Saturated Hydrocarbons in Comet 153P/Ikeya‐Zhang: Ethane, Methane, and Monodeuterio‐Methane

Abstract

Emissions of the methane 3 band and the ethane 7 band were detected in the high-dispersion infrared spectra of comet 153P/Ikeya-Zhang taken by the Subaru Telescope with the Infrared Camera and Spectrograph (IRCS) on 2002 May 28 and 29 UT. The rotational temperature is estimated to be about 40-50 K from R 0 and R 1 lines of the methane 3 band. The production rates of methane and ethane were estimated by applying the rotational temperature of 50 K. Resultant production rates of methane and ethane are ð2:13 AE 0:40Þ Â 10 26 and ð1:75 AE 0:48Þ Â 10 26 molecules s À1 , respectively. The abundance ratio between ethane and methane is 0:82 AE 0:27, which is comparable with other comets within error bars. Although the emissions of monodeuterio-methane (CH 3 D) were searched for carefully, there is no evidence of them. The 2 (95% confidence) upper limit of the CH 3 D/CH 4 ratio is 0.3 in comet 153P/Ikeya-Zhang. Comparing the relative abundance of methane and ethane in the interstellar ices, we discussed the formation conditions of cometary nuclei.

Infrared spectroscopic studies of hydrogenated silicon clusters

“…Ethylene (C 2 H 4 ) was only observed in Jupiter and Neptune (Encrenaz et al 2002;Fegley 1995). Ethane has also been identified in comets such as 153P/Ikeya-Zhang (Kawakita et al 2003). Note that ethylene (Goldhaber et al 1987), acetylene (Cernicharo et al 1999), and the ethinyl radical (Fuente et al 1998) have been detected in the circumstellar envelope of IRC+10216.…”

The compositional evolution of C/2012 S1 (ISON) from ground-based high-resolution infrared spectroscopy as part of a worldwide observing campaign

“…CH 4 is highly volatile, so its relative abundance in comets is likely influenced in some way by the formation temperature and processing history of cometary ices (Gibb et al, 2003;Kawakita et al, 2003Kawakita et al, , 2005. CH 4 has a strong infrared fundamental band (m 3 ) near 3.3 lm, which should make it one of the easier volatile species to detect in comets; however, CH 4 has a strong terrestrial component that requires a sufficiently large geocentric Dopplershift to prevent atmospheric extinction of cometary lines.…”

Laboratory Studies on the Infrared Absorptions of Hydrogenated Carbon‐Silicon Clusters: Directing the Identification of Organometallic SiCHxSpecies toward IRC +10216

“…Ethylene (C 2 H 4 ) was only observed in Jupiter and Neptune (Encrenaz et al 2002;Fegley 1995). Ethane has been also identified in comets such as 153P/Ikeya-Zhang (Kawakita et al 2003). Note that ethylene (Goldhaber et al 1987), acetylene (Cernicharo et al 1999), and the ethinyl radical (Fuente at al.…”