[P-CG22] Origin and evolution of materials in space

[PCG22-11] Chemical layered structures in the disk and envelope of NGC 1333 IRAS 4C: FAUST

★Invited Papers

*Shota Notsu¹, Nami Sakai², Yichen Zhang³, Ana Lopez-Sepulcre⁴, Claire Chandler⁵, Ziwei Zhang², Cecilia Ceccarelli⁴, Claudio Codella⁶, Yuri Aikawa⁷, Satoshi Yamamoto⁷ (1.Earth and Planetary System Science Group, Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, 2.Star and Planet Formation Laboratory, RIKEN Cluster for Pioneering Research, 3.Department of Astronomy, Shanghai Jiao Tong University, 4.IPAG, Universite Grenoble Alpes, 5.NRAO, 6.INAF, Osservatorio Astrofisico di Arcetri, 7.The University of Tokyo)

Keywords:Protoplanetary disks, ALMA, Protostellar disks, Astrochemistry, Ionisation

Recent ALMA’s molecular emission line observations with high spatial resolution have revealed structures in which the chemical composition changes with height in the vertical direction of the disk (= chemical layered structure) and a radial ionization rate distribution in Class I/II disks. However, the existence of such chemical layered structures in Class 0 disk and envelope system has not yet been investigated well. In this talk, we report the results of ALMA’s molecular line observations of the disk and envelope around the Class 0 low-mass protostar NGC 1333 IRAS 4C in the Perseus Molecular Cloud, as part of the ALMA large program FAUST (Fifty AU STudy of the chemistry in the disk/envelope system of solar-like protostars). Previous observations have shown that this object is an edge-on object with the disk rotation axis tilted almost perpendicular to the line of sight, making it suitable for studying the molecular abundance distribution along the disk height. We found that the molecules generated by photochemical reactions such as CCH and c-C₃H₂ are distributed in the low density upper layers of the disk, while the molecules such as C¹⁸O and H₂CO are distributed in the high density regions around the protostar, indicating a chemically layered structure in the disk vertical direction. The ionization rate distributions in the radial direction of the disk are estimated from the comparison of H¹³CO⁺ and C¹⁸O line emission, and we confirmed that the ionization rate increases in the outer region of the disk.