Modeling sunspot and starspot decay by turbulent erosion

Abstract

Disintegration of sunspots (and starspots) by fluxtube erosion, originally proposed by Simon and Leighton, is considered. A moving boundary problem is formulated for a nonlinear diffusion equation that describes the sunspot magnetic field profile. Explicit expressions for the sunspot decay rate and lifetime by turbulent erosion are derived analytically and verified numerically. A parabolic decay law for the sunspot area is obtained. For moderate sunspot magnetic field strengths, the predicted decay rate agrees with the results obtained by Petrovay and Moreno-Insertis. The new analytical and numerical solutions significantly improve the quantitative description of sunspot and starspot decay by turbulent erosion.

arXiv commentAstrophysical Journal, accepted

References in corpus (6)

• Numerical simulations of active region scale flux emergence: From spot formation to decay
• Turbulent Erosion of Magnetic Flux Tubes
• Bimodal Distribution of Magnetic Fields and Areas of Sunspots
• On Sunspot and Starspot Lifetimes
• Development of twist in an emerging magnetic flux tube by poloidal field accretion
• Making Sense of Sunspot Decay II: Deviations from the Mean Law and Plage Effects

Cited by in corpus (8)

• A Kepler Study of Starspot Lifetimes with Respect to Light Curve Amplitude and Spectral Type
• A combined spectroscopic and photometric stellar activity study of Epsilon Eridani
• The formation of an atypical sunspot light bridge as a result of large-scale flux emergence
• Study of the decay rates of the umbral area of sunspot groups by using a high resolution database
• The Decay of Two Adjacent Sunspots Associated with Moving Magnetic Features
• Variation of sunspot groups' polarity separation during their evolution
• The Decay Process of an α-configuration Sunspot
• Sunspot and starspot lifetimes in a turbulent erosion model