Morphological classification of galaxies

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The morphological classification of galaxies is a system used by astronomers to classify galaxies into groups based on their visual appearance. Different methods are used for this, the best known of which is the Hubble sequence .

Procedures used

  • Hubble Sequence : A system introduced by Edwin Hubble in 1926 . Colloquially it is often called "Hubble tuning fork" (English for "Hubble tuning fork") because of its traditional form of representation . It divides galaxies into three classes based on their appearance (elliptical galaxies, spiral galaxies, and lenticular galaxies) .
  • De Vaucouleurs System : A system often used as an extension of the Hubble sequence. Introduced in 1959 by Gérard-Henri de Vancouleurs , it describes the galaxies according to the properties of the spiral arms, as well as the presence of rings and bar-shaped cores.
  • Yerkes / Morgan system : Together with Philip Keenan , William Wilson Morgan developed the MK system , which is used to classify stars using their light spectrum . The Yerkes scheme transfers this to the spectra of all stars in a galaxy. The real and visible shape and the central star density of a galaxy are used as further criteria for classification.

Individual evidence

  1. ↑ information@eso.org: A remarkable galactic hybrid. Retrieved May 5, 2017 (UK English).
  2. ↑ Classification of galaxies: the Hubble sequence. Retrieved May 6, 2017 .
  3. ↑ galaxy - Types of galaxies | astronomy . In: Encyclopedia Britannica . ( britannica.com [accessed May 5, 2017]).
  4. ^ The Morgan – Keenan System | StarParty.com. Retrieved May 5, 2017 (UK English).