C1 - elliptical galaxies

they have a smooth light distribution with no evident structure
they appear redder in colour, suggesting a older composition
they have a lower gas content compared to spirals
they have a wide range in luminosities
ellipticals are numbered as $E_{n}$ with $n$ ranging from $0$ to $6 - 7$
$n = 10 (1 - \frac{b}{a}) $ $ w h e r e s e m i - m a j o r a n d s e m i - m i n o r a x e s a r e $ a $ a n d $ b $$
this can further be split into:
- dSph: dwarf spheroidals with $L \approx 10^{- 4} L_{M W}$
- dE: dwarf ellipticals with $L \approx 10^{- 2} L_{M W}$
- E/gE: normal/giant ellipticals with $L \approx L_{M W}$
- cD: cluster-dominant ellipticals with $L$ up to $20 - 30 L_{M W}$