Photopolarimetric activity of the Ae Herbig star SV Cep

Abstract

We present the results of simultaneous UBVRI photometric and polarimetric observations of the Ae Herbig star SV Cep made in 1987–1998. Over these 11 years, only a single deep (ΔV>1m) brightness minimum was observed. Near this minimum, the brightness decrease was accompanied by an increase of the linear polarization, as is typical of young UX Ori stars. The photometric observations of SV Cep indicate reversals of the color tracks in brightness minima, as is common for stars of this type, as well as variations of the slopes of the color tracks during and after minima. This provides evidence that the circumstellar dust clouds screening the star differ in their sizes and masses, and also in the optical properties of their dust particles. A Fourier analysis of the brightness variations of SV Cep (including data from the literature) confirms the presence of previously suspected activity cycles with periods P1=4000d and P2=670d The polarimetric observations indicate that, along with the inverse correlation between the degree of linear polarization and brightness, the polarization parameters vary on characteristic time scales of 4000 and 1000 days. This suggests the existence of large-scale inhomogeneities in the circumstellar dust disk rotating about the star.