It is currently Thu, 14-12-17, 2:33 GMT

All times are UTC




Post new topic Reply to topic  [ 24 posts ]  Go to page Previous  1, 2
Author Message
PostPosted: Wed, 19-10-16, 19:52 GMT 
Offline
User avatar

Joined: Mon, 07-01-08, 13:30 GMT
Posts: 339
Location: Switzerland
Apparently Gaia identifiers will be added to the NASA archive in the near future, so it should hopefully be possible to fill in the missing TYC identifiers. At the moment it would not be possible to combine this with the Gaia results as the TYC identifiers are not exposed via the API, so the script would end up generating duplicate stars.


Top
 Profile  
 
PostPosted: Wed, 04-01-17, 17:57 GMT 
Offline
User avatar

Joined: Mon, 07-01-08, 13:30 GMT
Posts: 339
Location: Switzerland
Going back to appearance of gas giant planets, it looks like I'll need to incorporate these results - temperate giant planets look like they're going to come out orange from the sulphur haze.


Top
 Profile  
 
PostPosted: Sun, 26-02-17, 22:49 GMT 
Offline
User avatar

Joined: Sat, 25-02-17, 23:25 GMT
Posts: 2
@ajtribick

I tried using your celestia-exoplanets script, but after copying the ssc and stc file into the data directory, celestia did not display any exoplanets at all.

I don't know what I'm doing wrong. Would you mind sending me a pm to help me?


Top
 Profile  
 
PostPosted: Mon, 27-02-17, 18:47 GMT 
Offline
User avatar

Joined: Mon, 07-01-08, 13:30 GMT
Posts: 339
Location: Switzerland
If you're using Celestia 1.6.1 then it will not work because I'm using the units syntax that unfortunately never made it into a released version of Celestia. The main reason is because it is a lot more convenient than using Celestia's defaults which tend to work best with our rather wide-spaced solar system and not so well once you start dealing with planetary orbital periods of a few days.

Either you'd need to compile Celestia from the SVN repository yourself (slightly annoying on Windows because qt4 and the latest Microsoft compiler don't seem to get along particularly well), or find someone else who's built it and has the binaries.


Top
 Profile  
 
PostPosted: Mon, 27-02-17, 22:10 GMT 
Offline
User avatar

Joined: Sat, 25-02-17, 16:07 GMT
Posts: 33
Location: Sherwood Park, AB, Canada
ajtribick wrote:
Either you'd need to compile Celestia from the SVN repository yourself (slightly annoying on Windows because qt4 and the latest Microsoft compiler don't seem to get along particularly well), or find someone else who's built it and has the binaries.


Maybe someone who has it can post it somewhere where only registered members can download it? :o

_________________
If we all did the things we are capable of doing we would literally astound ourselves.
Thomas Edison

Orbiter username ShuttleCommander.


Top
 Profile  
 
PostPosted: Sun, 05-03-17, 21:22 GMT 
Offline
User avatar

Joined: Sat, 25-02-17, 23:25 GMT
Posts: 2
I tried installing it on linux mint 18.1 using this guide, but it isn't working because I can not install glu from the repositories and I am not sure how to install it manually.


Top
 Profile  
 
PostPosted: Sun, 05-03-17, 21:39 GMT 
Offline
User avatar

Joined: Tue, 04-09-07, 21:55 GMT
Posts: 775
Location: N 42.38846 W 83.45456
hi cenysor

as to building on linux

you might want to use my code on github
https://github.com/JohnVV/MyCelestiaBuild

this builds with gcc4.8 and qt4

as to glu the name in apt will be a bit different than a RHEL rpm system

debian and redhat based systems use different naming for the same thing

_________________
"I don't pitch Linux to my friends, I let Microsoft do that for me."
Using OpenSUSE 42.1 & Scientific Linux 6.7


Top
 Profile  
 
PostPosted: Mon, 13-03-17, 19:45 GMT 
Offline
User avatar

Joined: Mon, 07-01-08, 13:30 GMT
Posts: 339
Location: Switzerland
The recent TRAPPIST-1 results have motivated me to do several updates to the scripts. In particular, the version currently on my GitHub is a mess, the logic for fixing holes in the data and doing the various processing is all mixed up with the parsing and outputting. Or to put it another way, the parser and the output know far too much astrophysics, and the stars and planets don't know any. This makes it rather tricky to add new features as there is no particularly good place to hook them in.

Over the weekend I extracted the astrophysics logic and gap filling into their own classes, which now gives a clear place to put features that fill in gaps in the data (e.g. mass-radius relationships, orientation of orbits, etc.) and hopefully will not be too difficult to extend for things like multiple star systems. I've also decided to go with Python 3 for now since I'm no longer using Forecaster, I may look into backporting to Python 2.7 when done but I no longer consider this a priority. I'm still using the mass-radius relationship from Chen & Kipping (2017) but I've written a "fast and nasty integrator" to do the estimation, as the Monte-Carlo approach is both too slow and as it is random-number based, gives different results each time you run it.

I've also implemented mass thresholds for rock and ice planets, plus tidal spindown models with pseudosynchronous rotation (for gas giants) and spin-orbit resonances (for rock/ice planets). Encouragingly, the code that predicts which spin-orbit resonance the planet will end up in gets the 3:2 state for Mercury correct.

