19
Stars as the Cooking Pots for Heavy Nuclei
The universe is full of many elements heavier than hydrogen, helium, lithium,
and beryllium, which were produced at the time of Big Bang Nucleosynthesis,
a major milestone in the history of evolution of the universe. Where did the
heavier elements come from, if the Big Bang cosmic evolution only produced
the lightest three or four elements given above? This question has occupied
the minds of physicists for many decades. Indeed, as we will see, there is a lot
of truth to this statement. A lot about how elements are made of stardust has
been understood but a lot remains to be resolved. In fact, late astronomer Carl
Sagan once said, “The nitrogen in our DNA, the calcium in our teeth, the
iron in our blood, the carbon in our apple pies were made in the interiors of
collapsing stars. We are made of “star-stuff.” To discuss this, we first note that
Fig. 19.1 shows the abundance of some low atomic number heavier elements
in the solar system. We then come to the discussion of the remaining heavy
elements.
19.1 Stellar Nucleosynthesis
After the Big Bang Nucleosynthesis, the next stage in the synthesis of nuclei
takes place in stars like the sun and others. The formation of stars takes place
when giant clouds of hydrogen get pulled together by gravity. Slowly, the
resulting cloud starts to spin, as a result of the strong pull of gravity and
other forces. This increases the temperature of the gas to about thirteen million
degrees, when hydrogen fusion to helium occurs. The cloud glows, and thus
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer
Nature Switzerland AG 2021
R. N. Mohapatra, The Neutrino Story: One Tiny Particle’s Grand Role in the Cosmos,
https://doi.org/10.1007/978-3-030-51846-2_19
141
Stars as the Cooking Pots for Heavy Nuclei
The universe is full of many elements heavier than hydrogen, helium, lithium,
and beryllium, which were produced at the time of Big Bang Nucleosynthesis,
a major milestone in the history of evolution of the universe. Where did the
heavier elements come from, if the Big Bang cosmic evolution only produced
the lightest three or four elements given above? This question has occupied
the minds of physicists for many decades. Indeed, as we will see, there is a lot
of truth to this statement. A lot about how elements are made of stardust has
been understood but a lot remains to be resolved. In fact, late astronomer Carl
Sagan once said, “The nitrogen in our DNA, the calcium in our teeth, the
iron in our blood, the carbon in our apple pies were made in the interiors of
collapsing stars. We are made of “star-stuff.” To discuss this, we first note that
Fig. 19.1 shows the abundance of some low atomic number heavier elements
in the solar system. We then come to the discussion of the remaining heavy
elements.
19.1 Stellar Nucleosynthesis
After the Big Bang Nucleosynthesis, the next stage in the synthesis of nuclei
takes place in stars like the sun and others. The formation of stars takes place
when giant clouds of hydrogen get pulled together by gravity. Slowly, the
resulting cloud starts to spin, as a result of the strong pull of gravity and
other forces. This increases the temperature of the gas to about thirteen million
degrees, when hydrogen fusion to helium occurs. The cloud glows, and thus
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer
Nature Switzerland AG 2021
R. N. Mohapatra, The Neutrino Story: One Tiny Particle’s Grand Role in the Cosmos,
https://doi.org/10.1007/978-3-030-51846-2_19
141