Magellanic spiral

A Magellanic spiral galaxy is a spiral galaxy with only one spiral arm. Magellanic spiral galaxies are classified as the type Sm (with sub-categories SAm, SBm, SABm); the prototype galaxy and namesake for Magellanic spirals is the Large Magellanic Cloud, an SBm galaxy. They are usually smaller dwarf galaxies and 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	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

List of Magellanic spirals

Barred (SBm)

Large Magellanic Cloud (LMC; prototype galaxy)
Small Magellanic Cloud (SMC)
NGC 1311^[3]
NGC 4618^[4]
NGC 4236
NGC 55
NGC 4214
NGC 3109
IC 4710

Intermediate (SABm)

Unbarred (SAm)

References

^ ^a ^b 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 Archived 14 February 2012 at the Wayback Machine; 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

[Sparke_and_Gallagher-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] teBase; 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)

[NED-5] NASA/IPAC Extragalactic Database

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[2]

[3]

[4]

[5]

v t e Galaxies
Morphology	Disc Lenticular barred unbarred Spiral anemic barred flocculent grand design intermediate Magellanic unbarred Dwarf galaxy elliptical irregular spheroidal spiral Elliptical galaxy cD Irregular barred Peculiar Ring Polar
Structure	Active galactic nucleus Bar Bulge Central massive object Galactic Center Dark matter halo Disc Disc galaxy Halo corona Galactic plane Galactic ridge Interstellar medium Protogalaxy Galaxy filament Spiral arm Supermassive black hole Ultramassive
Active nuclei	Blazar LINER Markarian Quasar BL Lacertae object Radio X-shaped DRAGN Relativistic jet Seyfert
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Low activity	Low surface brightness Ultra diffuse Dark galaxy Red nugget Blue Nugget Dead disk
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