Stellar atmospheres

by Cecilia Payne-Gaposchkin

No.	Elt.	1₁	2₁	2₂	3₁	3₂	3₃	4₁	4₂	4₃	4₄	5₁	5₂	5₃	5₄	5₅	6₁	6₂	6₃	6₄	6₅	6₆	7₁	7₂
1	H	1
2	He	2
3	Li	2	1
4	Be	2	2
5	B	2	2	(1)
6	C	2	2	2
7	N	2	4	1
8	O	2	4	2
9	F	2	4	3
10	Ne	2	4	4
11	Na	2	4	4	1
12	Mg	2	4	4	2
13	Al	2	4	4	2	1
14	Si	2	4	4	(2)	(2)
15	P	2	4	4	4	1
16	S	2	4	4	4	2
17	Cl	2	4	4	4	3
18	A	2	4	4	4	4
19	K	2	4	4	4	4	-	1
20	Ca	2	4	4	4	4	-	2
21	Sc	2	4	4	4	4	1	(2)
22	Ti	2	4	4	4	4	2	(2)
29	Cu	2	4	4	6	6	6	1
30	Zn	2	4	4	6	6	6	2
31	Ga	2	4	4	6	6	6	2	1
32	Ge	2	4	4	6	6	6	4
33	As	2	4	4	6	6	6	4	1
34	Se	2	4	4	6	6	6	4	2
36	Kr	2	4	4	6	6	6	4	3
37	Rb	2	4	4	6	6	6	4	4	-	-	1
38	Sr	2	4	4	6	6	6	4	4	-	-	2
39	Y	2	4	4	6	6	6	4	4	1	-	(2)
40	Zr	2	4	4	6	6	6	4	4	2	-	(2)
47	Ag	2	4	4	6	6	6	6	6	6	-	1
48	Cd	2	4	4	6	6	6	6	6	6	-	2
49	In	2	4	4	6	6	6	6	6	6	-	2	1
50	Sn	2	4	4	6	6	6	6	6	6	-	4
51	Sb	2	4	4	6	6	6	6	6	6	-	4	1
52	Te	2	4	4	6	6	6	6	6	6	-	4	2
53	I	2	4	4	6	6	6	6	6	6	-	4	3
54	Xe	2	4	4	6	6	6	6	6	6	-	4	4
55	Cs	2	4	4	6	6	6	6	6	6	-	4	4	-	-	-	1
56	Ba	2	4	4	6	6	6	6	6	6	-	4	4	-	-	-	2
57	La	2	4	4	6	6	6	6	6	6	-	4	4	1	-	-	(2)
58	Ce	2	4	4	6	6	6	6	6	6	-	4	4	2	-	-	(2)
59	Pr	2	4	4	6	6	6	6	6	6	2	4	4	3	-	-	1
71	Lu	2	4	4	6	6	6	8	8	8	8	4	4	1	-	-	(2)
72	Hf	2	4	4	6	6	6	8	8	8	8	4	4	2	-	-	(2)
79	Au	2	4	4	6	6	6	8	8	8	8	6	6	6	-	-	1
80	Hg	2	4	4	6	6	6	8	8	8	8	6	6	6	-	-	2
81	Ti	2	4	4	6	6	6	8	8	8	8	6	6	6	-	-	2	1
82	Pb	2	4	4	6	6	6	8	8	8	8	6	6	6	-	-	(4)
83	Bi	2	4	4	6	6	6	8	8	8	8	6	6	6	-	-	4	1
86	Rd	2	4	4	6	6	6	8	8	8	8	6	6	6	-	-	4	4
88	Ra	2	4	4	6	6	6	8	8	8	8	6	6	6	-	-	4	4	-	-	-	-	2
89	Ac	2	4	4	6	6	6	8	8	8	8	6	6	6	-	-	4	4	1	-	-	-	(2)
90	Th	2	4	4	6	6	6	8	8	8	8	6	6	6	-	-	4	4	2	-	-	-	(2)
118	?	2	4	4	6	6	6	8	8	8	8	8	8	8	8	-	6	6	6	-	-	-	4	4

The table also gives the number of spectroscopic valency electrons, a quantity which is required by the theory of thermal ionization. The spectroscopic valency electrons are those in equivalent outer orbits (outer orbits of equal total quantum number which have the same azimuthal quantum number). The number is not necessarily the same as the number of chemical valencies (the number of orbits with the same total quantum number) although the two values coincide for the alkali metals and for the alkaline earths. For carbon,[6] on the other hand, the number of spectroscopic valency electrons is two (the number of 22 orbits), while the chemical valency, corresponding to the total number of 2-quantum orbits, is four.

THE PRODUCTION OF LINE SPECTRA

It is not proposed to discuss the theory of the origin of line spectra here in any detail. What is important from the astrophysical point of view is the association of known lines in the spectrum with different levels of energy in the atom, these levels representing definite electron orbits. Absorption and emission of energy take place in an atom by the transfer of an electron from an orbit associated with low energy to an orbit associated with high energy, and vice versa. The frequency of the light which is thus absorbed or emitted is expressed by the familiar quantum relation:

where

and

are the initial and final energies,