Maps of energetic neutral atom flux from 2009 to 2022 and from 0.71 keV to 4.29 keV. Click to enlarge. [Noh et al. 2025]
“Characteristics of the IBEX Ribbon and Their Implications for a Source Region Outside the Heliopause,” Sung Jun Noh et al 2025 ApJ 980 8. doi:10.3847/1538-4357/ada36a
An increasingly large fleet of robotic explorers is flying by, orbiting, landing upon, and crawling around on the planetary bodies of our solar system, radioing home increasing amounts of data that often require labor-intensive analysis. Luckily, machine learning may be able to help researchers handle growing data demands. To explore how machine learning can assist planetary scientists, a team led by Frank Chuang (Planetary Science Institute) applied machine-learning techniques to the challenge of classifying surface materials on the Moon. Their goal was to differentiate between three types of surface materials: maria (dark areas where lava has pooled and cooled in ancient craters), cryptomaria (buried maria), and light plains (brighter regions thought to have been deposited by impacts). They first used unsupervised machine learning to identify different types of surface regions. As shown in the left-hand image above, the unsupervised algorithm easily recognized large dark areas corresponding to lunar maria (shown in red), but it was less proficient at discerning between the lighter cryptomaria and plains. The right-hand image shows the results of the second step, in which the classes identified in the first step guided a supervised machine-learning investigation. Here, the algorithm found that within areas mapped as cryptomaria, there are speckles of maria still visible, a finding that Chuang’s team suggests could be evidence for spotty resurfacing of these ancient lava seas. To get more detail on the results of this machine-learning exploration of the lunar surface, be sure to check out the full research article linked below.
“Application of Machine Learning Techniques to Distinguish Between Mare, Cryptomare, and Light Plains in Central Lunar South Pole−Aitken Basin,” Frank C. Chuang et al 2025 Planet. Sci. J. 6 35. doi:10.3847/PSJ/ada4a6
The full series of Hubble images of SN 1987A. The logarithmic color scale shows the brightness relative to the brightest hot spot in the December 2009 image. The bright spot that stands out at the lower right in early images is a star unrelated to the supernova remnant. [Tegkelidis et al. 2024]
“Tracing the Propagation of Shocks in the Equatorial Ring of SN 1987A over Decades with the Hubble Space Telescope,” Christos Tegkelidis et al 2024 ApJ 976 164. doi:10.3847/1538-4357/ad812e
Recurrent novae are repeated outbursts that happen in binary star systems containing a white dwarf and a red dwarf, subdwarf, or giant star. Locked in close quarters, the tiny, dense white dwarf collects material from its companion until the material ignites on the white dwarf’s surface and explodes into space. These systems outburst every century or so and are hypothesized to leave behind “super-remnants” that stretch to cover dozens of light-years. Though all recurrent novae are thought to create super-remnants, only two have been discovered. In advance of the highly anticipated outburst of T Coronae Borealis, Michael Shara (American Museum of Natural History) and collaborators used the Condor Array Telescope to search for a super-remnant. The team discovered a faint but distinct nebula with a hint of bilobed structure surrounding the star. In the image above, green shows Hα emission, red shows emission from singly ionized sulfur, and blue shows emission from singly ionized nitrogen. Based on the team’s calculations, the gaseous nebula is too tenuous to visibly light up when struck by photons from the next outburst, but they recommend post-outburst observations with Hubble and JWST to survey the aftermath. To learn more about the discovery of T Coronae Borealis’s super-remnant, be sure to check out the full research article linked below.
“The Newly Discovered Nova Super-Remnant Surrounding Recurrent Nova T Coronae Borealis: Will It Light Up During the Coming Eruption?” Michael M. Shara et al 2024 ApJL 977 L48. doi:10.3847/2041-8213/ad991e
The formation of stars and planets is a messy, multilayered, and energetic process. As part of the Early Planet Formation in Embedded Disks observing program, Sacha Gavino (Niels Bohr Institute, University of Copenhagen) and collaborators used the Atacama Large Millimeter/submillimeter Array (ALMA) to get a glimpse of this process. The images above show ALMA observations of two protostars, IRS1 and IRS2. In these images, green shows emission from fast-moving (<25 kilometers per second) carbon monoxide molecules, red shows emission from even faster-moving (>40 kilometers per second) carbon monoxide, and blue marks emission from silicon monoxide molecules. Each of these protostars is ringed by a dusty circumstellar disk, but what dominates the view are wide-angle outflows and narrow jets. Gavino’s team showed that the two protostars’ jets have different structures, with IRS1’s jet tracing out a complex double helix and IRS2’s jet emerging from the system in clumps. The helical structure of IRS1’s jet provides evidence for the rotation of outflowing material — a process that carries away angular momentum from the system. The clumps in IRS2’s jet, on the other hand, give insight into past periods of accretion onto the protostar. For more information about these two protostars, including details on their potentially planet-forming disks, be sure to check out the full research article linked below.
“Early Planet Formation in Embedded Disks. XI. A High-Resolution View Toward the BHR 71 Class 0 Protostellar Wide Binary,” Sacha Gavino et al 2024 ApJ 974 21. doi:10.3847/1538-4357/ad655e
This image shows the star-forming region RCW 38, which is located 5,500 light-years from Earth. At less than a million years old — and possibly as young as 100,000 years — RCW 38 is the youngest super star cluster in the Milky Way. In the image above, infrared light from the Spitzer Space Telescope is shown in red, X-rays from the Chandra X-ray Observatory are in green, and gamma rays from the Fermi Gamma-ray Space Telescope are in blue. Paarmita Pandey (The Ohio State University) and coauthors recently observed this cluster in order to test the hypothesis that the outflowing winds of massive stars are a source of cosmic rays: charged particles traveling near the speed of light. Cosmic rays might be generated when winds from several stars crash into one another or into the gas of the interstellar medium. Pandey’s team hoped to find evidence for this process in the form of gamma rays, which are produced when cosmic rays collide with other particles. Using data from Fermi, the team found clear evidence of gamma rays coming from the region, adding to the small but growing number of young star clusters that are known to be associated with gamma-ray production. To learn more about this work, be sure to check out the full study linked below.
