Nowhere Left to Hide: Uncovering All of the Massive Young Embedded Star Clusters in the Antennae with JWST*
Year: 2026
Type: article
Abstract: The Antennae galaxies merger produces the brightest infrared emission of any galaxy within ≈20 Mpc, mostly from intense star formation taking place in supergiant molecular cloud complexes in the overlap region. Here, we present new, high-resolution NIRCam and MIRI images of the Antennae galaxies taken with the F150W, F187N, F335M, F360M, F410M, and F770W filters on JWST to search for the predicted but as-yet-undiscovered population of deeply embedded, optically obscured star clusters. We identify a population of 45 sources, 40 previously unknown, with high Br α /H α and Pa α /H α flux ratios, which are likely very young clusters still embedded or just emerging from their natal cocoons, and estimate their age, extinction ( A V ), and mass. We find that all are extremely young (≲2.5 Myr), have A V between 2 and 10 mag, and masses between ≈10 4 and several ×10 6 M ⊙ . We believe we have now uncovered all clusters with M ≳ 3 × 10 4 M ⊙ and A V ≳ 2 mag in the Antennae. While our sample represents a small fraction (≈15%) of clusters younger than 3 Myr by number, it dominates the ionizing photon luminosity across the galaxy pair (≈60%). We find elevated H 2 /polycyclic aromatic hydrocarbon ratios of the interstellar medium surrounding the most massive pair of embedded clusters, supporting the idea that merger-induced shock-heated gas plays an important role in the formation of extremely massive clusters.
Source: The Astrophysical Journal
Institutions: University of Toledo, Space Telescope Science Institute, University of Arizona, Ontario College of Art and Design, Centre National de la Recherche Scientifique, Observatoire astronomique de Strasbourg, Université de Strasbourg, Joint Space Science Institute, University of Maryland, College Park, University of Wyoming, University of California San Diego, Heidelberg University, Max Planck Institute for Astronomy
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
OpenAlex ID: W7155985545