One Side of This White Dwarf is Covered in Hydrogen While the Other Side is Helium.

By Brian Koberlein - July 21, 2023 01:15 PM UTC | Stars
Here's a new one. Astronomers have found a white dwarf star - the dead remnant from a main sequence star like the Sun - with one hemisphere composed of hydrogen while the other is covered in helium. The star was discovered with the Zwicky Transient Facility, revealing that it rotates every 15 minutes. Spectroscopic data unveiled its two-sided nature. What?! Also. How?! Some white dwarfs transition from hydrogen- to helium-dominated surfaces, and astronomers might have caught it in the act.
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Thin Flat Lenses Could Unleash a Revolution in Space Telescopes

By Brian Koberlein - July 20, 2023 01:08 PM UTC | Telescopes
Space telescopes use traditional polished mirrors like ground telescopes, which are heavy, unwieldy, and expensive to build. A new type of flexible telescope lens could be lighter and larger, creating space telescopes that could collect 100 times more light than JWST. Instead of a single large, delicate telescope, the Nautilus Space Observatory would consist of a fleet of lighter, cheaper, identical spacecraft working together to produce images. They'd use thin diffractive lenses, which have been improved to the point that they can produce near-perfect image quality.
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Did That Message Come From Earth or Space? Now SETI Researchers can be Sure

By Brian Koberlein - July 19, 2023 02:45 PM UTC | Astrobiology
When SETI researchers discover an intriguing radio signal, their first instinct is to ask, "Is the signal coming from Earth?" So many alien messages turned out to be Earth signals reflecting off objects in space, like satellites. Scientists have developed a new technique to vet these signals and confirm whether they came from outer space, even with a single message. When a signal passes through the interstellar medium, it should be affected by free electrons from cold plasma, and it's possible to separate the genuine interstellar message from one that emanated close to Earth.
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Your Oven Gets Hotter Than This Star

By Brian Koberlein - July 18, 2023 12:36 PM UTC | Stars
Astronomers have an ultracool star that only has a surface temperature of 425 degrees centigrade, cooler than the cleaning cycle of a typical oven. For comparison, the Sun has a surface temperature of about 5600 C. This isn't the coldest star ever seen, but it's the coldest that was discovered using radio astronomy. This class of ultracool brown dwarfs is challenging to find because they don't have the kind of dynamics that produce magnetic fields and generate radio waves. Stars are active in the radio spectrum because of their magnetic fields, so it's puzzling to find these brown dwarves so inactive.
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Liquid Water on Rocky Planets Could be 100 Times More Likely

By Brian Koberlein - July 16, 2023 02:36 PM UTC | Exoplanets
Astronomers previously believed that you needed a special environment for a rocky planet to have liquid oceans on its surface, with just the right temperature and surface pressure. But a new study suggests that the radioactivity from rocks could melt water. Even if the surface is frozen, there could be oceans of water beneath the surface. Researchers suggest that there could be an average of one planet per star with these conditions in the Milky Way - 100 times more likely than previous estimates.
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We've Got to Go Back to Enceladus. Here's a Mission That Could Get the Science

By Brian Koberlein - July 14, 2023 11:21 AM UTC | Planetary Science
Saturn's moon Enceladus is one of the most promising places to look for life in the Solar System. It has an ocean of liquid water venting into space, and evidence from Cassini suggested that it's filled with organic molecules and nutrients for bacteria. A new mission that could continue the search, the Astrobiology eXploration at Enceladus (AXE), has been proposed. This would be a New Frontiers-class mission with a modest budget and a suite of instruments specifically chosen to maximize the science at Enceladus.
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Celebrate a Year of JWST With This Ludicrous Image of Rho Ophiuchi

By Brian Koberlein - July 13, 2023 12:00 PM UTC | Extragalactic
It's been a year since JWST began its operations, so the people behind the telescope released a stunning new image to celebrate. The Rho Ophiuchi complex is already a famous target for astrophotographers because of its many-colored splendor. Under JWST's infrared gaze reveals the closest star-forming region to Earth in all its glory. Jets are blasting out of newly forming stars, impacting the surrounding interstellar gas and lighting up molecular hydrogen. Some of the stars even have the shadows of circumstellar disks.
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Titanium Clouds Make This Exoplanet Shine Like a Mirror

