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 Post subject: Proxima Centauri b
PostPosted: Thu, 25-08-16, 12:58 GMT 
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https://en.wikipedia.org/wiki/Proxima_Centauri_b
Yeah it should be part of celestia.Sci...

F.

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 Post subject: Re: Proxima Centauri b
PostPosted: Thu, 25-08-16, 17:54 GMT 
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i am trying out an idea using grass and "r.teraflow" to erode the surface

"r.landscape.evol" seems not to be working in the GIS software "grass" and "QGis"
-- i might be using bad format of data ?

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 Post subject: Re: Proxima Centauri b
PostPosted: Thu, 25-08-16, 23:41 GMT 
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a test for B
some pretty pictures

Image Image Image Image Image

a zip of the 4k textures and a 32 bit heightmap - 69.4 MiB
https://drive.google.com/file/d/0B6ZYAd ... sp=sharing
Code:

"B" "Proxima Cen" 
{
       
    Class "planet"
    Texture "4k.basergb4.png" 
    NormalMap "4kNorm.png"
    SpecularTexture "4k.basespec.png"
    SpecularColor [ 0.25 0.2 0.2 ]
   SpecularPower 12.0
   #Mass      2     
   Radius     6800
   Oblateness    0.01
   
 
 
        Atmosphere {
      Height 60
      Lower [ 0.65 0.55 0.5 ]
      Upper [ 0.7 0.5 0.5 ]
      Sky [ 0.8 0.4 0.6 ]
      Sunset [ 1.0 0.5 0.25 ]

      CloudHeight 30
      CloudSpeed 930
      CloudMap "Cloud1234.png"
     

        Mie 0.001
      MieAsymmetry -0.25
      Rayleigh [ 0.004 0.0025 0.002 ]
      MieScaleHeight 12
   }

   EllipticalOrbit {
      Eccentricity          0.35   
      AscendingNode         1
      SemiMajorAxis         0.0485
      ArgOfPericenter       1
      MeanAnomaly           1
      Inclination           40
      Period                0.0306
      }
               
  UniformRotation
    {
       Period         177 #hours -- 3/2 sync
       Inclination    42
       AscendingNode  10.0
       MeridianAngle  0.0

    }

   
}


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 Post subject: Re: Proxima Centauri b
PostPosted: Fri, 07-10-16, 17:56 GMT 
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It is my understanding that Proxima B is tidally locked with Proxima Cen. If so, then one side would be warm/hot and the dark side would be cold, depending on global circulation winds. I do not know what a tidally locked planet with an atmosphere and liquid water would look like but I suspect the dark side would be permanently frozen and ice covered, with or without global winds, while the lit side would probably be free of ice.

What do you all think?

Frank


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 Post subject: Re: Proxima Centauri b
PostPosted: Sat, 08-10-16, 16:01 GMT 
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not necessarily, Frank...

see Venus.

I think it depends on atmospheric composition.


Michael


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 Post subject: Re: Proxima Centauri b
PostPosted: Sat, 08-10-16, 17:08 GMT 
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Posts: 57
https://en.wikipedia.org/wiki/Proxima_Centauri

Distance = 4.246 ± 0.006 ly
Parallaxes (mas) = 768.13 ±1.04
Apparent magnitude (V) = 11.13
Spectral type = M6Ve or M5.5Ve (1991)
Temperature = 3,042 ± 117 K
Radius = 0.141 ± 0.007 R☉
Rotation = 82.6 ± 0.1 days

HIP 70890 = V645 cen

GAIA DR1 => no signal


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 Post subject: Re: Proxima Centauri b
PostPosted: Sun, 09-10-16, 12:56 GMT 
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Location: Manassas. VA
Michael:

Thanks for the insight. Venus is a slow rotator but it is not tidally locked with the sun. Also, it has a thick atmosphere full of CO2 that blankets the surface. Both contribute to circulation of heat around the planet. While no one knows yet if Proxima B even has an atmosphere, I would suspect that it is rather thin, given its closeness to Proxima Cen's weak solar winds. We also do not know if it has a magnetic field, which would be vital to preserving any atmosphere it does have.

Assuming Proxima B has a modest atmosphere with water in it, what would its climate and surface look like as a tidally locked planet?


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 Post subject: Re: Proxima Centauri b
PostPosted: Mon, 10-10-16, 3:06 GMT 
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Frank

The problem with red dwarf stars like Proxima Centauri is that the habitable zone is too close to the star.
The strong gravitational force prevents a planetary rotation. At least the rotation is strongly inhibited.

The planet could have similar characteristics as Mercury. On the day side overheated. And the night freezing cold.
Also very dry.

But...
These are just some assumptions of an unprofessional layman.

Our cosmos is full of surprises.



Michael


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 Post subject: Re: Proxima Centauri b
PostPosted: Mon, 10-10-16, 3:55 GMT 
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as for the texture
it is something i was already working on and it mostly fits

there is also the issue of the 99.99999999% of all the information is theoretical and guesses

about the only real thing is i can say with any certainty is it will not look like this
Image

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 Post subject: Re: Proxima Centauri b
PostPosted: Sat, 15-10-16, 13:59 GMT 
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https://arxiv.org/abs/1609.09757

Possible Internal Structures and Compositions of Proxima Centauri b

:)


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 Post subject: Re: Proxima Centauri b
PostPosted: Tue, 29-11-16, 20:19 GMT 
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And here's the orbit for Proxima itself! I haven't yet tried setting up an .stc file for this, would need to figure out what conventions the orbital parameters are using.

Kervella, Thévenin & Lovis "Proxima's orbit around Alpha Centauri"


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 Post subject: Re: Proxima Centauri b
PostPosted: Wed, 30-11-16, 17:49 GMT 
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As an example of the issue with the orbital elements:

The orbital parameters for Alpha Centauri from Kervella et al. (2016) "Close stellar conjunctions of α Centauri A and B until 2050" gives the following orbital elements:
Code:
a = 17.592″, i = 79.320°, ω = 232.006°, Ω = 205.064°, e = 0.5208

Plotting this using the transformations that have already been derived for Celestia's binary stars (also used in my exoplanets scripts) gives the following:
Attachment:
File comment: Orbit plot for Alpha Centauri B
alpha.png
alpha.png [ 17.69 KiB | Viewed 1361 times ]

(North is up, East is left. Grid spacing = 5″. Red line indicates periastron position, red arc gives the direction of motion, blue line is the line of nodes, blue tick indicates the side of the orbit pointing away from the solar system). This matches the orbit plot shown in figure 5

The paper for the orbit of Proxima, which shares some of the authors with the paper I got the elements of Alpha Centauri from, gives the following elements for the Proxima orbit:
Code:
a = 8.7 kAU, i = 107.6°, ω = 72.3°, Ω = 126°, e = 0.50

Putting these into the same code results in the following:
Attachment:
File comment: Orbit plot for Proxima
proxima.png
proxima.png [ 16.04 KiB | Viewed 1361 times ]

(Grid spacing = 1°)

This looks completely different from the orbit plotted in their figure 1, including having the opposite sense of rotation!


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