New measurement of the facular contrast near the solar limb

Technical Report · Wed Feb 15 04:00:00 EST 1984

OSTI ID:5893591

Libbrecht, K G; Kuhn, J R

A new measurement of the contrast of solar faculae at 525 nm and 800 nm is presented using photometer data taken during the summer of 1982. The authors find that the contrast is decreasing with heliocentric angle Theta from mu approx. 0.2 to mu approx. 0.08, where mu = cos Theta. Parameterizing the contrast function with (Delta I)/I = 0.2 + alpha(mu - 0.2) over the range 0.08 < or = mu < or = 0.2, they obtain the best fit values of alpha: alpha(green) = 0.33 + or - 0.14, and alpha(red) = 0.25 + or - 0.08. These results differ from the facular contrast measurement of Chapman and Klabunde, who find the contrast increasing toward the limb. Selection effects in their data are suggested that could explain the discrepancy. These results are in good agreement with the facular model of Spruit, assuming a fixed magnetic field strength of 2000 gauss.

• Research Organization: Princeton Univ., NJ (USA). Dept. of Physics
• OSTI ID: 5893591
• Report Number(s): AD-A-162871/8/XAB
• Country of Publication: United States
• Language: English

Related Subjects

640104* -- Astrophysics &amp; Cosmology-- Solar Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BRIGHTNESS
FACULAE
FUNCTIONS
MAGNETIC FIELDS
OPTICAL PROPERTIES
PHOTOMETRY
PHYSICAL PROPERTIES
SOLAR ACTIVITY