An intermediate spiral galaxy is a galaxy that is in between the classifications of a barred spiral galaxy and an unbarred spiral galaxy. It is designated as SAB in the galaxy morphological classification system devised by Gerard de Vaucouleurs.[1] Subtypes are labeled as SAB0, SABa, SABb, or SABc, following a sequence analogous to the Hubble sequence for barred and unbarred spirals. The subtype (0, a, b, or c) is based on the relative prominence of the central bulge and how tightly wound the spiral arms are.
Diagram of the Hubble - de Vaucouleurs morphological classification system illustrating the class of intermediate spirals.
Examples
| Example | Type | Image | Information | Notes |
|---|---|---|---|---|
| SAB0- | SAB0- is a type of lenticular galaxy | |||
| SAB0 | SAB0 is a type of lenticular galaxy | |||
| SAB0+ | SAB0+ is a type of lenticular galaxy | |||
| SAB0/a | SAB0/a can also be considered a type of intermediate lenticular galaxy | |||
| Messier 65 | SABa |  |
M65 is an "SAB(rs)a" | |
| NGC 4725 | SABab |  |
NGC 4725 is an "SAB(r)ab pec" | |
| Messier 66 | SABb |  |
M66 is an "SAB(s)b" | |
| Messier 106 | SABbc |  |
M106 is an "SAB(s)bc" | |
| Sculptor Galaxy | SABc |  |
Sculptor is an "SAB(s)c" | |
| NGC 2403 | SABcd |  |
NGC 2403 is an "SAB(s)cd" | |
| SABd | ||||
| SABdm | SABdm can also be considered a type of intermediate Magellanic spiral | |||
| NGC 4625 | SABm |  |
SABm is a type of Magellanic spiral (Sm) | NGC 4625 is an "SAB(rs)m pec" |
| Fireworks Galaxy | SAB(rs)cd |  |
NGC 4625 is an "SAB(rs)cd" | |
References
- ↑ de Vaucouleurs, Gerard (1963). "Revised Classification of 1500 Bright Galaxies". Astrophysical Journal Supplement. 8: 31. Bibcode:1963ApJS....8...31D. doi:10.1086/190084.
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