Detection of submillimeter-wave [C I]emission in gaseous debris disks of 49 Ceti and β Pictoris
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Published:2017-03
Issue:S332
Volume:13
Page:81-87
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ISSN:1743-9213
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Container-title:Proceedings of the International Astronomical Union
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language:en
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Short-container-title:Proc. IAU
Author:
Higuchi Aya E.,Sato Aki,Tsukagoshi Takashi,Sakai Nami,Iwasaki Kazunari,Momose Munetake,Kobayashi Hiroshi,Ishihara Daisuke,Kaneda Hidehiro,Yamamoto Satoshi
Abstract
AbstractWe have detected [C I] 3P1–3P0 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) × 1017 and (2.5 ± 0.7) × 1016 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.
Publisher
Cambridge University Press (CUP)
Subject
Astronomy and Astrophysics,Space and Planetary Science