Analysis of BMR tilt from AutoTAB catalog: Hinting towards the thin flux tube model?

Abstract

One of the intriguing mechanisms of the Sun is the formation of the bipolar magnetic regions (BMRs) in the solar convection zone which are observed as regions of concentrated magnetic fields of opposite polarity on photosphere. These BMRs are tilted with respect to the equatorial line, which statistically increases with latitude. The thin flux tube model, employing the rise of magnetically buoyant flux loops and their twist by Coriolis force, is a popular paradigm for explaining the formation of tilted BMRs. In this study, we assess the validity of the thin flux tube model by analyzing the tracked BMR data obtained through the Automatic Tracking Algorithm for BMRs (AutoTAB). Our observations reveal that the tracked BMRs exhibit the expected collective behaviors. We find that the polarity separation of BMRs increases over their normalized lifetime, supporting the assumption of a rising flux tube from the CZ. Moreover, we observe an increasing trend of the tilt with the flux of the BMR, suggesting that rising flux tubes associated with lower flux regions are primarily influenced by drag force and Coriolis force, while in higher flux regions, magnetic buoyancy dominates. Furthermore, we observe Joy's law dependence for emerging BMRs from their first detection, indicating that at least a portion of the tilt observed in BMRs can be attributed to the Coriolis force. Notably, lower flux regions exhibit a higher amount of fluctuations associated with their tilt measurement compared to stronger flux regions, suggesting that lower flux regions are more susceptible to turbulent convection.

16 pages, 10 figures. Under consideration in ApJ. Comments are welcome

References in corpus (8)

• The Helioseismic and Magnetic Imager (HMI) Vector Magnetic Field Pipeline: Overview and Performance
• Solar Cycle Variability Induced by Tilt Angle Scatter in a Babcock--Leighton Solar Dynamo Model
• Models for the long-term variations of solar activity
• How good is the bipolar approximation of active regions for surface flux transport?
• Measurements of Solar Differential Rotation Using the Century Long Kodaikanal Sunspot Data
• Average motion of emerging solar active region polarities II: Joy's law
• Average motion of emerging solar active region polarities I: Two phases of emergence
• AutoTAB: Automatic Tracking Algorithm for Bipolar Magnetic Regions

Cited by in corpus (5)

• Role of sunspot latitude versus tilt in determining the polar field and amplitude of the next cycle: Cause of the weak Solar Cycle 20
• Observed Joys law of Bipolar Magnetic Region tilts at the emergence supports the thin flux tube model
• Observation-Based Iterative Map for Solar Cycles. I. Nature of Solar Cycle Variability
• Solar active region scaling laws revisited
• Solar Cycle Prediction: Challenges, Progress, and Future Perspectives