NASA directed astronauts on the ISS to shelter in a Crew Dragon spacecraft after Russian cosmonauts planned to perform repairs the agency thought created “elevated risk” to the station.
The post NASA concerns about Russian repairs prompted ISS safe haven decision appeared first on SpaceNews.
Com recurso a inteligência artificial, o Toyzie identifica Hot Wheels, figuras de ação, Funko Pops, cartas TCG e muito mais, e diz-lhe, em segundos, o que tem na coleção e quanto vale cada peça no mercado atual.
The post Toyzie: aponte a câmara a um brinquedo e a IA diz-lhe quanto vale appeared first on Tek Notícias.
How do massive galaxies form and evolve? A recent study traces the stellar and dust distributions across evolutionary phases of massive galaxies to better understand how massive dusty star-forming galaxies fit into the picture.
Massive galaxies, like the Milky Way or even larger, undergo phases of active star formation and quiescent phases of inactivity, but exactly how these galaxies evolve through these stages is not yet fully understood. Dusty star-forming galaxies, which are undergoing a period of intense star formation and shrouded in dust, might be the missing evolutionary step between star-forming and quiescent phases of massive galaxy evolution.
Currently, the leading explanation for massive galaxy formation and evolution is inside-out growth — star formation and quenching start in the inner regions of a galaxy and progress outward. However, it’s not clear whether dusty star-forming galaxies also follow the favored inside-out pathway, or if they instead proceed outside-in, first growing their disks and then assembling a central bulge.
Example of JWST NIRCam images with ALMA contour lines overlaid for select dusty star-forming galaxies in the sample. [Modified from Bodansky et al 2026]
To directly compare the star and dust morphologies across massive galaxies, Sarah Bodansky (University of Massachusetts, Amherst) and collaborators selected a sample of 33 dusty star-forming galaxies from the GOODS-ALMA 2.0 survey that searched the sky for 1.1-mm dust emission as well as star-forming and quiescent comparison samples drawn from JWST observations. Combining the ALMA survey data with JWST imaging, the authors studied the rest-frame optical (stars) and rest-frame near-infrared (dust) morphologies of dusty, star-forming, and quiescent galaxies at redshifts around cosmic noon (a few billion years after the Big Bang).
When comparing optical morphologies, the authors found that dusty star-forming galaxies and typical star-forming galaxies had similar distributions, but their near-infrared morphologies showed clear differences. Dusty galaxies tended to show more compact near-infrared emission, with dust tracing their stellar populations and more concentrated in the galaxies’ central regions. Though clearly different from star-forming galaxies, the authors noted striking similarities between the near-infrared morphologies of the dusty star-forming and quiescent galaxies, especially within their centers.
Average surface brightness profiles for the rest-optical (left) and rest-near-infrared (right) for the dusty (black), star-forming (blue), and quiescent (red) galaxies. In the near-infrared, the dusty star-forming galaxy profile appears very similar to the quiescent galaxy profile. [Bodansky et al 2026]
“JWST+ALMA Reveal the Buildup of Stellar Mass in the Cores of Dusty Star-forming Galaxies at Cosmic Noon,” Sarah Bodansky et al 2026 ApJ 1001 235. doi:10.3847/1538-4357/ae4f64
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The Sloan Digital Sky Survey (SDSS) fundamentally changed the way modern astronomy research is done. This “grand and bold thing” is not frozen in a museum exhibit, however: instead, the SDSS telescopes and team have continued to iterate. The collaboration recently described the fifth generation of this groundbreaking survey in The Astronomical Journal.
Astronomy is now without question a “big data” science. While a lucky few researchers still occasionally travel to distant mountaintops to sojourn with the stars, most astronomers who can describe their work as “observational” rarely ever leave their laptops. Petabytes of historical data, including images, spectra, enormous simulation archives, and more, are available the instant one’s fingers touch a keyboard. As a result, the speed of discovery has increased exponentially, and the barriers to cutting-edge research have dramatically shrunk.
A schematic of the SDSS-V survey facilities and targets. Click to enlarge. [Kollmeier et al. 2026]
While SDSS’s twin 2.5-meter telescopes (one in New Mexico and one in Chile, allowing the survey to observe the entire sky) are dwarfed by Rubin’s 8-meter mirror, there is still thrilling science to be done with these moderate-sized observatories. This is especially true after a series of upgrades to the spectrographs and thanks to a deep expertise in not only survey-style science, but also in project management and survey planning. In 2021, in the middle of COVID-19 delays and distancing requirements, the team began upgrades to their existing facilities and construction of a brand new telescope to kick off the latest survey, SDSS-V.
The density of target stars for the SDSS-V survey compared to a previous spectroscopic survey. Click to enlarge. [Kollmeier et al. 2026]
By the end of the survey, SDSS-V will have collected optical and near-infrared spectra for roughly 6 million objects spread across the whole sky, as well as time-series spectra from about a million of these sources. This dataset, which is unprecedented in both its spatial and temporal coverage, will allow researchers to probe questions ranging from how quasars evolve over time to how commonly young stars have brown-dwarf companions. Long since SDSS initiated the era of industrial survey astronomy, this latest publication shows how the survey continues to lead the way.
