53 - 55 ] Effective Temperatures 55 
Table VIII. Effective Temperatures ( Russell , Dugan and Stewart). 
Spectral 
Type 
Effective Temperature deduced from 
Adopted 
effective 
Temperature 
Colour- 
index 
Bolometric 
Radiation 
Energy 
Curves 
Angular 
Diameters 
BO 
23,000 
23,000 
B 5 
15,000 
— 
— 
— 
15,000 
AO 
11,200 
12,500 
10,000 
11,000 
A 5 
8,600 
— 
— 
8,000* 
8,600 
F 0 
7,400 
— 
— 
— 
7,400 
Fb 
6,500 
— 
8,000 
— 
6,500 
(GO 
5,500 
5,500 
5,800 
— 
5,600 
G 5 
4,700 
— 
— 
— 
4,700 
■+3 
a 
KO 
4,100 
4,200 
— 
4,300 
4,200 
_c3 - 
Kb 
3,300 
3,000 
3,800 
3,400 
3 
M 2 
3,050 
3,100 
2,700 
3,100 
3,100 
lif 7 
— 
2,750 
2,500 
2,650 
2,700 
Long period 
variables : 
max. 
2,300 
— 
2,400 
2.300 
min. 
— 
1,650 
— 
1,700 
1,650 
(GO 
6,000 
5,750+ 
6,000+ 
— 
6,000 
'S 
Gb 
5,600 
— 
— 
— 
5,600 
fei 
KO 
5,100 
— 
— 
— 
5,100 
Q 
Kb 
4,400 
— 
— 
— 
4,400 
[M 
3,400 
— 
3,400 
* Only one star is used, the companion of Sirius, and its spectral type is uncertain, 
t Values for sun (§§ 41, 45). 
Radiation and Physical Constants of Various Stars. 
55. We shall now consider the radiation and physical constants of various 
stars as given by the foregoing formulae. 
The Sun. For convenience the various data already given for the sun 
may be collected together. 
Sun’s diameter = 864,000 miles = 1391 x 10 n cms. 
„ surface = 6‘08 x 10 22 sq. cms. 
„ volume = 1'412 x 10 33 cu. cms. 
„ mass = 2 , 00 x 10 33 grammes. 
„ mean density = 1416 grammes per cu. cm. 
„ emission of energy = 3'80 x 10 33 ergs per second. 
„ emission of energy per gramme = 190 ergs per second. 
„ emission of energy per sq. cm. of surface = 6‘24 x 10 10 ergs per second. 
„ apparent visual mag. = — 26'72. 
„ absolute visual mag. = 4‘85. 
„ absolute bolometric mag. = 4 - 85. 
„ absolute photographic mag. = 5'4.