FEAST: JWST Uncovers the Emerging Timescales of Young Star Clusters in M83

November 2025 • 2025ApJ...993...13K

Authors • Knutas, Alice • Adamo, Angela • Pedrini, Alex • Linden, Sean T. • Bajaj, Varun • Ryon, Jenna E. • Gregg, Benjamin • Ali, Ahmad A. • Andersson, Eric P. • Bik, Arjan • Bortolini, Giacomo • Buckner, Anne S. M. • Calzetti, Daniela • Duarte-Cabral, Ana • Elmegreen, Bruce G. • Faustino Vieira, Helena • Gallagher, John S. • Grasha, Kathryn • Johnson, Kelsey • Lai, Thomas S.-Y. • Lapeer, Drew • Messa, Matteo • Östlin, Göran • Sabbi, Elena • Smith, Linda J. • Tosi, Monica

Abstract • We present JWST NIRCam observations of the emerging young star clusters (eYSCs) detected in the nearby spiral galaxy M83. The NIRcam mosaic encompasses the nuclear starburst, the bar, and the inner spiral arms. The eYSCs, detected in Paα and Brα maps, have been largely missed in previous optical campaigns of young star clusters (YSCs). We distinguish between eYSCI, if they also have compact 3.3 μm polycyclic aromatic hydrocarbon (PAH) emission associated with them, and eYSCII, if they only appear as compact Paα emitters. We find that the variations in the 3.3 μm PAH feature are consistent with an evolutionary sequence where eYSCI evolve into eYSCII and then optical YSCs. This sequence is clear in the F300M−F335M (tracing the excess in the 3.3 μm PAH feature) and the F115W−F187N (tracing the excess in Paα) colors, which become increasingly bluer as clusters emerge. The central starburst stands out as the region where the most massive eYSCs are currently forming in the galaxy. We estimate that only about 20% of eYSCs will remain detectable as compact YSCs. Combining eYSCs and YSCs (≤10 Myr), we recover an average clearing timescale of 6 Myr in which clusters transition from embedded to fully exposed. We see evidence of shorter emergence timescales (∼5 Myr) for more massive (>5 × 10³ M_⊙) clusters, while star clusters of ∼10³ M_⊙ about 7 Myr. We estimate that eYSCs remain associated with the 3.3 μm PAH emission for 3─4 Myr. Larger samples of eYSC and YSC populations will provide stronger statistics to further test environmental and cluster mass dependencies on the emergence timescale.

Links

• PDF https://iopscience.iop.org/article/10.3847/1538-4357/ae018c/pdf
• PREPRINT http://arxiv.org/abs/2505.08874
• DATA https://archive.stsci.edu/mastbibref.php?bibcode=2025ApJ...993...13K
• DATA https://doi.org/10.17909/6dc1-9h53
• DATA https://doi.org/10.17909/y4wf-yc58
• ELECTR https://doi.org/10.3847/1538-4357/ae018c