308 
The Evolution of Binary Systems 
[oh. XI 
The third and fourth columns give values of MG 2 , which would be precisely 
constant if the steady-state law were exactly obeyed. 
TABLE XXIV. Stellar Equipartition of Energy (Seares). 
Spectral Type 
log M 
log (P 
log MCfl- 
MC 2 
B 3 
0-95 
2-34 
(3*29) 
(1950) 
B 8-5 
0-81 
2-40 
(3-21) 
(1620) 
A 0 
0-78 
2-78 
3-56 
3630 
A 2 
0-70 
2-87 
3-57 
3720 
A 5 
0-60 
2 95 
3-55 
3550 
F 0 
0-40 
311 
3-51 
3240 
F 5 
0-19 
3-36 
3-55 
3550 
eo 
1*99 
3-62 
3-61 
4070 
0 5 
1-88 
3-78 
3*66 
4570 
KO 
1-83 
3-80 
3-63 
4270 
K 5 
1-79 
3-74 
3-53 
3390 
M a 
1-77 
3-78 
3-55 
3550 
Means, excluding B type stars ... 
3-57 
3754 
Excluding P-type stars, which are not included in the mean, we see that 
MG 2 is fairly uniform for all types of stars, its average value being 3754 in 
the units used by Seares, or 7 50 x 10 46 ergs. Putting the mean value of MG 2 
equal to 3/2 H as in formula (2723) we find 
H= 2xl0" 47 (276 2). 
If P is measured in years, and M, M' in terms of the sun’s mass as unity, 
the law of distribution (276T) becomes 
0-28 -g- P-3 
De ( M + M f dP (276*3). 
The exponential factor becomes very large when P is very small. For 
instance, if M, M' , the masses of the two components, are each equal to that 
of the sun, the exponential factor is found to have the following values: 
When P = 1 year the factor = 1’25, 
„ P = 1 month „ „ = 3T7, 
„ P = 4 days „ „ = 86. 
For large values of P the factor approximates to unity, so that the law 
approximates to DdP, shewing that in binaries of long period the steady- 
state distribution is one in which the periods are evenly distributed over all 
values up to P = oo . In binaries of short period the exponential factor gives 
an enormous preponderance of orbits having the shortest periods of all. 
Binaries which have been newly formed by fission have periods of only 
a few days (cf. Table XIX, p. 289). It now appears that the ultimate effect