My study area lies on Tekuo, an Earth-like planet inhabited by sentient hominids. Tekuo is one of six planets orbiting a type G6V sun, known as Ayu. The first three planets in the system are rocky. Tekuo is the second of these. Three gas giants lie in the outer part of the system. Tekuo lies in the habitable zone.
Ayu has 0.97 times the mass of our sun, Sol. The luminosity of a body is the cube of its mass, which should make Ayu 0.91 times as luminous as Sol (though Wikipedia says a G6V star is 0.79 times as luminous as Sol).
Ayu may be smaller, but Tekuo is proportionally nearer to it than Earth is to Sol. The distance between them is the square root of Ayu’s luminosity, i.e. 0.955 AU. At this distance, Tekuo receives as much light from Ayu as Earth does from Sol.
The time it takes a planet to orbit a sun is the square root of the cube of the distance between them. So Tekuo’s year lasts for 352.7 Earth days. A day on Tekuo however, lasts only 23 hours and 46 minutes. A year therefore lasts for 356.33 local days.
The radius of Tekuo is around 6,052 km, about the same as Venus. This is equivalent to 0.95 times the radius of Earth.
Earth has a single moon, 0.0123 times its size. The Moon orbits Earth in 27.3 days. Tekuo also has a single moon, called Sũto. Sũto is around 0.011 times the size of Tekuo.
As it is nearer to Tekuo than the Moon is to Earth, Sũto appears bigger than our moon when viewed from its host planet. It causes a greater tidal range and orbits Tekuo in 25.5 days.
I’ve rethought the year and the day to make sure the planet is as warm as Earth despite having a smaller sun.
I’ve added in the length of the Tekuan day, now I’m confident I can do so. I am now satisfied that the length of the day can be set independently of the other factors discussed above. It depends in part on some of the factors discussed above but also on the speed at which the planet is moving. This has, conveniently, not been mentioned.
Ayu is now back as Ayu and has been for a while.
07.07.19: I now have a full vision of the solar system. Tekuo is now the second planet out instead of the third. It only has one moon now, instead of two. This makes the calendar much easier!
There are also six planets instead of seven. The system felt a little crowded before.