SECRETARY'S REPORT 163 



atomic hydrogen have been extended ; these represent a considerable 

 refinement of the earlier work. Dr. Angelo J. Skalaf uris and Dr. Wolf- 

 gang Kalkofen worked with Dr. Whitney on the latter studies. Dr. 

 Owen Gingerich has examined some computational aspects of nongray 

 stellar atmosphere models. In this connection, he has investigated 

 several new opacity sources. Current work includes the addition of 

 electron-scattering and absorption-line profiles to the computer 

 program. 



Dr. Max Krook has developed a perturbation-iterative procedure 

 for solving the structure equations for nongray stellar atmospheres. 

 He and Dr. Eugene H. Avrett have applied this method to a number 

 of cases and have found it to converge very rapidly. 



Dr. Noyes has made theoretical investigation of velocity fields in 

 the solar atmosphere. The purpose of this work is to explain the recent 

 observations of pronounced oscillatory motions in the solar atmos- 

 phere. Particular goals are to reproduce the well-determined pe- 

 riod of 300 seconds for the oscillation. The relevant equations, includ- 

 ing the effects of radiative damping, have been put in a form suitable 

 for numerical analysis on an IBM-7090 computer. Preliminary re- 

 sults indicate that rapid change in radiative flux into the atmosphere 

 induced by convection in the granulation, does indeed cause oscillatory 

 motions of the solar atmosphere with the observed properties. 



In collaboration with Dr. Y. Ohman of the Stockholm Observatory, 

 Dr. Goldberg is carrying out a theoretical investigation of the scat- 

 tering of the Lyman-a emission line by tlie high-speed electrons of the 

 solar corona. Profiles of the scattering emission line are being cal- 

 culated for various assumed models of the corona as a function of dis- 

 tance from the center of the solar disk. 



The radiation pressure exerted on a nonstationary gaseous cloud by 

 a neighboring exciting star of high temperature has been considered 

 by Dr. Y. Hagihara.^ He has employed quantum mechanical tech- 

 niques and the assumptions that the atmosphere and the ions in the 

 cloud are in systematic and random thermal motions. 



SuTnmary. — During the past year we have once more witnessed the 

 ever-increasing recognition of astrophysical research as an essential 

 component of the scientific needs of the nation. A previously un- 

 heard-of situation now exists in which major national programs — 

 such as manned lunar exploration in this decade — depend on astro- 

 phj^sical information for their successful execution. 



The Smithsonian Astrophysical Observatory is proud that for 73 

 years it has been generating and disseminating such knowledge. We 

 also derive satisfaction from our realization that the research pro- 



See footnotes on p. 164. 



