Nightfall on Linux

I've looked at general astronomy programs in the past that are helpful for many tasks you might need to do in your stargazing career. But, several specific jobs are more complicated and require specialized software to make relevant calculations, so here, let's take a look at Nightfall.

Nightfall is a program that can handle calculations involving binary star systems. It can animate binary star systems, taking into account not only orbital speeds but also rotational motion and the changing shape of stars due to their close positions. You can model what it would look like and what kind of light curves you would register when observing a binary system. You even can take a set of actual observational data and find a best-fit model for the system you are studying.

Most distributions don't include a package for Nightfall, so you need to build it from source. There are several dependencies, so the instructions following assume that you are using a Debian-based distribution. If you are using something else, you should be able to find the comparable packages for your distribution of choice. To install the dependencies, run the command:


sudo apt-get install libgtk2.0-0 libgtk2.0-dev gnuplot

Nightfall also includes the ability to use OpenGL to handle 3D rendering of animations of the binary systems you want to model. If you want to use OpenGL, you also need to install:


sudo apt-get install libgl1-mesa-dev freeglut3-dev
 ↪libgtkgl2.0-dev libjpeg62-dev

Once all of the requirements are installed, you can install Nightfall itself. You should change directory into a temporary or source directory where you can do the unpacking and build the code. Once you are there, download the latest version of Nightfall with:


wget http://www.la-samhna.de/nightfall/nightfall-1.88.tar.gz

Then, unpack it with:


tar xvzf nightfall-1.88.tar.gz

When you go to configure Nightfall, you probably will want to include the openmp option. This allows Nightfall to use the multiple CPUs you probably have in your machine to speed up the calculations involved. You can build and install Nightfall with:


./configure --enable-openmp make sudo make install

This installs Nightfall under the /usr/local directory. You then can start Nightfall with:


nightfall -U

The -U option is necessary to force the GUI to be used interactively.

Figure 1. The GUI lets you configure all kinds of options within Nightfall to set up your model.

Now that Nightfall is up and running, you will start to see just how much control you have over the model that is being simulated. The first tab is where you can set up the core parameters for your binary system model. You can set the mass ratio and the inclination of the two stars. You also can set the surface temperatures and the Roche lobe filling factors for each of the stars. The temperature helps define their luminosities, and the Roche lobe filling factors define the distortion of the stars.

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Joey Bernard has a background in both physics and computer science. This serves him well in his day job as a computational research consultant at the University of New Brunswick. He also teaches computational physics and parallel programming.