I've read through several in-print lists of Isaac Asimov short stories, and have been unable to identify one short story. It may have been published in THE SATURDAY EVENING POST around 1976. In the story, a male astronaut rose from the Earth to save humans aboard an orbiting space station. Because he saved them from the effects of an unexpected solar storm, he was considered a hero by others. I do not know if this situation was the core of the story or a peripheral, brief bit of background (a story within a story). By the by, I can't find this story in any of the Asimov reprint collections, but that doesn't mean that this "hard" SF story hasn't been reprinted in book form.
Possibly Light Verse, published in The Saturday Evening Post, September / October, 1973.
If so, the (very) brief mention you're thinking of is:
The very last person anyone would expect to be a murderer was Mrs. Avis Lardner. Widow of the great astronaut-martyr, she was a philanthropist, an art collector, a hostess extraordinary, and, everyone agreed, an artistic genius. But above all, she was the gentlest and kindest human being one could imagine.
Her husband, William J. Lardner, died, as we all know, of the effects of radiation from a solar flare, after he had deliberately remained in space so that a passenger vessel might make it safely to Space Station 5.