Parameters of the spiral structure of the galaxy from data on δ Cephei stars

We determined the locations of Galactic spiral arm segments for various age groups from the available data on the positions, ages, radial velocities, and proper motions of 440 δ Cephei variables using a previously developed technique. We obtained such parameters of the Galactic spiral structure as the arm pitch angle, [graphic not available: see fulltext], and the pattern speed, ΩP = 21.7 ± 2.8 km s−1 kpc−1, which are comparable to [graphic not available: see fulltext] and ΩP = 20.4 ± 2.5 km s−1 kpc−1, respectively, determined previously from open star clusters. Based on the radial velocities and proper motions of the sample stars, we derived the rotation curve of the Galaxy for the range of Galactocentric distances approximately from 6 to 15 kpc. Using the pattern speed, we determined the positions of the corotation region and the inner and outer Lindblad resonances. We estimated the perturbation amplitudes of the Galactic velocity field, fR = −1.8 ± 2.5 km s−1 and fϑ = +4.0 ± 3.4 km s−1.