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Thread: If Brown Isn't a Color, What Color are Brown Dwarfs?

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    If Brown Isn't a Color, What Color are Brown Dwarfs?

    We've talked about brown dwarfs here on Universe Today for years and years. These are the "failed stars"; objects with too little mass to fully ignite nuclear fusion in their cores. Instead of blazing with red, yellow or the white light of our own stars, they're heated by the gravitational collapse of material. They're called [...]

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    Brown dwarfs have so many organics in their atmosphere, I would be surprised if some of them are not brown. They definetly will not be blackbody radiators, so they are not restricted to the hotter star temperatures that produce light somewhat evenly across the visible spectrum.

    I recall a T-class brown dwarf that had, essentially, only red and a lesser amount of blue light. This star is likely a maroon star, not far from brown. [There is an old thread on it somewhere. It was Grant's first post, IIRC. ]
    We know time flies, we just can't see its wings.

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    Oh, and when astronomy books favor the correct color of our own star, I will feel more confident in their assesment of others. [Not that "true" color is all that important to doing serious astronomy, in case people don't understand the colorful tone in my remarks. ]
    We know time flies, we just can't see its wings.

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    Okay, astronomers think that brown isn't a color, that there are no
    mixtures of photons that can produce light that looks brown to our
    eyes, that carbon, nitrogen, and oxygen are metals, and that the
    Universe is homogeneous and isotropic.

    That red-orange color sample appears to be somewhere in the range of:
    Code:
     800 deg C   Dull cherry-red
     900 deg C   Cherry-red
    1000 deg C   Bright cherry-red
    1100 deg C   Orange-red
    Saying that brown is a de-saturated yellow is about 1/2 right.
    The term "de-saturated" means that colors other than yellow are
    mixed in. On a computer monitor or TV, of course, there is no yellow
    at all, only a combination of red and green. Adding some blue to
    de-saturate it makes it whiter. So a de-saturated yellow would be
    a yellowish-white. Brown can be reddish, orangish, yellowish, or
    greenish, and I won't explicitly say where the "ish" comes from, but
    I think you've seen it for yourself. De-saturate brown enough and
    it becomes beige.

    -- Jeff, in Minneapolis

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    I assumed that it would be possible that brown dwarfs (cherry-red dwarfs?) could be banded as the one in the artists impression in the article is. Is this correct?

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    Quote Originally Posted by Jeff Root View Post
    Okay, astronomers think that brown isn't a color, that there are no
    mixtures of photons that can produce light that looks brown to our
    eyes, that carbon, nitrogen, and oxygen are metals, and that the
    Universe is homogeneous and isotropic.
    Huh? I can understand this if we are talking about near-blackbody radiators, but not sub-stellar bodies loaded with a host of organics in its photosphere. Perhaps they are rare, but, considering their number, they are bound to be out there.

    Brown is definitely producible using red, green, and blue colors as found on our monitors. But this is obvious, so what are you saying?
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by George View Post
    I recall a T-class brown dwarf that had, essentially, only red and a lesser amount of blue light. This star is likely a maroon star, not far from brown. [There is an old thread on it somewhere. It was Grant's first post, IIRC. ]
    Was indeed.
    The sodium lines in the T-dwarf spectrum are so broad they take a chunk right out of the centre, leaving a mix of blue and red. Adam Burrows described the result as "magenta" in a paper about T dwarfs. L dwarfs turn out to be reddish, as Fraser's sample shows.

    Grant Hutchison

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    Quote Originally Posted by grant hutchison View Post
    A memorable one for me as I did run that through the old SPACC and got somewhat favorable results, IIRC.

    Perhaps we should wait a month on this topic so we can have a 4th year anniversary and pick up where we left off.


    The sodium lines in the T-dwarf spectrum are so broad they take a chunk right out of the centre, leaving a mix of blue and red. Adam Burrows described the result as "magenta" in a paper about T dwarfs. L dwarfs turn out to be reddish, as Fraser's sample shows.
    Are Brown Dwarfs very convective (I assume so)? If not, perhaps compounds could remain in the photosphere after impacting it. I would expect there isn't that many SEDs on these little guys to indicate clearly that no brown one is likely.
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by George View Post
    Huh? I can understand this if we are talking about near-blackbody radiators, but not sub-stellar bodies loaded with a host of organics in its photosphere. Perhaps they are rare, but, considering their number, they are bound to be out there.