“Sloan Digital Sky Survey. V. Pioneering Panoptic Spectroscopy,” Juna A. Kollmeier et al 2026 AJ 171 52. doi:10.3847/1538-3881/ae0576
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One of the most luminous supergiant stars in the Andromeda Galaxy, M31-2014-DS1, has disappeared, potentially leaving behind a black hole shrouded in dusty gas. What do new infrared and X-ray observations tell us about this event?
This image from Gemini North shows the supernova SN 2023ixf along one of the spiral arms of Messier 101. Though less showy than core-collapse supernovae, “failed” supernovae may be another way to form stellar-mass black holes. [International Gemini Observatory/NOIRLab/NSF/AURA; CC BY 4.0]
But a splashy supernova explosion may not be the only way for a massive star to go out. As observations have begun to suggest, some massive stars may — for reasons not yet fully understood — quietly collapse in upon themselves, going out with a whimper rather than a bang. Though less spectacular and far harder to spot, these “failed” supernovae highlight a possible pathway for the formation of stellar-mass black holes.
Just last month, researchers reported their discovery of a potential failed supernova. The supergiant M31-2014-DS1 suddenly brightened in 2014 before fading to obscurity, leading researchers to suspect that the star had experienced a failed supernova and created a black hole. The event shared similarities with another failed supernova candidate, NGC6946-BH1.
Left: A JWST image of M31-2014-DS 1. Right: Spectral energy distributions of the progenitor star/the remnant using data from 2005 to 2012 (empty circles), 2022 to 2023 (filled circles), and 2024 (colored lines). Click to enlarge. [De et al. 2026]
Together, these observations support a model in which the collapsing star ejected its outer layers in a relatively low-energy event (somewhere in the broad ballpark of one hundred-millionth to one ten-thousandth the energy of a typical core-collapse supernova) and formed a black hole. Some of the ejected material fell backward and fed the newborn black hole, while the remainder created a dense blanket that blocked the light from the accreting black hole from view.
Cartoon showing the authors’ model and the model parameters inferred from the observations. Click to enlarge. [De et al. 2026]
Thanks to its location in a neighboring galaxy, M31-2014-DS1 has granted astronomers a front-row seat to a poorly understood pathway for black hole formation. Going forward, we can expect further insights into M31-2014-DS1 and, hopefully, the discovery of many more sources like it.
“Fading into Darkness: A Weak Mass Ejection and Low-Efficiency Fallback Accompanying Black Hole Formation in M31-2014-DS1,” Kishalay De et al 2026 ApJL 999 L25. doi:10.3847/2041-8213/ae468d
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Forecasting solar flares is one of the major challenges facing solar physicists today. New research finds that non-thermal emission can precede a solar flare by more than an hour, and this early emission may signal whether the flare will be accompanied by an explosion of plasma.
The Solar & Heliospheric Observatory (SOHO) took this coronagraphic image of a coronal mass ejection on 20 April 1998. [SOHO (ESA & NASA)]
Both solar flares and coronal mass ejections can disrupt everyday life on Earth, with flares knocking out radio communications and coronal mass ejections threatening spacecraft electronics and power grids. Given these real-life risks, as well as the potential for probing the physics behind the activity on the Sun and other stars, it’s critical to be able to identify signs of upcoming flares.
Luckily, there’s growing evidence that the Sun sends out subtle signals that a flare is soon to happen. One early sign of an impending flare is an increase in the non-thermal velocity of the plasma at the flare’s location. This phenomenon has been spotted in individual flares, but it hasn’t been studied and characterized for a large sample of flares — until now.
Demonstration of the increase in non-thermal velocity seen in an M-class flare compared to the onset and rise time of the soft X-ray flux (gray shaded area). [Adapted from To et al. 2025]
Of the flares in the sample, 83% were moderately powerful C-class flares, 18% were stronger M-class flares, and 1% were the most powerful X-class flares. To’s team identified a clear trend across all types of flares: the non-thermal velocity increases 4–25 minutes before the flare’s X-ray emission begins to rise, peaks when the X-ray emission peaks, and decays as the flare decays. The team found some evidence that for smaller flares, the velocity increase begins in spectral lines that trace cooler plasma before spreading to lines probing hotter plasma, but more work is needed to confirm this trend.
Examples of flares with and without coronal mass ejections. [Adapted from To et al. 2025]
These results suggest that changes in the non-thermal velocity of solar plasma can not only signal when and where a flare is likely to arise, but also whether the flare will be accompanied by a potentially destructive coronal mass ejection. Upcoming missions like the Multi-slit Solar Explorer and SOLAR-C will give an even better view of the early stages of solar flares, helping to illuminate the physics behind them and enhancing our ability to forecast them.
