James Webb Space Telescope Feed Post

Date: 6/12/2024

Arxiv: A JWST Survey of the Supernova Remnant Cassiopeia A Published: 1/4/2024 9:00:01 PM Updated: 6/10/2024 10:24:43 PM

Paper abstract: We present initial results from a JWST survey of the youngest Galacticcore-collapse supernova remnant Cassiopeia A (Cas A), made up of NIRCam andMIRI imaging mosaics that map emission from the main shell, interior, andsurrounding circumstellar/interstellar material (CSM/ISM). We also present fourexploratory positions of MIRI/MRS IFU spectroscopy that sample ejecta, CSM, andassociated dust from representative shocked and unshocked regions. Surprisingdiscoveries include: 1) a web-like network of unshocked ejecta filamentsresolved to 0.01 pc scales exhibiting an overall morphology consistent withturbulent mixing of cool, low-entropy matter from the progenitor's oxygen layerwith hot, high-entropy matter heated by neutrino interactions andradioactivity, 2) a thick sheet of dust-dominated emission from shocked CSMseen in projection toward the remnant's interior pockmarked with small(approximately one arcsecond) round holes formed by knots of high-velocityejecta that have pierced through the CSM and driven expanding tangentialshocks, 3) dozens of light echoes with angular sizes between 0.1 arcsecond to 1arcminute reflecting previously unseen fine-scale structure in the ISM. NIRCamobservations place new upper limits on infrared emission from the neutron starin Cas A's center and tightly constrain scenarios involving a possible fallbackdisk. These JWST survey data and initial findings help address unresolvedquestions about massive star explosions that have broad implications for theformation and evolution of stellar populations, the metal and dust enrichmentof galaxies, and the origin of compact remnant objects.