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. A nearby example of an unbarred spiral is the Triangulum 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
| 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 | 
|
SA0/a can also be considered a type of unbarred lenticular galaxy | NGC 3593 is an "SA(s)0/a" |
| NGC 3169 | SAa | 
|
NGC 3169 is an "SA(s)a pec" | |
| Messier 81 | SAab | 
|
M81 is an "SA(s)ab" | |
| Messier 88 | SAb | 
|
M88 is an "SA(rs)b" | |
| NGC 3949 | SAbc | 
|
NGC 3949 is an "SA(s)bc" | |
| NGC 4414 | SAc | 
|
NGC 4414 is an "SA(rs)c" | |
| Triangulum Galaxy | SAcd | 
|
Triangulum is an "SA(s)cd" | |
| NGC 300 | SAd | 
|
NGC 300 is an "SA(s)d" | |
| NGC 45 | SAdm | 
|
SAdm can also be considered a type of unbarred Magellanic spiral | NGC 45 is an "SA(s)dm" |
| NGC 4395 | SAm | 
|
SAm 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 Category:Unbarred lenticular galaxies.
References
- ^ Astronomical Journal, "Near-infrared surface photometry and morphology in virgo cluster spiral galaxy nuclear regions", Bernard J. Rauscher, April 1995, Bibcode:1995AJ....109.1608R, doi:10.1086/117389
- ^ Astronomy Pictures, "M99" (accessed 18 April 2010)