“Systematic Nonthermal Velocity Increase Preceding Soft X-Ray Flare Onset: A Large-Scale Hinode/EIS Study,” Andy S. H. To et al 2025 ApJ 993 102. doi:10.3847/1538-4357/ae07de
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Beautiful bubbles of hot ionized gas, supernova remnants trace the dying days of massive stars. A recent study uses the Chandra X-ray Observatory to detail the motion and understand the origins of one supernova remnant.
Massive stars, about 8 solar masses or larger, will end their short lives in violent core-collapse supernovae. These explosions barrel into any surrounding interstellar medium, carving out low-density cavities and blowing material outward. Appearing as a bubble or shell of hot gas, a supernova remnant carries the signatures of the type of star that produced it and the ways that star shaped its environment throughout its life.
Nearby, in the Large Magellanic Cloud, is the 2,500-year-old supernova remnant N132D — the most X-ray luminous supernova remnant within the Local Group. Though N132D’s size, likely progenitor mass, and chemical composition are well constrained, astronomers have yet to nail down the velocity of the X-ray shock front — the outer edge of the supernova remnant that rams into the interstellar medium. This measurement is critical to understanding the local conditions the supernova first encountered and how its expansion will continue to impact the interstellar medium over time.
Determining the shock front velocity requires astronomers to focus on the thin outer edge of the soaring supernova remnant — how do we measure the motion of such a narrow strip of gas? X-ray spectroscopy of N132D yields a measurement from a single epoch of observations, but it cannot isolate the narrow shock front, making a reliable velocity measurement difficult to attain.
The expansion of supernova remnant N132D around the rim for each of the regions analyzed in this study. The arrow lengths are proportional to their estimated expansion velocities. Click to enlarge. [Long et al 2025]
The authors focus on small regions on the very edge of the supernova shock front, six northern and eight southern, to carefully measure the motion of the shock between the two sets of observations. In separating the shock front into smaller regions, the authors can determine any variations in speed along the shock front. The southern edge of N132D moves with the same expansion rate of 1,620 km/s. The northern edge has an average expansion rate of 3,820 km/s, but its speed is more varied, which isn’t unexpected given its blown-out appearance.
Modeling results showing the supernova age versus ejecta mass for the northern (red) and southern (blue) regions compared to the age estimate from an optical study of N132D. For the explosion energies and estimated ejecta masses between 2 and 6 solar masses, the models are consistent for all three. Click to enlarge. [Long et al 2025]
In addition to determining the velocity of the forward shock, the authors model the evolution of the supernova remnant to estimate the initial conditions of N132D including progenitor star mass, explosion energy, and ejecta mass. Their results agree with other studies that suggested N132D originated from a roughly 15-solar-mass star that exploded 2,500 years ago into a low-density cavity.
This study showcases the unique ability of Chandra’s high-resolution instruments to carefully measure the evolution of supernova remnants, and further studies will continue to determine the detailed characteristics of supernova remnants across the Local Group.
“Chandra Large Project Observations of the Supernova Remnant N132D: Measuring the Expansion of the Forward Shock,” Xi Long et al 2025 ApJ 993 136. doi:10.3847/1538-4357/ae07c7
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By piecing together observations from dozens of radio telescopes in Chile, planetary scientists recently completed the first-ever map of Callisto’s emission at millimeter wavelengths.
In striking contrast to Io’s frenzied volcanism and Europa’s cracking ice shell, Jupiter’s moon Callisto is much quieter and colder than its Galilean siblings. Though a liquid water ocean hypothetically sloshes beneath its frigid surface, it’d be hard to infer that just by looking at the moon. Callisto’s terrain is ancient, static, and bears the scars of the millennia of exposure to space. There are no volcanoes, plate tectonics, or any other features to disturb what researchers call “evolved ruins” of the numerous craters. These have names like Valhalla, Asgard, and Lofn, since Callisto’s geologic features are named after settings and characters in Norse mythology to further reinforce their freezing existence.
This never-reset canvas makes Callisto an ideal laboratory for studying the long-term effects of asteroid impacts, dust accumulation from nearby natural satellites, and other processes that modify a planetary surface over time. One way to infer the composition and structure of the first few meters of material is to observe the way the temperature changes over the course of a day. For example, ice and rock respond differently to temperature changes; similarly, small-grains of either material warm up and cool down at different speeds than their larger-grain counterparts.
The residuals from one of ALMA’s observations of Callisto. [Adapted from Camarca et al. 2025]
A team led by Maria Camarca, California Institute of Technology, just finished churning through all of the data and assembling their map of Callisto’s temperature residuals. Though the final spatial resolution was at best a few hundred kilometers, meaning a comparable map of Earth would blur all of New England together, this represents the most detailed thermal map of Callisto yet. The map was detailed enough to easily spot the largest craters, and several impact craters including Valhalla stood out as being 3–5K colder than all of the surrounding terrain. The team spotted another anomalously cold region that coincides with the location of maximum carbon dioxide gas density recently seen with JWST.
