Huge clouds of hydrogen and helium gas hover in outer space; these are the birthplaces of stars.  Under gravity the clouds contract, heat up and eventually collapse.  Once temperatures reach several thousand degrees, the hydrogen molecules ionize (lose electrons) becoming protons.  The gas continues to compress until the temperature reaches 10 million degrees Celsius (18 million degrees Fahrenheit).  This is the hydrogen-burning phase and its duration depends on the star’s weight.  The heavier the star, the brighter it burns and the shorter its life.  In this stage of nuclear fusion, H+ protons join together to produce He++ atoms.  All heavier elements in the periodic table are created in stars.  During the fusion, matter also gets converted to energy, as light and heat.  Once all the hydrogen has been used up, the star, at its largest size is called a red giant.  From there it can become any of the following:

• Planetary Nebula

>Star continues to generate energy using hydrogen and helium; surface rises and falls until layers of gas spin off forming a gaseous shell known as a planetary nebula.

• White dwarf

>Small stars continue to shine as helium is produced, further contraction is prevented by the core’s electron repulsion.  White dwarfs have the mass of the sun and volume of the earth making the core incredibly dense.

• Supernova

>In massive stars nuclear fusion continues producing heavier elements and more energy.  Iron, once formed is very stable and harder to bind to other elements.  Eventually the star collapses under gravity and explodes massive amounts of gas leaving an extremely dense core composed entirely of neutrons (neutron star).

• Pulsars

>A neutron star spinning rapidly after a supernova explosion emits electromagnetic radiation: light & X-rays. These beams radiate in a circle because the star is spinning and looks as if it’s pulsing on and off.

• Black Holes

>Giant stars with an extremely heavy core continue to collapse under gravity; matter is squeezed into a smaller and smaller space.  Immensely dense, nothing can escape its gravity; not even light.

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Did you know, many of the stars you see no longer exist?  Long dead, their light is only now arriving at earth.

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Birth of a Star, 2mins: Hubble Site

Posted by: Annie Lalla

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