Unbarred spiral galaxy explained

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.

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

ExampleTypeImageInformationNotes
SA0-SA0- is a type of lenticular galaxy
SA0SA0 is a type of lenticular galaxy
SA0+SA0+ is a type of lenticular galaxy
NGC 3593SA0/aSA0/a can also be considered a type of unbarred lenticular galaxyNGC 3593 is an "SA(s)0/a"
NGC 3169SAaNGC 3169 is an "SA(s)a pec"
Messier 81SAabM81 is an "SA(s)ab"
Messier 88SAbM88 is an "SA(rs)b"
NGC 3949SAbcNGC 3949 is an "SA(s)bc"
NGC 4414SAcNGC 4414 is an "SA(rs)c"
Triangulum GalaxySAcdTriangulum is an "SA(s)cd"
NGC 300SAdNGC 300 is an "SA(s)d"
NGC 45SAdmSAdm can also be considered a type of unbarred Magellanic spiralNGC 45 is an "SA(s)dm"
NGC 4395SAmSAm is a type of Magellanic spiral (Sm)NGC 4395 is an "SA(s)m"

Unbarred lenticular galaxy

An unbarred lenticular galaxy is a lenticular version of an unbarred spiral galaxy. They have the Hubble type of SA0.

An example of this is the galaxy AM 0644-741. For other examples, see .

Notes and References

  1. Astronomical Journal, "Near-infrared surface photometry and morphology in virgo cluster spiral galaxy nuclear regions", Bernard J. Rauscher, April 1995,,
  2. Astronomy Pictures, "M99" (accessed 18 April 2010)