By Brian Koberlein - July 12, 2023 12:56 PM UTC | Exoplanets
ESA's Cheops mission has been studying an ultra-hot exoplanet around a nearby star and discovered its metallic clouds reflect about 80% of the light shining on it from its host star. The planet is about the size of Neptune, and its high-temperature clouds are filled with silicate mixed with metals like titanium. The planet takes only 19 hours to orbit its star, and astronomers are puzzled why it hasn't had its atmosphere blown away, leaving only bare rock behind. The metal clouds might actually be the solution, reflecting the heat away and preventing the atmospheric stripping.
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Wind Direction on Mars Changed Abruptly About 400,000 Years Ago

By Brian Koberlein - July 11, 2023 12:32 PM UTC | Planetary Science
China's Zhurong rover landed in the Utopia Planitia region of Mars, a vast plain in the northern hemisphere. Dunes surround the landing site, piled up by winds over eons. Images from the rover show that the landing area went through two main climatic stages, where the predominant wind changed direction by 70 degrees. Scientists think this change happened around 400,000 years ago and could have been due to a change in the planet's rotation axis, causing a global climate change that affected wind patterns.
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A Neutron Star is Unwinding a Companion Star

By Brian Koberlein - July 10, 2023 01:59 PM UTC | Stars
Astronomers have found a bizarre binary star system where a neutron star orbits with another star. Its companion used to be more massive, but the neutron star has torn away and consumed its outer layers, leaving only three solar masses of material. The neutron star has increased its rotation speed due to all the material stolen from its companion. Although the stripped star looks similar to regular main sequence stars, this is only because it still has a thin shell of hydrogen around its largely helium core. It should explode as a supernova about a million years from now, becoming a neutron star. Eventually, they'll collide, creating a kilonova.
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A Planet has Whipped Up Spiral Arms Around a Young Star

By Brian Koberlein - July 09, 2023 10:25 AM UTC | Exoplanets
Astronomers have observed dozens of newly forming stars surrounded by protoplanetary disks. Some look like grooved vinyl records, while others have developed bizarre spiral galaxy-like arms. These spiral arms account for about a third of the disks. Astronomers have finally directly observed a giant exoplanet that appears to be responsible for a set of protoplanetary arms. The planet has twice the mass of Jupiter and is unexpectedly red, the reddest planet ever seen because of all the dust surrounding it.
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Supernovae are the Source of Dust in Early Galaxies

By Brian Koberlein - July 08, 2023 11:35 AM UTC | Extragalactic
Dust is the building block for much of the Universe, including the planet you were born on. But where did all this dust come from? New research using JWST shows large quantities of dust surrounding two Type II supernovae that detonated in a galaxy 22 million light-years away. The observations from JWST showed that each remnant contained more than 5,000 times the mass of Earth in dust. This helps explain why the earliest galaxies are filled with dust and young stars that exploded as supernovae.
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Astronomers Map out the Radio Waves Coming From Large Satellite Constellations

By Brian Koberlein - July 07, 2023 11:42 AM UTC | Observing
You've heard that satellite constellations like Starlink are a problem for astronomers and their telescopes. Because the satellites are communicating with radio waves, they're also an issue for radio astronomers. A new study used the Low-Frequency Array to observe 68 Starlink satellites as they flew overhead. The telescopes could detect the "unintended electromagnetic radiation" emanating from electronics onboard the Starlink satellites. These could impact radio observations, and unlike visible light, the glare isn't coming from reflected light but emissions from the satellites themselves.
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Did the Pulsar Timing Array Actually Detect Colliding Primordial Black Holes?

By Brian Koberlein - July 06, 2023 11:10 AM UTC | Black Holes
With last week's announcement of the gravitational wave background detected by timing arrays, the assumption was that these are the constant thrum of supermassive black holes orbiting each other. A new paper investigates whether these gravitational wave signals come from a much earlier time in the Universe and a much greater distance. Instead of relatively nearby supermassive black holes, could these be coming from primordial black holes interacting early on in the Universe?
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