Blackbody curve in RGB for objects less than 1500 K? We know the colors of stars that have a temperature greater than 1000-1500 K, shown here. However, I am wondering about those stars/brown dwarfs with surface temperatures of less than 1500 K. Is there a blackbody curve for these temperatures, and are there any set RGB values for them?
So I use the following logic:

Define 'red', 'green' and 'blue' light in terms of the wavelength ranges those colours encompass (from here)
Calculate the average spectral radiance across each wavelength range, for a defined temperature
Define the RGB value to be the relative ratios of each colour's spectral radiance with 255 defined as the colour with the largest spectral radiance

I made a Python script which you can find here to calculate, display and show the appearance of the corresponding RGB value. Within the script, just change the value of the stellar_temperature variable to see the RGB values of stars of different temperatures.
The script is then finished off with a simple plot to show the appearance of that RGB value.
Now there are a couple of assumptions of course:

RGB values can be defined in terms of radiance/luminosity/flux ratios at each wavelength... This obviously breaks down if you have a detector which gets saturated at certain flux levels! I presume the human eye might fit that description.
Stars can be modelled by perfect blackbody spectra. I believe this to be a pretty valid assumption when the accuracy level needed is differentiation of different RGB tones...
No foreground extinction/absorption by atmosphere/dust etc.