I'm assuming he's going back to the formation of the Sun, but not so far back as the origin of its components.
The energy was in the mass itself; the gas and dust that coalesced, through universal gravitation, to eventually formed a mass so dense and hot that the hydrogen began to fuse into helium, releasing tremendous energy and becoming a star.
Of course, valjean. You are right, I don’t have to go that far back.
I would guess my points in the original reply was to show the most abundant element in the universe, BACK THEN, and NOW, have always been hydrogen, the lightest of all atoms, and yet hydrogen are the main components - or the main building blocks - of every stars to existed, now and, since then.
In every gas or plasma clouds in space, the main raw materials are hydrogen, with other elements, such as helium, carbon, nitrogen, oxygen in various degrees of abundance. Such clouds are called
molecular clouds or
stellar nurseries, because the most abundant of materials, are molecular hydrogen (H
2), hence it also referred to as
H II region.
H II regions (stellar nurseries) are found in nebulae, where they would form new stars, when the clouds are dense enough to gravitational collapse, to form into star’s core, in a shape of sphere or ball. The clouds form the core and outer layers surrounding this core. So gravity play larger role in forming the shape and interiors of the new stars.
The denser the core, the hotter the core get, till it is hot enough to trigger nuclear fusion to form -
- helium from hydrogen fusion (proton-proton chain, example of type of nucleosynthesis is the sun)
- or with more massive stars to cycle through 3 heavier elements from hydrogen fusion (carbon-nitrogen-oxygen cycle, CNO cycle).
Both proton-proton chain & CNO cycle, are the 2 most common Stellar Nucleosynthesis types of hydrogen fusion. I have heard of 3rd hydrogen fusion,
deuterium fusion, but I have read up on this type of nucleosynthesis, yet.
Generally, helium fusion or fusions of heavier elements (eg carbon burning, oxygen burning, etc) only occur if the core run out of hydrogen fuel, to fuse.
Anyway gravity (plus gravitational collapse) and heat played large roles in the energy (via Stellar Nucleosynthesis) produced by the stars (including the Sun), to get back to
@chinu OP).