ON THE DISTANCES OF RED STARS. 

 (Abstract.) 



By henry NORRIS RUSSELL. 

 {Read April 23, 1910.) 



Comparison of the parallaxes of stars, derived by the writer 

 from photographs taken at the Cambridge Observatory (England) 

 by Mr. A. R. Hinks and himself, and their spectra, determined at 

 Harvard under the direction of Professor Pickering, shows a 

 marked correlation between spectral type and parallax. 



K the stars observed are divided into four groups: (i) Those 

 chosen at random for comparison purposes in fields near the Milky 

 Way, (2) similar stars remote from the Galaxy, (3) stars of con- 

 siderable proper motion, (4) those shown by observation to be 

 relatively very near us (parallaxes greater than o".io) ; then the 

 percentages of stars of the dififerent spectral types in these groups 

 are as follows : 



The percentage of orange and red stars increases steadily with 

 increasing nearness of the group to our system. 



Conversely, if the observed parallaxes of the stars of considerable 

 proper motion are compared with the predictions of Kapteyn's 

 formula, it is found that the means for groups including all spectral 

 types are closely represented, but that the means by spectral types 

 show marked systematic deviations, as follows : 



