Re-determining the parameters of the Galactic spiral density wave from data on masers with trigonometric parallaxes
Abstract
The parameters of the Galactic spiral wave are re-determined using a modified periodogram (spectral) analysis of the galactocentric radial velocities of 58 masers with known trigonometric parallaxes, proper motions, and line-of-site velocities. The masers span a wide range of galactocentric distances, 3 < R < 14 kpc, which, combined with a large scatter of position angles θ of these objects in the Galactic plane required an accurate account of logarithmic dependence of spiral-wave perturbations on both the galactocentric distance and position angle. A periodic signal was detected corresponding to a spiral density wave with wavelength of λ = 2.4 ± 0.4 kpc, peak velocity of wave perturbations of fR = 7.5 ± 1.5 km s–1, phase of the Sun of χ⊙ = –160 ± 15°, and pitch angle of –5.5 ± 1°. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
