James Webb Space Telescope Feed Post

Arxiv: Hidden Gems on a Ring: Infant Massive Clusters and Their Formation Timeline Unveiled by ALMA, HST, and JWST in NGC 3351 Published: 1/25/2024 9:00:00 PM Updated: 1/25/2024 9:00:00 PM

Paper abstract: We study young massive clusters (YMCs) in their embedded "infant" phase with~0.1" ALMA, HST, and JWST observations targeting the central starburstring in NGC 3351, a nearby Milky Way analog galaxy. Our new ALMA data reveal 18bright and compact (sub-)millimeter continuum sources, of which 11 haveapparent counterparts in JWST images and only 6 have counterparts in HSTimages. Based on the ALMA continuum and molecular line data, as well asancillary measurements for the HST and JWST counterparts, we identify 14sources as infant star clusters with high stellar and/or gas masses({~}10^5\;\mathrm{M_\odot}), small radii ({<~}\,5\;\mathrm{pc}),large escape velocities (6{-}10\;\mathrm{km/s}), and short free-fall times(0.5{-}1\;\mathrm{Myr}). Their multiwavelength properties motivate us todivide them into four categories, likely corresponding to four evolutionarystages from starless clumps to exposed HII region-cluster complexes. Leveragingage estimates for HST-identified clusters in the same region, we infer anevolutionary timeline going from 1{-}2\;\mathrm{Myr} before cluster formationas starless clumps, to 4{-}6\;\mathrm{Myr} after as exposed HIIregion-cluster complexes. Finally, we show that the YMCs make up a substantialfraction of recent star formation across the ring, exhibit an non-uniformazimuthal distribution without a very coherent evolutionary trend along thering, and are capable of driving large-scale gas outflows.