The first step of building any setting is figuring out where the action is going to take place. For ENIGMATIC, I've already decided on the area of space covering a sector sized area around Earth. So, I know where the stars are, and since we're working with actual data, those details can be looked up rather than generated for the most part.
One of the things that I wanted to incorporate from the beginning was some detail about known exoplanets, which I'm discovering is a daunting task - more are discovered every day, and more effort is being made to detect them. Currently, we've found on the order of 2,100 planets in 1342 system, including 509 multiple planet systems. That's a lot of data, and it's growing all the time. Happily, I can cull it down to data for 110 stars close enough to show on the map.
9 14,400 km - 1.125 Earth
A 16,000 km - 1.25 Earth
B 17,600 km - 1.375 Earth
C 19,200 km - 1.5 Earth
D 20,800 km - 1.625 Earth
E 22,400 km - 1.75 Earth
F 24,000 km - 1.875 Earth
G 25,600 km - 2x Earth
H Neptune size - 2x to 6x Earth
J Jupiter size - >6x Earth
Digging into the information we have, the most commonly known data is the mass of the planet and quite often the orbit it occupies. That's enough to get started, if a couple of assumptions are made. Since Cepheus Engine doesn't track density, we can assume that radius and mass scale linearly for my purposes. That assumption is probably wrong, but we'll start with that. Looking at a lot of the exoplanet data, many are up to 2x the size of the Earth. The problem is, the planet size table in CE only goes up to size A, or 16,000 km. Since the UWP can handle expansion, we end up with something like thisH and J will essentially cover small and large gas giants (something lacking from the UWP anyway). Obviously, H and J won't be used for main worlds, but since I plan on having UWPs for all of the planets in a system, it's worth having a tag for it.
I was toying with a much shorter table, essentially 3 entries - one for generic Super-Earths, one for Neptune sized, and one for Jupiter sized. A quick Google search suggested humans could live on a world with as much as 3-g gravity, but it would be definitely unpleasant, and probably wouldn't happen. But, having access to a more definitive set of ratings gives referees the option to send their unsuspecting players down onto a 3-g world to retrieve the mcguffin, and that fits in with the grittier, more dangerous feel I'm going for with ENIGMATIC.
So, I've got the radius figured out, and Richard Hazelwood on the CE Facebook page mentioned that density does NOT scale linearly with size, so mass and gravity won't either. Since the CE size table includes gravity, I'll have to do some research into how density does scale, and figure out the respective gravity for each entry. Look for part 2 of this post in the near future. See you soon!