演講資訊

摘要：

Distances and velocities of coeval groups of objects in our Galaxy -- star-forming regions, OB associations, HII regions and long-period Cepheids -- were recently measured. Within the Lin—Shu density-wave proposal for the galactic spiral structure, we use these new data to find both the geometrical and physical parameters of the wave structure within a few kiloparsecs from the Sun. It is also proposed that better data samples provided by Gaia mission could reveal in the near future whether the wave structure near the Sun reported here does indeed exist.