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Hoyle is particularly interested in supernovae because he and Lyttleton believe that they are the source of planetary systems including the earth's. There are several features of the solar system that seem to fat the Hoyle-Lyttleton theory The planets, for instance, are made mostly of heavy elements, while the sun is made mostly of hydrogen and helium. Another fact is that the planets are revolving rapidly a long way from the slowly turning sun, which makes it unlikely that they were ever a part of it. Hoyle and Lyttleton believe that they never were. The planets, they say, came from a supernova.
About half the stars within man's sight hey point out, are members of "binary1 systems': two stars revolving around a common center. Some of these binary ystems contain stars that are doomed eventually to explode as supernovae. When the supernova in the binary blows up a large part of its matter is shot out t the system, even out of the galaxy ltsel| Some of the hot gas emitted toward the end of the explosion, however does not move quite fast enough. Part of it comes near the companion star (in the local case, the sun), and is captured by it (see diagram). It forms a gaseous ^ which gathers into loose clots that eventually break up into planets, satellites, asteroids, and all the other oddments that constitute a planetary system.
Foster Mother' These null are made argely of heavy elements, not of hydrogen and helium like the sun. This is natural enough, says Hoyle. The supernova blows up just after (and because) it has produced within itself a large amount of heavy elements. As for the nucleus of the supernova, the martyred mother of plans, it recoils out of the system as a dim white dwarf, leaving the companion star in charge of its offspring.
Since the sun, once the companion star of a supernova, is an average, conservative citizen of the galaxy, it will probably take good care of its adopted planets for quite a while. In about ten billion years however, thinks Hoyle, it will begin to get hotter, frying its planets clean of life After some 50 billion years, it will swell up monstrously and consume the inner ones (including the earth). Eventually it will fade slowly, first to a white dwarf hen to a black dwarf, and cruise through space in darkness, surrounded by its dead outer planets.
As Hoyle points out, the number of spendthrift stars in the local galaxy can be calculated, and also the number that happen to be members of binary systems. He figures that nearly ten million such stars have blown up since the Milky Way galaxy formed its first stars nearly four million years ago. Each explosion, he thinks, gave birth to a brood of planets not very different, except in details, from the solar system.