A map of Callisto’s thermal emission (red/blue) overlaid atop visible images of the surface collected by spacecraft. Click to enlarge. [Camarca et al. 2025]
“A Multifrequency Global View of Callisto’s Thermal Properties from ALMA,” Maria Camarca et al 2025 Planet. Sci. J. 6 183. doi:10.3847/PSJ/ade7ee
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With a measurement 15 years in the making, astronomers have pinned down the path of a neutron star launched by a collapsing star. This finding helps to explain how neutron stars are “kicked” into space by supernovae.
This multiwavelength image shows the pulsar — a type of neutron star — at the center of the Crab Nebula supernova remnant. [X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA-JPL-Caltech]
Many neutron stars have been observed to zip through space at hundreds of kilometers per second, which suggests that these stars get a “kick” when they’re born in a supernova. However, the details of this kick are not yet clear. Are neutron stars launched into space in the opposite direction from the material ejected in the explosion, as some studies suggest? Or is the neutron star’s motion determined by the burst of neutrinos that carries off most of the supernova’s energy, as other studies hint?
To answer these questions, astronomers must compare the velocities of young neutron stars to the movement of their associated supernova remnants. In a recent research article, Tyler Holland-Ashford (NASA Goddard Space Flight Center) and collaborators measured the motion of the neutron star affiliated with the G18.9–1.1 supernova remnant, using Chandra observations made 15 years apart in September 2009 and July 2024.
Chandra images from 2009 (left) and 2024 (right; this image is the merged product of two observations). The neutron star is shown in black. Blue and red sources were used for astrometric correction. The red sources were present in both observations. Click to enlarge. [Holland-Ashford et al. 2025]
Because the distance to the supernova remnant is uncertain, this proper motion could correspond to a range of transverse velocities. For distance estimates of 6,800 and 12,400 light-years, this puts the neutron star’s transverse velocity at 264 or 474 km/s, respectively.
Current location of the neutron star (purple) compared to the geometric center of the supernova remnant (red) and the center of its X-ray emission (green). Even assuming the oldest reasonable age for the supernova remnant, there is a distinct offset between the neutron star’s birthplace and the center of the remnant. Click to enlarge. [Holland-Ashford et al. 2025]
Currently, Chandra is the only X-ray observatory with fine enough resolution to make the kind of measurement needed in this study. Luckily, Chandra’s observations of neutron stars stretch back to 1999, and combining this wealth of data with sensitive measurements from future high-resolution X-ray instruments should provide the long time baselines needed to trace the trajectories of more neutron stars and further explore the origins of neutron star kicks.
“Proper Motion of the Neutron Star in the Supernova Remnant G18.9–1.1,” Tyler Holland-Ashford et al 2025 ApJ 988 218. doi:10.3847/1538-4357/adeb7e
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Spacecraft scattered throughout the solar system keep tabs on the solar wind, but the measurements are dotted with data gaps. How can scientists prevent these gaps from biasing their studies of the solar wind?
Left: the distribution of hot gas between the galaxies in the cluster Abell 2029. Right: the visible light from the galaxies in the cluster. [X-ray: NASA/CXC/UCI/A.Lewis et al. Optical: Pal.Obs. DSS]
Luckily, there are many spacecraft that sample the solar wind from various locations within our solar system. Unluckily, many of these spacecraft do not continuously monitor the solar wind. For example, when a spacecraft orbiting a planet dips into the planet’s atmosphere, this detour creates an hours-long gap in solar wind monitoring.
How do these data gaps affect studies of the solar wind? In a recent research article, Daniel Wrench and Tulasi Parashar (Victoria University of Wellington) approached this question in terms of how gaps affect the structure function: a mathematical description of how the solar wind fluctuates over different length or time scales.
Wrench and Parashar introduced random artificial gaps into data from the Parker Solar Probe, which monitors the solar wind continuously, and compared the structure functions calculated from the continuous and interrupted data sets. They used the difference between the true structure function — calculated from the continuous data set — and the structure functions from the artificially gapped data sets to develop a correction factor.
Performance of the correction factor method (black) compared to the uncorrected, gapped data (red) or gaps filled using linear interpolation (blue). MAPE is the mean absolute percentage error. [Wrench & Parashar 2025]
Structure function calculated from uncorrected Voyager 1 data (red), linearly interpolated data (blue), and corrected data (black). Both the linear interpolation method and the correction factor method remove the artifact around a lag of 3×104 seconds, but the correction factor method does not suppress the signal like the linear interpolation method does. [Adapted from Wrench & Parashar 2025]
Finally, the authors applied their validated method to data from Voyager 1. Data from the two Voyager spacecraft are extremely scientifically valuable — no other spacecraft have ventured as far from the Sun and can measure the solar wind at such large distances. The data are also extremely sparse; one segment used in this work was missing 85% of the data. This means that an effective method of correcting these data has potentially huge scientific significance.
