New magnetic field configurations (work in progress)

[Cham]

I had an interesting idea today. I'll try to exploit it for my charged particle paths. The picture below is showing a testing model :



A free particle is moving with a constant velocity along the blue line, as seen by a stationary INERTIAL observer. The same particle as seen by a ROTATING observer is following the *rotating* orange curve. That curve is "sweeping" the blue line and this gives the feeling of a moving particle along the straight line (or the blue line is sweeping the orange curve, which gives the same impression the other way around). I don't know how far I can push this idea, but I think it may be interesting to show the SAME MOTION according to two different observers, especially since there's no question of using an .xyz file to show the particle's motion.

The problem I'm trying to solve is this : my charged particle is moving in the rotating magnetic field of two stars moving around their barycenter. I want to show the particle's path in that field, and I want the path to be visually correlated to the field. The particle's PATH model shown on the previous page were made assuming a static field only (fixed, nonrotating stars). If I solve the path equations for the rotating field, in the stationary inertial frame, I'll get a curve which will be uncorrelated with the moving field : there will be no synchronisation between the static path and the rotating field. If I solve the path equations in the rotating frame (in which the field appears to be stationary), I should get a rotating curve visually correlated with the field, but may be looking weird for the stationary inertial observer (the user in Celestia). Should I show BOTH paths at the same time (same particle, as seen by two observers) ?

[Cham]

Update :

I applied the idea exposed in my previous message. It works, but I think I'm experiencing the cahotic behavior of the system and the limitations in numerical accuracy, since both curves don't locally match exactly at all points. It match perfectly at some points, but some parts don't.

The green curve shown below is the path defined by the inertial observer (the usual stationary user in Celestia), for which the field is steadily rotating with the white dwarfs. The blue curve is the path defined by the rotating observer, for which the field is stationary (of course, I've included all the rotating frame effects : Coriolis non-inertial "force", etc). Of course, the green curve has some distortions caused by the rotating field, so it doesn't **apparently** match the moving field. The blue curve match the field everywhere.



Because of the computation accuracy limitations (if it's really what is causing the small curves mismatches), I'll drop the green curve associated to the inertial observer. From now on, I'll design paths for the rotating frame only.

[Cham]

Here's a very long particle path in the rotating frame (proper frame of the white dwarfs). Celetia is an amazing visualisation tool to show crazy stuff like this. The curve associated to the inertial frame (not shown here) fits very well that one below, so the numerical integration is doing a fine job.

Since the testing phase is almost finished, I'll be ready soon to release some of the models. The longest thing to do is just to select the fields and paths which are worth a public release.

Two .gif pictures below. I recall that the blue curve represents the path of a SINGLE relativistic particle following the magnetic field lines, as seen in the rotating frame attached to the white dwarfs. For the needs of the numerical integration, I used a Carbon 12 nucleus moving at 80% light speed in the inertial frame. The time elapsed, to follow all the curve shown, is about 2 min 51 sec. Stars not shown on the pictures :

[Cham]

An attempt at jets modelisation, using the Navier-Stokes equation. Spinning ball falling in a fluid. Bad jets model



Here's a small CMOD model to try. Very funny to watch rotating in Celestia, and you can really feel the ball falling in the fluid :

http://nho.ohn.free.fr/celestia/Cham/Di ... l.cmod.zip (136 KB zip file)

[selden]

o_O

[Cham]

Here's an attempt at solving some magnetohydrodynamical equations. A dipolar field is steadily rotating in a plasma flowing outward. The magnetic field is deformed by the plasma, which is trying to built two jets around the rotation axis :

[Cham]

I've just found an interesting PDF document which presents things very similar to mine :

http://www.mpi-hd.mpg.de/theory/pulsar04/PSR_frack.pdf

Near the center of that document, there are 3D field representations very similar to what I'm doing for Celestia. I'll try to contact the author.

[buggs_moran]

An attempt at jets modelisation, using the Navier-Stokes equation. Spinning ball falling in a fluid. Bad jets model

Here's a small CMOD model to try. Very funny to watch rotating in Celestia, and you can really feel the ball falling in the fluid :

http://nho.ohn.free.fr/celestia/Cham/Di ... l.cmod.zip (136 KB zip file)

That is very, very cool...

