Astrophysics (Index)About

luminosity class

(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:

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.

Further reading:

Referenced by pages:
astronomical quantities
David Dunlap Observatory Catalog (DDO)
galaxy classification
main sequence star (MS)
M-type star (M)
spectral type
stellar astronomy
subdwarf (sd)