Abstract:
We use the largest catalog of open clusters in the post-Gaia era to provide an observational view of the Galactic
disk. By compiling physical parameters such as age, distance, and kinematic information, we investigate the spatial
distribution of open clusters and revisit the spiral arms and other asymmetries in the Galactic disk. Using young
open clusters as a tracer of spiral arms, we map the spiral structure of the Galaxy and find that most of the clusters
start migrating away from the spiral arms in about 10–20 Myr and fill the interarm regions as they age. Using the
3D kinematic information on 371 open star clusters, we derive different individual pattern speeds for spiral arms
that closely follow the rotation curve of the Milky Way, hence favoring the transient nature of spiral arms in the
Milky Way. The pattern rotation speeds of each spiral arm suggest that the spiral arms have not accelerated in the
last 80 Myr. Based on the distribution of open clusters younger than 700 Myr above or below the Galactic plane,
we found a solar offset of ze = 17.0 ± 0.9 pc north of the Galactic plane and estimated the scale height
zh = 91.7 ± 1.9 pc from the Galactic plane.
