This week in cosmology brought new insights into the universe's large-scale structure, composition, and expansion. Observations of galaxy clusters revealed previously hidden complexity: radio observations of Abell 2034 uncovered a diverse population of diffuse radio sources and identified a hidden gas filament connecting galaxies, while detailed magnetic field mapping in cluster A2255 traced how magnetic structures form during galaxy mergers and collisions. On the computational side, researchers developed a new technique to map the cosmic web—the universe's large-scale filamentary structure—across billions of light-years by dividing enormous datasets into overlapping blocks, recovering cosmic filaments with 99.6% accuracy and confirming that more massive galaxies preferentially connect together in a power-law relationship. Turning to the universe's expansion history, astronomers using H II galaxies (star-forming regions) as cosmic distance markers mapped the expansion rate from the present day back to just 800 million years after the Big Bang, finding a surprisingly smooth and stable expansion history. Finally, studies of dark energy and dark matter interactions using multiple datasets found hints that these mysterious components may exchange energy, though tension remains between different measurement techniques when determining the universe's current expansion rate.
This week in exoplanet science brought discoveries about atmospheric escape, disk properties, and planetary origins. Astronomers detected helium escaping from the atmosphere of LHS1140b, a rocky planet in a habitable zone, with the intriguing finding that this escape varied between observations in 2024 and 2025, suggesting it may fluctuate like a weather pattern. A new analysis of protoplanetary disks in the Upper Scorpius star cluster revealed median dust masses about six times lower than in the similar Chamaeleon I cluster, suggesting that dust depletes as planets form and grow. Separately, researchers used computer simulations to show that at least six of nine studied hot Jupiters likely formed beyond the water and carbon dioxide snowlines—the cold regions where volatile molecules freeze out—before migrating inward to their current close orbits around their stars. Looking ahead, predictions suggest the PLATO mission could discover 170 to 280 terrestrial planets in the hot regions near their stars, including 40 to 80 Earth-sized worlds that will enable the first tests of their atmospheric compositions. Finally, tidal dynamics simulations found that an Earth-mass planet could host multiple moons—up to two Luna-sized, three Pluto-mass, or five Ceres-mass moons—if the orbits are precisely aligned, though weaker tides than Earth's would allow even more moons to coexist stably over billions of years.
This week in galaxy research, astronomers discovered a new star called S301 orbiting the supermassive black hole Sgr A* with an orbital period of 8.7 years and speeds reaching 25,000 km/s, offering a fresh opportunity to measure the black hole's spin—a property that has remained difficult to determine until now. In separate work, computer simulations of the starburst galaxy M82 produced significantly less X-ray emission than observations from the Chandra space telescope reveal, suggesting that current models are missing important physics such as cosmic ray effects or heat transport that will be needed to accurately simulate galactic winds driven by supernovae. Observations of the young radio galaxy 3C 303.1 found little molecular gas present and evidence that powerful jets from its active nucleus are driving rapid outflows, supporting the idea that supermassive black hole activity significantly shapes its host galaxy's environment. Researchers sifting through Gaia data identified 649 candidate symbiotic binary stars—systems where one star feeds material onto a companion—but machine learning analysis revealed that roughly half are actually pulsating red giants mimicking the symbiotic signature, leaving only eight strong candidates for this rare stellar class. Dust masses in protoplanetary disks around young stars in the Upper Scorpius cluster average about 0.95 Earth masses, roughly six times lower than similar disks in the Chamaeleon I cluster, indicating that dust depletes as planets form. Finally, magnetic fields in the massive star-forming region GGD 27 are being overwhelmed by gravity in accretion streams flowing toward a newborn star, though the magnetic fields still help guide the infalling material.
This week in high-energy astrophysics saw discoveries spanning supernova remnants, distant black holes, and newly detected transients. Researchers using the Einstein Probe identified fast X-ray transients with unusually low energy levels that may represent a new class of relativistic jet sources distinct from typical gamma-ray bursts. A study of the supernova remnant N63A using Chandra and XMM-Newton data revealed three distinct temperature zones within the blast wave and determined the progenitor star was a supergiant roughly four times the Sun's mass. Meanwhile, simulations of the starburst galaxy M82 consistently produce less X-ray emission from galactic winds than observed, suggesting missing physics like cosmic rays or thermal conduction in the models. On larger scales, clustering analysis of the Fermi-LAT gamma-ray catalog identified 48 potential extended source clusters containing 124 previously unidentified sources, with three appearing entirely new to the astronomical record. Finally, researchers studying the galaxy cluster Abell 2255 used LOFAR radio observations to map magnetic fields out to the cluster's edge with unprecedented detail, revealing patterns shaped by the galaxies' merger history over billions of years.
A new software tool has expanded stellar population modeling to include brown dwarfs—cool, dim substellar objects that don't shine like regular stars—allowing more accurate simulations of young star clusters where planets are born. Researchers have also built calibration databases and analysis pipelines for two major X-ray telescopes: the Einstein Probe's wide-field instrument, which tracks over 200 million calibration points to interpret scattered X-ray signals, and the Swift satellite's gamma-ray burst detector, which can now locate high-energy explosions even during spacecraft maneuvers using imaging and mosaic reconstruction techniques. On the data analysis side, astronomers developed a new mathematical method using Gaussian processes to extract detailed dust and temperature maps from protoplanetary disks—the swirling clouds where planets form—and tested it on the young disk around the star HD 169142. Additionally, machine learning has uncovered two previously hidden tidal disruption events in archival data, cases where stars were torn apart by black holes, using a transformer-based spectrum classifier to recognize their distinctive light signatures in old galaxy surveys. Finally, a method called Constrained Diffusion Decomposition helps radio telescope observations recover missing large-scale signals that are lost when instruments focus too much on fine details, allowing a more complete picture of star-forming regions.
Researchers studying stellar systems have identified several distinct findings this week. A fast-moving white dwarf in a triple star system is shaping the nebula K 1-6 by photoionizing surrounding gas rather than relying on stellar remnants, and the system's cool orange companion star has been dramatically inflated by past interactions. A new analysis of Gaia data found that roughly 300 of 649 symbiotic star candidates are actually pulsating red giants—ordinary aging stars masquerading as the rare binary systems they were mistaken for, leaving only eight strong genuine candidates. Measurements of a brown dwarf's atmosphere revealed that clouds concentrate near its equator and that different molecules rotate at different rates depending on latitude, with methane and ammonia notably depleted in equatorial regions. Data from the Parker Solar Probe showed that stochastic heating—where plasma particles move randomly in sync with electromagnetic waves—is the dominant heating mechanism in the solar wind near the Sun, outperforming the alternative resonant heating model. The dust mass of protoplanetary disks around young stars in Upper Scorpius averages about 0.95 Earth masses, roughly six times lower than similar disks in the Chamaeleon I cluster, suggesting dust disappears as stars age, likely consumed in planet formation. In the massive star-forming region around GGD 27, gravity overwhelms magnetic fields to drive accretion streams toward the growing star, though magnetic fields do help guide some of the infalling material.