We study the relationship between the brightness I and magnetic field B distributions of sunspots using 272 samples observed at the San Fernando Observatory and the National Solar Observatory, Kitt Peak whose characteristics varied widely. We find that the I-B relationship has a quadratic form for the spots with magnetic field less than about 2000 G. The slope of the linear part of the I-B curve varies by about a factor of three for different types of spots. In general the slope increases as the spot approaches disk center. The I-B slope does not have a clear dependency on the spot size but the lower limit appears to increase as a function of the ratio of umbra and penumbra area. The I-B slope changes as a function of age of the sunspots. We discuss various sunspot models using these results.
Authors: T. Leonard and D. P. Choudhary
Publication Status: Accepted for publication in Solar Physics
Last Modified: 2008-09-23 20:52