# The stability of habitable planets around Binary stars

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So, I was screwing around in Universe Sandbox 2, after a couple of people were discussing the stability of habitable zones around planets around Alpha Centauri, so I placed down Alpha Centauri A/B, and separated them at a distance of 11.2 AU )I couldn't get the 11.2 by 35 something AU thing), and over the course of almost 2,000 years I stimulated Alpha Centauri Bb around both stars, around Alpha Cen B, the planet was flung out, but around Alpha Cen A, it was pretty stable, then I decided to put a planet 4 AU from both stars, Alpha Cen B had its planet slung out, but around Alpha Cen A, again, it was stable.

Now, I would've simulated it longer, but I need to go somewhere soon, so I can't, anyway, about binary's in general, how stable would various binary systems be?

Also, here's an example of a real life Tatoonie )The view would be much cooler as there's not only 2 stars, but there's also a gas giant in the sky!)

Edited by Spaceception
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If your willing to do a lot of math, look up Artifexian on YouTube. His vids give you a lot of mathematical formulae that was never taught in school to create a planetary system.

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6 hours ago, Spaceception said:

So, I was screwing around in Universe Sandbox 2, after a couple of people were discussing the stability of habitable zones around planets around Alpha Centauri, so I placed down Alpha Centauri A/B, and separated them at a distance of 11.2 AU )I couldn't get the 11.2 by 35 something AU thing), and over the course of almost 2,000 years I stimulated Alpha Centauri Bb around both stars, around Alpha Cen B, the planet was flung out, but around Alpha Cen A, it was pretty stable, then I decided to put a planet 4 AU from both stars, Alpha Cen B had its planet slung out, but around Alpha Cen A, again, it was stable.

Now, I would've simulated it longer, but I need to go somewhere soon, so I can't, anyway, about binary's in general, how stable would various binary systems be?

Also, here's an example of a real life Tatoonie )The view would be much cooler as there's not only 2 stars, but there's also a gas giant in the sky!)

But for life, which adapt to the circumstances in which they live, the question is how stable are the surface temperatures. There is stability and choas.

Because the stars are so similar in size you have to examine then in the double elliptical. Geeze you pay 25\$ for a program and it can't even do an elliptical binary, rip.

yep.

Edited by PB666
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8 hours ago, Spaceception said:

So, I was screwing around in Universe Sandbox 2, after a couple of people were discussing the stability of habitable zones around planets around Alpha Centauri, so I placed down Alpha Centauri A/B, and separated them at a distance of 11.2 AU )I couldn't get the 11.2 by 35 something AU thing), and over the course of almost 2,000 years I stimulated Alpha Centauri Bb around both stars, around Alpha Cen B, the planet was flung out, but around Alpha Cen A, it was pretty stable, then I decided to put a planet 4 AU from both stars, Alpha Cen B had its planet slung out, but around Alpha Cen A, again, it was stable.

Now, I would've simulated it longer, but I need to go somewhere soon, so I can't, anyway, about binary's in general, how stable would various binary systems be?

Also, here's an example of a real life Tatoonie )The view would be much cooler as there's not only 2 stars, but there's also a gas giant in the sky!)

From Wikipedia:

Quote

To be in the star's habitable zone, any suspected planet around Alpha Centauri A would have to be placed about 1.25 AU away [citation needed] – about halfway between the distances of Earth's orbit and Mars's orbit in the Solar System – so as to have similar planetary temperatures and conditions for liquid water to exist. For the slightly less luminous and cooler Alpha Centauri B, the habitable zone would lie closer at about 0.7 AU (100 million km), approximately the distance that Venus is from the Sun.[102][104]

The main problem with planets is not the possible orbit of a planet around Alpha Centauri A and B, that's the easy part, and is almost certainly possible. The problem is more that it would be difficult to form a planetary system via protoplanetary disk around Alpha Centauri A and B in the habitable zone.

3 hours ago, PB666 said:

But for life, which adapt to the circumstances in which they live, the question is how stable are the surface temperatures. There is stability and choas.

Because the stars are so similar in size you have to examine then in the double elliptical. Geeze you pay 25\$ for a program and it can't even do an elliptical binary, rip.

It can, it's just Spaceception doesn't know all the keyboard shortcuts.

Edited by fredinno
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There's no reason a planet couldn't be stable in a binary star system... if the stars are far enough apart from each other.  The closer the two stars are, the tighter the orbit of a planet would have to be around one of them in order to have a long-term stable orbit.

The problem with the Alpha Centauri A/B system is that the stars are relatively close together, which means that the "stability zone" around each star would be fairly small.  I don't know how big it would be, but I wouldn't be surprised if it's smaller than the inner radius of the habitable zone-- in other words, it may be that for a planet to have a stable orbit around Alpha Centauri A or B, it might have to be orbiting so close to its star that it would be too hot to be habitable.

That's quite aside from the problem of forming the planet from a protoplanetary disk in the first place, as @fredinno points out.

