In astronomy, quenching is a process in which a

galaxy A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. ...

loses cold

gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

, thus strongly suppressing

star formation Star formation is the process by which dense regions within molecular clouds in The "medium" is present further soon.-->interstellar space

, because stars are formed from

Nebulae A nebula ('cloud' or 'fog' in Latin; pl. nebulae, nebulæ or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral or molecular hydrogen and also cosmic dust. Nebulae are often star-forming region ...

and Nebulae (before star formation kickstarts with increasing metallicity) are formed from accumulated Interstellar gas in the Interstellar medium (ISM). Evidence suggests that active

supermassive black holes A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical ob ...

drive the process. One common evolutionary path on the

galaxy color–magnitude diagram The galaxy color–magnitude diagram shows the relationship between absolute magnitude (a measure of luminosity) and mass of galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by g ...

may start with a blue

spiral galaxy Spiral galaxies form a class of galaxy originally described by Edwin Hubble in his 1936 work ''The Realm of the Nebulae''black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...

at its center may start growing rapidly, and somehow start quenching the galaxy, which relatively quickly transitions through the "green valley", ending up more red.

References

Star formation Black holes {{improve categories, date=July 2020