He's not the first to imagine life developing on a star. I remember a fanciful sci-fi story with solar creatures who couldn't even see the "dark bodies" near their home world. It has to be a good 50 years old at least.
Edit: I have not been able to find out as much as I'd like to, so I'm not entirely sure. But I think what I'm remembering is Hal Clement's story "Proof", first published in the June 1942 issue of Astounding magazine. The concept I think is plasma-based life.
Edit 2: This is the only thing close to a synopsis I've run across so far:
"Proof" (1942), Clement's first story, is actually more speculative than most of his work — and also, in a sense, reverses the premise of Iceworld. It's based around a race that lives in the solar photosphere, and that has based its civilisation on the ultra-heavy element neutronium, which periodically needs to be harvested from the sun's core. Because of the temperature, their bodies are "simply constructed: a mass of close-packed electrons — really an unimaginably dense electrostatic field, possessing quasi-solid properties — surrounded a core of neutrons, compacted to the ultimate degree." One of the characters puts forward the theory that "matter — ordinary substances like iron and calcium — might actually take on solid properties, like neutronium, under the proper conditions."
http://www.locusmag.com/Reviews/2009/10/graham-sleights-yesterdays-tomorrows.htmlFrom that, I'm fairly sure now that this is the story I read, probably in the anthology book
Where do We Go from Here? (1971), edited by Isaac Asimov. Planetary bodies were a theory to this race, which needed proof. The story proceeds along those lines, culminating in a crash against an invisible body, which happens to be Earth. To an Earth observer, this amazingly bright and hot object doesn't last long, sinking through the solid ground like a torpedoed ship at sea.
I think my brother has this book now. I'm going to have to borrow it now.