Near-infrared Spectroscopic Observations of Comet C/2013 R1 (Lovejoy) by WINERED: CN Red-system Band Emission

作者：Shinnaka Yoshiharu; Kawakita Hideyo; Kondo Sohei; Ikeda Yuji; Kobayashi Naoto; Hamano Satoshi; Sameshima Hiroaki; Fukue Kei; Matsunaga Noriyuki; Yasui Chikako; Izumi Natsuko; Mizumoto Misaki; Otsubo Shogo; Takenaka Keiichi; Watase Ayaka; Kawanishi Takafumi; Nakanishi Kenshi; Nakaoka Tetsuya

来源：Astronomical Journal, 2017, 154(1): 45.

DOI：10.3847/1538-3881/aa7576

• comets: general
• comets: individual (C/2013 R1 (Lovejoy))
• instrumentation: spectrographs

Although high-resolution spectra of the CN red-system band are considered useful in cometary sciences, e.g., in the study of isotopic ratios of carbon and nitrogen in cometary volatiles, there have been few reports to date due to the lack of high-resolution (R equivalent to lambda/Delta lambda > 20,000) spectrographs in the near-infrared region around similar to 1 mu m. Here, we present the high-resolution emission spectrum of the CN red-system band in comet C/2013 R1 (Lovejoy), acquired by the near-infrared high-resolution spectrograph WINERED mounted on the 1.3 m Araki telescope at the Koyama Astronomical Observatory, Kyoto, Japan. We applied our fluorescence excitation models for CN, based on modern spectroscopic studies, to the observed spectrum of comet C/2013 R1 (Lovejoy) to search for CN isotopologues ((CN)-C-13-N-14 and (CN)-C-12-N-15). We used a CN fluorescence excitation model involving both a "pure" fluorescence excitation model for the outer coma and a "fully collisional" fluorescence excitation model for the inner coma region. Our emission model could reproduce the observed (CN)-C-12-N-14 red-system band of comet C/2013 R1 (Lovejoy). The derived mixing ratio between the two excitation models was 0.94(+0.02/-0.03):0.06(+0.03/-0.02), corresponding to the radius of the collision-dominant region of similar to 800-1600 km from the nucleus. No isotopologues were detected. The observed spectrum is consistent, within error, with previous estimates in comets of C-12/C-13 (similar to 90) and N-14/N-15 (similar to 150).

• 出版日期2017-7
• 单位中国科学院国家天文台