Unbarred spiral galaxy

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The Whirlpool Galaxy and its companion satellite. The Whirlpool is an unbarred spiral galaxy

An unbarred spiral galaxy[1][2] is a type of spiral galaxy without a central bar, or one that is not a barred spiral galaxy. It is designated with an SA in the galaxy morphological classification scheme.

The Sombrero Galaxy is an unbarred spiral galaxy.

Barless spiral galaxies are one of three general types of spiral galaxies under the de Vaucouleurs system classification system, the other two being intermediate spiral galaxy and barred spiral galaxy. Under the Hubble tuning fork, it is one of two general types of spiral galaxy, the other being barred spirals.

Grades[edit]

Under the de Vaucouleurs classification system, SA-galaxies are one of three types of spiral galaxy


Example Type Image Information Notes
SA0- SA0- is a type of lenticular galaxy
SA0 SA0 is a type of lenticular galaxy
SA0+ SA0+ is a type of lenticular galaxy
NGC 3593 SA0/a Ngc3593.jpg SA0/a can also be considered a type of unbarred lenticular galaxy NGC 3593 is actually an "SA(s)0/a"
NGC 3169 SAa NGC 3169.jpg NGC 3169 is actually an "SA(s)a pec"
Messier 81 SAab Messier 81 HST.jpg M81 is actually an "SA(s)ab"
Messier 88 SAb M88HunterWilson.jpg M88 is actually an "SA(rs)b"
NGC 3949 SAbc NGC 3949.jpg NGC 3949 is actually an "SA(s)bc"
NGC 4414 SAc NGC 4414 (NASA-med).jpg NGC 4414 is actually an "SA(rs)c"
Triangulum Galaxy SAcd M33.jpg Triangulum is actually an "SA(s)cd"
NGC 300 SAd Composite Image of NGC 300.jpg NGC 300 is actually an "SA(s)d"
NGC 45 SAdm NGC 45 GALEX WikiSky.jpg SAdm can also be considered a type of unbarred Magellanic spiral NGC 45 is actually an "SA(s)dm"
NGC 4395 SAm Ngc4395.jpg SAm is a type of Magellanic spiral (Sm) NGC 4395 is actually an "SA(s)m"

References[edit]

  1. ^ Astronomical Journal, "Near-infrared surface photometry and morphology in virgo cluster spiral galaxy nuclear regions", Bernard J. Rauscher, April 1995, Bibcode1995AJ....109.1608R, doi:10.1086/117389
  2. ^ Astronomy Pictures, "M99" (accessed 18 April 2010)