THE VARIABLE STARS TV, TW, TX CASSIOPEIA AND 

 T LEONIS MINORIS. 



By R. J. McDIARMID. 



(Read April 24, 19 15.) 



The four Algol variable stars TV, TW , TX Cassiopeise and T 

 Leonis Minoris have been under observation by the writer for the 

 last three years with the polarizing photometer attached to the 

 23-inch equatorial of the Princeton Observatory. 



The total number of measures made on the four systems is over 

 35,000, distributed among the four stars as follows, TV 9,920, 

 TW 12)^7 ~^' ^^ 8,486 and T Leonis 3,792. The light curves of the 

 first three are well defined, while the observations on the last system 

 are not so complete. The periods of the light variation with the 

 exception of TV Cass, have been determined from my visual ob- 

 servations combined with photographic measures kindly sent me by 

 Professor Pickering, of Harvard. 



The systems will be discussed in slightly different order than 

 the above, the more important left to the last. 



The system TW Cass, has been observed by other astronomers, 

 and notes published pronounced it as irregular in its variation, later 

 Zinner found it regular in its variation and of the Algol type with 

 a period i'' 10'' 16.6°". From the discussion of the Princeton ob- 

 servations I found that the period was double the published period 

 and instead of one eclipse there were two differing by 0.05 magni- 

 tude. The double period is confirmed by the three observed phe- 

 nomena, 1st, the difference in depth of the two minima of 0.05 mg. ; 

 2d, the interval from primary eclipse to secondary is 7.8 minutes 

 longer than from secondary to the following primary; 3d, the 

 primary eclipse is 36 minutes longer in duration than the secondary. 

 It is from the knowledge of the last two facts that we are able to 

 determine both components of the eccentricity — the quantities e and 



(longitude of periastron). The period is 2 days, 20 hours, and 



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