The spiral pattern rotation speed of the Galaxy and the corotation radius with Gaia DR2

• Published in: Monthly notices of the Royal Astronomical Society Vol. 486; no. 4; pp. 5726 - 5736
• Main Authors: Dias, W S, Monteiro, H, Lépine, J R D, Barros, D A
• Format: Journal Article
• Language: English
• Published: Oxford University Press 01-07-2019
• Subjects: Galaxy: structure; Galaxy: kinematics and dynamics
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stz1196

ABSTRACT
In this work we revisit the issue of the rotation speed of the spiral arms and the location of the corotation radius of our Galaxy. This research was performed using homogeneous data set of young open clusters (age < 50 Myr) determined from Gaia Data Release 2 (DR2) data. The stellar astrometric membership was determined using proper motions and parallaxes, taking into account the full covariance matrix. The distance, age, reddening, and metallicity of the clusters were determined by our non-subjective multidimensional global optimization tool to fit theoretical isochrones to Gaia DR2 photometric data. The rotation speed of the arms is obtained from the relation between age and angular distance of the birthplace of the clusters to the present-day position of the arms. Using the clusters belonging to the Sagittarius–Carina, Local, and Perseus arms, and adopting the Galactic parameters R0 = 8.3 kpc and V0 = 240 km s−1, we determine a pattern speed of 28.2 ± 2.1 km s−1 kpc−1, with no difference between the arms. This implies that the corotation radius is Rc = 8.51 ± 0.64 kpc, close to the solar Galactic orbit (Rc/R0 = 1.02 ± 0.07).