Figure 16. Parameter ρ changes with time for M51 galaxy (Rotation angle of the galactic bar (in degree), (Equivalent to the time scale from the past to current))

From

New Formulas and Mechanism for the Spiral Arm Formation of Galaxies

Hongjun Pan

International Journal of Physics. 2019, 7(3), 73-85 doi:10.12691/ijp-7-3-2