Kathy Chant, age 1,3, of Athens, Ont., for her question:
Why are the stars different colors?
If you are a careful stargazer you can detect slight differences of color in the stars. Bright Sirius sparkles like a clear white diamond. Aldebaran, in Taurus, the Bull, glows with a bright orange color and big Betelgeuse in Orion glows with a dull rod. This is not imagination. The stars actually do shine with d.iffcrant colors.
All stars are very hot, but some are much hotter than others. And, we are told, it is temperature which causes the differences ire star colors. To an astronomer, the color of a star gives a clue to its temperature. Star colors range from dull red to brilliant blue‑white. And the Stars may be classed according to their color. Each color class is given a letter of the alphabet.
The spectrum of a star is a band of rainbow colors. In etch star spectrum there are dark bands across certain colors. These tell the expert what materials are prcsont in the star. Molecules, or compounds of elements, cannot exist in a hot star. But a few do exist in a cool star. The spectrum indicates whet elements and whit compounds, if any, are present.
There are seven main star classes and ten sub‑classes in each. There are four classes for stars which do not fit into the seven major groups.
Betelgeuse is in star class M. Its spectrum shows that titanium oxides a compound, is present. Big Bet is a giant rod star. Its temperature is 5,500 degrees Fahrenheit, about half as hot as our sun. Aldebaran is a K type star. Its spectrum shows that it contains more metals than hydrogen. Its temperature is around 7,00 degrees Fahrenheit and it is an orange colored star.
Still warmer is a G type star. Our sun is in this class. It is a yellow star containing mrny metals in gaseous form. Its surface temperature is about 11,000 degrees Fahrenheit. The stars in class F are yellowish white. They contain less hydrogen than our sun end more gaseous metals. F metals. An F type star is Procyon, the bright stir in Canus Minor, the Little Dog. We see it in the; sky a little to the cast and G little higher than bright Sirius. Procyon and its classmates are around 13,500 degrees Fahrenheit.
Brilliant Sirius is a white star in Class A. Its spectrum shows that hydrogen gas is predominant and its temperature is about 20,004 degrees Fahrenheit, almost twice as hot as the sun. Class B includes the blue white stars in which helium gas is most noticeable. Rigel, at the foot of Orion, is a blue white star of Class B. Its surface temperature soothes around 36,000 degrees Fahrenheit.
Hotter still are the stars in Class 0. This class is represented by the white dwarf stars. These little fallows are too small to point out in the sky. Instead of being .red hot, like the rod dents in Class M, those little stars are white hot. An 0 type star is over 55,000 degrees Fahrenheit.
The coolest stars are the dull red stars. The temperatures increase through the orange, yellow, yellow‑white, white and blue‑white stars. Hottest of all, of course, are the tiny white dwarfs.