//Galaxsee Version 2.0 Scale: Galactic 2 200 1 1.5 2 0 0 0 1 1500 -1 2.1 .5 1 0 0 2The first line contains information regarding the version number. The second line contains information regarding the unit scale used in the model. Acceptable values for this are 'Galactic', 'Solar System', and 'Earth-Sun'. The next number specifies the number of stars. The next eight numbers describe the first star's properties. If the scale is set to galactic, the computer will understand this to be a star of 200 solar masses, with x-coordinate 1 kly (kilo-light year), y-coordinate 1.5 kly, z-coordinate 2 kly, moving at 0 kly/Myear in the x-direction, 0 kly/Myear in the y-direction, and 0 kly/Myear in the z-direction. It is colored color number 1, which is red (the colors are numberered in the order in which they appear in the View menu under Star Color--1 is red, 2 is green, 3 is blue, 4 is yellow, 5 is purple, 6 is cyan, 7 is white). Similarly, the second star would a mass of 1500 solar masses, is at the loaction (-1,2.1,.5) kly, and is moving at a speed of 1 kly/Myear in the x direction, and is colored green. Note that if the scale was set to Solar System, the interpretation of these numbers would be different--for example, the distances would be in astronomical units (the distance of the earth from the sun) rather than in kilo light years.
Another thing to keep in mind is that GalaxSee displays the stars in a cube, the size of which is visible in the Info Window. It will perform calculations on stars outside the viewing area (as long as there is at least one visible), but you won't be able to see them unless they move into (or near) that box.
GalaxSee accepts scientific notation (like 1e+2 for 100, etc).
While the Mac version of GalaxSee did not store inormation
regarding the scale, this information is a part of the Windows data file.
Also, the Mac version scaled all velocity values by a factor of 1000, and
used a left handed coordinate system (y and z are swapped from traditional
values). To convert Mac input files, add a version number line at the beginning,
and a line indicating the scale that was used. If galactic scale was used,
divide all velocities by 1000. Swap the y and z values for both position
and velocity.
Go to the Help Index.
The galaxy "random_vel.gxy" was created in a similar way, except that in this instance, the colors were left alone and the spreadsheet's random number function was used to produce random numbers in the range (-2.5 , 2.5) for the velocity components.
It is also possible to start from scratch in the spreadsheet, but it's easier to be sure the format is right if you first generate a galaxy of the appropriate size and save it, then alter it with a text editor or spreadsheet program.
It is also possible to write a simple computer program to generate various galaxies and save them as text files.
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Shodor Education Foundation, Inc.
© Copyright 1996