how? A new paper proposes that ultralight dark matter near the black holes could help to carry away orbital energy from the black holes, driving them together.

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CERN Has Joined the Search for Dark Photons

Now that the Large Hadron Collider has measured the mass of the Higgs boson, physicists are trying to understand how these particles interact with the rest of the Universe. One theory is that decaying Higgs bosons could produce “dark photons,” which would only live for about a tenth of a billionth of a second. That doesn’t sound like much, but it’s long enough to detect “displaced muons,” a by-product of the decay that would indicate the presence of dark photons.

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The Universe Can't Hide Behind the Zone of Avoidance Any Longer

The Solar System sits within the galactic plane, so it was once impossible to look past the core of the Milky Way through countless stars and clogging dust to the distant cosmos. This region was called “The Zone of Avoidance.” But those days are over. While visible light is blocked, infrared and radio can pierce through the region, revealing galaxies on the far side of the Milky Way. Astronomers are finding thousands of previously hidden galaxies behind the core.

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The Oort Cloud Might be More Active Than We Thought

Astronomers have seen meteors strike the Earth on hyperbolic trajectories for decades; they would have escaped the Solar System if our planet hadn’t gotten in the way. They could have come from other solar systems, but an interstellar meteorite has never been found. Instead, these might be coming from the Oort Cloud, perturbed by a rogue planet or star passing close to the Solar System. It might be happening more often than we thought.

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Want to Find Life? Compare a Planet to its Neighbors

Astrobiologists have difficulty finding a single chemical that proves conclusive life on an exoplanet. A new paper suggests that studying a planet’s atmosphere in context with its neighbors might be the way. You could measure carbon compared to other planets in the same system. A low amount of carbon could indicate oceans, plate tectonics, or life itself. The good news is that JWST is sensitive enough to make the observations in the TRAPPIST-1 system.

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An Asteroid Came Uncomfortably Close to Earth in July. Could we Have Stopped it?

On July 15th, 2023, astronomers discovered an asteroid 43 meters across, two days before it passed within a quarter of the distance from the Earth to the Moon. If it had struck the Earth, it would have impacted with 1.5 megatonnes of energy and caused significant local damage. Is there anything we could do to stop asteroids this size from causing damage, even if we have just hours or days of notice? Surprisingly, yes, with the “pulverize it” method.

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Misaligned Binary Star Systems are Rogue Planet Factories

Astronomers are discovering that free-floating, rogue planets are common in the Milky Way. Hundreds were recently found in the Orion Nebula. Discovering the mechanism for these rogue planets is still a challenge. A new paper suggests that misaligned binary star systems are unstable shortly after formation, with more massive planets kicking out the smaller worlds. They predict that there should be many more low-mass planets out there to find as instruments improve.

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The Milky Way's Black Hole is Spinning as Fast as it Can

Is the supermassive black hole at the heart of the Milky Way (SagA*) spinning? And how fast? It’s tricky to know how fast a black hole is spinning without an accretion disk, but astronomers can estimate using polar outflows of material streaming from the black hole. Researchers observed the region around SagA* with the Chandra X-Ray Observatory and estimated that it is spinning. In fact, it’s spinning as quickly as the laws of physics will permit.