An abundance analysis of AK Sco, a Herbig Ae SB2 system with a magnetic component

AK Sco is an SB2 system formed by two nearly identical Herbig Ae stars, with Teff = 6500K and log g = 4.5, surrounded by a circumbinary disk. This actively accreting system is of special interest among the pre-main-sequence binaries because of its prominent ultraviolet excess and the high eccentricity of its orbit. Moreover, recent spectropolarimetric observations using HARPSpol indicate the presence of a weak magnetic field in the secondary component (Järvinen et al. 2018). An abundance analysis of both components has shown that all elements have a solar abundance in the two stars, except for Li and Ba. These elements are enhanced by 2.2 and 0.5 dex, respectively, in the A component and by 2.4 and 0.5 dex, respectively, in the B component.

On the Connection Between Galaxies with Ultraviolet Excess

A possible correlation between the characteristic parameters of physically coupled galaxies with ultraviolet excess is discussed. It is known that for mutually independent combinations the observed number of galactic pairs with Markarian components is greater than expected. It is shown, that the most of nearby Kazarian galaxies with ultraviolet excess form physical systems.