File:Nogreenstars.gif
No higher resolution available.
Nogreenstars.gif (549 × 222 pixels, file size: 2.61 MB, MIME type: image/gif, looped, 199 frames)
Captions
Captions
Add a one-line explanation of what this file represents
Summary edit
| Description |
English: Cold stars look red. Hot stars look blue. But there is no green star. To be more precise: stars emit a very broad and temperature-dependent spectrum, so intermediate temperature stars excite in roughly equal measure all 3 of the color receptors in our eyes.
For the sake of the animation I approximated the emission of a star with a black body spectrum. Spectrum to perceived color mapping is a bit approximate, but should give the right idea (luminosity is normalized to make everything nice and visible, so cold stars look a lot brighter than they should). All color matching functions downloaded from www.cvrl.org. Several ideas on how to convert between color spaces taken from https://mathematica.stackexchange.com/questions/57389/convert-spectral-distribution-to-rgb-color |
| Date | |
| Source | https://twitter.com/j_bertolotti/status/1069963625979437060 |
| Author | Jacopo Bertolotti |
| Permission (Reusing this file) |
https://twitter.com/j_bertolotti/status/1030470604418428929 |
Mathematica 11.0 code edit
LMS = Import[<path>]; (*All color matching functions downloaded from www.cvrl.org*)
Lr = LMS[[All, 1 ;; 2]];
Mr = LMS[[All, 1 ;; 3 ;; 2]];
Sr = LMS[[All, 1 ;; 4 ;; 3]];
{\[Lambda], X, Y, Z} = Transpose@Import[<path>];
h = 6.62607*10^-34; c = 299792458; k = 1.38065*10^-23;
bb[T_] := (2 h c^2)/((E^((h c/k)/(T \[Lambda] 10^-9)) - 1) \[Lambda]^5);
XYZ[T_] := ({X, Y, Z}.(bb[T]) // #/#[[2]] &);
rgbcolor[T_] := ColorConvert[1*XYZ[T], "XYZ" -> "RGB"]
bbf[T_, \[Lambda]_] := (2 h c^2)/((E^((h c/k)/(T \[Lambda] 10^-9)) - 1) \[Lambda]^5)*1/( 4.095684031906566`*^-51 T^5)
p1 = Table[ Grid[{{
Show[
ListPlot[{Lr, Mr, Sr}, PlotStyle -> {Red, Green, Blue}, Joined -> True, Axes -> {True, False}, Frame -> False, AxesLabel -> {"\[Lambda] (nm)", ""}, LabelStyle -> {FontSize -> 14, Bold, Black}],
Plot[bbf[T, \[Lambda]], {\[Lambda], Lr[[1, 1]], Lr[[-1, 1]]}, PlotStyle -> {Thick, Black}],
Graphics[{FontSize -> 14, Blue, Text[Style["S", Bold], {465, 0.95}], Green, Text[Style["M", Bold], {515, 0.95}], Red, Text[Style["L", Bold], {610, 0.95}]}]
, PlotLabel -> Style[StringForm["Star temperature:``", T, T], Medium]
, ImageSize -> Medium
],
Graphics[{rgbcolor[T], Disk[], Black, Thick, Circle[]}, PlotLabel -> "Perceived color", LabelStyle -> {FontSize -> 14, Bold, Black}]
}}], {T, 100, 10000, 50}];
ListAnimate[p1]
Licensing edit
I, the copyright holder of this work, hereby publish it under the following license:
 
|
This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication. |
| The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.
|
|
This file, which was originally posted to
https://twitter.com/j_bertolotti/status/1030470604418428929, was reviewed on 5 December 2018 by reviewer Ronhjones, who confirmed that it was available there under the stated license on that date.
|
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 10:18, 5 December 2018 | | 549 × 222 (2.61 MB) | Berto (talk | contribs) | User created page with UploadWizard |
You cannot overwrite this file.
File usage on Commons
There are no pages that use this file.
