I'm shocked that anybody wearing a tin foil hat has yet to comment on the supposed "brown" dwarf orbiting our Sun and how it's being steered by advanced beings on a crash course with our planet.

Nevertheless, this exotic effect aside, as an object cools, the light it emits will go from orange to red, and then will go to a dimmer and dimmer red. If you were close to a brown dwarf and could see it as a disc, then it would be pretty dim even if it was acting as a perfect blackbody. It would be hard to spot by its own light. Probably this is why the artist added other stars nearby to light it.

Giving the colour match as an RGB triplet is not brilliantly accurate if the colour is well off neutral. Most displays have a tone curve that departs from a uniform gamma at the bottom end, and CRTs and LCDs depart from gamma in different ways. However, in an imperfect world, it does give the right sort of dirty orange colour.

I like the term 'brown dwarf'. It will give off a very dull red glow. The red won't be a deep LED red, but something duller and more orange. We want a word that describes an unexciting orange color, but it must also stress the low intensity. The word 'brown' comes about as close as we can get without having to invent another word. In fact, we are sort-of inventing a new color term because we are applying it to an emissive colour rather than a reflective one. 'Brown' also carries connotations of 'brown-out' – of something not working properly because there isn't enough power, and so forth. The first time I met the term 'brown dwarf' I understood it straight away – I doubt if I would have done the same with 'planetar' or 'substar'.

We control words, not the other way around. Let there be brown light!

Sorry for nitpicking, but brown is not a de-saturated yellow. It's dark yellow, or dark orange, or dark red. If yellow is 100% red, 100% green and 0% blue, then brown would be something like 50% red plus 50% green to 90% red plus 10% green, with blue at 0%. This color is still fully saturated though.

Provided you wish to keep the lightness, de-saturation of yellow would mean adding twice as much blue as you take from green and red respectively. For instance 80% red, 80% green and 40% blue would be a de-saturated yellow and it would look something like light olive.

However, this is certainly not the case for brown dwarfs. The organic soup of these objects may and do alter their SED (spectral energy distribution) allowing brown to be a strong candidate for their color.

I sure do like the site you linked to, Frasier. Thanks.

I think the issue here is that astronomy has a simple "one-dimensional" notion of color which is simply "the dominant visible spectral wavelength".

This has very little relation to our everyday human notion of color which has three independent components. The components are derived from the receptivity of our three different types of photoreceptors to different parts of the spectrum.

There's no meaningful way to translate our notion of brown (partly greenish, partly reddish, a bit of bluish) to the astronomical notion of color (ie dominant wavelength of ~700nm, also known as red). If the color is not "in the rainbow", it's not a spectral color.