Quote:
Originally Posted by George
I must be misunderstanding your original question.
I have a spreadsheet that uses Planck's equation for any given range of wavelengths and increments.
However, something may be wrong. In using the inverse square law to calculate Fomalhaut's magnitude at a 1 AU distance, I find that it is about 15 times brighter than the Sun and not the 5x brighter I estimated from the Planck equations (using 8500K for its surface temp. -- an A3 star).
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Did you account for the fact Fomalhaut's area is about 3.4 times solar? I think Fomalhaut's bolometric luminosity is about 17 times solar.
Quote:
Originally Posted by George
[Added: BTW, I calculate that Fomalhaut b should be around 27.5 in apparent magnitude using a Jupiter radius for its size and a 0.6 albedo.]
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So it could be imaged in reflected light (as opposed to in its own IR emissions), if they were willing to point HST at it for long enough. I've read that the albedo of gas giants varies greatly with their temperature though.