Wrench and Parashar applied their correction factor to the Voyager 1 data, showing that this method handily removes artifacts while avoiding the underestimation introduced by linear interpolation. While the authors saved the interpretation of the newly corrected Voyager 1 data for future research, this study makes it clear that even large data gaps needn’t hinder studies of the solar wind.
“Debiasing Structure Function Estimates from Sparse Time Series of the Solar Wind: A Data-Driven Approach,” Daniel Wrench and Tulasi N. Parashar 2025 ApJ 987 28. doi:10.3847/1538-4357/addc6a
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Motivated by a desire to support community members financially during the coronavirus pandemic, researchers employed 30 local citizen scientists in the Hubble Image Similarity Project. This project quantified the similarities between astronomical images, providing a way to test the results of image-search algorithms.
The Eagle Nebula, pictured here in an image from Kitt Peak National Observatory, is a star-forming region in the Milky Way. [T.A.Rector (NRAO/AUI/NSF and NOIRLab/NSF/AURA) and B.A.Wolpa (NOIRLab/NSF/AURA); CC BY 4.0]
You might start your search with an astronomical image database, using filters for object type or instrument to sift through thousands and thousands of options. But even filtering out everything but star-forming regions might yield vastly different results, given the widely varying shapes, colors, and sizes of these regions.
Or maybe you’ll feed your image into a neural network that has been trained to spot similar images. The results may seem promising, but how can you tell whether the algorithm has found the images that are the most similar? Would another algorithm do better?
Astronomical image collections rarely contain information about similarities between images in their metadata, and while neural networks appear to excel at gathering similar images, the results of these models are generally unverified. The Hubble Image Similarity Project, led by Richard White (Space Telescope Science Institute) and Josh Peek (Space Telescope Science Institute and Johns Hopkins University), addressed these issues with a team of citizen scientists who generated similarity information for astronomical images, providing a quantitative means to test the results of neural networks.
An example of individual test images (green squares) extracted from a Hubble Legacy Archive image (red square). Low-contrast areas have been excluded, leaving the galaxy’s spiral arms for analysis. Click to enlarge. [White & Peek 2025]
White and Peek recruited 30 members of the community within walking distance of the Space Telescope Science Institute to identify similar astronomical images, and the reviewers were paid for their work. In the three phases of the project, reviewers considered test images one at a time and 1) selected all similar images from a set of 15 comparison images, 2) selected the most similar image from a narrowed-down set of 6 comparison images, and finally 3) selected the most similar image from a set of 3 comparison images.
Examples of similar images according to the image similarity matrix. In the lower-right corner is a visualization of the similarity data. The semicircle of data points in the bottom half of this visualization represents galaxies, while star clusters occupy the small arc near the top and nebulae sit in the island in the center of the plot. Click to enlarge. [Adapted from White & Peek 2025]
Similar images resemble one another in terms of structure, texture, and other factors that White and Peek say are “difficult even to describe in words” — for example, the diffuse glow of a galaxy interrupted by a bright star with diffraction spikes, or a nebula speckled with stars and dense dusty clumps. The similarity data from this study are available online and can be used to test the performance of image-search algorithms. In future work, the authors plan to carry out a similar project using images of the Martian landscape.
“The Hubble Image Similarity Project,” Richard L. White and J. E. G. Peek 2025 AJ 169 306. doi:10.3847/1538-3881/adcb43
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Editor’s Note: Astrobites is a graduate-student-run organization that digests astrophysical literature for undergraduate students. As part of the partnership between the AAS and astrobites, we occasionally repost astrobites content here at AAS Nova. We hope you enjoy this post from astrobites; the original can be viewed at astrobites.org.
Title: A High-Caliber View of the Bullet Cluster Through JWST Strong and Weak Lensing Analyses
Authors: Sangjun Cha et al.
First Author’s Institution: Yonsei University
Status: Published in ApJL
Despite the extreme depth and resolution of JWST observations, there’s still no smoking gun to be found in the hunt for dark matter. Yet, the extremely high-velocity collision in today’s article might aid in the search for what this mysterious material is made of. The target of today’s article is the Bullet Cluster (Figure 1). Despite its name, the Bullet Cluster is not one, but actually two massive clusters of galaxies gravitationally interacting with one another. Due to the high speed with which the smaller “bullet” subcluster collided and passed through the larger one, a strong bow shock caused the gas in the system to compress and heat to millions of degrees. Typically, this alone would make this system interesting to astronomers, but the real kicker here is that this collision was powerful enough to separate the dark matter from the normal, luminous matter. This has made the Bullet Cluster an important testing ground for theories on the nature of dark matter and is exactly what the authors of today’s article attempt to use it for.