    Brown is definitely producible using red, green, and blue colors as found on our monitors. But this is obvious, so what are you saying?
    I think Jeff may have been employing an ancient rhetorical device known as sarcasm to express his disagreement with some of the statements in the article linked to in the OP and elsewhere in the astronomical literature.

    According to wikipedia, T dwarfs are the color of magenta coal tar dye, which I have never seen. I suspect they would look fairly dull.

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    Quote Originally Posted by George View Post
    Quote Originally Posted by Jeff Root
    Okay, astronomers think that brown isn't a color, that there are no
    mixtures of photons that can produce light that looks brown to our
    eyes, that carbon, nitrogen, and oxygen are metals, and that the
    Universe is homogeneous and isotropic.
    Huh? I can understand this if we are talking about near-blackbody
    radiators, but not sub-stellar bodies loaded with a host of organics
    in its photosphere. Perhaps they are rare, but, considering their
    number, they are bound to be out there.

    Brown is definitely producible using red, green, and blue
    colors as found on our monitors. But this is obvious, so what
    are you saying?
    I thought that what I was saying was obvious, too, and I am
    competely at a loss as to why we don't understand each other.
    You seem to be arguing something about the nature of brown
    dwarfs, while I was only talking about the nature of color, vision,
    and the semantics of terms used to describe them. Obviously
    brown IS a color. Obviously there are MANY mixtures of
    photons that can produce light that looks brown to our eyes.
    So why do these people say that brown is NOT a color and
    that there are no mixtures of photons that can produce light
    that looks brown to our eyes? It's just goofy!

    -- Jeff, in Minneapolis

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    Quote Originally Posted by Jeff Root View Post
    I thought that what I was saying was obvious, too, and I am
    competely at a loss as to why we don't understand each other.
    You seem to be arguing something about the nature of brown
    dwarfs, while I was only talking about the nature of color, vision,
    and the semantics of terms used to describe them. Obviously
    brown IS a color.
    My thought here [for their reasoning] is that it isn't part of the spectrum, but it is certainly a color as you say, only one made-up of more than one color of the spectrum. The other thought I had was they were thinking in terms of bb radiators which eliminates green, for instance.

    I assume then that you, like me, suspect some brown dwarfs might look brown?
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by Jeff Root View Post
    So why do these people say that brown is NOT a color and
    that there are no mixtures of photons that can produce light
    that looks brown to our eyes?
    Because there is no mixture of photons from a single luminous source that will uniquely convey the sensation of "brown" to your eyes, any more than there is a mixture of photons from a single luminous source that will uniquely convey the sensation of "grey" to your eyes (or of "black", for that matter).
    Judging "brown" and "grey" needs other cues, which are extracted from contrast effects and estimates of the ambient illumination. They're properties of illuminated surfaces, rather than luminous surfaces. You see them in an environment, rather than in isolation.

    Grant Hutchison
    Last edited by grant hutchison; 2009-Jan-09 at 06:05 PM. Reason: Initially omitted the word "uniquely" (x2)

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    Quote Originally Posted by grant hutchison View Post
    Because there is no mixture of photons from a single luminous source that will convey the sensation of "brown" to your eyes, any more than there is a mixture of photons from a single luminous source that will convey the sensation of "grey" to your eyes (or of "black", for that matter).
    Judging "brown" and "grey" needs other cues, which are extracted from contrast effects and estimates of the ambient illumination. They're properties of illuminated surfaces, rather than luminous surfaces. You see them in an environment, rather than in isolation.

    Grant Hutchison
    That's an interesting explanation that would explain some things. However, such a claim is easy enough to test, I think...

    I filled my montior screen to output "brown" and eliminated ambient lighting and surroundings so that all I could see was the center of my screen. It still looked brown, though there may have been some slight variation to it, perhaps.

    Assuming color constancy or some other pyschological effect was influencing my deciesion, since I already knew it was brown before I looked, I added overlays of various colors that I then deleted leaving the original brown-colored screen. It seems to me that the brain will register brown if the right combination of r,g,b intensities are used, regardless of ambient influences.
    We know time flies, we just can't see its wings.

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    And yet it's easy enough to convert brown to orange-yellow and back again, simply by adjusting external cues.
    The two coloured spots here are the same colour. And, perhaps even more surprisingly, the two grey squares on which the coloured spots lie are the same shade of grey.

