Horizontal flow fields observed in Hinode G-band images II. Flow fields in the final stages of sunspot decay

Abstract

We present a subset of multi-wavelengths observations obtained with the Japanese Hinode mission, the Solar Dynamics Observatory (SDO), and the Vacuum Tower Telescope (VTT) at Observatorio del Teide, Tenerife, Spain during the time period from 2010 November 18-23. Horizontal proper motions were derived from G-band and Ca II H images, whereas line-of-sight velocities were extracted from VTT Echelle H-alpha 656.28 nm spectra and Fe I 630.25 nm spectral data of the Hinode/Spectro-Polarimeter, which also provided three-dimensional magnetic field information. The Helioseismic and Magnetic Imager on board SDO provided continuum images and line-of-sight magnetograms as context for the high-resolution observations for the entire disk passage of the active region. We have performed a quantitative study of photospheric and chromospheric flow fields in and around decaying sunspots. In one of the trailing sunspots of active region NOAA 11126, we observed moat flow and moving magnetic features (MMFs), even after its penumbra had decayed. We also noticed a superpenumbral structure around this pore. MMFs follow well-defined, radial paths from the spot all the way to the border of a supergranular cell surrounding the spot. In contrast, flux emergence near the other sunspot prevented it from establishing such well ordered flow patterns, which could even be observed around a tiny pore of just 2 Mm diameter. After the disappearance of the sunspots/pores a coherent patch of abnormal granulation remained at their location, which was characterized by more uniform horizontal proper motions, low divergence values, and diminished photospheric Doppler velocities. This region, thus, differs significantly from granulation and other areas covered by G-band bright points. We conclude that this peculiar flow pattern is a signature of sunspot decay and the dispersal of magnetic flux.

13 pages, 11 figures, accepted for publication in Astronomy and Astrophysics

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• Magnetic Flux Loss and Flux Transport in a Decaying Active Region
• Moat flow in the vicinity of sunspots for various penumbral configurations
• Spectropolarimetry of a decaying sunspot penumbra
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Cited by in corpus (28)

• Numerical simulations of active region scale flux emergence: From spot formation to decay
• Evaluating local correlation tracking using CO5BOLD simulations of solar granulation
• Three-dimensional structure of a sunspot light bridge
• Correlations between sunspots and their moat flows
• A comparative study of two X2.2 and X9.3 solar flares observed with HARPS-N: Reconciling Sun-as-a-star spectroscopy and high-spatial resolution solar observations in the context of the solar-stellar connection
• A giant quiescent solar filament observed with high-resolution spectroscopy
• Horizontal flow fields in and around a small active region-- The transition period between flux emergence and decay
• Horizontal flow fields observed in Hinode G-band images IV. Statistical properties of the dynamical environment around pores
• Properties of the inner penumbral boundary and temporal evolution of a decaying sunspot
• High-resolution imaging and near-infrared spectroscopy of penumbral decay
• High cadence spectropolarimetry of moving magnetic features observed around a pore
• Emergence of small-scale magnetic flux in the quiet Sun
• High-resolution spectroscopy of a surge in an emerging flux region
• Horizontal flow fields observed in Hinode G-band images III. The decay of a satellite sunspot and the role of magnetic flux removal in flaring
• On the extent of the moat flow in axisymmetric sunspots
• Moving Magnetic Features around a Pore
• Background-subtracted Solar Activity Maps
• Evolution of the flow field in decaying active regions, Transition from a moat flow to a supergranular flow
• Near-infrared spectropolarimetry of a delta-spot
• On the (in)stability of sunspots
• The formation and decay of sunspot penumbra in Active Region NOAA 12673
• The Decay of Two Adjacent Sunspots Associated with Moving Magnetic Features
• Evolution of the flow field in decaying active regions II. Converging flows at the periphery of naked spots
• Spectral Background-Subtracted Activity Maps
• The Decay Process of an α-configuration Sunspot
• Cloud model inversions of strong chromospheric absorption lines using principal component analysis
• Infrared spectropolarimetry of a C-class solar flare footpoint plasma -- I. Spectral features and forward modelling
• The dependence of the magnetism of a near-limb sunspot on height