But a close approach of that kind would be expected to result in the
formation of a binary system, with orbits of great eccentricity,
perhaps, and after the lapse of a certain time the outburst should be
renewed by another approximation of the two bodies. A temporary star
of that kind would rather be ranked as a variable.
The celebrated French astronomer, Janssen, had a different theory of
Nova Persei, and of temporary stars in general. According to his idea,
such phenomena might be the result of chemical changes taking place in
a sun without interference by, or collision with, another body.
Janssen was engaged for many years in trying to discover evidence of
the existence of oxygen in the sun, and he constructed his observatory
on the summit of Mount Blanc specially to pursue that research. He
believed that oxygen must surely exist in the sun since we find so
many other familiar elements included in the constitution of the solar
globe, and as he was unable to discover satisfactory evidence of its
presence he assumed that it existed in a form unknown on the earth. If
it were normally in the sun's chromosphere, or coronal atmosphere, he
said, it would combine with the hydrogen which we know is there and
form an obscuring envelope of water vapor. It exists, then, in a
special state, uncombined with hydrogen; but let the temperature of
the sun sink to a critical point and the oxygen will assume its normal
properties and combine with the hydrogen, producing a mighty outburst
of light and heat.
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