Everybody familiar with SF knows about the habitable zone, at least the basics. It’s that area around a star where life is possible. A look at any astronomy educational site would provide a more detailed and technical definition: “The Circumstellar Habitable Zone (hereafter CHZ) is defined as the region around a star where water could exist on the surface of an Earth-like planet. Water is believed to have been vital in the formation of life on Earth due to its function as a solvent in biochemistry. Although the region is a spherical shell that surrounds a star, it is often shown as a ring in diagrams looking down onto the plane of a star system. Realize that the CHZ is closely related to the inverse square law – how energy falls off with distance from a star. Thus, the size and location of the CHZ change over time as a star evolves. For the Sun at present the CHZ ranges from 0.97 AU to 1.37 AU.” (Source: University of Nebraska-Lincoln).
This actually means two things: one, different stars have different HZs; two, as a star goes on its stellar evolution, its HZs changes too. These are elements that need to be taken into account when you create your planetary system and you want to make it inhabitable. Fortunately, there are a few tools and free apps that can help.
These are my favourites:
- The classic from NAAP, the famous and very easy to use Circumstellar Habitable Zone Simulator
- For the cases in which NAAP is not enough (for example, when you have double or multiple star system the position and shape of habitable zones can change rapidly), here’s another powerful “HZ calculator“, developed by a team of scientists.
- For something more technical and flexible, try this other Habitable Zone Calculator from the University of Washington, which also offers a FORTRAN code to calculate HZs for a number of stars. Both calculator and code are based on: Kopparapu et al. (2013), Habitable Zones around Main-sequence stars: New Estimates. Astrophysical Journal, 765, 131, available here.
Finally, there’s a nice infographic from Space.com, just to keep things handy.
Oh, thanks for these links, I look forward to exploring them, clearly great sites to mine for thought experiments as well as scenarios for speculative fiction.
They’re good, especially the one that allows you to play with multiple star systems, otherwise quite difficult to figure out! 🙂
Very cool and useful.
Thanks and happy if it was of use 🙂