The expanding and cooling shell of gas and dust that is visible for thousands of years after a supernova. After a few tens of thousands of years supernova remnants mix with the interstellar medium and dissipate.
- Black Hole
- Bubble (astronomy) - Text by M. Alan Kazlev
A roughly spheroidal shell of interstellar gas blown outward from a star by a stellar explosion or strong stellar wind. Large bubbles are caused by supernova explosions and contain gas that is much hotter but also much more diffuse (about one atom per cubic cm) than that of the surrunding interstellar medium. These are also called loops.
- Bubble (galactography) - Text by M. Alan Kazlev
The extent to which a starfaring civilization has expanded through interstellar space. Specifically used to refer to those civilizations that colonize and terraform worlds, mine asteroids, planets, and stars, build megastructures, and generally exploit resources and make a big environmental impact wherever they go, like the Terragens (hence - the "Terragen Bubble"), rather than nomads like Meistersingers.
- Gum Nebula
- Local Bubble - Text by M. Alan Kazlev
"Low density" plasma region of space left by former supernova some tens of millions of year ago. Approximately equivalent to the Inner Sphere.
- Neutron Star
- Vela Supernova Remnant