THE MASS-LUMINOSITY RELATION 
155 
theory to be tested was put forward. Only two stars in Hertzsprung’s 
list are omitted, viz. the companions of Sirius and Procyon, the former 
because it is a “white dwarf” to which our theory does not apply and the 
latter because the spectrum is unknown and it is impossible to guess what 
corrections may be involved. The bright component of o 2 Eridani which 
is also a white dwarf is for that reason not represented in Fig. 2, although 
(presumably by a cancelling of errors) it happens to agree with the curve. 
Table 19. 
Eclipsing Variables. 
Star 
Gr. 
Type 
T e 
cos i 
Mass 
B/a 
-R(® =1) 
m (bol.) 
m (cale.) 
O-G 
V Puppis 
1 
B 1 
19000 
•274 
19-2 
•417 
7-60 
m 
- 4-61 
m 
- 5-00 
m 
+ 0-4 
YCygni 
3 
B 2 
18000 
•088 
16-6 
•166 
4-60 
- 3-29 
- 4-66 
+ 1-4 
¡3 Lyrae 
2 
B 8 
12500 
•467 
13-9 
•219 
12-09 
- 3-80 
- 3-98 
+ 0-2 
u Herculis 
1 
B 3 
17000 
•268 
7-6 
•290 
4-29 
- 2-89 
- 2-90 
0-0 
U Ophiuchi 
1 
B 9 
11500 
•105 
5-36 
•240 
3-07 
- 0-47 
- 1-69 
+ 1-2 
Z Vulpec. 
2 
B 3 
17000 
•013 
5-24 
•262 
3-94 
- 2-70 
- 1-98 
- 0-7 
RS Vulpec. 
4 
A 0 
10500 
•000 
4-34 
•252 
5-16 
- 1-20 
- 1-05 
- 0-2 
U Coronae 
2 
B 3 
17000 
•148 
4-27 
•167 
2-90 
- 2-04 
- 1-43 
- 0-6 
[3 Aurigae 
1 
A 0 p 
10500 
•228 
2-38 
•158 
2-80 
0-13 
0-77 
- 0-6 
TX Herculis 
3 
A 2 
9800 
•065 
2-04 
•125 
1-33 
2-04 
1-35 
+ 0-7 
TV Cassiop. 
4 
A 0 
10500 
•176 
1-83 
•272 
2-45 
0-34 
1-68 
- 1-3 
Z Herculis 
2 
F 2 
7600 
•139 
1-56 
•117 
1-77 
2-53 
2-55 
0-0 
W Ursae Maj. 
1 
F 8 p 
6200 
•244 
0-74 
•323 
0-70 
5-42 
5-81 
- 0-4 
Table 20. 
Cepheid Variables. 
Star 
Type 
T e 
Period 
Mass 
m (vis.) 
m (bol.) 
m (cale.) 
O-C 
d 
m 
m 
m 
m 
Y Ophiuchi 
G 2 
4800 
17-113 
26-2 
- 4-0 
- 4-21 
- 4-43 
+ 0-22 
rj Aquilae 
G 0 
5100 
7-176 
13-9 
- 2-62 
- 2-76 
- 3-19 
+ 0-43 
S Cephei 
F 9 
5200 
5-366 
11-3 
- 2-19 
- 2-30 
- 2-77 
+ 0-47 
SU Cassiop. 
F 5 
6000 
1-950 
6-82 
- 1-2 
- 1-20 
- 1-74 
+ 0-54 
RR Lyrae 
A 9 
7300 
0-567 
4-14 
- 0-35 
- 0-36 
- 0-61 
+ 0-25 
The star 80 Tauri omitted here is included in the fuller discussion of the 
Hyades which follows. The parallax given by Hertzsprung for /3 Aurigae 
depends on the probable assumption that it is a member of the Ursa 
Major stream, but since it is near the stream apex the probable error is 
rather large. 
The stars 8 Equulei and e Hydrae have been added*. Their parallaxes 
are obtained by a comparison of the visual and spectroscopic orbits 
* Aitken, The Binary Stars, p. 209.