HCN observations of C/Ikeya-Zhang using the NRO 45 m telescope

Abstract

Millimetric spectral-line observations of C/Ikeya-Zhang were performed using the NRO 45m telescope. The rotational transitions of HCN (J=1-0) at 88.63 GHz were detected. The production rate of HCN molecules was about 10²⁷ molecules s^-1 after perihelion passage. The out flow velocity of the coma, deduced from the HCN linewidths, is about 1 km s^-1. The 5 points mapping of HCN coma in 15 arcsec distances was established in the direction to the Sun, opposite to the Sun and 2 perpendicular direction to the Sun, however, there was no clear solar dependence on the expansion of HCN coma.