Astronomy: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.
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).[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 |
| NGC 4676A | SABdm | Part of a galaxy merger, to the left of it is the galaxy NGC 4676B. | |
| 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 |
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List of Magellanic spirals
Barred (SBm)
- Large Magellanic Cloud (LMC [prototype])
- Small Magellanic Cloud (SMC)
- NGC 1311[3]
- NGC 4618[4]
- NGC 4236
- NGC 55
- NGC 4214
- NGC 3109
- IC 4710
Intermediate (SABm)
Unbarred (SAm)
See also
References
- ↑ 1.0 1.1 Linda S. Sparke, John Sill Gallagher, Galaxies in the Universe: An Introduction, 2ed., Cambridge University Press, 2007, ISBN:978-0-521-85593-8
- ↑ citeBase; Neutral Hydrogen in the Interacting Magellanic Spirals NGC 4618/4625 ; Stephanie J. Bush; Eric M. Wilcots; (accessed 1 March 2009)
- ↑ 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)
- ↑ University of Wisconsin, BARRED MAGELLANIC SPIRALS (accessed 1 March 2009)
- ↑ NASA/IPAC Extragalactic Database
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