A couple of examples: first, the HD 38529 system - the inner gas giant is in an eccentric orbit and has reached a pseudosynchronous rotation state, while the outer giant has not been slowed down, and has a rotation derived from the solar system mass-equatorial velocity relationship (observations of Beta Pictoris b and 2M1207b seem to indicate it is fairly consistent out to superjovian masses).

Code:
# WARNING - WORK IN PROGRESS, NO GUARANTEES THIS IS CORRECT

"b" "HD 38529"
{
   Radius<rE> 13.9378 # from mass-radius relationship
   Mass 266.648 # Msini

   Texture "exo-class3.*"

   EllipticalOrbit {
      SemiMajorAxis<AU> 0.131
      Period<d> 14.3098
      Eccentricity 0.257

      Epoch 2454012.640000 # time of periastron
      MeanAnomaly<deg> 0.000

      ArgOfPericenter<deg> 268.877
      Inclination<deg> 0.000 # unknown, using ecliptic
      AscendingNode<deg> 0.000 # unknown, using ecliptic
   }

   UniformRotation {
      Period<d> 10.19 # likely in pseudosynchronous rotation
      Epoch 2454012.640000 # to match orbit
      MeridianAngle<deg> 0.000 # to match orbit
      Inclination<deg> 0.000 # to match orbit
      AscendingNode<deg> 0.000 # to match orbit
   }
}

"c" "HD 38529"
{
   Radius<rE> 12.3388 # from mass-radius relationship
   Mass 4252.39 # Msini
   Oblateness 0.09 # estimated

   Texture "exo-class3.*"

   EllipticalOrbit {
      SemiMajorAxis<AU> 3.712
      Period<d> 2140.2
      Eccentricity 0.341

      Epoch 2452256.400000 # time of periastron
      MeanAnomaly<deg> 0.000

      ArgOfPericenter<deg> 194.177
      Inclination<deg> 0.000 # unknown, using ecliptic
      AscendingNode<deg> 0.000 # unknown, using ecliptic
   }

   UniformRotation {
      Period<d> 0.11 # from mass-velocity relationship
      Epoch 2452256.400000 # to match orbit
      MeridianAngle<deg> 0.000 # to match orbit
      Inclination<deg> 0.000 # to match orbit
      AscendingNode<deg> 0.000 # to match orbit
   }
}


An example of a spin-orbit resonance: the inner planet of KOI-94:
Code:
# WARNING - WORK IN PROGRESS, NO GUARANTEES THIS IS CORRECT

"b" "KOI-94"
{
   Radius<rE> 1.71
   Mass 10.5

   Texture "asteroid.*"

   EllipticalOrbit {
      SemiMajorAxis<AU> 0.05119
      Period<d> 3.74321
      Eccentricity 0.25

      Epoch 2454964.617500 # time of transit
      MeanAnomaly<deg> 61.653 # mean anomaly at transit

      ArgOfPericenter<deg> 180.000 # unknown, 0 assumed
      Inclination<deg> 61.824
      AscendingNode<deg> 225.057 # unknown, using ecliptic
   }

   UniformRotation {
      Period<d> 2.4954733333333334 # likely in 3:2 spin-orbit resonance
      Epoch 2454964.617500 # to match orbit
      MeridianAngle<deg> 61.653 # to match orbit
      Inclination<deg> 61.824 # to match orbit
      AscendingNode<deg> 225.057 # to match orbit
   }
}


Current priorities:
  • Tidying up existing features, e.g. check I didn't break anything regarding accurate simulation of transits, ensure all references are output in the ssc/stc file headers, not just as comments in the code
  • Use orientation information from other planets in the system to stop systems of transiting and non-transiting planets being wildly misaligned
  • Further characteristation of planets based on temperature, mass, rotation, etc.


Top
 Profile  
 
PostPosted: Tue, 14-03-17, 9:07 GMT 
Offline
Site Admin
User avatar

Joined: Fri, 31-08-07, 7:01 GMT
Posts: 4514
Location: Hamburg, Germany
ajtribick wrote:
I'm still using the mass-radius relationship from Chen & Kipping (2017)

Perhaps it would be a good strategy to relate or unify the used mass-radius relationship and the mass-luminosity (ML) relationship that Dawoon and myself have used in our Lensing framework code/papers. The ML relation holds over a huge range of masses from stars to galaxy clusters! While the paper by Torres et al (2009) refers mainly to stars, the recent paper by Bahcall and Kulier(2014) has become quickly a standard reference for galaxies and galaxy clusters...

Torres, G. et al., 2009. Accurate masses and radii of normal stars: modern results and applications.
The Astronomy and Astrophysics Review, 18(1-2), pp.67–126.

Bahcall, N. A. and Kulier, A., 2014. Tracing Mass and Light in the Universe: Where is the Dark Matter? MNRAS, 439(3), pp.2505–2514.

Neta A. Bahcall is the Eugene Higgins Professor of Astrophysics at Princeton University...

See also Dawoon's ISU thesis on page 18ff and in Fig. 12:
http://dwj.freeshell.org/work/file/djung_ipr.pdf

Fridger

_________________
Image


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 24 posts ]  Go to page Previous  1, 2

All times are UTC


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Group