MAN’S THEATER OF ACTION 
knowledge has advanced so far that we may now summa- 
rize the evolution of a star. Separating from the parent 
nebula as an enormously extended gaseous ball, hundreds 
of millions of miles in diameter and rare as the residual of 
gas in what we are apt to call a high vacuum, the newly- 
born star is of low temperature, glows but feebly red, and 
shows in its spectrum the bands of molecular compounds. 
Condensing and rising in temperature by the fall inwards 
of its gaseous matter under its own gravitation, the star 
glows yellowish red, its spectrum loses its compound bands, 
because heat dissociates the compounds which produce 
them, and substitutes for these bands the lines of moder- 
ately heated metals. Still enhancing its temperature by 
internal gravitation, the density of the star becomes yet 
greater, and its light glows yellowish. Its spectrum lines 
begin to show the effects of the high temperature involved 
in the shattering of the atoms from which are stripped off 
one or more electrons by the violent agitation of the power- 
ful heat within. 
This process goes on through the white to the blue stage, 
when the atoms become so far dissociated as to render the 
spectrum unfamiliar, for it corresponds to temperatures 
too exalted to be commanded for any considerable time in 
our laboratories. If this be the exterior condition, much 
more is the interior of the star in tremendous exalta- 
tions of heat and pressure. It is believed that under these 
conditions matter is gradually annihilated by the collapse 
of the atoms, and that the enormous output of radiation is 
made possible only by the actual passing out of existence 
of interior matter, with a diminution of the mass of the 
star. Thus the star grows smaller both by condensation 
and by annihilation. 
With great density the star material, though gaseous, be- 
comes so little transparent that the inner heat is no longer 
able to force to the exterior a sufficient supply to maintain 
the radiation outward. The star then visibly cools, and 
passes in reverse order through the series of colors and of 
[7] 