Figure 1: The Bullet Cluster, colour coded based on the strong and weak lensing–based mass reconstruction (blue/JWST), X-ray intensity (pink/Chandra), and radio intensity (green/MeerKAT) using three different telescopes. The dashed rectangle indicates JWST’s smaller field of view compared to Chandra and MeerKAT. [Cha et al., in press]
The authors used JWST imaging of the majority of the Bullet Cluster system to obtain high-resolution, multi-wavelength data. They then identified over 146 areas in the image subject to strong lensing, which is when the light from a background galaxy is bent around mass in the foreground Bullet Cluster system, since that mass distorts spacetime. They also obtained a weak lensing model for the image through statistical analysis, since the effects of weak lensing, while similar, are much more subtle than strong lensing. They then created a mass map for the system by feeding their strong lensing and weak lensing model into a reconstruction algorithm. Essentially, this algorithm creates the most likely distribution of mass, both dark matter and normal matter, that would re-create all the lensing that they observed.
What’s special about the algorithm that they used here is that it does not assume that light traces mass. In general, this assumption is correct, so other algorithms use it to get the most accurate mass estimate. But the authors here wanted to confirm that even in extreme environments like the Bullet Cluster that this is still the case, so they sent their algorithm in “blind.”
Once they had their mass map, which is dominated mostly by the dark matter in the system, they could compare it to the optical light between the system’s galaxies, referred to as the intracluster light (ICL). They used a statistical test called the modified Hausdorff distance to determine how similar the distribution of ICL and dark matter were to each other. They found that, despite the extreme gravitational interactions going on in the Bullet Cluster, the ICL still does an excellent job overall of tracing the system’s mass (see Figure 2).
Figure 2: Comparison of the dark matter mass map from the strong and weak lensing data (pink) and the distribution of light from the ICL and the most massive galaxy, also known as the brightest cluster galaxy (BCG), combined (blue). Note how the bottom-most centroid’s dark matter and ICL contours are offset from one another. [Cha et al., in press]
Finally, the authors were able to use their mass map to put some constraints on one of the theories of dark matter: self-interacting dark matter. If dark matter particles interact with each other, then they have a cross section that can be calculated. Here, the authors calculate it from the offset between the position of the most massive galaxy in the Bullet Cluster and the position of the highest density of dark matter, which is about 60,000 light-years (see Figure 2). They were able to determine that the upper limit of this cross section is 0.5 cm2/g. This is the tightest constraint on self-interacting dark matter’s cross section to date, but we still have that pesky “per gram” in our units since we don’t know the mass of a dark matter particle (but this is being studied!).
This cross section is near the lower limit of what is thought to be a reasonable range for self-interacting dark matter theories (about 0.5–2 cm2/g), but it certainly doesn’t rule anything out. For further context, when dividing by mass, the cross section of a hydrogen atom is about 1.7×107 cm2/g, which is much bigger, but we would expect that when comparing an atom to a potential subatomic dark matter particle.
Altogether, the authors of this article were able to use both the precision of JWST and the impartiality of their mass-reconstruction algorithm to learn new things about both the structure of the Bullet Cluster and the nature of dark matter. Although there are still some open questions that will need to be answered, this study certainly is not just a shot in the dark!
Original astrobite edited by Maggie Verrico.
About the author, Veronika Dornan:
Veronika is a final-year PhD candidate at McMaster University. Her research is in observations of extragalactic globular star clusters and what they can tell us about galaxy evolution and dark matter distribution in the universe.
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Protoplanetary disks, the sites of planet formation around young stars, are rich and complex objects. An in-depth investigation of 15 protoplanetary disks has recently been published in a Focus Issue of the Astrophysical Journal Letters. This investigation leveraged the exquisite resolution and sensitivity of the Atacama Large Millimeter/submillimeter Array (ALMA), a moveable network of 66 radio dishes in the Atacama Desert in Chile.
Featuring high-resolution observations of multiple gas species, updated image processing techniques, and state-of-the-art modeling, the exoALMA project examines the early stages of planet formation, when protoplanets embedded within dusty disks induce rings, gaps, spirals, and other structures.
This Monthly Roundup consists of quick snippets describing each of the currently published research articles in the exoALMA Focus Issue of the Astrophysical Journal Letters. Each snippet links to the corresponding research article, and the Focus Issue landing page is linked at the bottom of this post.
The full exoALMA sample. All 15 disks show evidence of substructure in their gas emission. [Teague et al. 2025]
Interpreting interferometric data from ALMA requires special care, as Ryan Loomis (National Radio Astronomy Observatory) and coauthors show in their overview of the data calibration and imaging pipeline. The team described their methods of processing the data, including a recently developed alignment method that greatly reduces the number of artifacts that could be mistaken for planet-induced velocity perturbations.
Emitting height from images processed using the standard method (CLEAN) and using regularized maximum likelihood (RML). [Adapted from Zawadzki et al. 2025]
Analyzing observations of protoplanetary disks is challenging, motivating Thomas Hilder (Monash University) and collaborators to take the first step toward addressing issues like beam smearing, the creation of probabilistic data products, and incorporating a realistic noise model. Using their newly developed methods, the team analyzed several disks in the exoALMA sample, finding velocity substructures at greater velocities than existing methods.
