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written by Alex on Oct 13, 2003 01:32
Starways 1997

gravitational simulator
targeted to galactic interactions
1997 Alessandro Ghignola, HSP software
version 2003/en-intl

cd/zips/Alex/starways (314 Kb)

Starways approximates the attracting mass of a whole galaxy's core with a single central attractor, presumably a black hole plus the stars forming the core, then applies gravity from that point to all surrounding stars. Star masses are ignored, allowing for very fast REAL-TIME, interactive simulations. Also, star masses have proven almost uninfluent for the final result of such a simulation: normally, adding effective masses to the single stars only determines the formation of clusters. Such clusters rarely influence the final result of interactions between the galaxies themselves, and in the point of view of an experiment targetted to recreate the shapes of observed irregular galaxies, they often don't help.

Starways was created in 1997, written in Borland C++ 3.1 for DOS (although its calculation engine is highly optimized, and written in i80387+ assembly language), and in italian. In September 1998 it was appreciated and published in the "software corner" of an italian astronomy magazine (Nuovo Orione), and well, shortly after, some copies of its italian version were even sold, for the actual equivalent of about 12 US$. In February 2003, it was partly translated to english (program's text strings only, comments in the code still in italian). The source code is provided in the program's archive (starways.cpp is main source, assembly.h being a necessary header file). Starways has brief online instructions, and although it may take some practice, it might be considerably intuitive to use; because of this, and because I have actually no time to write an user guide in english, the online help is all you have. But really, it might be sufficient.

Starways can save and reload simulations (files having .SIM extension), and a few example files are included in the above archive (the simulation files were also included in the original italian package). An additional possibility of Starways1997 is the ability to save pictures out of simulations: the pictures try to imitate how the simulated galaxies would appear in a camera equipped with a CCD sensor (CCDs are also used in modern amateur telescopes to replace photographic films). In practice the program "accumulates" the light from each star on the simulated CCD matrix, resulting in a picture which brightness and appearence depend on focus and exposure time. The picture used as the title's background, in this post, is produced by Starways using the result of the file called "CARTWHEL.SIM".

└> last changed by Alex on October 30, 2004 at 01:23
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