Аннотация:
Abstract
The spatial distribution of blue stars in M31 is investigated in relation to spiral arms and HII regions of the galaxy. The global pattern of this distribution is determined by two largest concentrations in the arms N4 and S4. Only in the latter arm (near the complexes OB75, 80, 81) there is a stellar age gradient across the arm and this is connected with an unusually large pitch angle for this fragment of the arm. The most probable value of the radius of corotation in M31 is about 15 kpc and certainly larger than 10 kpc.