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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.

Citation

“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

Black Eye Galaxy NGC 4826

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.

Citation

“The Black Hole Mass and Photometric Components of NGC 4826,” Kayhan Gültekin et al 2024 ApJ 974 16. doi:10.3847/1538-4357/ad67dc

eight images of swirling clouds on Jupiter

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.

Citation

“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

19 spiral galaxies photographed by JWST

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.

Citation

“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 and its nova shells

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.

Citation

“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

two images showing the results of cosmic web finding algorithms

Astronomers have found a slimy solution to a tricky problem. Simulations show that matter in our universe is arranged along strands of what’s called the cosmic web — an interconnected series of filaments surrounding bubble-like voids — but discerning the structure of this web is challenging; the filaments that connect luminous galaxies are constructed from dark matter and dim, diffuse gas. In a recent research article, Farhanul Hasan (New Mexico State University) and collaborators demonstrated a new way to reconstruct the cosmic web from the positions of galaxies. The team’s algorithm takes cues from Physarum polycephalum, a type of slime mold that forms intricate filamentary structures as it searches for food. Applying this method to galaxies from the IllustrisTNG cosmological simulation, Hasan’s team showed that the slime-mold-inspired method (right-hand panel above) outperforms the method previously used by the authors (left-hand panel). The blue pattern in the background of the images above shows the dark matter density, gray circles represent galaxies, and the red and yellow lines show cosmic web filaments traced by the algorithm. To learn more about how slime mold informs studies of the cosmic web, be sure to check out the full article linked below.

Citation

“Filaments of the Slime Mold Cosmic Web and How They Affect Galaxy Evolution,” Farhanul Hasan et al 2024 ApJ 970 177. doi:10.3847/1538-4357/ad4ee2

visualization of the position and velocity structure of stars in the Milky Way

Ready to be mesmerized by an elegant data visualization? You can now watch the endless, swirling trajectories of 170 million stars in our galaxy using a simple interactive tool. A team led by Joshua Speagle (沈佳士) from the University of Toronto used data from five surveys — the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS), the Two Micron All Sky Survey (2MASS), the United Kingdom Infrared Telescope Infrared Deep Sky Survey (UKIDSS), the “unofficial” Wide-field Infrared Survey Explorer (unWISE), and the Gaia survey — to craft this visualization. In the image above, the color scale shows the tangential speed of stars within a certain distance bin, while the white streamlines show the stars’ tangential velocity. You can play around with the full visualization, which allows you to filter by distance and switch the color overlay between velocity, density, metallicity, and age. To learn more about the data selection process and the construction of the final star catalog, be sure to check out the full research article linked below.

Citation

“Mapping the Milky Way in 5D with 170 Million Stars,” Joshua S. Speagle et al 2024 ApJ 970 121. doi:10.3847/1538-4357/ad2b62

In stellar nurseries throughout the Milky Way, baby stars swaddled in dusty blankets are growing rapidly and shaping their birth environments. Recently, a research team led by Samuel Federman (University of Toledo) used JWST to investigate the behavior of five young protostars, two of which are shown in the image above. The new JWST images capture the squalls of protostars in their earliest stages, about which relatively little is known. During these early stages, protostars are swathed in dense, dusty envelopes of gas that fall onto the star, spurring rapid growth through accretion. The accretion, in turn, powers narrow outflowing jets and wide outflowing winds that carve out a cavity in the surrounding envelope, creating the characteristic hourglass shapes in the images above. For more information and a closer look at all of the protostars in the sample, be sure to check out the full research article linked below.

Citation

“Investigating Protostellar Accretion-driven Outflows across the Mass Spectrum: JWST NIRSpec Integral Field Unit 3–5 μm Spectral Mapping of Five Young Protostars,” Samuel A. Federman et al 2024 ApJ 966 41. doi:10.3847/1538-4357/ad2fa0

Nereides supernova remnant

Full view of the Nereides supernova remnant

Full view of the newly discovered Nereides supernova remnant G107.7-5.1. [Fesen et al. 2024]

The images above and to the right show the delicate gaseous filaments of a newly discovered supernova remnant, the Nereides Nebula. Over the past two years, a team led by Robert Fesen (Dartmouth College) has studied supernova remnants from 10 observing sites across Europe, Africa, New Zealand, and the US. Through the course of this campaign, the team racked up more than 1,000 hours of exposure time and produced more than 12,000 images, greatly improving the quality of data available for nine known Milky Way supernova remnants — and they discovered three more supernova remnants along the way. The new images demonstrate the immense size and intricate tracery of these exploded stars, and in some cases, reveal never-before-seen emission structures. It was a challenge to pick just a single image to appear in today’s post — be sure to check out the article linked below to see all of the new images!

Citation

“Deep Optical Emission-Line Images of Nine Known and Three New Galactic Supernova Remnants,” Robert A. Fesen et al 2024 ApJS 272 36. doi:10.3847/1538-4365/ad410a

Cassiopeia A supernova remnant as seen by JWST

Cassiopeia A is a much-photographed supernova remnant in the northern celestial hemisphere, and now, thanks to JWST, it has a stunning new portrait. Using data from JWST’s Near-Infrared Camera and Mid-Infrared Instrument, Jeonghee Rho (SETI Institute and Seoul National University) and collaborators crafted the three-color image shown above. The diffuse blue areas show the light emitted by electrons spiraling around magnetic field lines, while the more finely detailed red and green areas trace light from argon and carbon monoxide, respectively. Coupled with spectra of two dense knots of gas within the shell of the supernova remnant, these observations allowed Rho’s team to study the connections between the formation of molecules like carbon monoxide and the creation of cosmic dust. For more new images of Cassiopeia A, including some incredible closeups of filamentary gas, be sure to check out the full research article linked below!

Citation

“Shockingly Bright Warm Carbon Monoxide Molecular Features in the Supernova Remnant Cassiopeia A Revealed by JWST,” J. Rho et al 2024 ApJL 969 L9. doi:10.3847/2041-8213/ad5186

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