    Grant Hutchison

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    Quote Originally Posted by George View Post
    Quote Originally Posted by Jeff Root
    I thought that what I was saying was obvious, too, and I am
    competely at a loss as to why we don't understand each other.
    You seem to be arguing something about the nature of brown
    dwarfs, while I was only talking about the nature of color, vision,
    and the semantics of terms used to describe them. Obviously
    brown IS a color.
    My thought here [for their reasoning] is that it isn't part of the
    spectrum, but it is certainly a color as you say, only one made-up
    of more than one color of the spectrum.
    So according to you, it isn't part of the spectrum, but it is parts
    of the spectrum. :need a cross-eyed smiley:

    Quote Originally Posted by George View Post
    The other thought I had was they were thinking in terms of bb
    radiators which eliminates green, for instance.
    Although the list of colors/temperatures I gave a few posts back
    (from an old Starrett Tools catalog) was indeed for approximate
    blackbody radiators (judging the temperature of steel by sight,
    in that case), the idea that anybody would limit their definition
    of "color" to that which can be emitted by a black body is just
    goofy. Goofy Goofy Goofy. Maybe Donald Duck, too.

    Quote Originally Posted by George View Post
    I assume then that you, like me, suspect some brown dwarfs
    might look brown?
    I haven't given it as much thought as you, but that seems likely.
    With Jupiter and Saturn as our closest comparisons, brown dwarfs
    would be very likely to look at least partly brown by reflected light.
    I'd expect a fairly dim brown dwarf to look dull cherry-red by its
    own emitted light, with no significant orange, yellow, green, or blue.

    -- Jeff, in Minneapolis

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    Quote Originally Posted by grant hutchison View Post
    Quote Originally Posted by Jeff Root
    So why do these people say that brown is NOT a color and
    that there are no mixtures of photons that can produce light
    that looks brown to our eyes?
    Because there is no mixture of photons from a single luminous source
    that will convey the sensation of "brown" to your eyes, any more than
    there is a mixture of photons from a single luminous source that will
    convey the sensation of "grey" to your eyes.
    Both depend on what you mean by "from a single luminous source".

    Quote Originally Posted by grant hutchison View Post
    Judging "brown" and "grey" needs other cues, which are extracted
    from contrast effects and estimates of the ambient illumination.
    They're properties of illuminated surfaces, rather than luminous
    surfaces. You see them in an environment, rather than in isolation.
    I don't entirely disagree with that, but...

    Without external cues, you can't tell any difference between a
    luminous surface and an illuminated surface. If the arrangement
    of materials, geometry, colors, and lighting is right, you could not
    see that a heating element glowing red is not just red paint.

    As George's test and my own observations suggest, the idea that
    brown can only be seen in context isn't always true. Any color's
    appearance depends to a large extent on what else is going on in
    the visual field. That may be more true for brown than for most
    colors, but it isn't absolutely true. Brown will still look brown in a
    very wide range of circumstances, and that does not depend on
    whether the light is reflected, transmitted, or emitted from the
    surface being viewed.

    -- Jeff, in Minneapolis

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    Quote Originally Posted by grant hutchison View Post
    And yet it's easy enough to convert brown to orange-yellow and back
    again, simply by adjusting external cues.
    Well, duh! orange-yellow = brown. They are different names for
    the same thing.

    (I feel the need to note again at this point that "brown" covers an
    extremely wide range of colors, from red-orange through yellow to
    yellow-green, and from nearly black to light beige.)

    Quote Originally Posted by grant hutchison View Post
    The two coloured spots
    here are the same colour. And, perhaps even more surprisingly, the two grey squares on which the coloured spots lie are the same shade of grey.
    I haven't had much success with SVG files. Is the format very new
    or very old? In IrfanView 4.20, most of the top of the checkerboard
    is solid almost-black (000504). Reduced-size screenshot below.

    -- Jeff, in Minneapolis
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	spots.png 
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    Technically, gray and brown aren't colors, but "shades". Both depend on surrounding context--there is no such thing as brown light. Feynman's Lectures on Physics (I forgot which volume--probably the first) explains this in detail in the lecture on color vision.

