Canopus

https://github.com/ZyadHamed/NasaSpaceAppsCairo

https://docs.google.com/presentation/d/1Ihu0LwvrMeiRCYokNSAd2BFKOATcjA7p/edit?usp=sharing&ouid=106415761805316227248&rtpof=true&sd=true

Problem and Purpose.

Variable stars were always interesting for astronomy enjoyers to observe, always wondering why the brightness of the very same star changes as time passes. However, most people don’t really know the reason behind the variability of these stars, and thus remain clueless about why and how they change their luminosity and brightness. Previous star visualizers such as KStars, Celestia, and Stellarium didn’t allow the user to get a full experience of the variable stars and modify their properties (period, magnitude, temperature..etc). As a result, we aspired to create a web-based visualizer to deliver to the user a comprehensive experience of understanding the concept of stellar variability in a better fashion than its contemporaries of visualizers.

What does our project do?

Our project aims at providing the user with a comprehensive interactive experience of 20 variable stars from the GCVS database. Our challenge is also to allow users to understand the factors that affect the change in brightness of the star and how each individual factor contributes to the overall brightness. The user has the complete freedom to change and alter the properties of the star such as the radius, and surface temperature. After changing any of these parameters, the program recalculates the rest of data such as luminosity and magnitude. The user can also change the variable data of the star, such as the period of stellar variability, amplitude, and average magnitude. In addition the user is allowed to add a customized star with the properties they want.

Idea of operation:

Our project was done in the environment of THREE.js. We start by requiring all the libraries of the shaders, lightning, and the core library. Afterwards, we collected the data in a csv file, which was used to calculate the rest of features such as the maximum and minimum temperatures using the flux equation of the star. At first, we used 4 spotlights around the sphere to represent the variability in the light emitted by the star. However, this method produced only a solid color that did not resemble an emissive and radiative star. In addition, this method was resource consuming, since each star requires 4 different lighting sources. Thus, we switched to the post-processing libraries: UnrealBloomPass and EffectComposer, which light up the sphere by simulating a light shader from the layers of the sphere that undergoes refraction and remission in the inner layers just like a normal star. Afterwards, we began simulating the effect of variability by using the sine trigonometric functions, where the period of the star was determined by the rate at which angles are propagated during the loop function. Finally, a base class called star was created, which carries all the effects, shaders, and properties of the sphere that were required to simulate a variable star. Multiple stars were created using the data from the Nasa Variable Catalog and scattered across the sky to simulate a real night sky with some variables almost never changing and some always flickering.

To kick off our learning journey about stellar variability and cepheid stars, we used reference indexed [1]. We also started learning about the types of variability in variable stars from the reference indexed [2].

In reference indexed [3] presents an image of the night sky with variable stars in the background twinkling.

Then, we used reference indexed [4] to organize a dataset of 20 variable stars.

[1] https://starchild.gsfc.nasa.gov/docs/StarChild/questions/cepheids.html

[2] https://www.atnf.csiro.au/outreach/education/senior/astrophysics/variable_types.html

[3] https://sci.esa.int/web/hubble/-/variable-stars-in-hubble-s-sky

[4] https://heasarc.gsfc.nasa.gov/W3Browse/all/gcvs.html

Nasa Space Apps' journey was pleasant to us. Entertainment wasn't its only feature. We could learn how to avoid stress and pressure along the competition journey. We faced errors we never dealt with, such as the library can't be imported manually or automatically on the Visual Studio Code.

Our team CANOPUS involves three mentors from STEM Astronomy Club, where they teach students from all over Egypt about Astronomy and Astrophysics. So, when we first saw the "Twinkle Twinkle Little Star" challenge and learned about its objectives, we were inspired to use the developed website for the challenge to help the mentees that our team members guide to learn about the properties of the stars, and instead of the only theoretical lessons, the mentors can show them how the properties are linked together by controlling each property. Subsequently, the project has more social benefits.

The Engineering Design Process was used in developing our project. We first studied the challenge and its prior solutions. Then, the tasks were distributed among the team members according to their roles. During the hackathon, we faced some technical issues that we could solve later. For instance, when we uploaded 100 stars to the website, the data was too much, which could crash the website itself. So, we decreased the number of stars to only 20 stars, with the option that the user can add an additional new star with its own characteristics.

We would like to thank Eng. Ahmed for advising us when we faced some challenges during the hackathon, and give special thanks to NASA Space Apps Cairo for providing us with this chance to meet and work together.

Background, Data, and Resources:

[1] https://starchild.gsfc.nasa.gov/docs/StarChild/questions/cepheids.html

[2] https://www.atnf.csiro.au/outreach/education/senior/astrophysics/variable_types.html

[3] https://sci.esa.int/web/hubble/-/variable-stars-in-hubble-s-sky

[4] https://heasarc.gsfc.nasa.gov/W3Browse/all/gcvs.html

[5] https://stackoverflow.com/questions/1472514/convert-light-frequency-to-rgb

[6] https://threejs.org/examples/webgl_postprocessing_unreal_bloom.html

Tools:

[7] three.js

[8] three.js addons

[9] VS Code

#Variable_Stars, #Cepheids, #Star_Magnitude, #Stellar_Variability, #3D_Visualizer