82 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1961 



an interesting "jump" at 23.3 A. in the curve of optical depth versus 

 wavelength. 



Dr. Charles A. Whitney continued his research in stellar atmos- 

 pheres. From computations , based on novel analytical methods, 

 carried out by Angelo J. Skalafuris, he has formulated a simplified 

 analytical description of the cooling rate behind shock waves. This 

 work corrects the erroneous results of an earlier investigator, and 

 also serves to check the range of validity of assumptions of "optically 

 thin" perturbations (i.e., neglect of reabsorption of shock radiation). 

 In his investigation of the gas dynamics of stellar atmospheres, also 

 assisted by Mr. Skalafuris, he is concentrating initially on the struc- 

 ture of shock fronts in pure hydrogen, and in successive stages will 

 work toward a unified theory incorporating the effects of radiation 

 and the wide departures from thermodynamic equilibrium. Dr. 

 Wliitney's continuing project on the cause and nature of stellar pul- 

 sation has closely approached a definitive statement of the cause of 

 pulsation aided by the success of Dr. John P. Cox, who served as 

 consultant, in obtaining exact solutions for the nonadiabatic linear- 

 ized wave equation. Miss Sylvia Boyd began compilation of spec- 

 trographic and photometric data on pulsating stars, which will un- 

 dergo analysis in the light of the Cox-Wliitney theory; Dr. K. G. 

 Teske's investigation, under Dr. Wliitney's supervision, of spectrum- 

 line formation in pulsating stellar atmospheres indicates the need 

 for revision of earlier interpretations. 



To provide a foundation for the analysis of astrophysical data ex- 

 pected from future orbiting observatories, Dr. Whitney began pre- 

 liminary work on methods of constructing accurate model stellar at- 

 mospheres. Using electronic computations provided by SAO, 

 he is extending and modifying recent theoretical developments, in- 

 cluding the work of Dr. Max Krook and his students. Owen Gin- 

 gerich's completed computer program for the construction of accu- 

 rate model atmospheres in radiative equilibrium has demonstrated the 

 inadequacy of nmch earlier work in solar radiation and its implica- 

 tions for the model of the sun's atmosphere. Shiv Kumar has vir- 

 tually completed the construction of several models for the atmos- 

 phere of very hot stars. 



Dr. Kichard IMcCrosky, with the use of infrared-sensitive detectors 

 on the 61-inch telescope of the Harvard College Observatory, con- 

 tinues his observations of Raman-scattered Lyman a to determine the 

 presence of hydrogen molecules in interstellar space. 



Dr. Max Krook is proceeding with his theoretical research into the 

 further development and application of methods for determining the 

 structure of nongray atmospheres. In collaboration with Dr. Whit- 

 ney, he is now calculating a number of model atmospheres. He is 

 also applying the methods developed in continuum theories in gas 



