Aerodynamics. — Aerodynamical problems connected with the motion of a cloud of gas emitted by Nova Persei. I

Abstract

The present paper is a continuation of a preliminary investigation concerning cases of motion presented by interstellar gas clouds, published last year ¹). Its aim is to consider one particular example, referring to the motion of a presumably very thin cloud or shell of gas emitted by Nova Persei and retarded by the resistance of interstellar material encountered in its course; it will be attempted to work out in some detail various features which had been indicated in outline only in the former publication. It is found that the resistance experienced in retarded motion cannot be calculated immediately from the instantaneous value of the velocity, as it is influenced by expansion phenomena; this has the consequence that the law of retardation now obtained is different from that provisionally assumed in § § 6 and 7 of the paper mentioned. Attention further must be given to the transmission of heat by conduction from the compressed gas to the advancing cloud; and it has been attempted to work out the energy balance for the cloud with the aid of a somewhat improved form of the method of calculation, introduced l.c. in § 6.