Tidal Stream

Tidal Stream shows a spiral galaxy slowly eating its neighbours. Up to three dwarf galaxies orbit a large spiral; on every pass its gravity pulls stars off them into long glowing arcs, shells and rings that wrap around the host.

How it works

The stars of each dwarf galaxy are simulated one by one as they orbit through the host's gravity, which is what tears them into leading and trailing tails. The host's arms form the way real spiral arms do, as a wave in which stars crowd together and spread out again as they orbit. Every star glows at a colour set by its temperature, and stars moving toward the camera shift blue while those moving away shift red.

Settings

• Satellite Count and Satellite Mass: how many dwarfs are being torn apart, and how long they hold on to their stars.
• Orbit Eccentricity: how stretched the main dwarf's orbit is.
• Disc Stars and Arm Count: the size of the host galaxy and its number of arms.
• Doppler Scale, Color and Redshift Color: how strong the colour shift is, and its two tints.
• Nebula Color: the glowing gas along the arms.

The cursor can be a dark-matter clump that carves gaps in the streams, a spinning black hole, or a spectroscope loupe that magnifies the sky and exaggerates the colour shift.

Use it for

Space and astronomy scenes, science stories and cosmic hero backgrounds. See also the Galaxy and Black Hole effects.