Emissions of the methane ν3, band and the ethane ν 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 R0 and R1 lines of the methane ν3 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 (2.13 ± 0.40) × 1026 and (1.75 ± 0.48) × 1026 molecules s-1, respectively. The abundance ratio between ethane and methane is 0.82 ± 0.27, which is comparable with other comets within error bars. Although the emissions of monodeuterio-methane (CH3D) were searched for carefully, there is no evidence of them. The 2 σ (95% confidence) upper limit of the CH3D/CH4 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.
- Comets: general
- Comets: individual (153P/Ikeya-Zhang)
- Infrared: solar system
- Molecular data