Author(s)

Jacques P. Vallée

Herzberg Astronomy and Astrophysics, National Research Council of Canada, Victoria, Canada.

From the Sun, a look at the edge of each spiral arm in our Milky Way (seen tangentially, along the line of sight) can yield numerous insights. Using different arm tracers (dust, masers, synchrotron emission, CO gas, open star clusters), we observe here for the first time an age gradient (about 12 ± 2 Myrs/kpc), much as predicted by the density wave theory. This implies that the arm tracers are leaving the dust lane at a relative speed of about 81 ± 10 km/s. We then compare with recent optical data obtained from the Gaia satellite, pertaining to the spiral arms.

Astrophysics, Galaxy, Milky Way, Spiral Arms

Vallée, J. (2021) Arm Tangents and the Spiral Structure of the Milky Way—The Age Gradient. International Journal of Astronomy and Astrophysics, 11, 445-457. doi: 10.4236/ijaa.2021.114022.