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#1
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palette or chart of star colors ?
Hi,
To create renderings of stars I need to know their spectral color to represent them the best I can using a calibrated screen. For example, I try to render Pollux and its exoplanet. http://www.astrosurf.org/lombry/alie...renderings.htm (close to mid of page, left) This bright star is a K0III, thus orangeous. But a K5 or K7 star is also "orangeous" but with redder. So how to know what is the exact tint or palette to use to render exactly a K0III star (and tens of others) ? NB. Of course nobody will never tell me that my Pollux is G6 instead of K0 on his creen, but better to render them correctly ;-) Is there somewhere on the web something that could help me to pick up the exact color of each spectral class ? No color palettes includes in office applications uses such a system (but rather CMY, RGB, etc). So how to proceed ? I think to a high resolution true color H-R diagram, maybe, but where could I find such a chart in hires, and online ? Or isn't there an astronomy application that shows them all correctly (I think to Starry Night Pro 6 as I'm going to buy it) or even a small freeware dedicated to stars ? Do you have another idea to check spectral colors electronically (and if possible with all intermediate stages, G0, G3, G7...) Thanks in advance Thierry http://www.astrosurf.org/lombry/ |
#2
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palette or chart of star colors ?
On Tue, 29 Aug 2006 17:39:23 +0200, Thierry wrote:
To create renderings of stars I need to know their spectral color to represent them the best I can using a calibrated screen. Try this: http://hubblesource.stsci.edu/source.../color_swatch/ _________________________________________________ Chris L Peterson Cloudbait Observatory http://www.cloudbait.com |
#3
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palette or chart of star colors ?
On Tue, 29 Aug 2006 17:39:23 +0200, Thierry wrote:
Is there somewhere on the web something that could help me to pick up the exact color of each spectral class ? Stars are almost black bodies, so you could use the Planck energy distribution formula to calculate the energy emitted at visual wavelengths. You also can look up spectra in reference books. It might be easier to create a tint based on color temperature corrections in graphics arts software, each spectral class having a characteristic surface temperatu Class Temperature Star color O 30,000 - 60,000 K Bluish ("blue") B 10,000 - 30,000 K Bluish-white ("blue-white") A 7,500 - 10,000 K White with bluish tinge ("white") F 6,000 - 7,500 K White ("yellow-white") G 5,000 - 6,000 K Light yellow ("yellow") K 3,500 - 5,000 K Light orange ("orange") M 2,000 - 3,500 K Reddish orange ("red") The tints of real stars are very unsaturated and you would want to exaggerate the colors to get a good appearance. An ordinary incandescent lamp filament at 2,900 K is similar in temperature to a class M star and appears "white" to most eyes. Bud -- The night is just the shadow of the Earth. |
#4
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palette or chart of star colors ?
"Chris L Peterson" wrote in message ... On Tue, 29 Aug 2006 17:39:23 +0200, Thierry wrote: To create renderings of stars I need to know their spectral color to represent them the best I can using a calibrated screen. Try this: http://hubblesource.stsci.edu/source.../color_swatch/ Yes Chris ! (at least it looks fine, I will try, all the more I use Photoshop ;-)) Thanks Thierry _________________________________________________ Chris L Peterson Cloudbait Observatory http://www.cloudbait.com |
#5
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palette or chart of star colors ?
"William Hamblen" wrote in message ... On Tue, 29 Aug 2006 17:39:23 +0200, Thierry wrote: Is there somewhere on the web something that could help me to pick up the exact color of each spectral class ? Stars are almost black bodies, so you could use the Planck energy distribution formula to calculate the energy emitted at visual wavelengths. You also can look up spectra in reference books. It might be easier to create a tint based on color temperature corrections in graphics arts software, each spectral class having a characteristic surface temperatu Class Temperature Star color O 30,000 - 60,000 K Bluish ("blue") B 10,000 - 30,000 K Bluish-white ("blue-white") A 7,500 - 10,000 K White with bluish tinge ("white") F 6,000 - 7,500 K White ("yellow-white") G 5,000 - 6,000 K Light yellow ("yellow") K 3,500 - 5,000 K Light orange ("orange") M 2,000 - 3,500 K Reddish orange ("red") Hi, What I need is a way to compute a high resolution version of this graph (title "la couleur des étoiles", the color of stars) http://www.astrosurf.org/lombry/vie-etoiles.htm to know for example that 14000 K is B7 I, and conversely, etc Maybe using a formula ? Thierry The tints of real stars are very unsaturated and you would want to exaggerate the colors to get a good appearance. An ordinary incandescent lamp filament at 2,900 K is similar in temperature to a class M star and appears "white" to most eyes. Bud -- The night is just the shadow of the Earth. |
#6
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palette or chart of star colors ?
Thierry wrote:
What I need is a way to compute a high resolution version of this graph (title "la couleur des étoiles", the color of stars) http://www.astrosurf.org/lombry/vie-etoiles.htm to know for example that 14000 K is B7 I, and conversely, etc Maybe using a formula ? I've found that it's much easier to use the B-V color index, rather than the spectral class. Harwit gives the formula T = 7300 / ( bv + 0.73 ) where T is color temperature and bv is the B-V index. (There are other formulas that give slightly different answers.) You can then use a table like http://www.vendian.org/mncharity/dir3/blackbody/ or a program like http://www.fourmilab.ch/documents/specrend/ to relate color temperature to an RGB value. - Ernie http://home.comcast.net/~erniew |
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