A Spectrographic Study of the Eclipsing Binary RZ Scuti.

Observations consisting of 72 spectrograms obtained with the 100-inch telescope at the Mount Wilson Observatory were analyzed for radial velocities, equivalent widths, and line profiles. Analysis of lineprofile changes in the He lines and measurements of changes in the central intensities of the H lines reveal that considerable absorption takes place in gas streams which surround the system. Measurements of the amount that the cores of the He lines are shifted make possible a corrected velocity-curve, and this corrected curve gives the orbital elements K = 36.5 km/sec, = -14.5 km/sec, a sin i = 7620000 km, andJ(m) = 0.0766 Q The range of the observed velocity-curve is less for the Ha line than for the average of the H lines or for the He lines. Doubling of the H lines is observed during eclipse. The range of the rotational disturbance is 325 km/sec. Rotational-velocity measurements made from the profiles of four different He lines indicate that there is differential rotation in the atmosphere of the B2 star, with the smaller rotational velocities being observed at higher levels. The maximum rotational velocity (V sin i) measured by this method is 250 km/sec. Computing the masses by assuming the primary star to be on the main sequence results in dimensions for the secondary star that put it beyond its Roche limit. Similar computations from the assumption that the secondary star just fills this limit result in a very small mass for the primary star. Comparison of the contradictions involved in the two results gives some insight into the probable masses of the components of the system. Rotational breakup considerations indicate that the mass of the primary star is probably greater than 2.0 0. A schematic model of the gas streams which surround the system is developed from the observations. The spectrum of the secondary star was not detected.