Planetary nebula luminosity function (PNLF) is a secondary distance indicator used in astronomy. It makes use of the λ5007 forbidden line found in all planetary nebula which are members of the old stellar populations (Population II). It works well for both spiral and elliptical galaxies despite their completely different stellar populations and is part of the Extragalactic Distance Scale.
Read more about Planetary Nebula Luminosity Function: Procedure, Physics Behind Process
Famous quotes containing the words planetary and/or function:
“We cannot cheat on DNA. We cannot get round photosynthesis. We cannot say I am not going to give a damn about phytoplankton. All these tiny mechanisms provide the preconditions of our planetary life. To say we do not care is to say in the most literal sense that “we choose death.””
—Barbara Ward (1914–1981)
“The function of literature, through all its mutations, has been to make us aware of the particularity of selves, and the high authority of the self in its quarrel with its society and its culture. Literature is in that sense subversive.”
—Lionel Trilling (1905–1975)