Hα Luminosity Function Of H II Regions: Preliminary Calibration of a Powerful Standard Candle

  • Maite Rozas
  • Andrew Cardwell
  • Almudena Zurita
  • John E. Beckman
Conference paper
Part of the Astrophysics and Space Science Library book series (ASSL, volume 274)


We propose the use of the H II region luminosity function (LF) as a refined powerful standard candle for extragalactic distances. We have found evidence of a change in the properties of H II regions in spirals at a fixed luminosity in Hα which we term the Strömgren luminosity (L = 3.39 1038 erg s-1). The key piece of evidence is the presence in the Hα H II region LF of a change in gradient and a local sharp peak. The invariance and high luminosity of the change measured in the LF was proposed in previous studies as a possible secondary standard candle, but it is calibrated here for the first time using the LFs of NGC 925, NGC 4535 and M100, whose Cepheid distances have been determined in the HST Extragalactic Distance Scale Key Project. Using this method we derive a value of H 0 of 73±7 km s-1 Mpc-1.


Cosmic Microwave Background Luminosity Function Planetary Nebula Galactic Rotation Standard Candle 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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Copyright information

© Springer Science+Business Media Dordrecht 2002

Authors and Affiliations

  • Maite Rozas
    • 1
  • Andrew Cardwell
    • 2
  • Almudena Zurita
    • 3
  • John E. Beckman
    • 4
  1. 1.Observatorio de San Pedro MártirMéxico and Instituto de Astrofísica de CanariasSpain
  2. 2.Instituto de Astrofísica de CanariasSpain and The Open UniversityUnited Kingdom
  3. 3.Isaac Newton Group of TelescopesLa Palma, Spain and Instituto de Astrofísica de CanariasSpain
  4. 4.Instituto de Astrofísica de Canarias, Spain and CSICSpain

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