The SSPSF model of star formation was proposed by Mueller & Arnett in 1976, generalized afterward by Gerola & Seiden in 1978 and Gerola, Seiden, & Schulman in 1980. This model proposes that star formation propagates via the action of shock waves produced by stellar wind

Stellar wind

A stellar wind is a flow of neutral or charged gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric.Different types of stars have...

s and supernovae that compose the interstellar medium

Interstellar medium

In astronomy, the interstellar medium is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, dust, and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space...

.

SSPSF processes were demonstrated in an early prototype ("Gaslight") of the 2008 video game Spore

Spore (2008 video game)

Spore is a multi-genre single-player god game developed by Maxis and designed by Will Wright. The game was released for the Microsoft Windows and Macintosh operating systems in September 2008 as Spore...

.