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    Quote Originally Posted by Jeff Root View Post
    As George's test and my own observations suggest, the idea that
    brown can only be seen in context isn't always true. Any color's
    appearance depends to a large extent on what else is going on in
    the visual field. That may be more true for brown than for most
    colors, but it isn't absolutely true. Brown will still look brown in a
    very wide range of circumstances, and that does not depend on
    whether the light is reflected, transmitted, or emitted from the
    surface being viewed.
    Have you been working off-line on this reply for twelve hours? Your quote from me misses a clarifying edit I made quite soon after posting (the word "uniquely").
    I don't contest that there are photon combinations that will elicit the sensation "brown" under some circumstances. It's just that the same combination of photons will elicit the sensation yellow (or greenish-yellow, or orange-yellow) under other circumstances. You can search as long as you look on the CIE colour triangle, and you won't find a mix of red, green and blue that you'd call brown: that requires a change in luminance as well as hue.
    Brown is not a property of the power spectrum of light of alone, in exactly the same way as grey is not a property of the power spectrum of light alone.

    Just saying "goofy, goofy, goofy" probably won't change that for you.

    Quote Originally Posted by Jeff Root View Post
    Well, duh! orange-yellow = brown. They are different names for
    the same thing.
    Reclassifying brown to include its high-luminance equivalents is certainly one way to defend your point. But perhaps not a good way.

    Grant Hutchison

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    Quote Originally Posted by Jeff Root View Post
    I haven't had much success with SVG files. Is the format very new
    or very old?
    Kind of middling. It has been around since the turn of the millennium, and is one of those web standards that Microsoft has contrived to ignore while everyone else implemented them.
    I'm therefore guessing that you're running a very old browser, or a current version of Internet Explorer.
    If you have IE, you need to download an ActiveX plug-in in order to view SVG. Adobe SVG Viewer is one such. I just hunted down IE on my own machine and installed the plug-in, and can confirm that the image is then viewable with IE7 under Vista, although the plug-in itself is only XP-rated.

    Grant Hutchison

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    Quote Originally Posted by tdvance View Post
    Technically, gray and brown aren't colors, but "shades". Both depend on surrounding context--there is no such thing as brown light. Feynman's Lectures on Physics (I forgot which volume--probably the first) explains this in detail in the lecture on color vision.
    Yes, section 35-3 in Volume 1. To judge from the text, it looks as if Feynman did some sort of experiment during the lecture, mixing red and yellow spotlights and then increasing the level of surrounding illumination to shift the visual sensation from orange to brown.

    Grant Hutchison

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    What are these brown dwarfs what are they talking about?M class brown dwarfs would have the same color and light intensity as the lowest mass M stars (lightbulb white), L class dwarfs are still hotter or around the temperature of wood or candle flame or lava and T dwarfs are around the temperature of a dimly burning fire, T8 brown dwarfs are still as hot as just visible smoldering cinders.

    You shouldn't imagine brown dwarfs as "extremely dim", they are, but only relatively, compared to most other stars, in fact even these "red" dwarfs that are typically portrayed on artists impressions as "crismon red" are WHITE, and such stars as Barnard's star are about as hot as acetylene torch, most "brown" dwarfs are still hotter than ordinary fire or about the same temperature so IMHO they are NOT banded purple dim cinders, only the coolest T dwarfs are like that, most of BDs should appear as bright balls of bright orange or cherry color, they still radiate more energy than we will ever produce on Earth if we mined all the hydrogen and deuterium and tritium from all the water here and fed it to the most effective theoretical nuclear fusion plant.

    It doesn't matter if the energy is from active fusion or not, temperature still makes L and M class BDs dazzlingly bright from close distances.

    Practically every star close up would appear white, just differently tinted, and even L class BDs should still appear as fire orange.

    And I think the molecules would cause some of the effects typically seen in flames, like soot, mega fire tornadoes etc., not Jupiter-like cold chemical colors.

    Think of a BD as a giant ball of fire the size of two Jupiters and you'll get the idea.

    There is no reason to expect temperature and intensity colours would appear anyhow different that they do in things with similiar temperature on Earth -that's why I used the fire comparision.

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    Quote Originally Posted by tdvance
    Technically, gray and brown aren't colors, but "shades". Both depend on surrounding context--there is no such thing as brown light.
    Brown may not be an allowable monochromatic color, but that is not the general use of the meaning of color. I do agree that a good way to see brown is with the understanding of our use of color that includes gray or white. Nevertheless, all of these are found in my Crayola box, so they are colors. [Here again, science lacks an appropriate term that could be used to help eschew obfuscation. "Metamer" kind of works since it is associated with more than one "color", but something that sounds like color should be found. Colorply or colorplex or something to indicate that more than one wavelength is involved in producing the sensation. Cougar? ] "Shade" seems a bit weak. [I refuse to say it sounds too "shady". ]

    Quote Originally Posted by grant hutchison View Post
    You can search as long as you look on the CIE colour triangle, and you won't find a mix of red, green and blue that you'd call brown: that requires a change in luminance as well as hue.
    This may be part of the confussion, if my assumption of what you are saying is correct. [I assume the CIE color triangle use only even luminance values? That would explain some things.] But, of course, there is no reason a star is restricted to a flat spectral luminance. Brown dwarfs may have a vast number of different SEDs due to all the various molecular cocktails allowable in its outer atmospheres.

