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1980A&AS...42..283N
Nicolet (1980)
B0
A0F0
G0
K0
M0
B5
Color-Color Diagrams
U−B is sensitive to Hydrogen in n = 2 state (eg, A stars).
N = ~ 40,000 starsphotoelectric mags.
ASTR 511/O’Connell Lec 15 4
Location of the UBV Filters (Johnson & Morgan 1953)
1980A&AS...42..283N
Nicolet (1980)
A0
B0
F0
G0
B0
A0F0
G0
K0
M0
B5
Color-Color Diagrams
U−B is sensitive to Hydrogen in n = 2 state (eg, A stars).
Dust displaces data points along reddening vector.
Q = (U−B) − 0.72 (B−V)
Reddening-independent index:
N = ~ 40,000 starsphotoelectric mags.
(Supergiants are different b/cnarrow lines block less light.)
Can remove reddening effects for O and early B stars.
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