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_Augustus_

Nemesis, Tyche, and/or the Hills Cloud Super-Earths: Real or unreal?

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I am starting this thread to collect everyone's opinion on this rarely-discussed topic.

My personal opinion is that at least one of these exists.

The Hills-Cloud Super-Earths could be one of these following:

*Mars-sized object at up to a few hundred AU

*One or two Super-Earths at up to 1000 AU

*A small gas giant at up to 1500 AU

Also, WISE only ruled out Tyche/a brown dwarf Nemesis within 0.5 or so light-years. Sol's SOI extends about 6 times that. Nemesis could be within 2.5 light-years of us, or simply be an already-discovered red dwarf in some obscure star catalog that hasn't had it's parallax measured.

Edited by _Augustus_

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WISE didn't see anything like Tyche out there. Not really conclusive, but there you go.

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WISE ruled out a large gas giant such as Tyche, which was supposed to be in the inner Oort Cloud. A Super-Earth (smaller than Uranus/Neptune) there would probably not have been seen.

Nemesis (a red or brown dwarf) would have been even more visible in that kind of survey, since it would put out much more heat.

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WISE ruled out a large gas giant such as Tyche, which was supposed to be in the inner Oort Cloud. A Super-Earth (smaller than Uranus/Neptune) there would probably not have been seen.

Nemesis (a red or brown dwarf) would have been even more visible in that kind of survey, since it would put out much more heat.

They only ruled out a brown dwarf/large gas giant within 0.5 or so light-years. Sol's SOI extends out 3 light-years, and the Oort cloud extends 1.5 light-years. Tyche could be within 1 light-year and Nemesis within 2.5.

There are also a few red dwarfs with no measured parallax, so one of them may be Nemesis.

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Even if one exists, we'll never go there until we get FTL. If at all. So it matters little.

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Even if one exists, we'll never go there until we get FTL. If at all. So it matters little.

It kind of does matter, especially considering this:

1. 1000 AU is nothing compared to a few light-years.

2. Nemesis, if it exists, will come within 0.5 or so light-years within 15 million years

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It kind of does matter, especially considering this:

1. 1000 AU is nothing compared to a few light-years.

2. Nemesis, if it exists, will come within 0.5 or so light-years within 15 million years

Humans will likely be gone within 15 million years, by some catastrophe or other.

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Humans will likely be gone within 15 million years, by some catastrophe or other.

Naaah, we'll probably quarantine the solar system, let Earth return to it's natural state, and leave some robots behind on Europa.

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It kind of does matter, especially considering this:

1. 1000 AU is nothing compared to a few light-years.

2. Nemesis, if it exists, will come within 0.5 or so light-years within 15 million years

It takes an immense amount of time to get anywhere beyond Saturn, let alone beyond Pluto ( which is only about 40 AU from the Sun). And all the while you're slowing down. So it takes centuries to get there.

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The orbital period of Pluto is ~250 years. The orbital period of an object orders of magnitude farther away, will be in the hundreds of millenia. Exploration by spacecraft to determine properties of the celestial body will be impossible.

Even New Horizons, a craft that's going Pluto, won't get anywhere near it.

The Voyager probes, some of the fastest objects ever built, are 130 AU away at most, after DECADES of travel at many kilometers a second. Study of any objects beyond Pluto will have to wait, for a very long time.

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Study of any objects beyond Pluto will have to wait, for a very long time.

I was meaning study as in, look at it with telescopes. We can study objects way farther out (generally way bigger too, granted) than any of those planets could be. Orbiting them, or flying past them will have to wait certainly, but we can study them as soon as we know if they exist/where they are.

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the true is that it can be planets so big out there but far as 1000 AU that are almost impossible to detect. We would need to know the perfect location to detect them.

Is highly unlikely that such planet has been in our solar system and then escape due "x encounters". Or is a wanderer planet from another star system.

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Here's the thing:

Our Sun has a SoI that's pretty large. However, if you're any further than about a light-year out, it is very difficult for a smaller body to orbit the Sun consistently and for long periods of time.

