The Birth and Death of Stars

Stars have fascinated humans ever since the beginning of our existence on earth. In all places all over the world, including Egypt, Northern England, Mexico, and the Bretagne, you can find remnants of millennia-old cultures who have adored the huge, 150 million kilometers distant ball of gas that we call the sun. For the peoples of these ancient civilizations, the bowl-like conglomerate of hydrogen and helium was what it still is today for many astrophysicists: the provider of life.

When the principle of conservation of energy was discovered in the mid-nineteenth century, the question of the origin of the energy created by the sun could, for the first time, be settled. This principle is the idea that all matter and energy in the universe is constant, i.e. there can be no more matter and energy in the universe than there was at its creation, at the present, or at any given time. Because of this principle, it is actually logical that all stars in the universe - just like our sun - consist of a finite amount of matter. So, the resources for the creation of energy are limited. As stars produce their energy by nuclear fusion, and the mass of a star is limited, they are subjected to a cycle which makes them age. So, how can we watch and predict this process of aging?

First off, it is necessary to know how a sun is created. When we start from the beginning - the big bang - it turns out that our universe started to exist at this moment. During the first, unimaginably small fractions of a second, the relatively small and extremely compacted universe containing quarks, electrons, and radiation expands abruptly.

Quarks Emerging

Quark in context

Quarks, the original components of matter, team up and form single protons and neutrons. These elements of an atomic nucleus attain a stable state in the next 100 seconds. The recently created protons and neutrons team up within the next 30 minutes and form the very first hydrogen and helium atoms. The negatively charged electrons (whereas each has a mass about 1/2000 that of the proton) combine with the positive atomic nuclei during the next one million years. After 300,000 years of this time period, the first atoms begin to exist. The largest of them consist of two of each protons, neutrons, and electrons. All this is only possible because the universe is expanding and cooling down, hence the particles begin moving more slowly, putting them in a combinable state. Hereafter, the forces of attraction, including gravity, cause them to condense. The forces compel the remaining gas particles to form larger and larger groups of atoms. As the young universe forms, the first clouds of hydrogen and helium develop. If their mass is great enough, they form stellar nebulae.