| Class | Temperature | Class | Temperature | |
|---|---|---|---|---|
| 3000° | 9000° | |||
| 3000 | 10000 | |||
| 3500 | 13500 | |||
| 4000 | 15000 | |||
| 5000 | 17000 | |||
| 5600 | 18000 | |||
| 7000 | 20000 | |||
| 7500 | 25000 | |||
| 8400 | to | 35000 |
FOOTNOTES:
[408] H. C. 258, 1924.
[409] M. N. R. A. S., 84, 499, 1924.
[410] M. N. R. A. S., 84, 499, 1924.
CHAPTER X
EFFECTS OF ABSOLUTE MAGNITUDE UPON THE SPECTRUM
DIFFERENCES between the spectra of stars of the same spectral class have long been recognized. The empirical correlation of relative line intensities with absolute magnitude was made the basis for the estimation of spectroscopic parallaxes.[412] Such differences within a class were later related in a qualitative way to differences of pressure, in conjunction with the theory of thermal ionization, and have been regarded as corroborative evidence that the type of process contemplated by that theory actually represents what goes on in the atmospheres of the stars.
In the present chapter the theory of the various effects will first be discussed, and later the predictions from the theory will be compared with observational data.
INFLUENCE OF SURFACE GRAVITY ON THE SPECTRUM