Hay Cmdrs,
I have been trying to understand the orbital mechanics of SYMUEFE XR-H D11-102 1 and its moons. I know there is an Orrery at Elite Galaxy Online but none of my browsers seem to be able to handle it...plus it's good to try and understand the raw numbers anyway.
In the table below I lay out all the data for the Planet 1 system but I'm just going to focus on Planet 1 and Moon 1B (ruins moon) and 1Ba (moon of ruins moon):
Orbital Mechanics | Planet 1 | Moon 1A | Moon 1B | Moon 1Ba | Moon 1C | Moon 1D | Moon 1E |
Orbital Period | 617.7 D | 2.9 D | 6.9 D | 0.3 D | 0.4 D | 0.4 D | 34.7 D |
Semi-Major Axis | 1.60 AU | 0.01 AU | 0.02 AU | 0.00 AU | 0.00 AU | 0.00 AU | 0.05 AU |
Orbital Eccentricity | 0.0003 | 0.0003 | 0.0005 | 0.0000 | 0.1444 | 0.1444 | 0.0000 |
Orbital Inclination | -0.11 deg | 0.35 deg | -0.43 deg | -6.8 deg | -0.69 deg | -0.69 deg | -76.33 deg |
Arg of Periapsis | 288.71 deg | 110.10 deg | 6.67 deg | 131.04 deg | 244.96 deg | 64.96 deg | 36.28 deg |
Rotational Period | | 2.9 D (TL) | -6.9 D | 0.3 D (TL) | -0.9 D | 0.5 D (TL) | 34.7 D (TL) |
Axial Tilt | | -25.14 deg | -94.91 deg | 5.21 deg | 121.90 deg | -1.21 deg | 23.01 deg |
Feel free to correct my interpretations of the numbers below as I am new to orbital mechanics.
Planet 1 has an orbital eccentricity of 0.0003 which means its orbit is very close to circular with a radius of 1.6 AU. Its orbital inclination is -0.11 degrees which means its orbit around the main star is very close to the ecliptic plane. It takes 617.7 earth days to orbit the main star.
Moon 1B is where things get interesting. Its orbital period (year) is 6.9 earth days and its rotational period is -6.9 earth days, suggesting its day is the same length as its year except it rotates upon its axis in the opposite direction to which it rotates around Planet 1. Its orbital eccentricity is 0.0005 so very close to circular and orbital inclination is -0.43 degrees so very close to Planet 1's ecliptic plane. However, Moon 1B's axial tilt is -94.91 degrees which means it has essentially "fallen over" .
If we assume that its axial tilt is -90 degrees this means that its axis is lying within its ecliptic plane. My confusion comes in when trying to figure out whether this moon is moving around Planet 1 with north or south pointing in the direction of travel, or whether it is "rolling" around its orbit with its axis perpendicular to the direction of travel...or something in between these two possibilities. If the moon is "rolling" around its orbit, this would mean that one of its hemispheres (north or south) would perpetually point to planet 1, essentially being tidally locked without be officially tidally locked.
Are there any numbers in the table which tell us which of the above possibilities is true or do we have to make observations from the moon surface to determine this?
Another interesting feature of this system is the moon of moon 1B (1Ba). It orbits moon 1B in 0.3 earth days, which means it goes around moon 1B three times in an earth day but goes around moon 1B 23 times in a moon 1B day/year. It is orbiting crazy fast and is tidally locked to boot! Otherwise its orbit around 1B is close to circular (and very close). It does have a small amount of wobble above and below moon 1B's ecliptic plane (-6.8 degrees).
Given that moon 1Ba is orbiting moon 1B around its ecliptic, knowing the orientation of moon 1B around Planet 1 (as discussed above) is important to know. If moon 1B is orbiting Planet 1 with its north/south axis point in the direction of travel, this would mean that moon 1Ba is orbiting around the orbit line. If moon 1B is "rolling" around its orbit with its axis perpendicular to the direction of travel then moon 1Ba would be rotating in the direction of travel or away from the direction of travel.
I guess the real question is, even if we understand the above information, will it make a difference to understand the ruins any better? I think it will help understand how the ruins interact with the main star of the system...the light dark cycle for the ruins.
Apologies for the ramble...just trying to get my thoughts down about this. I appreciate any corrections or clarifications.
Frawd