Emission sparks around M 81 and in some dwarf spheroidal galaxies

Abstract

We use Hα images of three clumps of young stars situated between M 81 and NGC 3077 to estimate their star formation rate. Radial velocities of the clumps measured by us, as well as the velocity of the H II region in the dwarf spheroidal (dSph) galaxy KDG 61, are compatible with their location at the outskirts of a large rotating gaseous disc around M 81. In contrast to KDG 61, the radial velocity of the emission knot in the dSph galaxy DDO 44, +213 ± 25 km s^-1, tells us that this Hα spark belongs to the dSph galaxy itself. F475W and F814W images of DDO 44 extracted from the Hubble Space Telescope archive reveal eight bluish (B - I < 0.8) stars apparently associated with the Hα knot.