Stellar Temperature Scales

Stellar Temperature Scales 

relations between quantities obtained from observations characterizing the energy distribution in the spectrum of a star (spectral class, color index, and others) and the effective temperature. These relations are used when comparing the results of theoretical studies of stellar structure and evolution with observations.

In order to determine stellar temperature scales, it is necessary to know the linear dimensions of the star and the total quantity of energy radiated by it. These circumstances introduce difficulties in determining stellar temperature scales associated with the necessity of photometry of stars in the far ultraviolet and infrared regions of the spectrum and with the small number of stars of known radii (principally the closest stars—supergiants and eclipsing variable stars). In the same spectral class the dwarfs are hotter than the giants and supergiants, since, because of the lesser force of gravity on the surface of the last two, the same degree of ionization and excitation of the atoms, which determines the spectral class, is attained at a lesser temperature. Table 1 gives a stellar

Table 1. Stellar temperature scale
Spectral class	Effective temperature (°K)
	Dwarfs	Giants
BO	28,000	21,000
B5	15,500	11,500
AO	9850	9400
FO	7030	7500
GO	5900	5800
KO	5240	4900
MO	3750	3750
M5	3100	2950
M8	2750

temperature scale compiled on the basis of the data of the American astronomers H. Johnson (1966) and D. Morton and T. Adams (1968), which has been confirmed by the latest measurements.

IU. N. EFREMOV