Black Hole
Spiraling gas and distant stars round a black hole, with the disk bent over its shadow by gravity, after Luminet's 1979 picture.
Pens
Stars get the first pen of their own from two pens up. The rest follow the redshift, from the side of the disk coming towards you to the side going away, with disk line lengths balanced between them. Starts with 3 pens and works with anywhere from 1 to 8.
Settings
Inclination (°), Tilt (°), Disk pattern, Flow strength, Winding (turns), Outer radius, Rings, Underside image, Photon ring, Shade by brightness, Contrast, Redshift contours, Finest spacing (mm), Stars.
The preview uses the default settings on A4. Press R in the app for random variations. The SVG export is in millimeters with one Inkscape layer per pen, so it works with the AxiDraw extension, vpype and saxi.