370 
THE OUTSIDE OF A STAR 
spond to the simple theory that if 1 fn is the fraction of atoms in the 
appropriate absorbing condition when the line just becomes visible then 
the abundance of the element is proportional to n. 
Table 47. 
Stellar Abundance of the Elements. 
z 
Element 
Abundance 
Z 
Element 
Abundance 
14 
Si 
5-7 
22 
Ti 
•43 
11 
Na 
5-7 
25 
Mn 
•36 
12 
Mg 
4-2 
24 
Cr 
•29 
13 
Al 
3-6 
19 
K 
•11 
6 
C 
3-6 
23 
V 
•05 
20 
Ca 
2-9 
38 
Sr 
•002 
26 
Fe 
2-5 
54 
Ba 
•005 
30 
Zn 
0-57 
3 
Li 
•0000 
Other elements which are probably abundant are O, S, N, Ni, but quantita 
tive determination is not yet possible. Information is not obtainable as 
to P, Cl, F, Zr which are terrestrially abundant. Miss Payne considers 
that there is a fairly close parallelism shown between stellar abundance 
and terrestrial abundance. 
A study of this table does not suggest any need for amending the view 
expressed in § 173 that the mean molecular weight should be taken to 
correspond to a predominance of elements in the neighbourhood of Fe 
with some admixture of lighter elements. But this evidence is not to be 
stressed very much. The abundance here determined depends on the ability 
of the element to rise to the upper part of the photosphere and may not 
be typical even of the photosphere itself. The heavy elements are likely 
to be badly handicapped in showing themselves.