DIFFUSE [CII] 158 MICRON LINE EMISSION FROM THE INTERSTELLAR MATTER AT HIGH GALACTIC LATITUDE

We present the results of an rocket-borne observation of far-infrared [CII] line at 157.7 ${\mu}m$ from the diffuse inter-stellar medium in the Ursa Major. We also introduce a part of results on the [CII] emission recently obtained by the IRTS, a liquid-helium cooled 15cm telescope onboard the Space Flyer Unit. From the rocket-borne observation we obtained the cooling rate of the diffuse HI gas due to the [CII] line emission, which is $1.3{\pm}0.2 {\times} 10^{-26}$ $ergss^{-1} H^{-1}_{atom}$. We also observed appreciable [CII] emission from the molecular clouds, with average CII/CO intensity ratio of 420. The IRTS observation provided the [CII] line emission distribution over large area of the sky along great circles crossing the Galactic plane at I = $50^{\circ}$ and I = $230^{\circ}$. We found two components in their intensity distributions, one concentrates on the Galactic plane and the another extends over at least $20^{\circ}$ in Galactic latitude. We ascribe one component to the emission from the Galactic disk, and the another one to the emission from the local interstellar gas. The [CII] cooling rate of the latter component is $5.6 {\pm} 2.2 {\times}10$.