IT’S BEEN dark for a long time, ever since the fireball of the big bang faded
away. But now, all over the Universe, the stars are coming out. These are no
ordinary stars. Burning 10 million times brighter than our own Sun, they race
through their lives at breakneck speed and die spectacularly. In the first and
greatest of all firework displays, space is rocked by a rash of titanic
explosions, each brighter than a hundred galaxies. Only there aren’t any
galaxies. Not yet. Welcome to the age of the megasuns.
Evidence is mounting that the first stars were monsters, hundreds of times
the mass of the Sun. Now, astronomers have begun to produce realistic
simulations of these megasuns, illuminating their strange lives and deaths. The
research offers solutions to two intergalactic puzzles. And it reveals that
these monsters may have left behind gigantic fossils.
The biggest stars in our sky are only about a hundred times as massive as the
Sun. Theorists believe that anything larger would be unstable. The greater a
star’s mass, the hotter it is, and the greater the pressure from internal
radiation. When that pressure nearly balances the force of gravity, adding just
a little heat causes a star to expand a lot.
In the 1970s, Immo Appenzeller of the Landessternwarte in Heidelberg,
Germany, showed that this makes stars of more than a hundred solar masses
unstable. Their inner regions, where nuclear energy is generated, pulsate,
making the nuclear burning occur in spurts. Each spurt is like a nuclear
explosion, ejecting matter from the star about once a day. “People thought these
pulsations would reduce