TITLE:
Arm Tangents and the Spiral Structure of the Milky Way—The Age Gradient
AUTHORS:
Jacques P. Vallée
KEYWORDS:
Astrophysics, Galaxy, Milky Way, Spiral Arms
JOURNAL NAME:
International Journal of Astronomy and Astrophysics,
Vol.11 No.4,
October
27,
2021
ABSTRACT: 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.