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November 2011

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Computer Program Detail Page

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written by Drew Onken
The Solar Photon Random Walk Model simulates the path of photons in radiative transport as they escape from the Sun. Photons do not travel in a straight line, but rather collide with larger particles and get redirected in a fashion. This simulation models that process using a random walk in polar coordinates. The step size for this random walk are determined by the mean free path, the average distance the photon will travel before colliding with another particle. This mean free path (l) is equal to the inverse of the product of the density (p) and the opacity (k): l = 1/(k*p). The density and opacity of the Sun are not constant throughout, but rather change at different distances from the center. However, these values are not agreed upon among the scientific community. Using different values of the mean free path, physicists give the average escape time of photons anywhere from between 100,000 years and 1,000,000 years. As a result, the program was designed not only to take into account a few different physicists' values (both average and linearly decreasing values) but it also allows the user to input their own values.

The Solar Photon Random Walk Model was developed as a final project in a sophomore-level Computational Physics course (Phy 200) using the Easy Java Simulations (EJS) modeling tool.  It is distributed as a ready-to-run (compiled) Java archive.  Double clicking the ejs_comp_phys_photon_random_walk.jar file will run the program if Java is installed.

Please note that this resource requires at least version 1.5 of Java (JRE).
View the supplemental documents attached to this resource (2)
View the source code document attached to this resource
Subjects Levels Resource Types
Astronomy
- Fundamentals
= Properties of Light
- The Sun
= Solar Structure
Thermo & Stat Mech
- Probability
= Random Walks
- Lower Undergraduate
- Upper Undergraduate
- Instructional Material
= Simulation
Intended Users Formats Ratings
- Learners
- Educators
- General Publics
- application/java
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Access Rights:
Free access
License:
This material is released under a GNU General Public License Version 3 license.
Rights Holder:
Drew Onken
Merlot:
pending
Keywords:
EJS, Easy Java Simulations, photons, radiation, radiative zone, random walk, solar, sun
Record Cloner:
Metadata instance created July 26, 2011 by Mario Belloni
Record Updated:
June 12, 2014 by Andreu Glasmann
Last Update
when Cataloged:
July 26, 2011
Other Collections:

Easy JavaScript

Author: Wolfgang
Posted: March 20, 2013 at 4:01PM

Francisco Esquembre and his team are working on a JavaScript version of EJS.  The new version should make it easy to convert EJS models to EJSS models.

» reply

Dashcode widget for random walk simulation?

Author: Jamie Formato
Posted: March 20, 2013 at 2:53PM

I'm putting together an iBook for my astro class.  I would like to include this simulation in the body of the text as an interactive widget.  Apparently this can be done through apples Dashcode-  do you have any plans to create a JavaScript widget with this code?

» reply

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Record Link
AIP Format
D. Onken, Computer Program SOLAR PHOTON RANDOM WALK, Version 1.0 (2011), WWW Document, (http://www.compadre.org/Repository/document/ServeFile.cfm?ID=11349&DocID=2343).
AJP/PRST-PER
D. Onken, Computer Program SOLAR PHOTON RANDOM WALK, Version 1.0 (2011), <http://www.compadre.org/Repository/document/ServeFile.cfm?ID=11349&DocID=2343>.
APA Format
Onken, D. (2011). Solar Photon Random Walk (Version 1.0) [Computer software]. Retrieved October 1, 2014, from http://www.compadre.org/Repository/document/ServeFile.cfm?ID=11349&DocID=2343
Chicago Format
Onken, Drew. "Solar Photon Random Walk." Version 1.0. http://www.compadre.org/Repository/document/ServeFile.cfm?ID=11349&DocID=2343 (accessed 1 October 2014).
MLA Format
Onken, Drew. Solar Photon Random Walk. Vers. 1.0. Computer software. 2011. Java (JRE) 1.5. 1 Oct. 2014 <http://www.compadre.org/Repository/document/ServeFile.cfm?ID=11349&DocID=2343>.
BibTeX Export Format
@misc{ Author = "Drew Onken", Title = {Solar Photon Random Walk}, Month = {July}, Year = {2011} }
Refer Export Format

%A Drew Onken
%T Solar Photon Random Walk
%D July 26, 2011
%U http://www.compadre.org/Repository/document/ServeFile.cfm?ID=11349&DocID=2343
%O 1.0
%O application/java

EndNote Export Format

%0 Computer Program
%A Onken, Drew
%D July 26, 2011
%T Solar Photon Random Walk
%7 1.0
%8 July 26, 2011
%U http://www.compadre.org/Repository/document/ServeFile.cfm?ID=11349&DocID=2343


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Solar Photon Random Walk:

Is Based On Easy Java Simulations Modeling and Authoring Tool

The Easy Java Simulations Modeling and Authoring Tool is needed to explore the computational model used in the Solar Photon Random Walk.

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