Magellanic spiral

Magellanic spiral galaxies are (usually) dwarf galaxies which are classified as the type Sm (and SAm, SBm, SABm). They are galaxies with one single spiral arm, and are named after their prototype, the Large Magellanic Cloud, an SBm galaxy. They can be considered to be intermediate between dwarf spiral galaxies and irregular galaxies.

"SBm" redirects here. For other uses, see SBM.

Magellanic spirals

SAm galaxies are a type of unbarred spiral galaxy, while SBm are a type of barred spiral galaxy.[1] SABm are a type of intermediate spiral galaxy.

Type Sm and Im galaxies have also been categorized as irregular galaxies with some structure (type Irr-1). Sm galaxies are typically disrupted and asymmetric.[2] dSm galaxies are dwarf spiral galaxies or dwarf irregular galaxies, depending on categorization scheme.

The Magellanic spiral classification was introduced by Gerard de Vaucouleurs, along with Magellanic irregular (Im), when he revamped the Hubble classification of galaxies.

Grades of Magellanic Spiral Galaxies
Example Type Image Information and Notes
Magellanic Spirals
SAdm
NGC 5204 SAm Satellite of Pinwheel Galaxy
SABdm
NGC 4625 SABm It has only one spiral arm. In ultraviolet it extends four times farther than in visible light.
NGC 4236 SBdm In M81 Group
Large Magellanic Cloud SBm Prototype galaxy for this galaxy class, and satellite of Milky Way
Sdm
Sm
Dwarf Magellanic Spirals
dSAdm
dSAm
dSABdm
dSABm
dSBdm
dSBm
dSdm
NGC 5474 dSm Satellite of Pinwheel Galaxy

List of Magellanic spirals

Barred (SBm)

Intermediate (SABm)

Unbarred (SAm)

See also

References
  1. Linda S. Sparke, John Sill Gallagher, Galaxies in the Universe: An Introduction, 2ed., Cambridge University Press, 2007, ISBN 978-0-521-85593-8
  2. citeBase; Neutral Hydrogen in the Interacting Magellanic Spirals NGC 4618/4625 Archived 14 February 2012 at the Wayback Machine; Stephanie J. Bush; Eric M. Wilcots; (accessed 1 March 2009)
  3. Paul B. Eskridge; "Recent Star and Cluster Formation in the Nearby Magellanic Spiral NGC 1311"; 'American Astronomical Society Meeting' 208, #14.04; Bulletin of the American Astronomical Society, Vol. 38, p.93; (accessed 1 March 2009)
  4. University of Wisconsin, BARRED MAGELLANIC SPIRALS (accessed 1 March 2009)
  5. NASA/IPAC Extragalactic Database

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