If you had a different binary system, where the stars are very far apart from each other (e.g. thousands of AU), I don't see any reason why each one of them couldn't have a fairly normal solar system of its own.

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See the video, the most stable habitable zone orbits are binaries that are close together within the orbit of mercury and the habitable zone begins at earth orbit and extends to Mars.

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On March 26, 2016 at 8:05 AM, Spaceception said:

So, I was screwing around in Universe Sandbox 2, after a couple of people were discussing the stability of habitable zones around planets around Alpha Centauri, so I placed down Alpha Centauri A/B, and separated them at a distance of 11.2 AU )I couldn't get the 11.2 by 35 something AU thing), and over the course of almost 2,000 years I stimulated Alpha Centauri Bb around both stars, around Alpha Cen B, the planet was flung out, but around Alpha Cen A, it was pretty stable, then I decided to put a planet 4 AU from both stars, Alpha Cen B had its planet slung out, but around Alpha Cen A, again, it was stable.

Now, I would've simulated it longer, but I need to go somewhere soon, so I can't, anyway, about binary's in general, how stable would various binary systems be?

Also, here's an example of a real life Tatoonie )The view would be much cooler as there's not only 2 stars, but there's also a gas giant in the sky!)

That gas giant is in the habitable zone! Could it have exomoons with life?

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Just now, KAL 9000 said:

That gas giant is in the habitable zone! Could it have exomoons with life?

Possibly, that's why I like the system, and it's definitely big enough to have a moon the size of Mars

Edited by Spaceception
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So, the hypothetical Planet 9 is accused in dwarf planets kidnapping.
And it's (if  's) presumably just several Earth masses heavy and 1000 AU far.

Sun is 300000 Earth masses. So, a companion star, say 100000 Earth masses, orbiting 100 times farther than the hypothetical Plan.9, i.e. in 10000 AU from here, would:
1) kidnap outer dwarf planets, making their orbits unstable;
2) stir the Oort cloud as a skimmer, periodically throwing the comets in all directions, also towards us.

Dinosaurs would have no chances.

Edited by kerbiloid
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1 hour ago, KAL 9000 said:

That gas giant is in the habitable zone! Could it have exomoons with life?

It's smaller than Jupiter (4.7x vs ~11 Earth Radius), and its moons are likely to be too small, so I doubt it.

2 minutes ago, kerbiloid said:

So, the hypothetical Planet 9 is accused in dwarf planets kidnapping.
And it's (if  's) presumably just several Earth masses heavy and 1000 AU far.

Sun is 300000 Earth masses. So, a companion star, say 100000 Earth masses, orbiting 100 times farther than the hypothetical Plan.9, i.e. in 10000 AU from here, would:
1) kidnap outer dwarf planets, making their orbits unstable;
2) stir the Oort cloud as a skimmer, periodically throwing the comets in all directions, also towards us.

Dinosaurs would have no chances.

Thankfully, most of that would be in the early solar system (not to mention gravitational bodies not only sling objects, in, but also out.)

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Just now, fredinno said:

Thankfully, most of that would be in the early solar system

Oort cloud still exists (if exists).

Orbital speed is ~=50..100 m/s there, and orbital period ~= 100 mln years, i.e. less than 50 turns since the Solar System had appeared.
So, "early" time there lasts for 108..109 years.

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4 hours ago, Andem said:

If your willing to do a lot of math, look up Artifexian on YouTube. His vids give you a lot of mathematical formulae that was never taught in school to create a planetary system.

I wonder if he knows about Universe Sandbox...

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On 26/03/2016 at 11:05 AM, Spaceception said:

So, I was screwing around in Universe Sandbox 2, after a couple of people were discussing the stability of habitable zones around planets around Alpha Centauri, so I placed down Alpha Centauri A/B, and separated them at a distance of 11.2 AU )I couldn't get the 11.2 by 35 something AU thing), and over the course of almost 2,000 years I stimulated Alpha Centauri Bb around both stars, around Alpha Cen B, the planet was flung out, but around Alpha Cen A, it was pretty stable, then I decided to put a planet 4 AU from both stars, Alpha Cen B had its planet slung out, but around Alpha Cen A, again, it was stable.

Now, I would've simulated it longer, but I need to go somewhere soon, so I can't, anyway, about binary's in general, how stable would various binary systems be?

Also, here's an example of a real life Tatoonie )The view would be much cooler as there's not only 2 stars, but there's also a gas giant in the sky!)

First off, Universe sandbox 2 is fairly inaccurate over longer periods of time and I really wish it wasn't.

I was creating my own simulation using another software recently and used alfa centauri as control for my model.

The region of stability is defined by the hill sphere (https://en.wikipedia.org/wiki/Hill_sphere) around each star, you can calculate that yourself, but here is an image to help you view this.

Yellow = orbit of Alpha centauri A

Orange = orbit of Alpha centauri B

Black = orbit of B as seen from the surface of A.

Dotted region is the hill sphere of each star, distances are in AU.

