abstract:
The structure and evolution of the spiral arms of our Milky Way are basic but long-standing questions in astronomy. In particular, the lifetime of spiral arms is still a puzzle and has not been well constrained from observations. We used a large catalogue of open clusters in Gaia EDR3 to inspect these issues by analysing the distributions, kinematic properties, vertical distributions, and regressed properties of open clusters. We find evidence that the nearby spiral arms are compatible with a long-lived spiral pattern and might have remained approximately stable for the past 80 million years. In particular, the Local Arm, where our Sun is currently located, is also suggested to be long-lived in nature and probably a major arm segment of the Milky Way. The evolutionary characteristics of nearby spiral arms show that the density wave theory is more consistent with the observational properties of Galactic clusters.
