Milky Way phase spiral animations

Animations of the Gaia phase spiral in the Milky Way disc

This record contains three animations showing the number density of stars in the Milky Way disc in the Z-V_Z phase plane in a range of azimuthal angles.

Stars in the Z-V_Z phase plane in the Milky Way disc form a spiral pattern, a phase spiral, and the orientation of this spiral depends on the location in the Galaxy of the stars. 

The animations show the phase spiral in a moving 5 degree range going from 210 degrees to 150 degrees in Galactic azimuth, showing an apparent rotation of approximately 90 degrees. The stars are located in the outer part of the MW disc, selected by vertical angular momentum, L_Z. The ranges of angular momentum are 2000-2200, 2200-2400, and 2400-2600 kpc km / s for the low, medium, and high angular momentum animations respectively. The phase spiral pattern is clearest by far in the medium range.

The Sun lays at an azimuthal angle of 180 degrees in this system, and the azimuthal angle is decreasing in the direction of Galactic rotation.