[P-CG22] 宇宙における物質の形成と進化

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

★Invited Papers

*野津 翔太¹、坂井 南美²、Zhang Yichen³、Lopez-Sepulcre Ana⁴、Chandler Claire⁵、Zhang Ziwei²、Ceccarelli Cecilia⁴、Codella Claudio⁶、相川 祐理⁷、山本 智⁷ (1.東京大学 大学院理学系研究科 地球惑星科学専攻 地球惑星システム科学講座、2.理化学研究所 開拓研究本部 坂井星・惑星形成研究室、3.上海交通大学、4.グルノーブル大学、5.アメリカ国立電波天文台、6.アルチェトリ天文台、7.東京大学)

キーワード：原始惑星系円盤、アルマ望遠鏡、原始星円盤、アストロケミストリー、電離

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.