Our home galaxy
The Milky Way has two disks, the thin disk where most of the stars dwell, and the thick disk, populated by much older stars. The ESA's Gaia mission showed us that the thick disk rotates more slowly than the thin disk. The culprit, according to powerful simulations, was a disk flip in the MW's past, driven by a merger.
Astronomers have conclusively identified a source of the highest energy cosmic ray protons in the Milky Way, solving a long standing puzzle near the star Altair. By combining gamma ray, radio, and X-ray data from three separate observatories, a Hiroshima University led team ruled out competing explanations and confirmed the object as a genuine “PeVatron”. These natural particle accelerators are far more powerful than anything humans have ever built and helps us in the hunt for similar sources across the Galaxy.
A new result using NASA’s Chandra X-ray Observatory shows that the outer spiral arms in the Milky Way galaxy may reach wider than previously thought. This finding may lead astronomers to adjust their understanding of our home galaxy’s structure.
Observations of a distant cluster of stars in our galaxy have resulted in a new class of objects that turn out to be galactic building blocks. Researchers used Hubble Space Telescope (HST) and the James Webb Space Telescope (JWST) to study the stars that make up Terzan 5, long though to be a globular cluster. What they found puts that cluster into a very rare class of objects called "bulge fossil fragments."
The ESA's Euclid space telescope took 26 hours to capture this portrait of the Milky Way's central bulge. This isn't part of its primary mission; instead it's kind of like bonus science. It'll be used in the Roman Space Telescope's gravitational microlensing search for exoplanets. Regardless of the science, it's an impressive image.
We are used to thinking of gravitational waves as messengers from catastrophes in space, the ringing of spacetime after black holes collide for example. But our own Galaxy hums with a fainter, steadier signal, a chorus of millions of unseen binary stars. A new study has found that this hum carries a hidden fingerprint of the Milky Way's spin, and that if a future space mission ignores it, our picture of the Galaxy itself could come out subtly wrong.
3I/ATLAS has caused quite a stir over the last year, inviting astronomers to update what they know about other solar systems as well as our own. However, this third interstellar visitor may have an unexpected impact on our understanding of dark matter. A new paper, available in pre-print on arXiv from researchers at the University of Hamburg, attempts to calculate the impact that the presence of large amounts of interstellar objects (ISOs) would have on our calculation of dark matter in our galaxy.
Galaxies grow through mergers and collisions, and astronomers want to know more about the mergers in the Milky Way's past. But mergers can stir up the stars in the resulting galaxy, making it difficult to determine exactly when an ancient merger occurred. A new study led by researchers at the Institute of Cosmos Sciences of the University of Barcelona (ICCUB) and the Institute of Space Studies of Catalonia (IEEC) may have overcome that challenge.
Our Solar System is currently passing through the Local Interstellar Cloud, a region of highly diluted gas and dust between the stars. On its path, Earth continuously accumulates iron-60, a rare radioactive isotope of iron produced in stellar explosions. This has now been confirmed by an international research team led by the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) through the analysis of Antarctic ice tens of thousands of years old. From the steady but time-varying influx, the researchers conclude that the radioactive isotope has been stored within the cloud since a long-past stellar explosion.
We may be getting better images of the Milky Way's supermassive black hole in the future. Astronomers used 10 years of observations of a distant blazar to detect turbulence in the Milky Way's interstellar medium. This turbulence makes images of Sagittarius A-star blurry.
Our most massive satellite galaxy, the Large Magellanic Cloud (LMC), has been the center of a heated debate in the astrophysics community over the last few years. That debate centers on whether this is the LMC’s first or second “pass” by the Milky Way itself - and it has huge implications for the evolution of our galaxy given the disruption such a large grouping of stars has. A new paper from Scott Lucchini, Jiwon Jesse Han, Sapna Mishra, and Andrew J. Fox and his co-authors, currently available in pre-print on arXiv, provides what they claim to be definitive evidence that this is, in fact, the first time LMC has encountered the Milky Way.
Our Sun is a bit of an outlier in the general stellar population. We typically think of stars as being solitary wanderers throughout the galaxy. But roughly half of Sun-like stars are locked in with more than one companion star. If there are two, it’s known as a “binary” system, but in many cases there are even more stars all collectively tied together by gravity. Astronomers have long debated why this happens, and a new paper, available in pre-print on arXiv from Ryan Sponzilli, a graduate student at the University of Illinois, makes an argument for a mechanism known as disk fragmentation.
Our Galaxy's halo of hot gas is measurably warmer on one side than the other and a team of scientists have found the culprit. The gravitational pull of the Large Magellanic Cloud is drawing the Milky Way slowly southward, compressing the gas in its path and heating it up, much like a piston in an engine. The discovery solves a puzzle that has intrigued astronomers since the temperature difference was first detected in 2024.
Where exactly is the edge of the Milky Way? That question is harder to answer than one might expect. Since we’re inside of the galaxy itself, it’s obviously hard to judge the “edge” to begin with. But it gets even more complicated when defining what the edge even is - the galaxy simply gets less dense the farther away from the center it goes. A new paper by researchers originally at the University of Malta thinks they have an answer though. The “edge” can be defined as the star-forming region, and in their paper, published in Astronomy & Astrophysics, they very clearly show that “edge” to be between 11.28 and 12.15 kiloparsecs (or about 40,000 light years) from the center.
The Milky Way has a sizable retinue of dwarf galaxies, and they may hold important clues about conditions in the early Universe. However, they're difficult to observe because many of them are so faint. The tiniest ones are called Ultra-faint dwarf galaxies, and a new simulation aimed at how they form is showing how these faint collections of stars and gas mirror the conditions of the early Universe.
At the heart of our Galaxy lurks a supermassive black hole four million times the mass of our Sun. For decades, astronomers have watched mysterious gas clouds drifting towards it on almost identical paths, wondering where they came from and why. Now, a team of researchers think they have finally cracked the puzzle and the answer involves two massive stars locked in a violent embrace!
New missions mean new capabilities - and one particularly interesting new mission is finally up and running. Data is starting to come in from SPHEREx, the medium-class surveyor that is mapping the entire sky every six months. A paper based on some of that early data was recently published in The Astrophysical Journal, mapping ice and compounds called Polycyclic Aromatic Hydrocarbons (PAHs) throughout some interesting regions of our Milky Way.
The Milky Way's center is densely-packed with stars and there should be abundant pulsars there. But for some reason, we can't find them. New research presents a candidate pulsar in the GC. It's close enough to the Milky Way's supermassive black hole that it can test Einstein's General Relativity. But first, it has to be confirmed.
There's been widespread agreement that a supermassive black hole resides in the Milky Way's Center. But that may not be true. Researchers say that a dense clump of fermionic dark matter can also explain the motions of stars and gas clouds in the region. Crucially, it can also explain the famous Event Horizon Telescope image of the SMBH.
An international team of researchers have published two papers that reveal a new model for how the magnetic field of the Milky Way evolved.
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