Horvath et al.
e20200160-11
they are being born in the middle of the gas and the dust
of the “mother cloud”. However, there is a consensus,
reached after more than a century of interdisciplinary
studies involving physicists, astronomers, geologists and
other scientists to say that the formation of the Solar
System must have happened something like this:
About 5 billion years ago, a large cloud of gas (en-
riched by elements heavier than helium accumulated by
the successive ejections of stellar material) began to con-
tract due to gravitation. It is likely that the collapse
process started with the passage of waves that disturbed
the cloud, exchanging energy with the gaseous compo-
nents, facilitating its physical transformation. A recent
idea is that the collision of the Milky Way with dwarf
galaxies acted as a trigger of star formation, a type of
event speculated for the origin of the Sun and Solar Sys-
tem [27]. As gravitation imposed itself on the resistance
offered by the internal pressure of the cloud, smaller re-
gions were isolated within it, and continued to collapse to
form “cocoons” where these processes continued (called
Bok globules). The addition of neighboring matter over
the denser regions gave rise to the first phases of what
would become a star (stage known as TTauri, Figure
9b), with jets emerging from it. After a few million years,
the contraction raised the temperature to the millions of
degrees, allowing the young Sun to establish the energy
generation that keeps it shining today. Even though it
was at least 30% less bright, it already had all the char-
acteristics observed today and was already accompanied
by the equally young planets.
An important fact to be taken into account is that the
orbits of all the planets in the Solar System are practically
contained in one plane (with the exception of the orbit
of the Pluto-Charon binary system). The initial nebula
must have been roughly spherical, and when collapsing,
formed a disk around it as the speed of rotation increased,
flattening it. In fact, the nebula could not have collapsed
without causing the rotation to be ”transferred” outwards,
in other words, centrifugal forces would have prevented
the contraction if this transfer had not happened (more
strictly, astronomers speak of the transfer of angular
momentum in the proto-planetary nebula, that is, the
Dostları ilə paylaş: