2.4.2 The Meteoroid Theory of Stellar Evolution
In the 1910s, Shinjo started contemplating an idea on the evolution of stars based on
his own observations of meteors. His initial aim was to explain the mechanism of
Cepheid variables, but gradually, Shinjo extended this idea to the evolution of stars
in general. His basic assumption on was the condensation, rotation, and conservation
of the angular momentum of meteoroid clouds.
2.4.2.1 Universal Existence of Meteoroids
Shinjo first observed the inflow of meteors from space into the terrestrial atmosphere. He estimated the total mass of meteors falling into the atmosphere through an
excess of rotational velocity of the upper atmosphere affected by the falling meteorites. He also assumed that meteors are ranging widely in size, from 1 μm up to
several 10 km. Furthermore, he regarded all meteor showers, comets, zodiacal light,
and Saturn’s rings as being composed of meteoroids. Outside the Solar System, dark
clouds may be a conglomeration of meteoroids (Shinjo 1914).
In this way, he claimed that meteoroids were ubiquitously distributed in space and
that stars were formed in gravitationally condensed parts of the Universe. Condensation of meteoroid cloud takes place in usual accompanying some overall rotation. The
combination of condensation and rotation in the meteoroid clouds is the basic factor
for the formation of stars and their variabilities. Whether the primordial matter is gas or
meteoroid could be distinguished by the existence of average angular momentum in
the primary conglomeration. The overall rotation observable in most celestial objects
yields reliable evidence for the meteoroid origin of star formation.
2.4.2.2 Theory of Stellar Variability
Shinjo proposed an eccentric-nucleus theory of Cepheid variables, against the pulsation theory of Harlow Shapley (1914). Shinjo supposed that the primordial state of
stellar evolution was a kind of meteoric swarm of immense dimension, and the
subsequent evolution consisted of progressive condensation as a result of mutual
attraction. Each condensation episode may develop in several different ways, based
on the initial values of mass and angular momentum. Systems with large angular
momenta would naturally condense into two or more separate nuclei and, hence,
develop into binary or multiple systems, while those with comparatively small values
of angular momentum may condense into a single star. In the latter case, however,
Shinjo supposed that the condensing nuclei might not coincide with the centers of
mass of the whole system. This notion of eccentric condensation of nuclei was the
starting point of Shinjo’s theory on the nature of Cepheid variables (Shinjo 1922a, b).
As a simple case, he considered a system of meteoric swarm as shown in
Fig. 2.12, where the system is composed of a central sphere (center O 1 ) and an
eccentric nucleus (center O, radius R, mass m, mean density ρ). The central sphere is
2.4 Shinjo Shinzo and Astrophysics
33
In the 1910s, Shinjo started contemplating an idea on the evolution of stars based on
his own observations of meteors. His initial aim was to explain the mechanism of
Cepheid variables, but gradually, Shinjo extended this idea to the evolution of stars
in general. His basic assumption on was the condensation, rotation, and conservation
of the angular momentum of meteoroid clouds.
2.4.2.1 Universal Existence of Meteoroids
Shinjo first observed the inflow of meteors from space into the terrestrial atmosphere. He estimated the total mass of meteors falling into the atmosphere through an
excess of rotational velocity of the upper atmosphere affected by the falling meteorites. He also assumed that meteors are ranging widely in size, from 1 μm up to
several 10 km. Furthermore, he regarded all meteor showers, comets, zodiacal light,
and Saturn’s rings as being composed of meteoroids. Outside the Solar System, dark
clouds may be a conglomeration of meteoroids (Shinjo 1914).
In this way, he claimed that meteoroids were ubiquitously distributed in space and
that stars were formed in gravitationally condensed parts of the Universe. Condensation of meteoroid cloud takes place in usual accompanying some overall rotation. The
combination of condensation and rotation in the meteoroid clouds is the basic factor
for the formation of stars and their variabilities. Whether the primordial matter is gas or
meteoroid could be distinguished by the existence of average angular momentum in
the primary conglomeration. The overall rotation observable in most celestial objects
yields reliable evidence for the meteoroid origin of star formation.
2.4.2.2 Theory of Stellar Variability
Shinjo proposed an eccentric-nucleus theory of Cepheid variables, against the pulsation theory of Harlow Shapley (1914). Shinjo supposed that the primordial state of
stellar evolution was a kind of meteoric swarm of immense dimension, and the
subsequent evolution consisted of progressive condensation as a result of mutual
attraction. Each condensation episode may develop in several different ways, based
on the initial values of mass and angular momentum. Systems with large angular
momenta would naturally condense into two or more separate nuclei and, hence,
develop into binary or multiple systems, while those with comparatively small values
of angular momentum may condense into a single star. In the latter case, however,
Shinjo supposed that the condensing nuclei might not coincide with the centers of
mass of the whole system. This notion of eccentric condensation of nuclei was the
starting point of Shinjo’s theory on the nature of Cepheid variables (Shinjo 1922a, b).
As a simple case, he considered a system of meteoric swarm as shown in
Fig. 2.12, where the system is composed of a central sphere (center O 1 ) and an
eccentric nucleus (center O, radius R, mass m, mean density ρ). The central sphere is
2.4 Shinjo Shinzo and Astrophysics
33