Does anyone know when a gas giant planet that orbits very close to its star was first used in science fiction? The first one was discovered in 1995 and no planet formation theory predicted it (according to the discovery team). Thus, I'm wondering if the first use in fiction pre-dates the discovery or not.
An early example might be planet Thett from John Campbells "Invaders from the Infinite" (serialized in 1934, published as novel in the early 1960s). While Thetts distance to its sun is given as 4,5 billion miles, its sun is described as having a diameter of six hundred and fifty million miles, so in relation the orbit seems rather close. In fact it is specifically mentioned that
even from the billions of miles of distance that its planet revolved, the disc was enormous, a titanic disc of dull red flame.
Thett itself is described thusly:
The planet's atmosphere stretched out tens of thousands of miles into space, and under the enormous gravitational acceleration of the tremendous mass of that planet, it was near the surface a blanket dense as water. [...] And such an atmosphere! At a temperature of almost exactly 360 degrees centigrade, there was no liquid water on the planet, naturally.[...] But--there were no guns on this world. A man could throw a stone perhaps a short distance, but when a gravitational acceleration of more than a half a mile per second acted on it, and it was hurled through an atmosphere dense as water--what chance was there for a long range ?
In another part of the book Thetts gravity is described as being so high that it affects geometry, so despite was he believed himself Campbell did not really convey scientific accuracy. But it rather seems that a kind of hot Jupiter is what he had in mind.
The earliest such planet I'm aware of is Goldblatt's World, part of the setting of Larry Niven's The Integral Trees. It was first published in the SF magazine Analog in 1983. Goldblatt's World is a gas giant orbiting just outside the Roche limit of its neutron star primary, the planet's atmosphere pulled into a million kilometer wide torus around the star. The central portion of the torus (and thus Goldblatt's World) is close enough to the star's warmth to develop an oxygen-carbon based ecosystem over the course of a billion years, and to sustain human life.
He remembered reviewing and updating his files on gas torus mechanics. Two planets circled wide around the twin stars: Jupiter-style gas giants with no moons. The old supernova must have blasted away anything smaller.
A body did circle the neutron star. One limb of the Smoke Ring was curdled, a distorted whirlpool of storm. Hidden within was a core of rock and metals at 2.5 Earth masses. There was some oxygen and some water vapor in its thick, hot atmosphere. Goldblatt's World was tidally locked, and uninhabitable. Strip away its atmosphere and it might have harbored Earthly life--- but its atmosphere was tremendous, dwindling indefinitely into the Smoke Ring itself.
So Goldblatt's World is the lone surviving planet of a binary star system that evolved into the classic type Ia supernova scenario, leaving a neutron star, the rocky core of Goldblatt's World and a torus of gas surrounding the planet and the star.