‘The Star’ by Arthur C. Clarke
We came slowly in through the concentric shells of gas that had been blasted out six thousand years before, yet were expanding still. They where immensely hot, radiating even now with a fierce violet light, but were far too tenuous to do us any damage. When the star had exploded, its outer layers had been driven upward with such speed that they had escaped completely from its gravitational field. Now they formed a hollow shell large enough to engulf a thousand solar systems, and at its center burned the tiny, fantastic object which the star had now become – a White Dwarf, smaller than the Earth, yet weighing a million times as much.
This is the sort of thing hard SF is meant to be about and Clarke does it very well. At the same time though, he is happy to just handwave away the speed of light with “the secret of the Transfinite Drive”. I can imagine fewer things duller than getting into a debate about whether FTL travel should be consistent with hard SF but I think this is worth pointing out.
The story itself unfortunately hinges on a silly punchline that is adolescent and hack-ish. To his credit, Clarke treats this with great seriousness but this only makes it even more baffling that he constructed the story around a cheap joke. The reaction of the characters to the revelation is no more plausible than the existence of a Transfinite Drive either.