    Using your old T-class brown dwarf SED, which has strong red and weak blue (maroon, if an object has blue at half or less of the intensity of red ), were to include green at an intensity of about 20% or so more than blue, then brown it is. If you prefer a lighter tone of brown, then add yellow in lieu of green. Brown is what we would see to be the color of the star. [Assuming it is one of the hotter ones and not 700K, for example.]

    The bigger problem is whether such mid-range wavelength peaks would ever be found in their SED. Admitedly, it seems unlikely given that their magenta or maroon (depending on blue intensity) comes from the absence of the midrange colors -- apparently due to sodium and potasium absorption.

    Brown is not a property of the power spectrum of light of alone, in exactly the same way as grey is not a property of the power spectrum of light alone.
    My spectrum can whip your spectrum.

    Just saying "goofy, goofy, goofy" probably won't change that for you.
    Well.... nevermind, I may have said too much already.

    Reclassifying brown to include its high-luminance equivalents is certainly one way to defend your point. But perhaps not a good way.
    I don't understand this. Why not?
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by m1omg View Post
    You shouldn't imagine brown dwarfs as "extremely dim", they are, but only relatively, compared to most other stars, in fact even these "red" dwarfs that are typically portrayed on artists impressions as "crismon red" are WHITE,...
    You are right that they would be much brighter than they are portrayed, but they would only be white if their spectrum were more that of a blackbody, which is true of most of the hotter stars. Brown dwarfs are not blackbody radiators due to the host of molecular compounds in their atmospheres.
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by George View Post
    Reclassifying brown to include its high-luminance equivalents is certainly one way to defend your point. But perhaps not a good way.
    I don't understand this. Why not?
    Because I would guess your crayon collection contains both an orange-yellow and a brown crayon. And I would guess that you don't see a stripe of brown between the orange and green of a rainbow.
    We have different names for things because we perceive salient differences between them.

    I'm untroubled if you and Jeff want to call "brown" a colour. I was just responding to Jeff's question "So why do these people say that brown is NOT a color and that there are no mixtures of photons that can produce light that looks brown to our eyes?"
    The answer is that, because astronomers deal with pure photon mixtures, they use the word "colour" to designate the combination of hue and saturation; relative luminance (the sort of effect that produces brown) is not part of their colour language. That's how life is. Poor Jill Tarter was just being reprimanded for a non-technical usage.

    Grant Hutchison

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    Quote Originally Posted by George View Post
    You are right that they would be much brighter than they are portrayed, but they would only be white if their spectrum were more that of a blackbody, which is true of most of the hotter stars. Brown dwarfs are not blackbody radiators due to the host of molecular compounds in their atmospheres.
    Yeah, but flames are not perfect blackbodies either, and I would guess the molecular components would create some interesting freatures but not attenuate the radiation too much, definitely not to the "crismon, blood red, or pink ball with stripes that shines like a 10 W lightbulb from China" point as on usual illustrations.

    And I wrote that red dwarfs (that are much closer to perfect blackbodies) would be white when viewed from close distances, not brown dwarfs, these would be more orange to cherry color, or like smouldering embers with a more maroonish color in case of colder T dwarfs.

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    Quote Originally Posted by grant hutchison View Post
    Because I would guess your crayon collection contains both an orange-yellow and a brown crayon.
    Wrong, I ate the orange-yellow one long ago. [Not near the citrus flavor that I had for, admittedly.]

    I would guess that you don't see a stripe of brown between the orange and green of a rainbow.
    Quite true, but why are we chasing rainbows, not that I don't like gold? Polychromatic radiance is a given for brown dwarfs. [Perhaps, polychromatic illuminance from brown dwarfs would be more a accurate statement.]

