2022RNAAS...6...22M

Twenty-four spectra of 52 Her (A1p SiSrCr) obtained through the large apertures of the SWP and LWP cameras on board International Ultraviolet Explorer are compared to look for variations of the absolute flux over the spectral range 1200-3000 Å. Large variations of the spectral energy distribution occur in the far-ultraviolet shortwards of 2000 Å. In contrast, the flux at wavelengths larger than 2000 Å does not vary but several lines are variable between phases of FUV maximum and FUV minimum. The large FUV variability is probably caused by changes in the continuous and line opacity driven by modest horizontal gradients of the abundances of chemical elements over the surface of 52 Her. The TESS lightcurve of 52 Her is slightly asymetric and has a period close to 3.83 days.