See also: Kaywell

Name: Limnel, "The Limb of Kaywell," Irgaster's Star.

Designation: Kaywell C

Discovered (Kerbin): Spectroscopic Binary.

Rediscovered (Mesbin): Telescopic Projection.

Limnel was discovered by the first sungazing astronomer, Irgaster von Kerman, when he decided that it couldn't be THAT bad if one stared into the Sun for a long period of time. He noticed that there seemed to be a bright spot on the limb of Kaywell, and dubbed it "The Limb of Kaywell," which was eventually shortened into Limnel. He went blind in his small eye, but using a telescope as a projector he was eventually able to take more precise measurements of Limnel, and published his findings in the scientific journal "Space And Some Things To Find In It." The revelation that Kaywell was actually two stars caused some fuss in the astronomical community, and it is still debated whether or not "Kaywell" refers to the pair of stars or to just the larger of the two. Limnel is also an M1Ve red dwarf flare star, periodically releasing bright UV flares which make it much brighter, and one of the earliest duties of the Space Program had been determining the space weather produced by the interacting magnetic fields of the two stars.

Physical Properties

Use of "solar" in this case really means a 1/10th scale, 1/100th mass, 1/100th luminosity ksp-scale Sol, not Kerbol and not the real-scale Sun.

• Radius = 40,400,000 meters. 0.5807 Solar Radii.
• Mass = 1.054 x 10^28 kg. 0.53 Solar Masses.
• Luminosity = 0.072 Solar Luminosities
• Surface Temperature = 4,020 Kelvins.
• Star Color = RGB(255,206,167)
• Rotation Period = 25,453 seconds. (7 hours, 4 minutes, 13 seconds.)
• Spectral Type = M1Ve
• Age = 2.0 Billion Years.
• Main Sequence Lifetime = 48.9 Billion Years.
• Metallicity [Fe/H] = 0.66696 dex. (Approximately 4.6 times as metal rich as the Sun)

Orbital Elements

*The Semi-Major-Axis of Limnel is different depending upon whether you are measuring from Kaywell or from the Kaywell/Limnel Barycenter. All other orbital elements are the same between the two reference frames, and are the same as Kaywell's barycentric elements as well except for Argument of Periapsis, which is exactly 180° more.

• Parent Body: Kaywell

• Semi Major Axis: 333,422,925 m

• Parent Body: Kaywell/Limnel Barycenter

• SemiMajorAxis: 229,472,992 m

• Orbital Period: 25,453 seconds. (7 hours, 4 minutes, 13 seconds.)

• Eccentricity: 0.00001

• Inclination: 0.01°

• Argument of Periapsis: 358°

• Longitude of Ascending Node: 322°

• Mean Anomaly at Epoch: -107°

Why does Limnel exist?

This is an out-of-universe answer

When I invented Kaywell, I thought I had invented a realistic star, the goal having been to make it more luminous that most stars of its mass, so that I could put Mesbin and Derbin as far apart as I could. I thought, for a long time, that I had succeeded. The WW version 0.11 was meant to be the last version before 1.0. In the reddit post announcing the update, a player commented that Kaywell wasn't luminous enough. I told them they were wrong.

They were right. It turned out that, somehow, my star was MUCH less luminous than it should have been--closer to 6-10 Lsol rather than 2.52. For a long time after I struggled with trying to reconcile my star--and the very much already finished system--with the unrealistic mass/luminosity ratio. Most people would probably never notice... but it would always nag at me. I came up with several different possible ways to change Kaywell, and sat on those for a month or so.

I had resolved to keep Kaywell as it was, unrealistic, until I remade the system from scratch when KSP2 was released. Then KSP2 got delayed, and I realized Whirligig World would have perhaps another full year of relevance. So I decided to go ahead and fix the star. I made it more luminous, and moved all the orbits out. And finally Kaywell was realistic, and it didn't even take that much effort!

But there was one small problem: those new orbits sucked. They were almost three times slower, which would have slowed gameplay down to a crawl, ruined any missions planned or in progress to the planets between the updates, and it just wouldn't have been fun. I felt defeated. Here it was, a more realistic system that was worse than the original. I have long maintained (and generally still do) that realism doesn't detract from gameplay in most cases, and can actively produce interesting situations. But extremely slow orbits isn't interesting, it's just boring.

So I undid my changes, and resolved yet again that yes, I really would keep Kaywell as it was.

Then I woke up with a start on December 1st 2019. "MAKE IT BINARY!" I said, and I made a note of it to deal with later. The reasoning is that two main sequence stars of a given total mass will almost always have a lower luminosity than a single star of the same mass. So all I had to do was find the right mass and luminosity ratios and do a lot of last minute work splicing an entire star into the game's configs and lore.

And so Limnel is born.