Planetary Nebula Luminosity Function

The Planetary Nebula Luminosity Function ( PNLF short, German translation luminosity function Planetary Nebula ) is a method of astronomy for distance determination of galaxies. It is based on a universal luminosity distribution of planetary nebulae in the region of the forbidden emission line [ OIII ]. With the help of the PNLF can be determined with current technology Distances up to 25 Megaparcec with an accuracy of 10 percent.

Most of the stars with an initial mass of one to eight solar masses through a phase as a planetary nebula before they evolve into a white dwarf. During this time, the fog can be very effective to implement the UV radiation of the post-AGB star in optical radiation. Here, the UV radiation in the [ OIII ] emission line radiated at a wavelength of 5007 angstroms up to 15 percent.

To determine the luminosity function of planetary nebulae of a galaxy, the galaxy is taken with a filter schmallbandigen to 5007 angstroms. The continuum of the galaxy is taken over with a broad-band filter and all sources that can be detected in the narrow-band filters and in the continuum below the detection limit are candidates for planetary nebulae. The candidate may also be a matter of H II regions, supernova remnants or lying in the background Lyman-alpha galaxies. These objects are also strong in the field emitter of the other lines and can thus be excluded. As a last step, the extinction within the Milky Way and the Galaxy has yet to be eliminated.

The distribution of the brightness of the planetary nebulae and their maximum brightness is universal and not dependent on the type of galaxy, the metallicity or the age of the star. Independence from the metallicity arises in that in a lower oxygen content, the electron temperature of the plasma is increased due to lack of cooling and this results in an increased collision rate of ions. This compensates approximately the lower density of the fog. The physics behind the age independence of the PNLF is not understood, however, as older stars produce white dwarfs with a lower mass and lower UV luminosity.

Within a distance of 25 megaparsecs the PNLF achieves an accuracy of 10 percent. If only the maximum brightness planetary nebulae considered, the method can also be extended up to distances of 80 to 100 megaparsecs, with the error but more than doubled. Opposite the Surface Brightness Fluctuation method, the Planetary Nebula Luminosity Function provides a systematic ten percent greater distance.

Cite

  • Magda Arnaboldi, Alessia Longobardi, Ortwin Gerhard, S. Okamura: The Planetary Nebulae Luminosity Function and distances to the Virgo, Hydra I and Coma clusters. In: Astrophysics. Solar and Stellar Astrophysics. 2012, arXiv: 1212.0652v1.
  • Robin Ciardullo: The Planetary Nebula Luminosity Function: Pieces of the Puzzle. In: Astrophysics. Solar and Stellar Astrophysics. 2009, arXiv: 0909.4356v1.
  • Observation method of Astronomy
Asymptotic giant branch Extinction (astronomy)
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