The solar internetwork. III. Unipolar versus bipolar flux appearance

Abstract

Small-scale internetwork (IN) magnetic fields are considered to be the main building blocks of the quiet Sun magnetism. For this reason, it is crucial to understand how they appear on the solar surface. Here, we employ a high-resolution, high-sensitivity, long-duration Hinode/NFI magnetogram sequence to analyze the appearance modes and spatio-temporal evolution of individual IN magnetic elements inside a supergranular cell at the disk center. From identification of flux patches and magnetofrictional simulations, we show that there are two distinct populations of IN flux concentrations: unipolar and bipolar features. Bipolar features tend to be bigger and stronger than unipolar features. They also live longer and carry more flux per feature. Both types of flux concentrations appear uniformly over the solar surface. However, we argue that bipolar features truly represent the emergence of new flux on the solar surface, while unipolar features seem to be formed by coalescence of background flux. Magnetic bipoles appear at a faster rate than unipolar features (68 as opposed to 55 Mx cm${}^{-2}$ day${}^{-1}$), and provide about 70% of the total instantaneous IN flux detected in the interior of the supergranule.

arXiv comment14 pages, 11 figures. Accepted for publication in ApJ. Animations are available at https://www.lmsal.com/~mgosic/download/animations_apj_2021b.tgz

References in corpus (35)

• The Solar Optical Telescope for the Hinode Mission: An Overview
• A Substantial Amount of Hidden Magnetic Energy in the Quiet Sun
• Sunrise: instrument, mission, data and first results
• Numerical simulations of quiet Sun magnetism: On the contribution from a small-scale dynamo
• A solar surface dynamo
• The Imaging Magnetograph eXperiment (IMaX) for the Sunrise balloon-borne solar observatory
• The Sunrise Mission
• Emergence of Small-Scale Magnetic Loops in the Quiet Sun Internetwork
• A Method for Data-Driven Simulations of Evolving Solar Active Regions
• Small-scale solar magnetic fields
• Emergence of small-scale magnetic loops through the quiet solar atmosphere
• Probing quiet Sun magnetism using MURaM simulations and Hinode/SP results: support for a local dynamo
• Homologous Helical Jets: Observations by IRIS, SDO and Hinode and Magnetic Modeling with Data-Driven Simulations
• Transverse component of the magnetic field in the solar photosphere observed by Sunrise
• The Solar Internetwork. I. Contribution to the Network Magnetic Flux
• Turbulent small-scale dynamo action in solar surface simulations
• Low-lying magnetic loops in the solar internetwork
• DOT tomography of the solar atmosphere. IV. Magnetic patches in internetwork areas
• A Comprehensive Method of Estimating Electric Fields from Vector Magnetic Field and Doppler Measurements
• The Coronal Global Evolutionary Model: Using HMI Vector Magnetogram and Doppler Data to Model the Buildup of Free Magnetic Energy in the Solar Corona
• Magnetic loop emergence within a granule
• Magnetic field emergence in quiet Sun granules
• The Solar Internetwork. II. Magnetic Flux Appearance and Disappearance Rates
• The frontier between Small-scale bipoles and Ephemeral Regions in the solar photosphere: Emergence and Decay of an Intermediate-scale bipole observed with IMaX/SUNRISE
• Small-scale dynamo simulations: Magnetic field amplification in exploding granules and the role of deep and shallow recirculation
• The Coronal Global Evolutionary Model: Using HMI Vector Magnetogram and Doppler Data to Determine Coronal Magnetic Field Evolution
• Estimation of the magnetic flux emergence rate in the quiet Sun from Sunrise data
• Magnetic field emergence in mesogranular-sized exploding granules observed with SUNRISE/IMaX data
• Dead calm areas in the very quiet Sun
• Optimization of Photospheric Electric Field Estimates for Accurate Retrieval of Total Magnetic Energy Injection
• The relation between photospheric supergranular flows and magnetic flux emergence
• Statistical evolution of quiet-Sun small scale magnetic features using Sunrise observations
• Transport of magnetic flux from the canopy to the internetwork
• Chromospheric observations and magnetic configuration of a supergranular structure
• Interaction of magnetic fields with a vortex tube at solar subgranular scale

Cited by in corpus (8)

• The European Solar Telescope
• Small-scale dynamos: From idealized models to solar and stellar applications
• Numerical simulations and observations of Mg II in the solar chromosphere
• Global impact of emerging internetwork fields on the low solar atmosphere
• Exploring magnetic loops and serpentine fields in the quiet Sun with the GRIS-IFU
• Magnetic outbreak associated with exploding granulations
• Complexity-entropy analysis of solar photospheric turbulence: Hinode images of magnetic and Poynting fluxes
• Emergence of magnetic flux sheets in the quiet Sun. I. Statistical properties