So there you have it both hill radius

Hill A = 3.527 AU

Hill B = 2.699 AU

If you get the orbits right of course.

Ow just noticed you are mixing two different concepts the habitable zone, the region where you can find liquid water on a planets surface, that green region of kepler 47.

And the region of orbital stability (hill sphere) of a body where satellites could orbit without interference from another body.

Edited by Beduino
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On 26/03/2016 at 7:32 PM, fredinno said:

From Wikipedia:

To be in the star's habitable zone, any suspected planet around Alpha Centauri A would have to be placed about 1.25 AU away [citation needed] – about halfway between the distances of Earth's orbit and Mars's orbit in the Solar System – so as to have similar planetary temperatures and conditions for liquid water to exist. For the slightly less luminous and cooler Alpha Centauri B, the habitable zone would lie closer at about 0.7 AU (100 million km), approximately the distance that Venus is from the Sun.[102][104]

So yeah, there you have it. The habitable zones are inside the hill spheres of both stars where stable orbits could exist.

Isn't KSP community amazing?

Edited by Beduino
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4 minutes ago, Beduino said:

So yeah, there you have it. The habitable zones are inside the hill spheres of both stars where stable orbits could exist.

Isn't KSP community amazing?

This is nothing, take a look at the 'alien megastructure' thread. Eventually ole freddy will figure it out, he usually does, cannot say the same for other posters.

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3 minutes ago, PB666 said:

This is nothing, take a look at the 'alien megastructure' thread. Eventually ole freddy will figure it out, he usually does, cannot say the same for other posters.

You say alien megastructure?? http://imgur.com/a/Xb2NI

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35 minutes ago, Beduino said:

The habitable zones are inside the hill spheres of both stars where stable orbits could exist

Of course, they can exist.An ultimate question: how long. Biological evolution needs a billion terranean years,

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14 minutes ago, kerbiloid said:

Of course, they can exist.An ultimate question: how long. Biological evolution needs a billion terranean years,

You know that extinction level events happened on Earth, i'm not so sure our planet is so hospitable to life as we think, but again life itself seems pretty tough.

Orbital encounters with other stars in the galaxy could disrupt the orbits of binaries much easier, but other than these, here's what wiki says about alpha centauri.

Quote

Early computer-generated models of planetary formation predicted the existence of terrestrial planets around both Alpha Centauri A and B,[94][97][98] but most recent numerical investigations have shown that the gravitational pull of the companion star renders the accretion of planets very difficult.[93][99] Despite these difficulties, given the similarities to the Sun in spectral types, star type, age and probable stability of the orbits, it has been suggested that this stellar system could hold one of the best possibilities for harbouring extraterrestrial life on a potential planet.[6][85][100][101]

You know what.. you just gave me an idea.. i'm going to fire up spaceengine and land on some planet around alpha centauri, maybe drink some coffee in the process.

Edited by Beduino
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1 hour ago, Beduino said:

You know that extinction level events happened on Earth, i'm not so sure our planet is so hospitable to life as we think, but again life itself seems pretty tough.

Orbital encounters with other stars in the galaxy could disrupt the orbits of binaries much easier, but other than these, here's what wiki says about alpha centauri.

You know what.. you just gave me an idea.. i'm going to fire up spaceengine and land on some planet around alpha centauri, maybe drink some coffee in the process.

Coffee makes the worst circumstances tolerable.

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5 hours ago, Beduino said:

First off, Universe sandbox 2 is fairly inaccurate over longer periods of time and I really wish it wasn't.

I was creating my own simulation using another software recently and used alfa centauri as control for my model.

The region of stability is defined by the hill sphere (https://en.wikipedia.org/wiki/Hill_sphere) around each star, you can calculate that yourself, but here is an image to help you view this.

Yellow = orbit of Alpha centauri A

Orange = orbit of Alpha centauri B

Black = orbit of B as seen from the surface of A.

Dotted region is the hill sphere of each star, distances are in AU.

So there you have it both hill radius

Hill A = 3.527 AU

Hill B = 2.699 AU

If you get the orbits right of course.

Ow just noticed you are mixing two different concepts the habitable zone, the region where you can find liquid water on a planets surface, that green region of kepler 47.

And the region of orbital stability (hill sphere) of a body where satellites could orbit without interference from another body.

The Hill Sphere is misleading, since the SOIs can overlap.

Not to mention that it does not account for the formation of the solar system, which is far more complex. Current models show the protoplanetary disk may have beeneffected enough to prevent planeary formation in the habitable zone. But time will tell, we have little clue about how binary stars affect planetary formation- we still don't fully understand how our own solar system formed...

Edited by fredinno
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Edited by Spaceception
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2 hours ago, fredinno said:

The Hill Sphere is misleading, since the SOIs can overlap.

You are mixing up concepts there mate, SOI is for trajectory planning of spacecraft usually related with patched conics.

The hill sphere is associate with the Roche Lobe, which is the region around a star in a binary system within which orbiting material is gravitationally bound to that star.

Even though both formulas look similar, they have different applications

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