FreeLists / az-observing / [AZ-Observing] Re: Kappa Gemini

[Brian Skiff <bas@xxxxxxxxxx>]

>>  ...colors of the two stars as light yellow and AQUA--honest!!
>>  ...I don't have the actual spectrum, but I will try and find it.

     I'm not absolutely sure, but I think there is no spectral type
available for the companion.  However, kappa Gem is G8III (G8 giant),
in fact a standard of this spectral type.  The companion is shown in
several places as being between 5.5 and 6 magnitudes fainter than 
the primary.  This means it must be an early-K dwarf, and thus  
actually has almost identical B-V color as the giant.  So the color
difference you see is essentially entirely physiological, and with
the large brightness-difference, the pale-blue color of the fainter
star is exactly what you expect, in the sense that this is the common
impression.  Very convincing, and I've seen it on hundreds of pairs,
but it exists only inside your head.

\Brian
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