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From: symion <sy...@pr...> - 2008-12-21 13:19:48
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The following program, stars-5.py <http://home.primusonline.com.au/knoware/python/stars-5.py> is a simulation of Globular cluster Messier 80, using the new points object. It produces a huge volume of space with almost 6000 points. (you have to zoom in and in... to find the black hole at the centre) Pressing the Enter Key will select a specific 'star' that you can zoom toward to see it as a glowing disk. The position of each star is determined by the individual position of each point in the points(pos array), and I have found a strange effect. The stars near the outer edge of the cluster have a distinct wobble when spinning around them, apparently the position of each point becomes more unstable as you zoom in toward its limit and so the star wobbles! Apart from that the simulation looks close to Messier 80 <http://en.wikipedia.org/wiki/Globular_cluster> Symion |
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From: Bruce S. <Bru...@nc...> - 2008-12-21 20:53:39
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta content="text/html;charset=ISO-8859-1" http-equiv="Content-Type"> </head> <body bgcolor="#ffffff" text="#000000"> It's interesting and pretty, and it's good to see the value of the points object for representing a large amount of 3D data.<br> <br> However, be aware that the star positions aren't real, just generated from random numbers (and there's an odd effect in the random number generator, because a strong concentration in the form of a straight bar shows up at certain angles of view). <br> <br> I don't see any wobble on my computer.<br> <br> A quick search indicates that astronomers aren't sure whether we should expect to find black holes at the center of globular clusters or not. There is now some evidence for a black hole in one or more specific globular clusters, though I didn't see M80 mentioned.<br> <br> Bruce Sherwood<br> <br> symion wrote: <blockquote cite="mid:494...@pr..." type="cite">The following program, <a moz-do-not-send="true" href="http://home.primusonline.com.au/knoware/python/stars-5.py">stars-5.py</a> is a simulation of Globular cluster Messier 80, using the new points object. It produces a huge volume of space with almost 6000 points. (you have to zoom in and in... to find the black hole at the centre)<br> <br> Pressing the Enter Key will select a specific 'star' that you can zoom toward to see it as a glowing disk.<br> <br> The position of each star is determined by the individual position of each point in the points(pos array), and I have found a strange effect. The stars near the outer edge of the cluster have a distinct wobble when spinning around them, apparently the position of each point becomes more unstable as you zoom in toward its limit and so the star wobbles!<br> <br> Apart from that the simulation looks close to <a moz-do-not-send="true" href="http://en.wikipedia.org/wiki/Globular_cluster">Messier 80</a><br> <br> Symion<br> <br> <pre wrap=""> <hr size="4" width="90%"> ------------------------------------------------------------------------------ </pre> <pre wrap=""> <hr size="4" width="90%"> _______________________________________________ Visualpython-users mailing list <a class="moz-txt-link-abbreviated" href="mailto:Vis...@li...">Vis...@li...</a> <a class="moz-txt-link-freetext" href="https://lists.sourceforge.net/lists/listinfo/visualpython-users">https://lists.sourceforge.net/lists/listinfo/visualpython-users</a> </pre> </blockquote> </body> </html> |
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From: Anton S. <br...@po...> - 2008-12-23 04:40:00
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Bruce Sherwood wrote: > However, be aware that the star positions aren't real, just > generated from random numbers (and there's an odd effect in > the random number generator, because a strong concentration in > the form of a straight bar shows up at certain angles of view). The fault in the stars lies not in the RNG. Uniform distribution of latitude gives a concentration toward the z axis. The code should be: theta = uniform(0,2*pi) zn = uniform(-1,1) # iota = acos(zn) rn = sqrt(1-zn**2) rho = uniform(rmn*a,rmx*a) rxy = rho*rn x = rxy*cos(theta) y = rxy*sin(theta) z = rho*zn Another way is x = normalvariate(mean,sigma) y = normalvariate(mean,sigma) z = normalvariate(mean,sigma) This has spherical symmetry but may not give the radial distribution you want. -- Anton Sherwood *\\* www.ogre.nu "How'd ya like to climb this high without no mountain?" --Porky Pine |
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From: Stef M. <s.m...@ru...> - 2008-12-21 22:57:05
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symion wrote: > The following program, stars-5.py > <http://home.primusonline.com.au/knoware/python/stars-5.py> is a > simulation of Globular cluster Messier 80, using the new points > object. It produces a huge volume of space with almost 6000 points. > (you have to zoom in and in... to find the black hole at the centre) > > Pressing the Enter Key will select a specific 'star' that you can zoom > toward to see it as a glowing disk. > > The position of each star is determined by the individual position of > each point in the points(pos array), and I have found a strange > effect. The stars near the outer edge of the cluster have a distinct > wobble when spinning around them, apparently the position of each > point becomes more unstable as you zoom in toward its limit and so the > star wobbles! > > Apart from that the simulation looks close to Messier 80 > <http://en.wikipedia.org/wiki/Globular_cluster> nice work Symion ! few questions / remarks though: - is it true you can find the black hole only, when you've not pressed Enter before, to get the coordinates ? - why not use the left click instead of the Enter key to get the coordinates ? - you can only zoom with left+right mouse button and not with middle mouse button ( is this a VPython bug ?) - and wouldn't it be lovely to see the Color-magnitude diagram ;-) cheers, Stef > > Symion > > ------------------------------------------------------------------------ > > ------------------------------------------------------------------------------ > > ------------------------------------------------------------------------ > > _______________________________________________ > Visualpython-users mailing list > Vis...@li... > https://lists.sourceforge.net/lists/listinfo/visualpython-users > |
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From: Bruce S. <Bru...@nc...> - 2008-12-22 00:21:45
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The middle button not zooming does seem to be a bug. Thanks for the report. Bruce Sherwood Stef Mientki wrote > - you can only zoom with left+right mouse button and not with middle > mouse button ( is this a VPython bug ?) |