    I'm untroubled if you and Jeff want to call "brown" a colour. I was just responding to Jeff's question "So why do these people say that brown is NOT a color and that there are no mixtures of photons that can produce light that looks brown to our eyes?"
    The answer is that, because astronomers deal with pure photon mixtures, they use the word "colour" to designate the combination of hue and saturation; relative luminance (the sort of effect that produces brown) is not part of their colour language.
    That certainly makes sense for those that study blackbody objects, but this seems much too restrictive now that much diversity is found in the SEDs of so many new objects since the days before Hubble [person and telescope]. Astronomers should be light experts more than most the other scientists, including their view of the " true spectrum" (quintessential superspectrum), which is inclusive of metamers, shades, etcs.

    That's how life is. Poor Jill Tarter was just being reprimanded for a non-technical usage.
    All heliochromolgists feel her pain.
    We know time flies, we just can't see its wings.

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    Quote Originally Posted by George View Post
    Quite true, but why are we chasing rainbows, not that I don't like gold? Polychromatic radiance is a given for brown dwarfs. [Perhaps, polychromatic illuminance from brown dwarfs would be more a accurate statement.]

    That certainly makes sense for those that study blackbody objects, but this seems much too restrictive now that much diversity is found in the SEDs of so many new objects since the days before Hubble. Astronomers should be light experts more than most the other scientists, including the spectrum (quintessential superspectrum), which is inclusive of metamers, shades, etcs.
    This has nothing to do with black body spectra (emission nebulae have provided astronomers with a fine range of colours ever since the advent of photography). And it has nothing to do with spectral colours, or with the difference between pure colours and metamers.
    The only thing of relevance here is that I cannot, even in principle, take a box of photons, analyse their spectral mix, and say unequivocally that they will appear brown to the human eye. That information just isn't present in the box. All I can do is assign them confidently to the yellow region of the hue chart, and predict that under some conditions, when their relative luminance is perceived to be low, they may induce a brown sensation.

    It's because astronomers are light experts that they make this distinction, which is not intuitively obvious to the average crayon-user.

    Grant Hutchison

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    Quote Originally Posted by m1omg View Post
    Yeah, but flames are not perfect blackbodies either, and I would guess the molecular components would create some interesting freatures but not attenuate the radiation too much, definitely not to the "crismon, blood red, or pink ball with stripes that shines like a 10 W lightbulb from China" point as on usual illustrations.
    Yet flames come in many colors. Incandescent lighting (tungsten) is close to behaving like a blackbody radiator, but at a temperature between 2000K to 3300K. These temperatures still produce light across the spectrum, but 2000K is weighted heavily on the red end. It will not look white if the Sun or similar more color-balanced bright light source is arround.

    And I wrote that red dwarfs (that are much closer to perfect blackbodies) would be white when viewed from close distances,...
    Are they close to blackbody radiators? If so then they should look at least as white as a light bulb, though a hotter neighbor in the picture would yellow it.

    Also, it seems they are hot enough that their flux would exceed our photopic vision range and also force a white image, regardless of its color if seen at a lower flux. [BTW, getting closer to the disk will not make it more or less white except for this flux issue. Once you are close enough to see it as a disk, its surface brightness does not increase as you get closer.]
    We know time flies, we just can't see its wings.

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    12,825
    Quote Originally Posted by grant hutchison View Post
    The only thing of relevance here is that I cannot, even in principle, take a box of photons, analyse their spectral mix, and say unequivocally that they will appear brown to the human eye. That information just isn't present in the box. All I can do is assign them confidently to the yellow region of the hue chart, and predict that under some conditions, when their relative luminance is perceived to be low, they may induce a brown sensation.
    Odd, I can, at least in principle. Give me a box of "blue" photons that are half as many as "red" photons, then throw in about 20% more "green" ones [than blue ones] and, after appropriate shaking of course, ta dah... we will be bathed in the sensation of "brown" light. That is why my brown crayon looks brown, right?

    Give me an object's SED in the visible spectrum and I will give you an accurate "color" (colorplex) of the object presented. Your Spectrum(?) software package you shared with us does the same, but it may not be super accurate. But this you know, so where did I miss the bridge?

    It's because astronomers are light experts that they make this distinction, which is not intuitively obvious to the average crayon-user.
    Hence the problem, they should never have skipped those early coloring grades!! I hate to pick on my favorite scientists dedicated to my favorite hobby, but color is not their strong suit. This is justifiable as color alone is very limited information about an object compared to what they find in absorption and emission spectrums. So, it is unfair for anyone to be too critical of their colorful errors, but I feel obliged being that I am their friend and a volunteer heliochromologist.
    We know time flies, we just can't see its wings.

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