[Cham]

Here's a link to a web page made by the lecturer of a very interesting conference held last friday, at my university :

http://shayol.bartol.udel.edu/massivewi ... mics_model

This is all about rigidly rotating magnetic fields with plasma. Lots of figures and movies, nice 3D animations, etc. Just follow the links at the bottom of the page on that link. All those numerical simulations were presented at the conference, and there are some strong analogies with the 3D models I'm building.

[Cham]

Just for the beauty of it, here's a mysterious magnetized world of two sisters planets : Ziphyr and Tesli (click to enlarge) :



I played with the FOV, on the third picture, to see both planets at a reasonable size.

[jll]

Really beautifull

Searching informations about nebula, I notice another conference talking about magnetic fields around stars
http://www.iac.es/proyect/apn4/pages/topics-and-sessions.php

Main subject is about nebula, but session 5 seems to have connexion with this topics :

In this session we hear from experts on the inner workings of AGB stars and the factors that are likely to influence their evolution, such as their initial abundances, viscosity, rotations, thermal pulses, pulsations and other types of instabilities, external torques (from a nearby companion), and the pressure and dynamical effects of their internal magnetic fields.

JLL

[Cham]

I've found another good paper on stars with magnetic field, which could influence my experiments. The pictures presented in that paper are very nice :

http://arxiv.org/pdf/astro-ph/0610487

[Cham]

Just an update to show a new field configuration that I find pretty in Celestia (some of my fields are already available on the Motherlode, by the way). I have oversampled a bit the contrasts on the picture below, so you could see better the field lines.

[Cham]

I'm updating my basic model for the dipolar magnetic field. Now, it will have some nice shades of color and transparency, to depict the variation of field strength. The transitions are all continuous on screen, in full 3D. Here's a sample (work in progress) :



Of course, the red part represent the north magnetic pole, while the green part is the south magnetic pole.

The complete model will be much more sophisticated.

[ANDREA]

I'm updating my basic model for the dipolar magnetic field. Now, it will have some nice shades of color and transparency, to depict the variation of field strength. Of course, the red part represent the north magnetic pole, while the green part is the south magnetic pole.

Cham, if there is no particular reason to choose colors in such a way, could you please reverse the coding, i.e. green= North and red= South, in order to be the same of Selden's cmod_axis addon?



It would be pleasant, IMO.
Thank you anyway.
Bye

Andrea

[Cham]

Andrea, the reverse is easy ! Just flip the model upside-down !

And don't forget that Selden is showing the rotation axis, not the magnetic axis.

[ANDREA]

Andrea, the reverse is easy ! Just flip the model upside-down !
And don't forget that Selden is showing the rotation axis, not the magnetic axis.

Sorry Cham, I have no idea on how to flip your cmod up-down, perhaps modifying the ssc file?
If yes, what is the parameter(s) to be changed?
Regarding Selden's axis, I well know it's the rotational one, but it could be nice to have both, i.e. rotation axis AND magnetic field altogether, so to have a good reason to tell to students the reason of their different geographic position, without confusing them with reversed colors, don't you agree?
Well, if this is possible, obviously.
Bye

Andrea

[Cham]

Andrea, you can flip the model in the SSC. Just use that code :

Orientation [-90 1 0 0]

instead of :

Orientation [90 1 0 0]

That's all !

The students may be puzzled by the colors on Selden's rotation axis, and the colors on my model. They should be different, or else it will be graphically confused.

I'll use blue colors for the charged particles paths (the approximate color of lightnings and electric discharges).

[ANDREA]

Andrea, you can flip the model in the SSC. Just use that code :
Orientation [-90 1 0 0]
instead of :
Orientation [90 1 0 0]
That's all !
The students may be puzzled by the colors on Selden's rotation axis, and the colors on my model. They should be different, or else it will be graphically confused.
I'll use blue colors for the charged particles paths (the approximate color of lightnings and electric discharges).

OK Cham, I'll do so, thank you.
Bye

Andrea

[Cham]

Here's a nice field configuration, taking some plasma effects into account. The lines of the magnetized star are dragged by the flowing plasma around the binary and pushed away by the solar wind of the companion (click the pictures for a larger version) :

drag1.jpg

drag2.jpg

The magnetic field of the magnetized star is made up of three parts : dipolar, quadrupolar and a divergence free deformation field : [tex]\vec{\bf B}={\vec{\bf B}}_{dip}+{\vec{\bf B}}_{quad}+{\vec{\bf B}}_{plasma}[/tex]