. This line is regarded by A. Fowler[263] as the ultimate line of the neutral atom, and on this basis an ionization potential of 10.6 volts was assigned to silicon. In view of the fact that the line appears to have a maximum within the stellar sequence, and is of temperature class II, according to King,[264] while the true ultimate line[265] of silicon is at 2881, it seems possible that 3905 is actually a subordinate line.
IONIZED SILICON
Ionized silicon is represented by the lines 4128, 4131, which appear at
, attain maximum[266] at
, and disappear at
. These lines are of especial interest, as they form the characteristic feature of the “silicon stars” which occur in the early
