Robert Taylor, age 13, of Fairfield, CT for his question:
What are stars made of?
Everything in the universe is made from the basic chemical element .... Our world is made mostly of oxygen, either free oxygen in the air or combined with other elements to make water and the rocks of the earth's crust. Oxygen and seven other elements make up 99% of the world around us. The remaining 1% is made up from the remaining 84 chemical elements. Buried somewhere in this one percent are the elements hydrogen and helium. These two elements are rare on earth, but they make up 99% of the blazing stars.
The average star is made from about 75% hydrogen gas and about 24% helium gas. In the remaining one percent there are traces of many and perhaps all the elements found on earth and maybe a few radioactive elements not found on earth. There are variations in the proportions of hydrogen and helium in certain stars, but together the rule seems to be that 99% of a star is made from these two gases.
Our sun is estimated to be 55% hydrogen and 44% helium. Since the sun is the star nearest to us, it is the one we can study best. Hence we know more about the elements in that remaining one percent. Traces of more than 60 different elements have been identified in the sun and it is thought that we shall yet discover traces of all the elements which occur on earth. Since the sun, like all stars, is an atomic furnace, there may be short lived radioactive elements which do not occur on earth.
Carbon, oxygen, silicon and calcium in gaseous form are present in the sun. So also are iron, nickel, copper zinc, tungsten, platinum and lead. These metallic elements, of course* are not in solid form as they are on earth. They are gases.
The metals on earth are cool enough td reach their freezing point:' They are indeed frozen solid. In the blazing heat of the sun, these materials are separated into single atoms. In many cases, the heat is so intense that the atoms are stripped of their electrons and we have ions, or incomplete atoms.
The surface of the coolest stars is around 5,500 Fahrenheit degrees. The surface of the hottest stars is around 55,000 Fahrenheit degrees. But the surface of a star is always much coolor than its fiery heart. The surface of our sun is around 10,000 Fahrenheit degrees but in the center of the blazing atomic furnace the temperature reaches millions of degrees.
There is a vast difference in the density of star gases. In certain large red stars the gases are very thin and light. A quart bottle of air at sea level on earth would be equal to perhaps 2,000 quart bottles of the gases from one of the stars, At the opposite end of the scale axe the white dwarf stars. Their gases are so densely packed that a pint of this star dust might weigh 20 tons.