# In regards to mass and luminosity, what are those mystery stars?

Long ago (4.6 billion years, to be exact), a hyper-advanced alien civilization had created a solar system from scratch. Somehow, they had artificially prolonged the center of the solar system--a stellar binary--to last trillions of years, as long as red dwarves. But the combined mass and luminosity of the two stars indicates that neither one is a red dwarf. As a matter of fact, the combined stars are so massive and so bright that:

• The inner boundary of the habitable zone (the zone in which surface liquid water is possible) is 29 AUs from the two stars (29 times the distance from the sun to Earth) and any planet on that line with a rotation period of 36 hours would have an orbital period of 400 of these "days".
• The outer boundary of the habitable zone is roughly 152 AUs from the two stars and any planet on that line with a rotation period of 36 hours would have an orbital period of 728 of these "days".

So using the specified information above, what kinds of stars would the mystery binary be?

• A certain doctor Kepler observes that $\sqrt{(152/29)^3}$ is just about 12; or, 400 * 12 is 4800 rather than 728 -- and conversely, 728 / 12 is about 61 rather than 400. (Because the square of the orbital period is proportional with the cube of the semimajor axis.) Given that the stars exist in a universe where they have completely alien physics, the only answer is that they are, obviously, wondrously magical stars. Oct 15, 2021 at 22:15
• I'm with @AlexP, you have manufactured stars and want to know what their classification would be as if they were natural. That's kinda odd. They obviously exist in your universe and the classificaton would have been created by the very same creators. So... you tell us, what kind of stars are your mystery stars? (Said another way, what's the problem you're trying to solve, because identifying stars that violate known classifications by definition doesn't seem to be a worldbuilding problem. It feels like a storybuilding problem.)
– JBH
Oct 16, 2021 at 2:20
• Science-Based and Science-Fiction tags shouldn't be used together and have no meaning together Jun 21, 2023 at 11:01
• To create solar systems that make sense, you need to read a few introductory books on astronomy and physics, and learn how to do simple calculations using Newtonian gravity and Kepler's laws. This isn't hard math, but you do need to be able to use a calculator and put numbers into formulae correctly. The alternative is to give up on specifying numbers for anything, a la Star Wars. Giving precise numbers that are inconsistent is the worst way to write SF, and just attracts mockery and derision. Jan 11 at 20:50