Detection of submillimeter-wave [C I]emission in gaseous debris disks of 49 Ceti and β Pictoris. Issue Volume 13:Issue S332(2017) (4th September 2018)

• Record Type: Journal Article
• Authors: Higuchi, Aya E.; Sato, Aki; Tsukagoshi, Takashi; Sakai, Nami; Iwasaki, Kazunari; Momose, Munetake; Kobayashi, Hiroshi; Ishihara, Daisuke; Kaneda, Hidehiro; Yamamoto, Satoshi
• Editors: Cunningham, Maria; Millar, Tom; Aikawa, Yuri
• Is Part Of: Proceedings of the International Astronomical Union. Volume 13:Issue S332(2017)
• Page Start: 81
• Page End: 87
• Publication Date: 2018-09-04
• Subjects: (stars:) planetary systems: protoplanetary disks, -- ISM: atoms, -- radio lines: general; Astronomy -- Congresses; Astronomy -- Periodicals; 520
• DOI: 10.1017/S1743921317007402
• Languages: English
• ISSNs: 1743-9213

Abstract

Abstract: We have detected [C I] 3 P 1 – 3 P 0 emissions in the gaseous debris disks of 49 Ceti and β Pictoris with the 10 m telescope of the Atacama Submillimeter Telescope Experiment, which is the first detection of such emissions. The line profiles of [C I] are found to resemble those of CO( J =3–2) observed with the same telescope and the Atacama Large Millimeter/submillimeter Array. This result suggests that atomic carbon (C) coexists with CO in the debris disks, and is likely formed by the photodissociation of CO. Assuming an optically thin [C I] emission with the excitation temperature ranging from 30 to 100 K, the column density of C is evaluated to be (2.2 ± 0.2) × 10 17 and (2.5 ± 0.7) × 10 16 cm −2 for 49 Ceti and β Pictoris, respectively. The C/CO column density ratio is thus derived to be 54 ± 19 and 69 ± 42 for 49 Ceti and β Pictoris, respectively. These ratios are higher than those of molecular clouds and diffuse clouds by an order of magnitude. The unusually high ratios of C to CO are likely attributed to a lack of H2 molecules needed to reproduce CO molecules efficiently from C. This result implies a small number of H2 molecules in the gas disk; i.e., there is an appreciable contribution of secondary gas from dust grains.