# How To Make an Earth with 27 Suns Work, Attempt Two: Orbital Stability

This is the continuation of a thread of related posts on a hypothetical alternate universe/Light Plane.

Other posts from this thread are here: How To Make an Earth with 27 Suns Work

Radiation Levels and Effects on Planet with 27 Suns

This thread is related to this one, with modifications (hence the name, "attempt two") It is not a duplicate because the previous one was "impossible." This has been modified to try to make the hypothetical situation possible. I changed some of the physics and specifications. I also stopped editing my previous post because it would have invalidated (all) the answers.

# Background information

This is a setting in which a planet is in orbit of a star/stars in a solar system/tightly packed globular cluster with 27 suns. (Terms "sun" and "star" are used mostly interchangeably: suns is preferred because they are all very close to the planet (astronomically.)

You can manipulate what type(s) of light these suns emit : these suns can emit sub-infrared and super-gamma and anywhere in between.

A mysterious Source creates a mysteriously strong Field around the planet, which we'll call "Ex-vee" for short. XV is totally protected by this super-magnetic/magical Field, which, though small, deflects all that nasty gamma radiation and heat. A layer of reflective, metallic clouds further cool the planet down, and mountains colored dark black act as heat absorbents, capping off and sending the rippling warmth up into the higher atmosphere.

So the intensity of the light is certainly blinding, but not particularly hot. The planet is protected from the suns' radiation and heat. It has liquid water. (Though no breathable oxygen has been developed, that will come with photosynthesis, which is easy when you have the light of 27 suns on you nearly all the time.) So, all of this magnetic field/heat protection is currently being handwaved (may be covered in future questions).

Now, the size/type of the suns is up to you, but there must be at least one

1. blue giant

2. white dwarf

3. midrange star

Yay! So we have our stars. Toggle the types of light and we're halfway there.

Additionally:It's heliocentric. From what I understand, it would be best to have the largest blue star either at the center or in a binary orbit. Smaller stars orbit these stars (or are perhaps caught in between) and the even smaller stars orbit these pairs or single stars. Then finally come the planets, orbiting stars orbiting stars orbiting stars (or a single stationary star).

I figured out the distance from the inner edge of our real-world Kuiper Belt ($\approx 4$ lighthours.) Not that much. So I'm going to say, the suns must be within 1 light-day of each other and the entire group of stars must be within 1 light-month of each other. Ignore the effects of the compactness will have on the crushing gravity. The orbits must be long-term stable. I want all 27 suns to be visible from the planet (not necessarily at the same time, you manipulate as needed) and I want there to be a night (a point at which only 0-5 suns are visible, meaning 22-27 are not visible) and there should be such things as eclipses (a shadow falling on a sun, either from the planet/other planets/moons, if there are any other planets or if there are any moons.) You may insert a white hole of any mass at any point, but only one. It cannot replace one of the suns. There must be all 27 in addition to the white hole, if added.

### As For How It Formed And How Long It Must Last:

This is kind of a tough one to explain. Suffice it to say (hopefully) that the suns are kept alive for up to 20 billion years, even the giant blue star. A highly technological society and the fact that this is a "light plane" fuel the stars with enough energy to keep them alive for a very, very long time. (Please suspend disbelief.)

They also (sorry for making you wince, astronomers out there) formed very very very unimaginably fast. Like, in a couple thousand years. Some all-powerful entity (read: the author) commanded it to happen. Now we have super-healthy, long-lasting stars that formed very quickly and settled into their ideal orbits. Rocks smash together, etc etc, and our dear XV forms and settles into an orbit, orbiting one (or two) stars, each of which are orbiting other larger stars etc.

NO black holes(NO exceptions). You MAY insert a white hole(s) as needed. NO instability. NO supernovae. NO collisions (well, apart from asteroids/comets/whatevers that would get vaporized by XV's Field or the sun system's heat). The suns must indeed be suns! No fakes. 27 suns (though you may add additional non-stellar objects to make it work, (planets/moons/asteroids, NOT BLACK HOLES or gravitational/stellar anomalies!))

Oops! I just used the last atom of unobtanium in this universe and my hand(wavium) just fell off from all the handwaving to manipulate light and star lifetimes, heat, etc. Now it's up to YOU to figure this out (without any "magic"):

How would this work?

You need to figure out:

What orbits the stars follow/how they orbit each other. How XV orbits the star(s). (Not tidally locked, please.) Does XV have any moon(s)? Are there other planets in this solar system? (these are for stability). Things like seasons, day lengths, eclipses, sunrises/set times etc. will be left for another post.