“Constraining the Diffusion Coefficient and Cosmic-Ray Acceleration Efficiency Using Gamma-Ray Emission from the Star-Forming Region RCW 38,” Paarmita Pandey et al 2024 ApJ 976 98. doi:10.3847/1538-4357/ad83bc
The striking dust-obscured center of the galaxy NGC 4826, shown in this image from the Hubble Space Telescope, has inspired several inventive monikers including the Black Eye Galaxy and the Evil Eye Galaxy. At just 27 million light-years from Earth, NGC 4826 provides an excellent opportunity to study the connection between the structure of a galaxy and the properties of its central supermassive black hole. Kayhan Gültekin (University of Michigan) and collaborators paired infrared and optical data from multiple sources with dynamical modeling to assess the galaxy’s structure and calculate the mass of its central black hole. The data revealed multiple components to the galaxy’s structure, including a disk, an ellipsoidal bulge of stars protruding from the disk, and a second, slightly flattened bulge called a pseudobulge that is itself composed of multiple components. With a supermassive black hole mass of 8.4 million solar masses — roughly twice the mass of the Milky Way’s central black hole — NGC 4826 possesses the least-massive black hole to be measured via stellar dynamical modeling. To learn more about the intricate structure of this galaxy and what these measurements imply for the study of low-mass supermassive black holes, be sure to check out the full article linked below.
“The Black Hole Mass and Photometric Components of NGC 4826,” Kayhan Gültekin et al 2024 ApJ 974 16. doi:10.3847/1538-4357/ad67dc
As you gaze upon these images of swirling clouds on Jupiter, do you see vortices? This is the question posed by the Jovian Vortex Hunter citizen science project, which invites participants to examine Juno spacecraft images of Jupiter’s mesmerizing clouds. This project aims to advance our understanding of how Jovian vortices like the famous Great Red Spot form and evolve over time. Recently, Ramanakumar Sankar (University of California, Berkeley) and collaborators presented the project’s first results, which were drawn from more than a million classifications made by roughly 5,000 participants. The volunteers identified, located, and described 7,000 vortices, and their annotations led to some surprising findings, including an apparent correlation between the color of the vortex — related to its chemistry — and its size and location. For example, white or brown vortices seem to be larger than red or cloud-free vortices, and while white and cloud-free vortices tend to linger near the poles and brown vortices span moderate latitudes, red vortices crop up in specific latitude bands. To learn more about the results of this citizen study, and to see what the team plans to do next, be sure to check out the full research article linked below.
“Jovian Vortex Hunter: A Citizen Science Project to Study Jupiter’s Vortices,” Ramanakumar Sankar et al 2024 Planet. Sci. J. 5 203. doi:10.3847/PSJ/ad6e75
You may have seen these images individually, but here they are in one grand ensemble: the 19 nearby spiral galaxies surveyed with JWST by the Physics at High Angular resolution in Nearby GalaxieS (PHANGS) collaboration. These galaxies have also been observed with the Atacama Large Millimeter/submillimeter Array, the Very Large Array, and the Hubble Space Telescope, providing a multi-wavelength view of some of the Milky Way’s neighbors. The JWST images (click the image above for the full view) show filamentary structures of warm gas and reveal young star clusters that were hidden in previous observations. In this article, Thomas Williams (University of Oxford) and collaborators present the full PHANGS–JWST dataset and describe the image-processing pipeline developed for these observations. Though there already exists an official pipeline for processing JWST data, the authors’ method provides an alternative that is particularly well suited to observations of bright, extended objects such as nearby galaxies. This project is open source, meaning that all are welcome to squash bugs and suggest improvements. To learn more about the processing method that led to these fantastic images, be sure to check out the full article linked below.
“PHANGS-JWST: Data-processing Pipeline and First Full Public Data Release,” Thomas G. Williams et al 2024 ApJS 273 13. doi:10.3847/1538-4365/ad4be5
RX Puppis, marked with crosshairs in the image above, is a symbiotic star: a binary system containing a puffy red giant and a compact white dwarf or neutron star. As the compact object accretes matter from the red giant, the stolen gas can ignite in a flash of nuclear fusion, powering a nova outburst that brightens the system for anywhere from days to decades. In the 1970s, researchers observed a slowly evolving outburst from RX Puppis. But nova outbursts from symbiotic stars usually recur — is there any evidence of previous outbursts from this sytem? Using the 1-meter Swope telescope in Las Campanas, Chile, and the Southern African Large Telescope, Krystian Iłkiewicz (University of Warsaw, Durham University) and collaborators discovered an arc-like emission feature that appears to be the remnant of a shell of gas ejected during an outburst roughly 1,300 years ago. They also discovered a hint of a second shell that might be from an eruption 7,000 years ago. Given the locations of these two shells and the timing of the 1970s outburst, Iłkiewicz’s team concluded that the rate at which the white dwarf amasses gas from its companion has increased by a factor of three over the past 10,000 years. This is the first time a change in mass transfer rate has been measured in a binary system over such a long timescale. To learn more about this discovery, be sure to check out the full research article linked below.
“Ancient Nova Shells of RX Pup Indicate Evolution of Mass Transfer Rate,” Krystian Iłkiewicz et al 2024 ApJL 972 L14. doi:10.3847/2041-8213/ad6e5a