Emission line variability of RS Ophiuchi ⋆

We report that the Hα emission line of RS Oph was strongly variable during our 2004 observations on a time scale of 1 month. The line consisted of both a double peaked central narrow component (FWHM∼220 km s) and a strongly variable broad one (FWHM>2000 km s). The base of the Hα line was very broad with FWZI≈4600 km s on all spectra from 1986 to 2004. The variability of the broad component extends from −2000 to +2000 km s. Most probably this is due to either blobs ejected from the white dwarf (with a typical blob mass estimated to be ∼10 M⊙) or a variable accretion disk wind. We also detected variability of the HeIIλ4686 line on a time scale shorter than 1 day. The possible origin is discussed.