How long do stars live?

Answer

Dear Vicky,

Let us first look at the example of our sun. The sun, as you probably know, is also a star, and a star is nothing but a nuclear power plant, which means getting energy from nuclear fusion (merging of different atoms) of hydrogen (combustible chemical atom). This process can only take place at the very high temperatures near the center of the star (millions of degrees Celsius). The energy will run out there someday, and then the star will be done for. Our sun will run out of energy in about five billion years. The result is that the core shrinks, and the outside (due to the law of action and reaction) expands. Such an object is called a red giant. The sun will then grow so large that perhaps the earth will be swallowed up and at least scorched. Finally, the outer layers of the sun are completely blown away, leaving a dead, cooling object in the center: a white dwarf. But that’s not all for tomorrow!

But what about the other stars? From astrophysics (= explaining astronomy according to the laws of nature) it appears that the lifespan of a star depends on the mass (size and weight) it has at the beginning of its life. Although massive stars have more energy, they also use it up much faster than light stars because they give off much more light. So much faster, in fact, that the advantage of starting with more fuel is completely negated, and massive stars live shorter lives than light stars. Stars that are ten times lighter than the sun (this is about the minimum mass a star can have) live so long that even those born just after the universe was formed (13.7 billion years ago) have barely aged . Stars that are a few tens of times more massive than the sun, however, live only a few million years, thousands of times less than the sun. The end of their lives is also much worse than that of the sun: it is these stars that can form black holes through supernova explosions.