There must be a long-term stability. If it helps, you can manipulate gravity so that the stable orbit "freezes" for the long term. I also need to know if this system needs any other planets to work and if it can work with any other planets. Same with a moon or moons.

Finally:

# To summarize the Ultimate Question

What would it look like? What stars would orbit rough stars? I don't need an informative diagram. Just draw/show me a rough outline: Star 1 (blue star) is here, Star 7 orbits Star 9 which orbits Star one, during their orbits Star 16 is at the position opposite of Star 24, XV orbits Star ___ which orbits ___ at __ position...

Thank you to all in the Sandbox who helped me develop this question, especially @Renan and @Secespitus.

In accordance with this meta post, please do not use magic as an answer (handwavium is already used enough that I want a fairly science-based answer to this, please.)

• Will you please remove the "reality-check" tag - it's just farcical with this question's extreme "ignore the handwavium" approach. This just isn't realistically possible. – StephenG Jun 5 '18 at 6:49
• Even if the stars were in a tightly packed cluster, the planet presumably is just in orbit around one of them. The other stars in the cluster would, relatively speaking, be so much further away, that they couldn't reasonably be classified as suns. At best, they may appear as unusually bright stars. I can't see any astronomically plausible way to make this scenario work. – user1751825 Jun 5 '18 at 7:41
• You have so much technological magic and magical technology going on, honestly I don't think it matters how you make this. Make it however you want it to be, and any belief suspenders that are strong enough for everything else can easily handle this too. – Gene Jun 5 '18 at 23:02
• @StephenG The text of the reality-check tag is: "Asks if a given concept is realistic in a given context. Answers should say yes or no, with supporting info. Contrast with: science-based and hard-science tags. This tag should never be the only tag on a question, because this tag frames how a question should be answered, not the topic." You might consider removing your comment. – a4android Jun 7 '18 at 13:44
• Out of curiosity, why do you need precisely 27 suns? Isn't it simpler to tell us what you want as a result on your planet, and we try to retro-ingeneer it? – kikirex Jun 7 '18 at 14:34

Looking at some real examples of quaternary and larger star systems, all of the stable configurations appear to be in pairs. Take Castor, for instance, which is composed of six (known) stars: Aa, Ab, Ba, Bb, Ca, and Cb. Each pair, such as Aa and Ab, orbits fairly close together, like a normal binary star. Then the A and B pairs themselves orbit each other, exactly as if each pair was a single body. Then the C pair (which is itself two stars in a tight binary orbit) orbits the rest of the system as a whole. This produces an orbital chart that looks something like a championship bracket.

Most trinary star systems have the same structure, such as the familiar case of Alpha Centauri (A and B orbiting together, and Proxima as a distant companion). Trinaries where all three stars orbit one another at close range are normally unstable.

This suggests that, if a 27-body system exists, it will have a similar (but much larger) structure, with pairs of stars orbiting in close proximity, and those pairs orbiting together with other pairs, and so on. (At least five levels deep.) However, that poses its own problems. Taking Castor as an example again, the C pair orbits about 5,000 AU from the rest of the system. I wasn't able to find a particular "standard" distance in a hierarchical orbit like this, but it makes sense that it would have to be distant, or else the pairs' components would start to interact with one another and it all breaks down. There's also a point where it stops being a star system because they're just too attenuated - there are arguments that Proxima Centauri (at 13,000 AU from Alpha Centauri A/B) is not really gravitationally bound to the others and therefore doesn't count.

XV could basically orbit whichever of the stars you feel like. From thousands of AU away, the others would just be visible as stars, or at the outside, as planets. Telescopes might be able to resolve them as more than points of light, allowing them to have e.g. transits on the other stars, but not eclipses, and they wouldn't be bright enough to affect e.g. the day/night cycle or XV's overall heat budget. At best, one extra pair might be closer to its primary/primaries, but no more than that.

Of course, XV could be in a circumbinary orbit around one of these pairs (or it could be around a singleton; a 27-star system of course has at least one odd star out, and might have more). If it's in orbit around a binary it would see all the normal binary-star effects like eclipses of one star by the other.

