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Sunday, June 30, 2013

 

Three Exoplanets in a Habitable Zone? The Gliese 667 C System in Celestia

Gliese 667 C f (Exoplanet names in triple star systems are confusing) looking back towards it's primary (Gliese 667 C) and the binary it orbits (Cliese 667 A and B). Also visible are several of the other planets in the system. Visualised in Celestia. Click to embiggen.The Gliese 667 C system. I have tilted the orbital plane sightly so that  all three stars in the triple star system can be seen.

Our search for extrasolar planets keeps turning up science-fiction worlds! The latest is a planetery system around one star in a triple star system that hosts not one, but three planets in its habitable zone (c, f [illustrated above] and e).

The Gliese 667 system is well known, lying 22.1 light years away in Scoripius. The system is (just) visible to the unaided eye as a single dot of magnitude 5.9 (see image of Scorpius to the left, the Gliese system is circled, click to embiggen).

We already knew that there were three planets around Gliese 667, but longer data collection and reanalysis found more of them.

While there is a lot of to-do about habitable zones, it simply means the zone where liquid water can exists on a planets  surface. Other factors may be involved in habitability too. Mars is in our habitable zone, but was too small to hold on to a substantial atmosphere, and is now a freezing desert.  The M star these planets revolve around is potentially a flare star, with powerful solar eruptions that may make life difficult on these planets. We also don't know if they are rocky worlds of water worlds.

Still, the growing inventory of stars with terrestrial style planets in their habitable zones suggests that the possibility of life on other worlds is not remote.



The ESO press release is here, and nice backgrounders from the Universe Today and Space.com. Once again I've made Celestia files for the system.

As usual, copy the data here to a plain text file (GJ667.ssc), copy the file to the Celestia extras folder. Celestia already has Gliese 667 triple star system, so you don't need to have a star definition file. The images you get from Celestia look a bit different to the artists interpretations in the press release, in part because of the way the stars and planets are rendered in Celestia, and in part because of how the stars orbit is defined. But it will still give you a good feel fro the system.

I'll have to update my Celestia Exoplanet Tour as well.

===============GJ1667.stc======================================
"b" "Gliese 667 C"

# Neptune like world
# All data from original paper http://www.eso.org/public/archives/releases/sciencepapers/eso1328/eso1328a.pdf

{
    Texture "exo-class4.*"
    NightTexture "exo-class4night.*"


Mass 5.94 # M.sin(i) = 5.94 Earth
Radius 12181.98 # 1.91 Earth radii, guess

#InfoURL "https://en.wikipedia.org/wiki/Gliese_667_Cb"

EllipticalOrbit {
Period 0.019713845
SemiMajorAxis 0.050432
Eccentricity 0.112
ArgOfPericenter 267 #guess
Inclination 30 #greater than 30 actually, but no clear figure
#MeanAnomaly 271
}

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "Gliese 667 C/b"
{
    Texture "extrasolar-lok.*"

}

"c" "Gliese 667 C"

# Venus-like world maybe, on edge of habitable zone

{
Texture "venussurface.*"
# Using venus although it may be a water world


Mass 3.9 # M.sin(i) = 3.9 Earth
Radius 11480.4 # 1.8 Earth radi, from paper

#InfoURL "https://en.wikipedia.org/wiki/Gliese_667_Cc"

EllipticalOrbit {
Period 0.076995587
SemiMajorAxis 0.12507
Eccentricity 0.001
ArgOfPericenter 267 #guess
Inclination 30
#MeanAnomaly 271
}

}

AltSurface "limit of knowledge" "Gliese 667 C/c"
{
Texture "extrasolar-lok.*"
}

"d" "Gliese 667 C"

# Neptune like world

{
    Texture "exo-class4.*"
    NightTexture "exo-class4night.*"


Mass 10.4 # M.sin(i) = 10.4 Earth
Radius 17539.5 # 2.75 Earth radii, guess

#InfoURL "https://en.wikipedia.org/wiki/Gliese_667_Cd"

EllipticalOrbit {
Period 0.252131656
SemiMajorAxis 0.2758
Eccentricity 0.19
ArgOfPericenter 267 #guess
Inclination 30
#MeanAnomaly 271
}

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "Gliese 667 C/d"
{
    Texture "extrasolar-lok.*"
}

"e" "Gliese 667 C"

# earth like world

{
Texture "venussurface.*"
# Using venus although it may be a perfectly earth-like world


Mass 2.68 # M.sin(i) = 2.68 Earth, upper limit of theoretical range
Radius 9567 # 1.5 Earth radii,

#InfoURL "https://en.wikipedia.org/wiki/Gliese_667_Ce"

EllipticalOrbit {
Period 0.170471395
SemiMajorAxis 0.212
Eccentricity 0.001
ArgOfPericenter 267 #guess
Inclination 30
#MeanAnomaly 271
}

}

AltSurface "limit of knowledge" "Gliese 667 C/e"
{
Texture "venussurface.*"
OverlayTexture "ganymede-lok-mask.png"
}

"f" "Gliese 667 C"

# earth like world

{
    Texture "ganymede.*"
    # Using Ganymede as it may be giant water world
        # NightTexture "gasgiantnight.jpg"


Mass 1.94 # M.sin(i) = 1.94 Earth theoretical maximum
Radius 9567 # 1.5 Earth radii,

#InfoURL "https://en.wikipedia.org/wiki/Gliese_667_Cf"

EllipticalOrbit {
Period 0.106998653
SemiMajorAxis 0.15575
Eccentricity 0.001
ArgOfPericenter 267 #guess
Inclination 30
#MeanAnomaly 271
}

}

AltSurface "limit of knowledge" "Gliese 667 C/f"
{
    Texture "ganymede.*"
    OverlayTexture "ganymede-lok-mask.png"
}

"g" "Gliese 667 C"

# Neptune like world
# All data from original paper

{
    Texture "exo-class4.*"
    NightTexture "exo-class4night.*"


Mass 4.41 # M.sin(i) = 4.41 Earth
Radius 12181.98 # 1.91 Earth radii, guess

#InfoURL "https://en.wikipedia.org/wiki/Gliese_667_Cg"

EllipticalOrbit {
Period 0.68861018
SemiMajorAxis 0.5389
Eccentricity 0.107
ArgOfPericenter 267 #guess
Inclination 30 #greater than 30 actually, but no clear figure
#MeanAnomaly 271
}

# likely to be in captured synchronous rotation
}

AltSurface "limit of knowledge" "Gliese 667 C/g"
{
    Texture "extrasolar-lok.*"

}
============================end========================

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Comments:
....(O:
 
Inhabited planets near us! It's a great news!
 
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