A period study for RZ Cassiopeiae.
Abstract
The paper investigates how well the period variations of RZ Cas can be explained by the BiermannHall (1973) periodchange model. According to this model, a dynamical instability causes a sudden mass outflow from the cooler star, which fills its Roche lobe, the period decreases because angular momentum is taken from the orbit and stored temporarily as rotation in or around the hotter star, and the period subsequently increases as the rotating mass becomes synchronized and angular momentum is returned to the orbit on a friction time scale. A total of 72 weighted normal OC values and their residuals are used to construct an OC curve for the period between 1897 and 1970; this curve is then represented by 10 upwardcurving parabolic segments. Analysis of these segments shows that the average interval separating period decreases is 6.7 years, although this value is not constant. The amount of mass lost by the cooler star during each decrease is computed to be 6.5 millionths of a solar mass, and the average massloss rate is estimated to be 1 millionth of a solar mass per year, which equals the thermal rate for RZ Cas.
 Publication:

Acta Astronomica
 Pub Date:
 1976
 Bibcode:
 1976AcA....26..239H
 Keywords:

 Binary Stars;
 Stellar Mass Ejection;
 Stellar Models;
 Stellar Rotation;
 Variable Stars;
 Angular Momentum;
 Ephemerides;
 Mass Transfer;
 Periodic Variations;
 Astrophysics