Browsing by Author "MENNICKENT, R"

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    A SPECTROSCOPIC AND PHOTOMETRIC-STUDY OF THE LONG CYCLE DWARF NOVA WX CETI IN QUIESCENCE
    (1994) MENNICKENT, R
    We present non-simultaneous time resolved differential photometry and spectroscopy in the lambda5800-7000 angstrom wavelength range of WX Cet in quiescence. From the radial velocities of the Halpha emission lines, a most probable orbital period of 79.16 +/- 0.04 minutes is derived, but another of 83.81 minutes cannot be completely ruled out. The K semiamplitude of the radial velocity curves constrains the mass ratio to q greater than or similar to 0.11. Large variations in equivalent widths of Halpha, He lambda5875 angstrom, He lambda6678 angstrom and He lambda7065 angstrom are not phase dependent. The photometric observations reveal random variability and spikes on time scales T is similar to 0.5 P(orbital). An enhanced emission region 15 % brighter than the disk and located exactly opposite to the hot spot expected by the standard model is consistent with the V/R variations. An empirical relation was found between the mass ratio (q) and the orbital phase of maximal strength of the violet compared to the red peak in the double Halpha profile of SU UMa and U Gem subtype dwarf novae. The hot spot region seems to migrate towards the back side of the disk in low q systems. This ''hot spot reversed'' phenomenon could be explained by a gas stream which passes above the disk and hits its back side or alternatively, by disk thickenings in some resonating locations.
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    EVIDENCE FOR ELLIPSOIDAL VARIATIONS OF THE BE-STAR BINARY HD-50123
    (1994) STERKEN, C; VOGT, N; MENNICKENT, R
    On the basis of 8 years of photoelectric monitoring in the Stromgren system we were able to establish that HD 50123 is an interacting binary consisting of a B6 Ve primary and an early K giant secondary which fills its Roche lobe. The orbital period is 28.601 days. The secondary contributes considerably to the flux in the y and b bands, in which the double-sinusoidal light curve typical for ellipsoidal variables is seen. A few published radial velocities of the primary are consistent with a semiamplitude of K-1 = 25 +/- 6 km s(-1), and a mass function f(M) = 0.046 +/- 0.026 M.. Preliminary estimates of the stellar masses give 5 and 1.5 M., respectively, for primary and secondary. Some implications for the binary interpretation of Be stars, as well as for the period distribution of ellipsoidal variables, are discussed.