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Analysis and Interpretation of Astronomical Spectra 82

F3 6,850

F5 6,700 6,800

F6 6,550 6,150
5,800
F7 6,400
5,500
F8 6,300 5,100
5,050
G0 6,050 4,900
4,700
G1 5,930 4,500
4,300
G2 5,800 4,100
3,750
G5 5,660 5,010
3,660
G8 5,440 4,870 3,600
3,500
K0 5,240 4,720 3,300
3,100
K1 5,110 4,580 2,950

K2 4,960 4,460

K3 4,800 4,210

K4 4,600 4,010

K5 4,400 3,780

K7 4,000

M0 3,750 3,660

M1 3,700 3,600

M2 3,600 3,500

M3 3,500 3,300

M4 3,400 3,100

M5 3,200 2,950

M6 3,100 2,800

M7 2,900

M8 2,700

18.3 Temperature Estimation Applying Wien’s Displacement Law

A further approach is the estimation of with the principle of Wien's displacement law

(sect. 3.2). It is based on the assumption that the radiation characteristic of the star corre-
sponds approximately to that of a black body. Theoretically could be calculated, apply-

ing formula {2}, based on the wavelength , which has been measured at the maximum in-
tensity of the profile. This requires, however, a radiometrically corrected profile as de-

scribed in sect. 8.11. In sect. 3.3 it has already been demonstrated that the position of the
intensity maximum in the pseudo-continuum gives only a very rough indication for the tem-

perature of the radiator.

Further, the maximum intensity must lie within the recorded range – for a typical amateur
spectrograph about 3800 – 8000 Å. In the graphic below this criterion is met only by the
yellow graph for 6000 K. According to formula {2}, within this section, only profiles with

of about 7600 – 3600 K can be analysed by their maximum intensity. This corre-

sponds roughly to the spectral types M1 – F0.