H-alpha photometry of UX ARIETIS during 1979-80

Abstract

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.

RS CVn STARS: Photospheric Phenomena and Rotation

“…Generally the curve is strikingly asymmetric, the rise and decline having markedly different slopes, while the median brightness is now secularly decreasing (Rodono et al 1982). A similar decline was observed between I9I+0 and 1950 (Hartmann et al 1979)-UX Ari (P=6.U38 days) in less than ten years (1972)(1973)(1974)(1975)(1976)(1977)(1978)(1979)(1980) has shown alternate periods of small and large amplitudes of the wave (Guinan et al 1981). The largest amplitude values observed till now occurred when the system was at the maximum and the minimum of its median brightness.…”

Bluer colour of UX Arietis at fainter visual magnitudes

“…The differential V magnitudes given in Table 1 are plotted in Fig. 1 along with those compiled by Ulvas & Henry (2003), which in addition to their own data, include those obtained by Hall et al (1975), Hall (1977), Landis et al (1978), Guinan et al (1981), Sarma & Prakasa Rao (1984), Mohin & Raveendran (1989), Strassmeier et al (1989), Raveendran & Mohin (1995) and Padmakar & Pandey (1996). The previously reported observations indicated a fairly smooth variation for the mean V magnitude of UX Ari with a period around 25 years (Ulvas & Henry 2003).…”

BVphotometry of UX Ari in the period 1987–2002

“…Their light curve had an amplitude ∆V ≈ 0.1 mag and a period of 6.43791 d (determined spectroscopically by Carlos & Popper 1971). Since then, photometric observations have been presented by several authors (Hall 1977;Landis et al 1978;Weiler et al 1978;Guinan et al 1981;Zeilik et al 1982;Sarma & Prakasa Rao 1983, 1984Poe & Eaton 1985;Busso et al 1986;Wacker & Guinan 1987;Mohin & Raveendran 1989;Strassmeier et al 1989;Nelson & Zeilik 1990;Rodonò & Cutispoto 1992;Elias et al 1995;Raveendran & Mohin 1995;Ak et al 1996;Padmakar & Pandey 1996ESA 1997;Fabricius & Makarov 2000).…”