Rotational modulation and flares on RS Canum Venaticorum and BY Draconis stars. XIX. Simultaneous IUE, ROSAT, VLA, and visual observations of TY Pyxidis.

In November 1990, we observed the eclipsing binary system TY Pyxidis with the IUE satellite simultaneously with the ROSAT All-Sky Survey. The IUE and ROSAT/WFC observations covered the 3.2-day period of this system continuously, while the ROSAT/PSPC coverage was limited to 2.26days. We also observed TY Pyx with the VLA for a total of 22 hours throughout this period, and we obtained simultaneous visual photometry and spectroscopy. We compare the rotational and eclipse modulation of the ultraviolet line fluxes and line profiles with the x-ray, extreme-ultraviolet, radio, and visual-light variability. We present the multi-wavelength light curves, and we compare the high-resolution Mgiik profiles with the simultaneously obtained CaiiK profiles. Although the visual light curve suggests the presence of large photospheric spots, no rotational modulation is evident in the ultraviolet, x-ray, and radio flux. This suggests that the outer atmosphere is more uniformly covered with magnetic activity than the photosphere. The rare absence of large flux variations permits us to study an RS CVn system with large intrinsic ultraviolet, x-ray, and radio fluxes but without complications introduced by large active regions or flares. Until now, among the extensively monitored RS CVn systems, only the long-period Capella has shown such a constant radiative output.