382 T. C. CHAMBERLIN 



elasticity of large hot bodies under great self-gravitative com- 

 pression may so far aid in disruption, by cooperation with the 

 differential gravity of an adjacent body, as to cause dispersion 

 even before the Roche limit is reached. In the case of very 

 large bodies that are already gaseous, such as the sun, this phe- 

 nomenon gives rise to a special case of extreme interest. Under 

 this special case, there arise a large variety of particular instances 

 due to the varying sizes, velocities, paths, rotations, and consti- 

 tutions of the couplets of stars concerned, and also to the adven- 

 titious effects of their secondaries ; but, for a simple illustrative 

 case, let it be assumed that two bodies of equal masses and 

 equal velocities are approaching each other on parabolic paths, 

 and that at periastron they will pass through each other's spheres 

 of disruption, or rather, spheres of dispersion. For convenience, 

 let if be assumed that one of these bodies (/i. Fig. i) is gaseous, 

 while the other (5) has already become so cold and solid as to 

 act essentially as a unit, though disrupted. The history of the dis- 

 persion of the gaseous body may then be followed alone. Let 

 the rate of rotation of the gaseous body (^) be relatively low, 

 as in the case of our sun. It may then be neglected in a general 

 discussion, since as a dynamic factor it is trivial compared with 

 the enormous energies of momentum and of elastic dispersion 

 involved. This will appear clear in the outcome. Furthermore, 

 the direction of rotation with reference to the parabolic paths 

 might happen to be any one of an indefinite number, in many of 

 which the effect would be inconsequential, even if the energy 

 were large. In the close approach of these two bodies the 

 two great dynamic factors of special interest are (i) the 

 tidal distortion, and (2) the elastic expansion of the gaseous 

 body. 



While the two bodies are yet distant from each other, they 

 must begin to take on elongation of the tidal type as the result 

 of their mutual differential attraction, this elongation being aided 

 by the high internal mobility and elasticity of the gaseous body. 

 As the bodies approach periastron, this elongation must progress 

 at an accelerated rate. At the moment of the entrance of the 