• It seems that your model postulates four sets of Castor-like triplets of binary stars with a 27th star, perhaps, orbiting the four "Castors". If, as the question suggests the whole structure is within one light month, this is a plausible notion. Confirming its orbital mechanics may be tricky. Of course, most of the 27 suns will look like stars except for those the planet orbits. Well done. – a4android Jun 5 '18 at 13:31
• That's pretty cool! – Garret Gang Jun 5 '18 at 21:21
• @a4android I have no idea what you just said, but it sounded cool. – Reactgular Jun 5 '18 at 23:06
• @cgTag Aaagghh!! I thought I was clear. It seems I got that wrong. The real meat of the argument is in Cadence's answer (which is cool). My comment was intended to see if I understood it properly. I hope I did. Glad to know my comment sounded cool. – a4android Jun 6 '18 at 7:13
• If you look at this chart of a real-world septenary (7) star system ( en.wikipedia.org/wiki/Nu_Scorpii#Multiplicity ), it breaks down into exactly this kind of competition bracket. – SRM Jun 9 '18 at 5:36

The magic phrase you want to Google is "N-body choreography". A choreography is a special kind of orbit where the items chase each other instead of orbiting around each other (see the "competition hierarchy" mentioned in Cadence's excellent answer). I found someone who had worked out a stable orbit pattern for 21 bodies: That's not the 27 you were hoping for, but it might get you started. Now, that 21 pattern is Newtonian gravity... may not hold once General Relativity gets involved (the comments on the video don't say).

You say your system was artificially constructed. That's good because the probability of one of these choreographies forming naturally is so slim that, well...

Are there any figure eight orbits in the universe? Douglas Heggie, 2000 together with Piotr Hut performed numerical experiments by throwing binary pairs, all masses equal, at each other and seeing how often figure eight solutions formed. On the basis of these numerical experiments and other considerations, they estimate the number of figure eight orbits in the observable universe lies in the range of 1 to 100. One does not expect to see any of the other choreographies due to their dynamical instability. Thus choreographies are of extremely limited interest in astronomy.

(From Scholarpedia)

The fun part about choreographies is that, apparently, we can prove that high-order choreographies must exist, but we have almost no ability to actually identify one. So you could simply assert in your story, "The 27 suns existed in a 27-body choreography established by the Builders," and no one could gainsay you as long as you never went into detail about what the mechanics were.

There is a simple but apparently improbable way to construct such system of twenty-seven suns. Where the planet is quite straight forward, it must orbit only one sun. One of the three midrange stars, which suggests it would be either K or M star, and possibly even G class star.

There would have to be a high-mass object at the centre of the entire of twenty-seven suns. This arrangement is similar to the high-velocity stars orbiting the supermassive black hole at the centre of our galaxy.

Now one of the conditions for the fictional world depicted in this question excludes black holes. However, it does permit white holes. Fortunately, this makes the proposed arrangement workable. A white hole will also be a gravitationally massive object.

Like black holes, white holes have properties like mass, charge, and angular momentum. They attract matter like any other mass, but objects falling towards a white hole would never actually reach the white hole's event horizon.

This answer's proposed model for a system of twenty-seven (27) suns consists of a central high-mass object. Its mass will comparable with a supermassive black hole, but in this case that high-mass object will be a supermassive white hole. All twenty-seven suns will orbit the white hole like the planets of a solar system. The entire system of suns can be arranged in the 3:2 orbital resonance pattern. This will guarantee the stability of all twenty-seven suns.

The planet can be located orbiting a suitable star, where its surface conditions can be suitable for life.

The orbital velocities of the twenty-seven suns will be high. Probably, several times that of the Earth's around the central mass. Since the Earth has an orbital velocity of 30 km/s, they could have orbital velocities four or five times greater.

XV will just orbit one of the stars. Does it have a moon or moons? Possibly, but the high velocities of objects orbiting the central mass may make it difficult for planets to gravitationally capture matter to either become moons or to allow the formation of moons.

The other suns will appear as extremely large and bright stars in the planet's sky. Some might be visible the hours of daylight. This is due to the fact the other suns won't be too close. It won't be like having multiple suns in the sky at the same time. Nights will be much brighter and better illuminated than those on Earth during a Full Moon.

• Regarding moons, couldn't a large object impact possibly spall off enough matter from the still-forming XV to accrete into a moon? – Doktor J Oct 25 '18 at 14:59
• @DoktorJ So you're suggesting a moon forming in a similar manner to Earth's, and, yes, that's quite possible. I guess I was being pessimistic because of stuff flying around in the system as whole at high velocities. – a4android Oct 26 '18 at 1:42

There's another possibility here, which seems to have been overlooked in the other answers, and which may be closer to the author's original intent. The sizes of stars can vary tremendously, from 7.5% of our sun's mass to 35,000%. This is a bigger range than the difference between Jupiter and our sun. So put one enormous blue giant in the center, and let it be orbited by 26 much smaller red dwarves. Although there may not be a plausible way for such a system to form, it should be perfectly stable. It also has the interesting possibility that, if the planet in question orbits around one of the mid-range red dwarves, it can have two suns (one red and one blue) of nearly equal apparent magnitude, as well as 25 others of various relative intensities, which wax and wane on timescales varying from seasonal to millennial.