Vertical structure and Keplerian rotation of the exoALMA sample as inferred from modeling. Click to enlarge. [Izquierdo et al. 2025]
Jaehan Bae (University of Florida) and collaborators drew attention to the tools astronomers use to interpret observations of protoplanetary disks — namely, forward models. Bae’s team used five different hydrodynamics models to simulate a protoplanetary disk harboring an embedded giant planet. Then, they used two radiative transfer models to simulate carbon monoxide channel maps and calculate the temperature of the disk. Finally, they extracted the location of the synthetic planet. This investigation ultimately showed good agreements between the model outputs, showing that any combination of the models tested in this work is suitable.
Residual signal-to-noise ratio for the exoALMA sample, ordered from least to most nonaxisymmetric. Rings and gaps are marked with solid and dashed ellipses, respectively. Click to enlarge. [Curone et al. 2025]
A team headed by Pietro Curone (University of Milan; University of Chile) examined the rich ALMA dataset for signs of structure within the disks. The team modeled each disk with an axisymmetric model, then subtracted off the best-fitting model to reveal substructures and asymmetries in the disks. Several features were revealed, including shadows, offsets between inner and outer disks, spiral structures, and crescent-shaped asymmetries. Though one disk, PDS 66, was apparently without any internal structure, this investigation showed that structures are common in this sample of large, bright disks. Further work is needed, however, to explore whether these features are common in the disk population as a whole.
Maria Galloway-Sprietsma (University of Florida) and collaborators identified the disk surfaces that emit particular spectral lines. The team found that 12CO traced the upper atmosphere of the disks, while 13CO — an isotopologue of the more common molecule 12CO — and CS (carbon monosulfide) probed deeper regions. In addition, nearly all of the disks showed evidence of localized substructure, highlighting the need for theoretical work to explain the wide variety of disk structures and behaviors.
From top to bottom: velocity kinks associated with an embedded planet; 12CO observations with the identified velocity kinks; filtered ALMA observations, showing the location of the planetary wake; exoALMA continuum emission; and polarimetric images. The blue circles show the locations of the purported planets. Click to enlarge. [Pinte et al. 2025]
Charles Gardner (Rice University; Los Alamos National Laboratory) and coauthors focused on LkCa 15, a disk that appears markedly different in dust and gas emission. The disk’s dust continuum emission shows a 40-au-wide region depleted of dust, while the gas emission, traced by CO, shows no depletion of gas in the same region. Though previous infrared observations have suggested that this dust-depleted region could host massive planets, Gardner’s team concluded that a chain of small planets or processes unrelated to planet formation likely excavated the region instead.
A team led by Jochen Stadler (Côte d’Azur University) searched for deviations from Keplerian rotational velocity — potential evidence for embedded protoplanets. The team discovered deviations up to 15% from the background velocity, with deviations appearing at both large and small radial scales. Rings and gaps visible in the dust emission tended to align with gas pressure maxima and minima, respectively. However, the team also found gas pressure structures in the outer disk that were beyond the dust emission and were not accompanied by rings or gaps.
Comparison of kinematic and emission-line-derived masses. Click to enlarge. [Trapman et al. 2025]
A team led by Cristiano Longarini (University of Cambridge; University of Milan) put the disks of the exoALMA sample on the scale. By modeling the rotation curves of 12CO and 13CO, the team constrained the masses of 10 disks and their central stars. Leon Trapman (University of Wisconsin-Madison) and collaborators also considered the problem of disk masses. The team used CO and N2H+ emission to measure the gas masses of 11 disks in the exoALMA sample and compared the results to previous kinematic measurements. The two sets of measurements tend to agree within a factor of three.
Giovanni Rosotti (University of Milan) and collaborators introduced a new model that connects the emitting height of CO molecules to the gas surface density and temperature. Unlike existing models, the team’s new model can be applied to optically thick observations. Comparing the results of this new method with dynamical estimates relying on interstellar medium abundances of CO yields lower gas masses, suggesting that the CO abundance in the protoplanetary disks studied is depleted relative to the interstellar medium.
Protoplanetary disks are expected to experience turbulence, large-scale gas motions, and instabilities. Marcelo Barraza-Alfaro (Massachusetts Institute of Technology) and collaborators investigated whether a program like exoALMA could detect signs of these processes at work. The team used 3D numerical simulations to explore the observational signatures of the vertical shear instability, the magnetorotational instability, and the gravitational instability. They found that rings, arcs, and spirals can arise from instabilities. While spirals present in the disks in the exoALMA sample could feasibly be due to the magnetorotational instability or the gravitational instability, ring-like and arc-like features due to the vertical shear instability were not detected.
Tomohiro Yoshida (National Astronomical Observatory of Japan; The Graduate University for Advanced Studies) and collaborators reported on their detection of pressure-broadened emission-line wings in RX J1604.3−2130 A. This detection allowed the team to constrain the disk’s gas surface density — a critical property related to the mass available to form planets. They also clearly showed a dust ring coinciding with a gas pressure maximum, proving that gas pressure maxima can create dust traps. The gas-to-dust surface density ratio at the location of this dust trap suggests that the disk has already birthed protoplanets or the dust trapping efficiency is low.
