Accession Number : AD0282369

Title :   ABUNDANCES OF ELEMENTS IN STARS AND NEBULAE (STUDIES OF HYDROGEN-DEFICIENT STARS: I)

Corporate Author : MICHIGAN UNIV ANN ARBOR

Personal Author(s) : ALLER,L.H.

Report Date : JUN 1962

Pagination or Media Count : 1

Abstract : To interpret the spectrum of a star composed primarily of helium rather than of hydrogen, it is necessary to construct a model atmosphere which gives the variation of pressure temperature and density with depth. On the assumption that the atmosphere is in hydrostatic equilibrium and that flow of energy takes place by radiation rather than by convection currents, the calculation of an appropriate model is described. The essential boundary condition that the radiative flux is constant with depth can be applied only after temperature and pressure have been calculated for all different depths and the entire radiation field has been calculated. Hence an iterative process has to be applied. Procedures which work for the corresponding problem of a hydrogen atmosphere fail, and one must proceed by trial and error in order to obtain the final solution. (Author)

Descriptors :   *STARS, ATMOSPHERE MODELS, HELIUM, HYDROGEN, MODELS (SIMULATIONS)

Distribution Statement : APPROVED FOR PUBLIC RELEASE