A Dwarf Galaxy That's Almost All Dark Matter

By Brian Koberlein - November 02, 2023 12:51 PM UTC | Extragalactic
Thanks to new techniques, astronomers are mapping the Universe with more precision, finding galaxies with more and less dark matter. Now astronomers think they've found one that's almost all dark matter with few stars. Dubbed "Nube", the galaxy contains about the same mass as the Large Magellanic Cloud, measuring 22,000 light-years across, with almost no stars inside it. This is the most massive and extended "Almost Dark Galaxy" astronomers have ever found.
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Satellites Make up to 80,000 Flashing Glints Per Hour. It's a Big Problem for Astronomers

By Brian Koberlein - October 31, 2023 12:05 PM UTC | Observing
Telescopes searching for brief flashes like supernovae and asteroids have to contend with a rising number of glints from satellites. These glints can last for a fraction of a second, but they're bright enough to be recorded as a starlike object in the field of view of a survey like the Vera Rubin Observatory. In a new study, astronomers identified tens of thousands of these glints captured by a survey telescope, and there could be 80,000/hour happening across the sky.
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Want to Find Life? Compare a Planet to its Neighbors

By Brian Koberlein - October 30, 2023 12:48 PM UTC | Astrobiology
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?

By Brian Koberlein - October 29, 2023 11:53 AM UTC | Planetary Science
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

By Brian Koberlein - October 28, 2023 12:19 PM UTC | Stars
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

By Brian Koberlein - October 27, 2023 11:14 AM UTC | Black Holes
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.
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