Determining the parameters of the spiral arms of the Galaxy from kinematic tracers based on Gaia DR3 data

Abstract

ABSTRACT We present the results of determining the parameters of the spiral arms of the Galaxy using the stars Gaia DR3, whose absolute magnitude is MG < 4, and which allow tracing spiral arms at large distances from the Sun. As tracers of spiral arms, we use the centroids of stellar spherical regions with a radius of 0.5 kpc, in which the deformation velocities along the coordinate axis R are insignificant. These kinematic tracers cover the Galactic plane within the Galactocentric coordinate ranges 140° < θ < 220° and 4 kpc < R < 14 kpc. The numerical values of the pitch angles of the spirals and their Galactocentric distances to the point of intersection of the spiral with the direction of the Galactic Centre and the Sun are in good agreement with the results of other authors. By extrapolating beyond the data we have, we present a schematic four-arm global pattern, consisting of the Scutum–Centaurus, Sagittarius–Carina, Perseus, Norma-Outer arms, as well as the local arm Orion. The uncertainties of the determined spiral parameters confirm that the structures identified are not false, but are reliable from the statistical point of view.