Planetary nebula luminosity function: Difference between revisions

Revision as of 17:09, 18 September 2007

Revision as of 17:09, 18 September 2007

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== History and background ==

Starting with the time of [[Edwin Hubble]], the brightest stars have been employed as [[Extragalactic astronomy|extragalactic]] distance indicators. However, it was not until the early 1960s that planetary nebula (PNe) were recognized as being some of the “brightest stars” and consequently useful as extragalactic distance indicators. During the early stages of their evolution, a planetary nebula's luminosity is on par with their [[asymptotic giant branch]] (AGB) ancestors. Even though most of their continuum [[Emission (electromagnetic radiation)|emission]] emerges in the [[far-ultraviolet]], rather than the [[visible light|optical]] or [[near infrared]], their detectability is not hampered. In fact, since most of the [[central star|central star's]] [[flux]] is emitted at energies below 13.6 [[electron volt|eV]], the [[photoionization]] physics ensures that their energy is transformed into a series of optical, [[infrared]], and [[near-ultraviolet|near-UV]] [[emission line]]s. Fortuitously, approximately 10% of the flux emitted by a young PNe is in the one emission line of [[doubly-ionized oxygen]] at 5007 [[Ångström|Å]]. Therefore, for the purposes of [[cosmology]], a PNe may be thought of a cosmic machine that turns continuum emission into monochromatic [[flux]].

EAT MY PENIS!!!!!!!!!!!!!!!!!!!!!1

<ref name="Ciardullo2003">{{harvnb|Ciardullo|2003}}</ref>