Creating an interstellar empire (1 of 2)

I’ve linked before to the Internet Stellar Database.  Although it does not appear to have been updated in a few years, it’s still chock full of information on stars within 75 light years of us, and it has a nice feature that lets you pick a star, enter a distance of your choosing, and obtain a list of all stars that are within said distance of your chosen star.  That’s very useful if you want to create an interstellar empire, federation, or neutral zone that’s located some distance from Earth.  (For the sake of convenience, I’m just going to use the word “empire” to describe such an entity from here on.)

But there is no guarantee that the ISDB will be around forever.  And besides, you may want to locate your empire around a star that’s not listed there because it’s too far away.

So is there another way to set things up?

I’ve already mentioned the HabHyg database.  It’s a zipped CSV file (meaning it can be read with a spreadsheet program such as Excel) located at http://www.projectrho.com/HabHYG.zip, and it includes data on some 45,000 stars, most of them within a few hundred light years of Sol.  I suggest anyone interested in writing interstellar SF download and save a copy of it so you won’t have to go online when you need to consult it... and possibly find out it’s disappeared.

Now we’re ready to begin.  If you haven’t done so already, pick a star that will be at the centre of your empire.  For this exercise, we’ll use Gliese 838, a G2V star that’s located 13.7 parsecs (about 51 light years) away.  (I wrote it up briefly at http://jude-rook.dreamwidth.org/32638.html.)  If you read this journal regularly, you know I usually give distances in light years, so why am I now using parsecs?  We’ll see in a minute.  Just keep in mind for now that a parsec is 3.26 light years.

Next, decide what size and shape the empire will be.   To keep things simple, let’s assume it’s a perfect cube that is six parsecs (about 20 light years) on each side.  (If you want to make the shape irregular, I suggest you start with a cube and then whittle it down at the edges and corners.)

All right, we need to figure out what other stars are located within the cube.

Open your copy of the HabHyg database.  Before you do anything else, create a copy of the file and call it “Empire”.

Look up your central star and make a note of its the galactic X, Y and Z coordinates.  HabHyg tells us that in the case of Gliese 838, they are 10.1, -1.6 and -11.8.

(Now you see why I’m using parsecs – they’re the unit HabHyg uses, so it’s easier to stick with them while creating the empire.  You can convert to light years, if you prefer them, once you’re done.)

Now sort the Empire spreadsheet so that the X coordinates are listed in ascending order.  Delete any lines with an X coordinate higher than 13.1 or lower than 7.1.  (That will be most of them.)

With the remaining stars, repeat the process for the Y coordinate, with -4.6 and 1.4 as your minimum and maximum values.

And with what you have left, eliminate all stars with a Z value that is not between -14.8 and -8.8.

What’s left?  Your brand-new empire.   We’ll explore it a bit in the next entry.