(Morgan-Keenan luminosity class, MK luminosity class, MK class, stellar luminosity class)
(classification of size/luminosity of stars)
A star's luminosity class (or Morgan-Keenan luminosity class
or MK luminosity class or MK class)
is a classification (star class) of the overall size of a star
(as are terms like giant star, supergiant, etc.)
which is a major contributor to its luminosity.
A star's spectral type is often cited with its luminosity
class as a suffix. A general class is indicated by a Roman numeral:
Additional more-specific classes:
- 0 (zero) (or Ia+ or IA-0) - extreme luminous supergiant, aka, hypergiant.
- Ia - luminous supergiant.
- Ib - supergiant less luminous than Ia.
- Iab - intermediate between Ia and Ib.
- D - white dwarf (or VII).
As an example, the Sun's spectral type (G2) is commonly given
with a "V" suffix indicating it is in the main sequence, as "G2 V"
or "G2V" .
An analogous classification (luminosity class) for galaxies is the
van den Bergh galaxy classification.
Referenced by pages:
David Dunlap Observatory Catalog (DDO)
main sequence star (MS)
M-type star (M)