Locations of crescent-shaped dust clumps in the four disks from this study. Click to enlarge. [Adapted from Wölfer et al. 2025]
The full list of articles in this Focus Issue can be found here.
“exoALMA. I. Science Goals, Project Design, and Data Products,” Richard Teague et al 2025 ApJL 984 L6. doi:10.3847/2041-8213/adc43b
The post Monthly Roundup: A Deep View of Planet-Forming Disks with ALMA appeared first on AAS Nova.
A new study suggests that subtle changes in the brain’s immune cells could help explain why some people remain mentally sharp despite Alzheimer’s pathology. For decades, Alzheimer’s research has focused on the buildup of amyloid plaques and tau tangles, the two hallmark features of the disease. Yet a puzzling reality has continued to challenge scientists: [...]
Apresentado na Côte d’Azur à sombra do Grande Prémio do Mónaco de Fórmula 1, o Nuvolari é o automóvel mais rápido e mais potente alguma vez produzido pela Audi. Limitado a 499 unidades e com entrega prevista para 2027, é também uma declaração sobre o futuro da marca.
The post Audi Nuvolari é o supercarro híbrido de 1.001 cv que marca o regresso da marca à sua melhor forma appeared first on Tek Notícias.
Criado em 2022 como Non Fungible Conference, numa altura em que os NFTs estavam no auge da popularidade, o NFC Summit tem vindo a evoluir e, este ano, a arte digital, a IA e a cultura contemporânea estão no centro da programação, numa edição que, pela primeira vez, teve como palco a Unicorn Factory Lisboa.
The post Da arte às novas formas de colecionismo: NFC Summit vai além dos NFTs e quer ser um espelho da cultura pop digital appeared first on Tek Notícias.
In May and June of most years, NASA satellites typically begin to detect large numbers of wildland fires throughout the Top End and Arnhem Land regions of Australia’s Northern Territory. On some days, especially in the afternoon, the blazes can resemble sizable wildfires in satellite imagery, spreading widely and producing expansive smoke plumes.
That was the case when NASA’s Aqua satellite acquired this image of smoke and fires on the afternoon of May 28, 2026. Often, however, fires burning in this area look smaller and less imposing. In the mornings just a few days earlier and later, for instance, NASA satellites detected little smoke despite observing many thermal anomalies, or hotspots, that indicated fire activity.
The pattern of burning, location, and timing are consistent with prescribed fires lit intentionally to manage the landscape. Land managers tend to light fires in the morning, and smoke builds over the course of the day. The process sometimes creates sizable plumes when there are updrafts and winds of moderate strength that carry smoke away from the fires, as happened on May 28 and again on June 2. The fires typically burn through the fire-adapted grasses, underbrush, and scattered trees in the region’s tropical savanna ecosystems.
Over the past few decades, the region’s land managers have combined deep-rooted Indigenous land management practices and modern technologies to establish large-scale landscape management programs such as the West Arnhem Land Fire Abatement project and Arnhem Land Fire Abatement. The goal of such efforts is to intentionally burn some of the savanna underbrush to create firebreaks and reduce fuel loads early in the dry season, reducing more destructive and emissions-intensive fires later in the season. The dry season generally begins in May and extends through September, according to Australia’s Bureau of Meteorology.
While research is ongoing, there are signs that the prescribed burning efforts are having the intended effect. Analysis of satellite observations of the fires suggests that prescribed burning efforts have shifted fire activity from late to early in the dry season, leading to a reduction in high-intensity fires and emissions.
NASA Earth Observatory image by Michala Garrison, using MODIS data from NASA EOSDIS LANCE and GIBS/Worldview. Story by Adam Voiland.
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Dry, warm, and windy conditions across the U.S. Great Plains led to extreme fire activity in March 2026.
Firefighters are battling two destructive blazes in the southern part of the state as drought grips the U.S. Southeast.
A wildland fire charred grassland, coastal sage scrub, and chaparral across one-third of the island, the second largest of the…
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An interstellar comet just revealed hidden methane and chemical clues from another star system. NASA’s James Webb Space Telescope has achieved another milestone by capturing the first mid-infrared chemical fingerprint of an interstellar object. The observations focused on comet 3I/ATLAS, a rare visitor from beyond our solar system, and the findings have been published in [...]O FSB afirma ter descoberto um esquema sofisticado de ciberespionagem que terá utilizado spyware para recolher dados, monitorizar conversas e espiar o ambiente em redor dos dispositivos móveis de altos responsáveis do Estado, com a captura de áudio e vídeo. No entanto, não apresenta provas de tal alegação.
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Lease deals get all the hype, but a lot of people would still rather buy their vehicles. If that sounds like you, you’re in luck, because there’s a whole bunch of great EVs you can buy with 0% financing this month – including the best-selling Tesla Model Y!
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