Highest Resolution Observations of the Quietest Sun

Goode, Philip R.; Yurchyshyn, Vasyl; Cao, Wenda; Abramenko, V. I.; Andic, Aleksandra; Ahn, Kwangsu; Chae, Jongchul

doi:10.1088/2041-8205/714/1/l31

Cited by 85 publications

(80 citation statements)

References 27 publications

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“…These interactions in the near-surface layers are also basic to local dynamo action (Schussler & Vogler 2008), which, if present, could explain the large amount of quiet-Sun magnetic flux inferred from high-resolution observations (Lites et al 2008;Goode et al 2010). An important aspect of these interactions is the role of helical or swirly fluid motions which can similarly twist or inject helicity to the magnetic field, and vice versa.…”

Section: Introductionmentioning

confidence: 95%

Relationships Between Fluid Vorticity, Kinetic Helicity, and Magnetic Field on Small-Scales (Quiet-Network) on the Sun

Sangeetha

Rajaguru

2016

ApJ

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We derive horizontal fluid motions on the solar surface over large areas covering the quiet-Sun magnetic network from local correlation tracking of convective granules imaged in continuum intensity and Doppler velocity by the Helioseismic and Magnetic Imager (HMI) on board the Solar Dynamics Observatory. From these we calculate the horizontal divergence, the vertical component of vorticity, and the kinetic helicity of fluid motions. We study the correlations between fluid divergence and vorticity, and between vorticity (kinetic helicity) and the magnetic field. We find that the vorticity (kinetic helicity) around small-scale fields exhibits a hemispherical pattern (in sign) similar to that followed by the magnetic helicity of large-scale active regions (containing sunspots). We identify this pattern to be a result of the Coriolis force acting on supergranular-scale flows (both the outflows and inflows), consistent with earlier studies using local helioseismology. Furthermore, we show that the magnetic fields cause transfer of vorticity from supergranular inflow regions to outflow regions, and that they tend to suppress the vortical motions around them when magnetic flux densities exceed about 300 G (from HMI). We also show that such an action of the magnetic fields leads to marked changes in the correlations between fluid divergence and vorticity. These results are speculated to be of importance to local dynamo action (if present) and to the dynamical evolution of magnetic helicity at the small-scale.

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Section: Introductionmentioning

confidence: 95%

Relationships Between Fluid Vorticity, Kinetic Helicity, and Magnetic Field on Small-Scales (Quiet-Network) on the Sun

Sangeetha

Rajaguru

2016

ApJ

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“…Recent observations made by Hinode and large ground-based solar telescopes have discovered that the chromosphere is even more dynamic than previously thought (Shibata et al 2007;Nishizuka et al 2008;Goode et al 2010b). It is believed that such activity is actually activated and driven by photospheric dynamics which exhibits a constantly evolving, multipolar magnetic flux distribution.…”

Section: Introductionmentioning

confidence: 96%

Observation of Magnetic Reconnection Driven by Granular Scale Advection

Zeng

Cao

2013

ApJ

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We report the first evidence of magnetic reconnection driven by advection in a rapidly developing large granule using high spatial resolution observations of a small surge event (base size ∼ 4 × 4 ) with the 1.6 m aperture New Solar Telescope at the Big Bear Solar Observatory. The observations were carried out in narrowband (0.5 Å) He i 10830 Å and broadband (10 Å) TiO 7057 Å. Since He i 10830 Å triplet has a very high excitation level and is optically thin, its filtergrams enable us to investigate the surge from the photosphere through the chromosphere into the lower corona. Simultaneous space data from the Atmospheric Imaging Assembly and Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory were used in the analysis. It is shown that the surge is spatio-temporally associated with magnetic flux emergence in the rapidly developing large granule. During the development of the granule, its advecting flow (∼2 km s −1 ) squeezed the magnetic flux into an intergranular lane area, where a magnetic flux concentration was formed and the neighboring flux with opposite magnetic polarity was canceled. During the cancellation, the surge was produced as absorption in He i 10830 Å filtergrams while simultaneous EUV brightening occurred at its base. The observations clearly indicate evidence of a finest-scale reconnection process driven by the granule's motion.

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“…Bonet et al (2008) traced the motions of bright points which follow spiral paths on the way to being engulfed by a downdraught. Goode et al (2010) noted that colliding granules create a vortex into which the encircled bright points enter and spin around each other. Additionally, Wedemeyer-Böhm et al (2012) demonstrated, using a series of co-spatial images at different atmospheric layers, that "magnetic tornadoes" in the chromosphere and transition region results in rotational motions of the associated photospheric bright points.…”

Section: Introductionmentioning

confidence: 99%

Characterizing motion types ofG-band bright points in the quiet Sun

Yang

et al. 2015

Res. Astron. Astrophys.

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We study the motions of G-band bright points (GBPs) in the quiet Sun to obtain the characteristics of different motion types. A high resolution image sequence taken with the Hinode/Solar Optical Telescope (SOT) is used, and GBPs are automatically tracked by segmenting 3D evolutional structures in a space-time cube. After putting the GBPs that don't move during their lifetimes aside, the non-stationary GBPs are categorized into three types based on an index of motion type. Most GBPs that move in straight or nearly straight lines are categorized into a straight motion type, a few moving in rotary paths into a rotary motion, and the others fall into a motion type we called erratic. The mean horizontal velocity is 2.18±0.08 km s −1 , 1.63±0.09 km s −1 and 1.33±0.07 km s −1 for straight, erratic and rotary motion type, respectively. We find that a GBP drifts at a higher and constant velocity during its whole life if it moves in a straight line. However, it has a lower and variational velocity if it moves in a rotary path. The diffusive process is ballistic-, super-and sub-diffusion for straight, erratic and rotary motion type, respectively. The corresponding diffusion index (γ) and coefficients (K) are 2.13±0.09 and 850±37 km 2 s −1 , 1.82±0.07 and 331±24 km 2 s −1 , 0.73±0.19 and 13±9 km 2 s −1 . In terms of direction of motion, it is homogeneous and isotropical, and usually persists between neighbouring frames, no matter what motion type a GBP belongs to.

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Highest Resolution Observations of the Quietest Sun

Cited by 85 publications

References 27 publications

Relationships Between Fluid Vorticity, Kinetic Helicity, and Magnetic Field on Small-Scales (Quiet-Network) on the Sun

Relationships Between Fluid Vorticity, Kinetic Helicity, and Magnetic Field on Small-Scales (Quiet-Network) on the Sun

Observation of Magnetic Reconnection Driven by Granular Scale Advection

Characterizing motion types ofG-band bright points in the quiet Sun

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