256 



Mr. J. N. Lockyer. 'On th^ Classification [Jan. 10, 



ponents are yellow and of nearly equal magnitudes. If both com- 

 ponents shall be found to have identical spectra, thus placing them in 

 the same group, a point which their colour leaves indeterminate, 

 their " life curves " will be coincident. If one is found to belong 

 to Group III, however, and tjie other to Group Y, they can still be 

 represented by two curves beginning p,t the same point, but with the 

 ascending side of one intersecting the descending side of the other 

 as in fig. 22. The places occupied by the stars are indicated by dots ; 

 the portions of the curves to the left of the dots represent the stages 

 already passed thr6ugh, those to the right the stages still to be gone 

 through. This also, applies to the diagrams which follow. In the 



FIG. 22. The light curves of the two components of a binary star, in which both| 

 components are yellow, and of equal or nearly equal magnitudes. 



former case the masses of the two components would evidently be 

 equal, or nearly so,' while in the latter case,' one would be considerably 

 larger than the other. Hence, in all cases where the components are 

 yellow and of nearly equal magnitudes, we are' justified in regarding 

 them as having possibly condensed from the same nebulosity. 



