Outline of galaxies
Template:SHORTDESC: The following outline is provided as an overview of and topical guide to galaxies:
Galaxies – gravitationally bound systems of stars, stellar remnants, interstellar gas, dust, and dark matter. The word galaxy is derived from the Greek galaxias (γαλαξίας), literally "milky", a reference to the Milky Way. Galaxies range in size from dwarfs with just a few billion (109) stars to giants with one hundred trillion (1014) stars, each orbiting its galaxy's center of mass. Galaxies are categorized according to their visual morphology as elliptical, spiral and irregular. Many galaxies are thought to have black holes at their active centers.
The Milky Way's central black hole, known as Sagittarius A*, has a mass four million times greater than the Sun. As of March 2016, GN-z11 is the oldest and most distant observed galaxy with a comoving distance of 32 billion light-years from Earth, and observed as it existed just 400 million years after the Big Bang. Previously, as of July 2015, EGSY8p7 was the most distant known galaxy, estimated to have a light travel distance of 13.2 billion light-years away.
Types of galaxies
[edit | edit source]By morphological classification
[edit | edit source]Galaxy morphological classification
- Disc galaxy
- Spiral galaxy (list)
- Dwarf galaxy
- Elliptical galaxy
- Irregular galaxy
- Peculiar galaxy
- Ring galaxy (list)
By nucleus
[edit | edit source]- Blazar
- Low-ionization nuclear emission-line region
- Markarian galaxies
- Quasar
- Radio galaxy
- Relativistic jet
- Seyfert galaxy
By emissions
[edit | edit source]- Energetic galaxies
- Low activity
By interaction
[edit | edit source]- Field galaxy
- Galactic tide
- Galaxy cloud
- Interacting galaxy
- Jellyfish galaxy
- Satellite galaxy
- Stellar kinematics § Stellar streams
- Superclusters
- Galaxy filament
- Void galaxy
By other aspect
[edit | edit source]Nature of galaxies
[edit | edit source]Galactic phenomena
[edit | edit source]- Galactic year – duration of time required for the Sun to orbit once around the center of the Milky Way Galaxy.[1]
- Galaxy formation and evolution
- Galaxy merger
- Hubble's law
Galaxy components
[edit | edit source]- Components of galaxies in general
- Structure of specific galaxies
- Milky Way components
- Galactic Center
- Galactic quadrant
- Spiral arms of the Milky Way
- Galactic ridge
- Milky Way components
Galactic cartography
[edit | edit source]Larger constructs composed of galaxies
[edit | edit source]- Galaxy groups and clusters (list)
- Local Group – galaxy group that includes the Milky Way
- Galaxy group
- Galaxy cluster
- Brightest cluster galaxy
- Fossil galaxy group
- Galaxy filament
Intergalactic phenomena
[edit | edit source]- Galactic orientation
- Galaxy merger
- Hypothetical intergalactic phenomena
- Intergalactic dust
- Intergalactic stars
- Void (list)
Fields that study galaxies
[edit | edit source]- Astronomy
- Galactic astronomy – studies the Milky Way galaxy.
- Extragalactic astronomy – studies everything outside the Milky Way galaxy, including other galaxies.
- Astrophysics
- Cosmology
Galaxy-related publications
[edit | edit source]Galaxy catalogs
[edit | edit source]- Atlas of Peculiar Galaxies
- Catalogue of Galaxies and Clusters of Galaxies
- David Dunlap Observatory Catalogue
- Lyon-Meudon Extragalactic Database
- Morphological Catalogue of Galaxies
- Multiwavelength Atlas of Galaxies
- Principal Galaxies Catalogue
- Shapley-Ames Catalog
- Uppsala General Catalogue
- Vorontsov-Vel'yaminov Interacting Galaxies
Persons influential in the study of galaxies
[edit | edit source]- Galileo Galilei – discovered that the Milky Way is composed of a huge number of faint stars.[2][3]
- Edwin Hubble
See also
[edit | edit source]- Barred spiral galaxy
- Galaxy color–magnitude diagram
- Dark galaxy
- Faint blue galaxy
- Galaxy color–magnitude diagram
- Illustris project
- Protogalaxy
- Metallicity § Stars
- Large quasar group § List of LQGs
- List of quasars
References
[edit | edit source]- ^ Cosmic Year Archived 2014-04-12 at the Wayback Machine, Fact Guru, University of Ottawa
- ^ Galileo Galilei, Sidereus Nuncius (Venice, (Italy): Thomas Baglioni, 1610), pages 15 and 16. English translation: Galileo Galilei with Edward Stafford Carlos, trans., The Sidereal Messenger (London, England: Rivingtons, 1880), pages 42 and 43.
- ^ Lua error in Module:Citation/CS1/Configuration at line 2172: attempt to index field '?' (a nil value).
External links
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- Galaxies on In Our Time at the BBC
- Galaxies, SEDS Messier pages
- An Atlas of The Universe
- Galaxies — Information and amateur observations
- The Oldest Galaxy Yet Found
- Galaxy classification project, harnessing the power of the internet and the human brain
- How many galaxies are in our Universe? Archived 2015-08-21 at the Wayback Machine
- 3-D Video (01:46) – Over a Million Galaxies of Billions of Stars each – BerkeleyLab/animated.