Nature asks the question raised by University of Florida astronomers: how did Roddenberry know there’d be a hot, heavy, but Earth-like planet orbiting 40 Eridani?:
Bo Ma at the University of Florida in Gainesville and his colleagues used a 1.3-metre telescope in Arizona to find the planet, which is about 8.5 times the mass of Earth and orbits its star every 42 days. That star, known as HD 26965 or 40 Eridani, is roughly the same age as the Sun, but slightly cooler and less massive. Star Trek creator Gene Roddenberry wrote in 1991 that 40 Eridani is Vulcan’s home star.
Like Earth, the planet may have a gassy atmosphere. However, it is a little too close to its star for life as we know it to prosper.