Arp 58 and Arp 68: two M 51-type systems

ABSTRACT We study two M 51-type systems Arp 68 and 58, which strongly differ by their stellar masses, gas content, environment. Long-slit spectral observations obtained at the Russian 6-m telescope were used to trace distributions of a line-of-sight (LOS) velocity gas-phase oxygen abundance along cuts. Two are compared observed properties. found very strong large-scale non-circular motion in both kpc-size saw-edged profile tidal spiral arm 68, probably caused outflow due feedback. A deep decrease LOS is also ‘hinge’ region where inner transforms into arm, was predicted earlier for galaxies. Local sites star formation satellites with evolutionary models colour–colour diagrams. Unlike galaxy main system experiencing an ongoing burst formation. Gas-phase metallicity estimates show that 58 has higher metal reveals shallow negative radial gradient abundance. The emission noticeably lower than it expected given luminosity this galaxy, may be connected its space position local void.