Encyclopædia Galactica Rami T. F. Rekola Tuorlan Astronomical Society Tuorla Observatory University of Turku

Classification of Galaxy Types

This table explains the classification of galaxies into different types. The table has been adopted from the Third Reference Catalogue of Bright Galaxies, Volume I by Gérard de Vaucouleurs et al.

Classes

Families

Varieties

Stages

T

Type

Code

Ellipticals

 

Compact

 

-6

cE

cE...

 

 

 

Ellipt. (0-6)

-5

E0

.E.0.

 

 

 

Intermediate

-5

E0-1

.E.0+

 

 

"cD"

 

-4

E+

.E+..

Lenticulars

 

 

 

 

S0

.L

 

Non-barred

 

 

 

SA0

.LA

 

Barred

 

 

 

SB0

.LB

 

Mixed

 

 

 

SAB0

.LX

 

 

Inner ring

 

 

S(r)0

.L.R

 

 

S-shaped

 

 

S(s)0

.L.S

 

 

Mixed

 

 

S(rs)0

.L.T

 

 

 

Early

-3

S0-

.L..-

 

 

 

Intermediate

-2

S0°

.L..0

 

 

 

Late

-1

S0+

.L..+

Spirals

Non-barred

 

 

 

SA

.SA

 

Barred

 

 

 

SB

.SB

 

Mixed

 

 

 

SAB

.SX

 

 

Inner ring

 

 

S(r)

.S.R

 

 

S-shaped

 

 

S(s)

.S.S

 

 

Mixed

 

 

S(rs)

.S.T

 

 

 

0/a

0

S0/a

.S..0

 

 

 

a

1

Sa

.S..1

 

 

 

ab

2

Sab

.S..2

 

 

 

b

3

Sb

.S..3

 

 

 

bc

4

Sbc

.S..4

 

 

 

c

5

Sc

.S..5

 

 

 

cd

6

Scd

.S..6

 

 

 

d

7

Sd

.S..7

 

 

 

dm

8

Sdm

.S..8

 

 

 

m

9

Sm

.S..9

Irregulars

Non-barred

 

 

 

IA

.IA

 

Barred

 

 

 

IB

.IB

 

Mixed

 

 

 

IAB

.IX

 

 

S-shaped

 

 

I(s)

.I.S

 

 

 

Non-Magellanic

90

I0

.I.0

 

 

 

Magellanic

10

Im

.I..9

 

 

Compact

 

11

cI

cI

Peculiars

 

 

 

99

Pec

.P

Peculiarities

 

 

Peculiarity

 

pec

.....P

(All types)

 

 

Uncertain

 

:

....*

 

 

 

Doubtful

 

?

....?

 

 

 

Spindle

 

sp

...../

 

 

 

Outer ring

 

(R)

R......

 

 

 

Pseudo-outer R

 

(R')

P......

Classes

Families

Varieties

Stages

T

Type

Code