Astrophysics (Index)About

Morgan classification

(Morgan's classification, Yerkes classification, Morgan galaxy classification, Yerkes galaxy classification)
(classification of galaxies by stellar spectrum and morphology)

The Morgan classification aka Yerkes classification (a galaxy classification scheme) classifies galaxies by their prominent stellar spectral class(s), then according to morphology, and then according to the angle of view.

symbol prominent stars
a A-type stars
f F-type stars
g G-type stars
k K-type stars
af a to f class
fg f to g class
gk g to k class
symbol shape, etc.
S spiral galaxy
B barred spiral
E elliptical galaxy
D other rotational symmetry (e.g., lenticular galaxy)
cD extremely large D galaxy
I irregular galaxy
L low surface brightness
N small bright nucleus (N galaxy)
Ep elliptical with dust absorption

Inclination (as seen from Earth) is indicated by a number 1-7, 1 for face-on to 7 for edge-on.


Note that variants on the phrases Morgan classification and Yerkes classification are also used for classifications of other types of astronomical objects, such as classifications of stars and of galaxy clusters.

Further reading:

Referenced by pages:
elliptical galaxy
galaxy classification
giant elliptical galaxy
N galaxy