Visible Light Extrapolation from Infrared Imaging

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Jim Leff
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Visible Light Extrapolation from Infrared Imaging

Post by Jim Leff » Sat Feb 12, 2022 5:09 pm

I can't seem to find an answer for this, and it seems like a pretty pertinent question:

Will we be able to extrapolate a reasonable approximation of visible light coloring from infrared data gathered by Webb telescope?

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Chris Peterson
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Re: Visible Light Extrapolation from Infrared Imaging

Post by Chris Peterson » Sat Feb 12, 2022 5:55 pm

Jim Leff wrote: Sat Feb 12, 2022 5:09 pm I can't seem to find an answer for this, and it seems like a pretty pertinent question:

Will we be able to extrapolate a reasonable approximation of visible light coloring from infrared data gathered by Webb telescope?
In most cases, no. It's looking at different things, so I doubt anybody will be much interested in trying.
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Re: Visible Light Extrapolation from Infrared Imaging

Post by Jim Leff » Sat Feb 12, 2022 11:05 pm

Hmm, thanks for the answer, but the "interested in trying" part threw me a little.

I don't think(?) you're denying it would be ideal if some of its output were extrapolatable into visible light, thus making it more accessible for human eyes. If that output could be post-processed to delight the funding public (like Hubble) without hampering the mission, why not? For one thing, it'd also make better fodder for APOD, which celebrates not just astronomical phenomena but their aesthetic appearance.

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Re: Visible Light Extrapolation from Infrared Imaging

Post by Chris Peterson » Sat Feb 12, 2022 11:22 pm

Jim Leff wrote: Sat Feb 12, 2022 11:05 pm Hmm, thanks for the answer, but the "interested in trying" part threw me a little.

I don't think(?) you're denying it would be ideal if some of its output were extrapolatable into visible light, thus making it more accessible for human eyes. If that output could be post-processed to delight the funding public (like Hubble) without hampering the mission, why not? For one thing, it'd also make better fodder for APOD, which celebrates not just astronomical phenomena but their aesthetic appearance.
How does such extrapolation make it "more accessible for human eyes"? The IR data will be displayed using a range of wavelengths that we can perceive, which is how that accessibility will be achieved. We're looking at radiation our eyes can't see. A part of the spectrum that provides information that visible light does not. Trying to guess what visible colors might be present in the object doesn't seem particularly useful.
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Re: Visible Light Extrapolation from Infrared Imaging

Post by Jim Leff » Sun Feb 13, 2022 1:25 am

“Useful” is an odd word choice. If I’m to take that literally, you’re brusquely dismissing something I and others might like to see, as if our interests are irrelevant while yours are paramount. If you mean scientifically useful, then you’re misunderstanding my inquiry despite multiple clarifications.

Thanks for giving it a shot, though!

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Re: Visible Light Extrapolation from Infrared Imaging

Post by Chris Peterson » Sun Feb 13, 2022 2:29 am

Jim Leff wrote: Sun Feb 13, 2022 1:25 am “Useful” is an odd word choice. If I’m to take that literally, you’re brusquely dismissing something I and others might like to see, as if our interests are irrelevant while yours are paramount. If you mean scientifically useful, then you’re misunderstanding my inquiry despite multiple clarifications.

Thanks for giving it a shot, though!
Regardless of your intent, the imaging is in a different part of the spectrum. There simply isn't the data required to know what's going on in the shorter wavelengths for anything other, perhaps, than stars.
Last edited by Chris Peterson on Sun Feb 13, 2022 2:30 pm, edited 1 time in total.
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Ann
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Re: Visible Light Extrapolation from Infrared Imaging

Post by Ann » Sun Feb 13, 2022 6:30 am

Jim Leff wrote: Sat Feb 12, 2022 5:09 pm I can't seem to find an answer for this, and it seems like a pretty pertinent question:

Will we be able to extrapolate a reasonable approximation of visible light coloring from infrared data gathered by Webb telescope?
It is indeed possible to classify stars just based on their infrared properties.

An example is the extremely luminous Pistol Star very close to the center of the Milky Way. Its optical light is blocked by the thick central dust lane of the Milky Way, but it can be detected infrared wavelengths. According to Wikipedia, the effective temperature (blackbody temperature) of the Pistol Star is about 12,000 K, similar to Rigel.

A.Z. Bonanos et al. have studied the infrared properties of OB stars in the Large and Small Magellanic Clouds.

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Re: Visible Light Extrapolation from Infrared Imaging

Post by Chris Peterson » Sun Feb 13, 2022 2:32 pm

Ann wrote: Sun Feb 13, 2022 6:30 am
Jim Leff wrote: Sat Feb 12, 2022 5:09 pm I can't seem to find an answer for this, and it seems like a pretty pertinent question:

Will we be able to extrapolate a reasonable approximation of visible light coloring from infrared data gathered by Webb telescope?
It is indeed possible to classify stars just based on their infrared properties.

An example is the extremely luminous Pistol Star very close to the center of the Milky Way. Its optical light is blocked by the thick central dust lane of the Milky Way, but it can be detected infrared wavelengths. According to Wikipedia, the effective temperature (blackbody temperature) of the Pistol Star is about 12,000 K, similar to Rigel.

A.Z. Bonanos et al. have studied the infrared properties of OB stars in the Large and Small Magellanic Clouds.

Ann
Any blackbody can be fully characterized by just two (occasionally three) measurements taken at different wavelengths.
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Re: Visible Light Extrapolation from Infrared Imaging

Post by Jim Leff » Sun Feb 13, 2022 7:20 pm

Chris Peterson wrote: Sun Feb 13, 2022 2:29 am
Regardless of your intent, the imaging is in a different part of the spectrum. There simply isn't the data required to know what's going on in the shorter wavelengths for anything other, perhaps, than stars.
Intent was something you brought up, not me. I simply asked whether it was possible. You chose to delve into the question of usefulness. But you've also answered my question, for which I thank you.

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Re: Visible Light Extrapolation from Infrared Imaging

Post by Jim Leff » Sun Feb 13, 2022 7:24 pm

Ann wrote: Sun Feb 13, 2022 6:30 am It is indeed possible to classify stars just based on their infrared properties.
So I guess this means we'll at least know enough to add, for instance, a broadly red glow to red stars if we want to make some nodding effort to interpret Webb's infrared images for human-visual.

It's not much (more akin to "artist's representation"), but I guess it's something!

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Re: Visible Light Extrapolation from Infrared Imaging

Post by Chris Peterson » Sun Feb 13, 2022 7:33 pm

Jim Leff wrote: Sun Feb 13, 2022 7:24 pm
Ann wrote: Sun Feb 13, 2022 6:30 am It is indeed possible to classify stars just based on their infrared properties.
So I guess this means we'll at least know enough to add, for instance, a broadly red glow to red stars if we want to make some nodding effort to interpret Webb's infrared images for human-visual.

It's not much (more akin to "artist's representation"), but I guess it's something!
Keep in mind that cosmologically distant targets are a major part of the Webb observing program, which means deeply redshifted. Recreating star color involves both characterizing the blackbody curve from two or three different measurements at IR wavelengths, and then compensating for redshift. All very doable.
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