Star Light, Star Bright

The idea of wishing on a star is a very ancient superstition. Many wide-eyed children–as well as some unfortunate adults–have wished upon a shooting or falling star in an effort to make magic work for them. But stars are not supernatural dabs of light shimmering like angels in the clear night sky. Stars are really gigantic incandescent balls of hot nuclear-fusing gas. They are unable to hear us, and certainly cannot grant wishes. However, the stars have done much more for us than merely that–they gave us life. 바카라사이트

The billions and billions of stars that dwell in our Universe are primarily composed of hydrogen–the lightest element in the Periodic Table–which they transform in their nuclear-fusing cores into heavier things, by way of a process termed “stellar nucleosynthesis”. How were the first stars in our Universe born? How big were they? What were they like?

The first stars were not like the stars we know today; they formed directly from the lightest primordial gases–hydrogen and helium–which were born in the hot Big Bang birth of the Universe almost 14 billion years ago. In fact, the only atomic elements formed in the Big Bang inferno were hydrogen, helium, and trace amounts of lithium. The rest of the elements of the Periodic Table were cooked deep in the hearts of stars, their glowing hot interiors progressively fusing the nuclei of atoms to form heavier and heavier elements. Without these heavy elements produced by our Universe’s stars, there would be no life. We would not be here. All of the carbon that is the basis for life on Earth, the oxygen we breathe, the elements composing the stones, dirt, and sand beneath our feet, were created deep inside the fiery hearts of ancient stars, billions and billions of years ago. We are made of star-stuff. When very massive stars die, they do not go gently into that good night, but blow themselves up in a magnificent supernova blast. When massive stars go supernova they hurl their newly formed batch of heavy elements out into space. The first stars were enormous, perhaps weighing as much as hundreds of times more than our own Sun. They lived fast and died young. The more massive the star, the shorter its life. When the first stars went supernova, they blasted out the very first newly-formed batch of heavy elements–so necessary for the emergence of life–into the Cosmos.

Hydrogen and helium were drawn together to create gravity-bound knots of gas. The cores of the very first protostars in our Universe ignited within the cold dark hearts of these dense knots of pristine primordial gas. The tight dark knots collapsed under their own gravitational weight, until nuclear-fusing fires started to burn. Many cosmologists think that the first stars grew to be enormous (compared to the stars of today’s Universe), because they did not form from the same elements, and did not form in the same way, as stars do now. Members of the first generation of stars are termed “Population III” stars. Our Sun is a member of the most recent population of stars, and is a so-called “Population I” star. In between the first stars, and the most recent generation of stars like our Sun, are the appropriately-named “Population II” stars.

The most ancient generation of stars did not catch fire until about 100 million years after the Big Bang. How did the dramatic transition from darkness to light come about? After decades of observations, simulations, and calculations, researchers have recently made significant progress in their endeavors to answer this question. Using sophisticated computer simulation techniques, cosmologists have constructed ingenious models that reveal how the first generation of stars might have been born. Observations made using large ground-based and space-borne telescopes have also probed into cosmic history back to the remote time when the Universe was less than one-tenth of its present age.

The great scientific detective Albert Einstein once said that “The most beautiful thing we can experience is the mysterious. It is the source of all true art and all science. He to whom this emotion is a stranger, who can no longer pause to wonder and stand rapt in awe is as good as dead: His eyes are closed.”

The birth of the first stars is one of the greatest mysteries haunting today’s cosmologists. It is currently most widely thought that the ancient Population III stars were not only extremely massive, but also dazzlingly luminous, and their emergence is primarily responsible for changing our Universe from what it was to what it is now. The ordinary atomic matter that was born in the Big Bang and subsequently cooked up in the hearts of stars is composed of protons, neutrons, and electrons. Protons and neutrons are bound together into atomic nuclei surrounded by a cloud of electrons. Hydrogen is made up of only one proton and one electron. Helium is made up of two protons, two neutrons, and two electrons. Carbon is made up of six protons, six neutrons, and six electrons. Heavier elements, such as iron, lead, and uranium, contain even larger numbers of protons, neutrons, and electrons.

 

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