제목: JWST Imaging and Spectroscopy of the Supernova Remnant Cassiopeia A and Molecule and Dust Formation​​​​​​​​

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​​​​​​​​​​​​​​​​​​연사: Dr. Jeong-hee Roh (SETI Institute)​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​

장소: 과학관 B103호​​

Abstract:

JWST produces unprecedented discoveries in high-redshift and nearby galaxies and transient Universe. JWST's high-resolution imaging and spectroscopy of our Galactic supernova remnants (SNRs) reveal unprecedented complex structures. The JWST images of Cassiopeia A (Cas A) show infrared emission from the shocked medium, a weblike network of unshocked ejecta filaments at the interior, and a thick sheet of dust from shocked circumstellar medium (CSM), SN ejecta, warm carbon monoxide (CO) molecules and dust structures. We suggest that the sheet of emission bright at 11.3 microns (dubbed the Green Monster) is associated with CSM, which was lost during a highly asymmetric mass loss phase. The CSM sheets contain numerous holes and rings that we show likely formed when enriched ejecta clumps pierce the CSM shell. JWST NIRSpec spectra show a forest of CO fundamental bands composed of a few tens of sinusoidal patterns of rovibrational lines from 1000 K CO gas and a few band heads near 4.3 microns from the high-rotational levels (J~ 90) and high-temperature components, indicating mixing of molecules and dust. The JWST spectra are to be compared with previously studied dust features to discuss dust formation and destruction and to show unidentified molecules, dust features, and gas lines for future discoveries. I will also highlight JWST results not only from other SNRs and recent SNe, as well as discoveries in different fields of astronomy for the cycle of the interstellar medium. Finally, the CO and dust formation in Cas A will be discussed, along with ground-based NIR observations of recent SNe.​​