Beyond the Milky Way galaxy
The Milky Way and other similar galaxies have two distinct disk sections. One is the thin disk section, and it contains mostly younger stars with higher metallicity. The second is the thick disk, and it contains older stars with lower metallicity. The effort to study these disks in more galaxies and in greater detail has been stymied. But now we have the JWST, and researchers used it to examine more than 100 distant, edge-on galaxies.
One of the most iconic cosmic scenes in the Universe lies nearly 3.8 billion light-years away from us in the direction of the constellation Carina. This is where two massive clusters of galaxies have collided. The resulting combined galaxies and other material is now called the Bullet Cluster, after one of the two members that interacted over several billion years. It's one of the hottest-known galaxy clusters, thanks to clouds of gas that were heated by shockwaves during the event. Astronomers have observed this scene with several different telescopes in multiple wavelengths of light, including X-ray and infrared. Those observations and others show that the dark matter makes up the majority of the cluster's mass. Its gravitational effect distorts light from more distant objects and makes it an ideal gravitational lens.
How do galaxies like ours continue producing stars long after they should have used up their star-forming gas. Somehow, an external gas source must find its way into the galaxy. New research has found evidence of gas clouds that found their way into a spiral galaxy, likely fueling continued star formation.
Astronomers used the JWST to examine M82, a nearby starburst galaxy. M82 is forming stars at a prodigious rate due to its interactions with its neighbour, M81. It produces thousands of solar masses of stars per year, much more than the Milky Way.
How do you search for a substance that doesn't give off any kind of light, but its gravitational influence shapes galaxies? That's the challenge researchers face as they try to find and explain the mysterious substance called dark matter. They're wrestling with an invisible "something" that appears to make up much of all matter in the Universe.
Population III stars are the first generation that formed in the Universe, made from pristine hydrogen and helium, without any heavier "metals." They're difficult to find, surrounded by the early cosmic fog and lasting for only a few million years, but a new paper proposes that Webb could detect the pollution from these first stars as they're enriching the gas around them. There would be a hybrid phase when the first galaxies could contain second-generation stars and the polluted gas from the first stars.
The early Universe was a busy place some 13 billion years ago. That's when countless young galaxies began to evolve and birthed stars at a prodigious rate. The hearts of those very distant galaxies show turbulent, lumpy disks studded with even thicker clumps of dust and gas that spawned huge batches of stars. Astronomers want to understand what's driving the clumping, so they've turned to recent surveys of closer galaxies in the "local Universe" that contain similar lumpy regions.
More than one third of the regular matter in the Universe is missing (we're not talking about dark matter, just regular matter). It's needed to make the current cosmological models work, so astronomers continue to search for it, and have found many indirect examples of it. Now a team of astronomers has directly observed it as a huge filament of hot gas bridging four galaxy clusters and containing 10 times the mass of the Milky Way.
You're probably aware that most of the matter of the Universe is "dark matter," and astronomers still don't know what it is. But 75% of the regular matter in the Universe is also hidden, located in the thin gas between galaxies. Probing this gas is difficult, but astronomers have used a new technique, analyzing the light from fast radio bursts as they pass through billions of light-years of gas. Longer, redder wavelengths are slowed down compared to shorter, bluer wavelengths, allowing the hidden material to be weighed.
For most of us, dust is just something we have to clean up. For astronomers, interstellar dust is a hindrance when they want to study distant objects. However, recent James Webb Space Telescope (JWST) observations of a distant galaxy are changing that. This infrared-sensitive observatory is letting them find a way to use dust to understand the evolution of early galaxies. In addition, it uncovered a special property of that galaxy's ice-covered dust, indicating it could be similar to the materials that formed our Solar System.
Astronomers recently used a pair of powerful telescopes to zero in on a cosmic battle going on some 11 billion light-years away from us. The combatants are a pair of galaxies charging at each other over and over again, at velocities upwards of 500 kilometers per second. According to one of the scientists studying the scene, one galaxy is cutting into the heart of the other with a blast of radiation.
The galaxy cluster Abell S1063 dominates the center of this JWST image. It's a massive cluster of galaxies about 4.5 billion light-years away. While it dominates the picture, it's not the primary target. It serves as a gravitational lens that magnifies even more distant galaxies that appear as glowing streaks of light around its circular edges.
Galaxies are stellar factories generating stars at different speeds—some working at a breakneck pace while others trickling along! We have known for a long time that the availability of raw materials makes a difference to stellar formation, but according to a new paper which surveyed 1,000 galaxies the location of the matter plays a role too. Those with a high stellar formation rate seem to have a high volume of gas reserves in the heart of their densest star clusters with the highest concentration of stars.
The Small Magellanic Cloud is one of our closest galactic neighbours. It's a dwarf irregular galaxy about 200,000 light-years away, containing several hundred million stars. New research based on massive stars in the SMC shows it's being stretched along two different axes.
How do you distinguish a galaxy from a mere cluster of stars? That's easy, right? A galaxy is a large collection of millions or billion of stars, while a star cluster only has a thousand or so. Well, that kind of thinking won't get you a Ph.D. in astronomy! Seriously, though, the line between galaxy and star cluster isn't always clear. Case in point, UMa3/U1.
The center of the Milky Way is a busy place, tightly packed with stars and dominated by the supermassive black hole Sagittarius A*. It also features powerful magnetic fields that regulate star production, influence gas dynamics and gas cloud formation, and even affect the accretion processes around Sagittarius A*. Gigantic filaments of gas that look like bones form along the magnetic field lines, and one of them appears to be fractured.
For decades, astronomers considered the Perseus cluster to be a stable grouping of galaxies, but more recent observations have shown signs that it experienced a merger in the past. Thanks to an international team of astronomers using the Subaru Telescope at Maunakea, Hawaii, a "Dark Matter bridge" connecting Perseus to a subcluster of galaxies has been discovered.
Magnetars are among the rarest - and weirdest - denizens of the galactic zoo. They have powerful magnetic fields and may be the source of fast radio bursts (FRBs). A team of astronomers led by European Space Agency researcher Ashley Chrimes recently used the Hubble Space Telescope to track one of these monsters called SGR 0501+4516 (SGR0501, for short, and SGR stands for Soft Gamma Repeater). It's whipping through the Milky Way at a rate that could be as high as 65 kilometers per second. The big challenge was to find its birthplace and figure out its origin.
The Milky Way has more than 30 known satellite galaxies. The Large and Small Magellanic Clouds are the largest and most well-known; other lesser-known ones, like the Sagittarius Dwarf Galaxy, are also on the list. Astronomers think there are many more small satellites that are difficult to detect but essential in understanding the Milky Way. The Vera Rubin Observatory should help astronomers find many more of them.
It's a cosmic shame, that we tend to only see flat-looking, 2-dimensional views of deep-sky objects. And while we can't just zoom out past the Andromeda galaxy for another perspective, or see the Crab Nebula from another vantage point in space, we can use existing data to simulate objects in 3D. A recent collection released by Marshall Space Flight Center's Chandra X-ray Center and the Harvard-Smithsonian Center for Astrophysics shows us familiar objects in a new way.
Universe Today