ON APIOIDAL BINARY STAR-SYSTEMS, 253 
TIL. Particular Stars, 
There are eight systems—four in the northern and four in the southern 
sky—known with certainty to belong to the apioidal class of variable 
stars. The light-changes of six of these, all typical stars, have been 
determined with some accuracy. The six stars are :— 
No. Star Position 1900 Variation Period | 
= / 
H, M. Ss. 2 , M. M. D,” Baye Me. | Set 
2852 V Puppis 7 5d 22) —48 58:4 | 4:7-5-3 110), 527) 27 
3055 X Carine 8 29 7] —58 53:2 | 7:9-87 isl (69%, 0) 
5099 RR. Centauri 1S oe bb | — "57 23*3) | 7-4—7:8 OQ 14 32aRit / 
6758 B Lyre 18 46 23] +33 14:8 | 35-46 ]12 21 59 10 
7394 V Vulpecule 20 32 17] +26 15:4) 82-98|75 0 0 O 
8598 U Pegasi 23 52 53} +15 23:9 | 9:3-9°9 OF °S. 59) ai / 
The light-curve of each of the above stars is given in the appendix to 
this paper. During the past two years I have been occupied in carrying 
out a rigorous investigation of these curves, and it may be of interest to 
state briefly the results already arrived at. Under the second part of 
the appendix to this paper the more precise numerical values will be 
given, 
V Tuppis (ch, 2852), 
The variation of this star was discovered by Williams! in 1886 and 
its duplicity by Pickering in 1896.2 It has been under observation at 
Lovedale since 1891. An examination of its light-curve indicates a 
slightly elliptical orbit, but spectroscopic observations do not as yet con- 
firm this. i 
The component stars, which are apparently equal in size, but slightly 
unequal in brightness, do not quite touch one another. A gap equal to 
the tenth part of either of their diameters divides them. 
When fission in this very interesting system took place it is impossible 
to say; but reasoning from the analogy of / Lyre, the birthday of 
V Puppis is but in the yesterdays of astronomical time. Probably 
400,000 years is an outside limit for its age as two separate stars. 
Both stars are considerably flattened; and there is evidence in the 
light-curve, of great tidal pulsations due to the slightly eccentric orbit of 
the system. 
Each component of V Puppis measures 16,000,000 miles? along its 
greatest diameter ; the total mass of the system is equal to 310 suns ; the 
density, however, is only 0-02, that is, the stars are two vast gaseous 
masses. 
X Carine (ch, 3055), 
The variation of this star was discovered at Lovedale twelve years 
ago. It is too faint to come within spectroscopic range. 
The mean light-curve indicates that X Carine is composed of two 
stars, almost equal in size and brightness, moving round each other, 
practically in contact, in an orbit only slightly eccentric. 
1 Astronomische Nahrichten, No. 3410. 
2 Harvard Circular, No. 21. 
8 Harvard Annals, vol. xxviii., pt. 2, p. 177. 
