Page 51 - analysis-and-interpretation-of-astronomical-sp

Analysis and Interpretation of Astronomical Spectra 51

ity class. Caveat: Dwarf or main sequence stars must not be confused with the White
Dwarfs. The latter are extremely dense, burned-out "stellar corpses" (sect. 14.3).

Examples: Sirius A: A1Vm, metal rich main sequence star (Dwarf), spectral class A1
Sirius B: DA2, White Dwarf (or „Degenerate“) spectral class A2
Omikron Andromedae: B6IIIep, Omikron Ceti (Mira): M7IIIe
Kapteyn‘s star: sdM1V

Suffix Sharp lines Prefixes
S Extraordinary sharp lines d Dwarf
c sd Sub Dwarf
Broad lines g Giant
B Normal lines
A Composite spectrum Special classes
comp Q Nova
H- emission lines by B- P Planetary Nebulae
e and O Stars D Dwarf, +additional letter for O, B,
He- and N- emission lines
F by O-stars A spectral class
Metallic emission lines W Wolf-Rayet Star + additional let-
Em
ter for C-, N- or O- lines
K Interstellar absorption S Stars with zirconium oxide ab-
M lines
n / nn Strong metal lines sorption bands
C Carbon stars
Wk Diffuse lines/strongly dif- L, Brown dwarfs
fuse lines T,
weak lines Y Theoretical class for brown

p, pec peculiar spectrum dwarfs <600 K

Sh Shell
V variation in spectrum
Fe, Mg… Excess or deficiency (–) of

the spec. element

Nowadays the special classes P (Planetary Nebulae) and Q (Novae) are barely in use!
The suffixes are not always applied consistently. We often see other versions. In the case of
shell stars e.g. pe, or shell is in use.