The 6^438 RS CVn-type binary UX Ari was observed photoelectrically on 17 nights from October 1979 through February 1980. The observations were made with a pair of narrow-and intermediate-band interference filters centered near the wavelength of the Balmer Ha line. An a index was formed from the data yielding a measure of the net Ha line strength. The light curve formed from the À6585 intermediate-band data is well defined and has an amplitude of about 0^04 with minimum light occurring near 0.87 phase computed with the ephemeris given by Hall, Montle, and Atkins. The value of the a index indicates the presence of Ha emission at all orbital phases with a possible weak correlation of Ha emission strength with phase. A study of all available photometry of the system reveals significant changes in the light amplitude and mean light level as well as changes in the phase at which light minimum occurs. The observed variations can be attributed to changes in both the area covered by star spots and in their location on the surface of the active member of the system.
The kinematics and statistics of the updated sample of C 2 (X4670) stars are examined. A blanketing correction for weak-to moderate-band strength C 2 stars is estimated based upon C 2 parallax stars. Space motions are calculated for the entire C 2 sample. A production rate for C 2 stars as a group is derived and compared with estimated production rates for carbon-rich, hydrogen-poor stars at higher luminosity. We conclude that C 2 white dwarfs cannot be linked exclusively with carbon-rich hydrogen-deficient giants as progenitors.The C 2 stars represent 7% of all white dwarfs in their observed absolute magnitude interval. Thus, the present number ratio of non-DA white dwarfs to DA white dwarfs implies that one out of six DB stars should be hotter versions of the À4670 stars.
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