Bit of a random question, but hypothetically could four terrestrial planets form in the goldilocks zone of a star? Or would their relatively close orbits screw with each other?
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Bit of a random question, but hypothetically could four terrestrial planets form in the goldilocks zone of a star? Or would their relatively close orbits screw with each other?
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Seems like kind of a stretch. Any star large enough to have a sufficiently wide green zone would not last long enough on the main sequence to allow life to develop.
Sharing the green zone through orbital resonances would likely involve inhospitable elliptical orbits. The mass limits on the Trojan points also rules out that approach to sharing an orbit.
A Jovian planet with terrestrial-sized moons might be more likely if you can work out the migration.
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What precisely are these mass limits?Originally Posted by baric
Order of Kilopi
Another possibility, maybe, is two sets of double-planets (like Pluto/Charon, but scaled up to Earth/Moon level). One pair is at the inner edge of the zone; the other pair is at the outer edge of the zone.
Also, you might be able to have a pair of companion planets in horseshoe orbits about each other. As far as exotic fictional settings go, these would be really neat--the planets spend most of the time far apart but every few centuries they get relatively close to each other. (Or every few decades, depending on the exact orbital details.)
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The mass in either L4/L5 Langrange point can be no more than 1/25th of the mass of the main body. That means you'd need a gas giant as the main orbiting body.
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Yes. And you could have it.
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Think about this for a minute.
You'd need a gas giant to form outside the frost line, then migrate into the green zone and stop. THEN you need enough remaining material in the nebula to form terrestrial planets in the Lagrange limits.
The 1:25 ratio is an absolute minimum. The masses that we see an our system's L4/L5 points is far, far smaller than that ratio would suggest. In addition, they seem to be more akin to collections of rubble rather than cohesive rocky bodies.
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Yes, Solar System has 1:1050. 1:25 would be in brown dwarf range.
Which do exist.
Solar System is highly unrepresentative. No hot Jupiters or hot Uranuses, no highly elliptic orbits, no orbital resonances...
A massive Trojan would not show up in Doppler shift, nor in astrometry. It can be detected only by direct observation, whether by eclipse, reflected or emitted light.
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The mass of the planet, along with the mass of the Lagrangian planets can be no more than about 1/25 the mass of the Sun. It's totally possible for Earth to share its orbit with 2 more Earths, one in L4 and one in L5, as 3MEarth<<MSun/25.
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Why stop at two when you can five?
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To have 4 earth like planets requires unlikely conditions for long term stability, such as very circular orbits. How about a neutron star or white dwarf that has been cooling for about 13 billion years, so the photosphere temperature is not much higher than our Sun. All 4 planets would be Mercury distance or closer because of the small disk size. But the gravity is higher than Mercury experiences at this distance so the orbits should be very stable, especially if there are no other high mass planets closer than one AU. There needs to be negligible accretion disk and very little matter falling into the white dwarf or neutron star. A quark star, if there are any, might work also. Neil
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As others have replied it's borderline, I guess you can fudge it with a double star system with each 2 planets in their respective habitable zones
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