The Bullet Cluster is best known for being considered a “smoking gun” for the existence of dark matter, but even a famous galaxy cluster like this one has its secrets. For more than two decades, different measurements of the merging clusters’ dynamical mass ratio have yielded vastly different results. In a recent research article, Boseong Young Cho (Yonsei University) and collaborators used data from JWST and the Dark Energy Camera to revisit the Bullet Cluster and measure its mass ratio using new data. The image above shows a near-infrared view of the Bullet Cluster from JWST, with an overlay of mass contours derived from gravitational-lensing measurements. The team’s analysis assigned a mass of 1.5 quadrillion solar masses for the main cluster (on the left side of the image above), and a mass of 150 trillion solar masses for the subcluster. This suggests a mass ratio of roughly 10, which matches the value supported by hydrodynamical simulations and cements the event as a minor merger. The team also identified three distinct cluster halos (two in the main cluster and one in the subcluster), providing an important constraint on the cluster configuration for future modeling. To learn more about this investigation of the Bullet Cluster, be sure to check out the full research article linked below!

Citation

“Joint JWST–DECam Lensing Reveals that the Bullet Cluster Is a Minor Merger,” Boseong Young Cho et al 2026 ApJ 1005 28. doi:10.3847/1538-4357/ae6a90

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Astronomers using the James Webb Space Telescope have observed extremely distant LRD galaxies, with redshifts greater than 14 at distances greater than 13.5 billion light-years. The question I raise here is how do we see these galaxies and their spectral features if the universe is less than 10,000 years old?

Fullerenes — a class of molecules composed entirely of interconnected carbon atoms — are the largest molecules definitively detected in space. Researchers using JWST to study a planetary nebula have found new spectral features from a fullerene composed of 60 carbon atoms, offering another way to study how these molecules form and survive in space.

Full of Fullerenes

The planetary nebula Tc 1 holds special significance in the field of astrochemistry. More than a decade ago, researchers using the Spitzer Space Telescope studied this wispy nebula illuminated by the core of a dead star. These observations led to the first confident identification of molecules called fullerenes in space. Fullerenes are large molecules constructed from interconnected rings of carbon atoms, forming hollow spheres, rugby-ball shapes, and long tubes. Spheroidal fullerenes, especially C₆₀, are commonly referred to as buckyballs.

Since that discovery, Tc 1 has been a hot spot for studies of buckyballs. However, researchers are still puzzling over how these large molecules form and survive in harsh space environments.

From Spitzer to JWST

Morgan Giese (The University of Western Ontario) and collaborators recently reported on the results of a JWST observing program that aimed to understand how fullerenes respond to changes in their environment. The team mapped the distribution of C₆₀ molecules at varying distances from the powerful ionizing radiation of Tc 1’s central star.

The team successfully spotted the emission features from the fullerene C₆₀ seen in earlier observations, but they also turned up something unexpected: a handful of prominent emission features from 3.5 to 5.2 microns that had not been reported previously.

Feature Presentation

What’s the source of these emission features? The distribution of the emission provides a strong clue: known spectral features from fullerenes C₆₀ and C₇₀ are concentrated in a narrow, bright ring around the center of the nebula, with diffuse emission suffusing the rest of the nebula — and the newfound spectral features follow the same distribution.

This evidence hints that C₆₀ or C₇₀ is the source of these new features, but Giese’s team took the investigation a step further. Using anharmonic quantum chemical calculations, they computed the spectrum of C₆₀‘s combination bands, which arise when multiple vibrational modes are excited at the same time. This is the first time this type of spectrum has been calculated for C₆₀, and the authors found good agreement between their computed spectrum and the JWST spectrum, providing further evidence that C₆₀ is the source of these bands.

Giese and coauthors found that 17% of the energy emitted by the C₆₀ molecules in Tc 1 is released in these  combination bands, suggesting that these features must be taken into account when modeling the cooling of C₆₀ molecules. The discovery of new fullerene spectral features also has implications for future studies of these molecules: since these features appear in a wavelength range where features from other complex molecules like polycyclic aromatic hydrocarbons are weak, these newly identified bands provide a promising way to spot and study fullerenes across space environments.

Citation

“Detection of C₆₀ Combination Bands in the Near-IR Spectrum of Tc 1,” Morgan M. Giese et al 2026 ApJL 1004 L32. doi:10.3847/2041-8213/ae76d5

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