This is because the SoI of objects doesn't work quite like it does in KSP. Instead of having only one object pulling on any given space rock, there are many different objects exerting their gravitational pull. Some of them would have a larger amount of pull than others.

Now, consider a space rock orbiting at about 1 AU.

A star, with about one solar mass, passes by our Sun at a distance of 2 AU. This is far from unusual: Our sun has many celestial neighbors, and they sometimes get rather close. And, after all, this planet has spent four billion years out there.

As the star passes, nobody really cares very much. Any inner planets are deep inside the Sun's gravity well. Their orbits will change very, very subtly, but it's no cause for alarm.

That outer planet, though? If it gets too close to that star, its orbit will be significantly disturbed. It may enter a highly elliptical trajectory around our Sun, it may be ejected from our Solar System, or it may even fall into orbit around the other star, if it's lucky.

Saying that such a planet could remain in orbit around our Sun for billions of years, on a relatively undisturbed path? That's a little unlikely.

...and saying that things could orbit the Sun if they were anywhere in the Sun's sphere of influence makes me think that you're subscribing a bit too much to the simpler physics of KSP. Not that there's anything wrong with KSP... it's just that the real world is a bit different.

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if there were anything beyond pluto close to earth size, we would have spotted them by now, I think there is a crowded belt there with pluto-mars size rocks. They should be responsible for the occasional visitor comets from oort cloud and small irregularities on outer planet orbits.

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I believe the net is, at it were, closing with WISE and other surveys. Of course there's a limit to how far out an object could orbit and not be perturbed by passing stars.

As for how we'd study it, well ion drive probe. Dawn packs something like 10 km/s of delta-V and its engines have proven highly reliable. No particular reason a probe couldn't have more.

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@UpsilonAerospace

It does not need to have an orbit to be there.

It can be in escape trajectory (very slow) or in aproximation to the solar system (also very slow)

At those distances with low speed, it may take hundred of thousands of years to have an encounter.

Also even at 1000 au, the sun is still the closest star by far, an orbit is unlikely but possible.

@yafeshan

Pluto is at 30 au aprox, we are talking of 1000 au.

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Voyagers 1 and 2 took 2 years to get to Jupiter. Juno, the last Jupiter mission launched, is going to take 5 years. JUICE, the next, is going to take nearly eight.

Did you follow the link? it goes to an article about pre-Voyager ideas of spacecraft to get to the outer planets, and most of those schemes would indeed take ages, possibly involve meeting up with refueling stations, and other things that we have avoided more recently. My point was that the ways we have of getting to certain locations, are not always the only ways, or the best ways.

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Did you follow the link? it goes to an article about pre-Voyager ideas of spacecraft to get to the outer planets, and most of those schemes would indeed take ages, possibly involve meeting up with refueling stations, and other things that we have avoided more recently. My point was that the ways we have of getting to certain locations, are not always the only ways, or the best ways.

If we really were lazy we could just send a Project-Orion-eqsue probe out there in just a few years.

Of course though this would require a repeal of the Partial Test Ban treaty.

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I think some solar sail proposals could get to the outer-outer solar system within a few decades too.

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Did you follow the link? it goes to an article about pre-Voyager ideas of spacecraft to get to the outer planets, and most of those schemes would indeed take ages, possibly involve meeting up with refueling stations, and other things that we have avoided more recently. My point was that the ways we have of getting to certain locations, are not always the only ways, or the best ways.

They are the cheapest ways. And what is worse they are only ways, because we do not even have better ways now, because nobody want to pay costs of building and maintaining for example huge launchers or fission reactor powered heavy ion propulsion systems. I hope that plans in USA, China and Russia would become real. However, I am not sure can any planet probe afford huge launcher or are they only for for military and national propaganda use.

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If there was a Mars or Earth sized planet out in the Oort cloud covered in coal black dust and not giving off heat, what type of equipment could detect it?

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