On the relation between photospheric flow fields and the magnetic field distribution on the solar surface

Simon, Gilles; Title, A. M.; Topka, K.; Tarbell, T. D.; Shine, R. A.; Ferguson, S. H.; Zirin, H.

doi:10.1086/166253

Cited by 90 publications

(46 citation statements)

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“…Simon & Leighton (1964) suggested that the supergranulation flow field carries the internetwork magnetic field to cell boundaries, forming the pattern of the chromospheric network. So far many observations have confirmed that most internetwork magnetic elements move toward the boundaries of the magnetic network (e.g., Martin 1988;Simon et al 1988;Wang & Zirin 1988;Zhang et al 1998). Using magnetograms obtained by the Big Bear Solar Observatory (BBSO), Zhang et al (2006) estimated the emergence rate of the new flux (ephemeral regions) to be ∼5 × 10 −19 cm −2 day −1 in the quiet Sun.…”

Section: Magneto-convection In the Chromospherementioning

confidence: 99%

“…Groups of theses granules tend to move in a systematic way, which is characterized by a cellular convective motion at scales of the order of 32 Mm (Leighton et al 1962). This larger-scale flow was termed supergranulation, with cells of which the boundaries coincide with the chromospheric network and lanes of magnetic concentrations (e.g., Leighton et al 1962;Simon & Leighton 1964;Simon et al 1988;Wang & Zirin 1988).…”

Section: Introductionmentioning

confidence: 99%

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Horizontal supergranule-scale motions inferred from TRACE ultraviolet observations of the chromosphere

Potts

Marsch

Attié

et al. 2010

A&A

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Aims. We study horizontal supergranule-scale motions revealed by TRACE observation of the chromospheric emission, and investigate the coupling between the chromosphere and the underlying photosphere. Methods. A highly efficient feature-tracking technique called balltracking has been applied for the first time to the image sequences obtained by TRACE (transition region and coronal explorer) in the passband of white light and the three ultraviolet passbands centered at 1700 Å, 1600 Å, and 1550 Å. The resulting velocity fields have been spatially smoothed and temporally averaged in order to reveal horizontal supergranule-scale motions that may exist at the emission heights of these passbands. Results. We find indeed a high correlation between the horizontal velocities derived in the white-light and ultraviolet passbands. The horizontal velocities derived from the chromospheric and photospheric emission are comparable in magnitude. Conclusions. The horizontal motions derived in the UV passbands might indicate the existence of a supergranule-scale magnetoconvection in the chromosphere, which may shed new light on the study of mass and energy supply to the corona and solar wind at the height of the chromosphere. However, it is also possible that the apparent motions reflect the chromospheric brightness evolution as produced by acoustic shocks which might be modulated by the photospheric granular motions in their excitation process, or advected partly by the supergranule-scale flow towards the network while propagating upward from the photosphere. To reach a firm conclusion, it is necessary to investigate the role of granular motions in the excitation of shocks through numerical modeling, and future high-cadence chromospheric magnetograms must be scrutinized.

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Section: Magneto-convection In the Chromospherementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Horizontal supergranule-scale motions inferred from TRACE ultraviolet observations of the chromosphere

Potts

Marsch

Attié

et al. 2010

A&A

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“…In the following, we collectively refer to these bright structures as bright points (BPs). The BPs are associated with regions of strong magnetic field (Chapman & Sheeley 1968;Title, Tarbell, & Topka 1987;Simon et al 1988;Title et al 1989Title et al , 1992Keller 1992) and correspond to magnetic flux tubes of kilogauss field strength that stand nearly vertically in the solar atmosphere (Stenflo 1973;Stenflo & Harvey 1985;Sánchez Almeida & Martínez Pillet 1994; see review by Solanki 1993).…”

Section: Introductionmentioning

confidence: 99%

Motions of IsolatedG‐Band Bright Points in the Solar Photosphere

Nisenson

Ballegooijen

Wijn

et al. 2003

ApJ

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Magnetic elements on the quiet Sun are buffeted by convective flows that cause lateral motions on timescales of minutes. The magnetic elements can be observed as bright points (BPs) in the G band at 4305 Å . We present observations of BPs based on a long sequence of G-band images recorded with the Dutch Open Telescope and postprocessed using speckle-masking techniques. From these images we measured the proper motions of isolated BPs and derived the autocorrelation function of their velocity relative to the solar granulation pattern. The accuracy of BP position measurements is estimated to be less than 23 km on the Sun. The rms velocity of BPs (corrected for measurement errors) is about 0.89 km s À1 , and the correlation time of BP motions is about 60 s. This rms velocity is about 3 times the velocity measured using cork tracking, almost certainly due to the fact that isolated BPs move more rapidly than clusters of BPs. We also searched for evidence of vorticity in the motions of G-band BPs.

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“…The newly formed granules are slower: 0.2−1.9 km s −1 , with a mean speed of 1.1 km s −1 . These velocities are slightly higher compared to the average speed of all outward moving PGs near the P/G border (0.9 km s −1 , Sobotka & Sütterlin 2001) and to the horizontal speed of granules close to sunspots (0.5−0.8 km s −1 , Muller & Ména 1987;Simon et al 1988). Figure 3 demonstrates the transformation of an outward moving PG into a small bright photospheric feature (top) and into a granule (bottom).…”

Section: Outward-moving Penumbral Grainsmentioning

confidence: 92%

“…They correspond to the facular and magnetic elements which are visible in lower resolution filtergrams and magnetograms. The granules (Muller & Ména 1987;Simon et al 1988) and the magnetic elements -either observed in filtergrams or in magnetograms - (Sheeley 1969(Sheeley , 1972Sheeley & Bhatnagar 1971;Vrabec 1971Vrabec , 1974Harvey & Harvey 1973;Muller & Ména 1987;Brickhouse & La Bonte 1988;Lee 1992;Ryutova et al 1998) move radially outwards, through an annular cell. This annular cell has been called a "moat" and the magnetic elements, moving accross, "moving magnetic features" or "MMFs" (Sheeley 1972;Harvey & Harvey 1973).…”

Section: Introductionmentioning

confidence: 99%

Phase diversity restoration of sunspot images

Bonet

Márquez

Müller

et al. 2004

A&A

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Abstract. We investigate the dynamics of and the relations between small-scale penumbral and photospheric features near the outer penumbral boundary: penumbral grains (PGs), dark penumbral fibrils, granules, and photospheric G-band bright points. The analysis is based on a 2 h time sequence of a sunspot close to disc center, taken simultaneously in the G-band and in the blue continuum at 450.7 nm. Observations were performed at the Swedish Vacuum Solar Telescope (La Palma) in July 1999. A total of 2564 images (46 ×75 ) were corrected for telescope aberrations and turbulence perturbations by applying the inversion method of phase diversity. Our findings can by summarized as follows: (a) one third of the outward-moving PGs pass through the outer penumbral boundary and then either continue moving as small bright features or expand and develop into granules. (b) Former PGs and G-band bright points next to the spot reveal a different nature. The latter have not been identified as a continuation of PGs escaping from the penumbra. The G-band bright points are mostly born close to dark penumbral fibrils where the magnetic field is strong, whereas PGs stem from the less-magnetized penumbral component and evolve presumably to non-magnetic granules or small bright features.

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On the relation between photospheric flow fields and the magnetic field distribution on the solar surface

Cited by 90 publications

References 0 publications

Horizontal supergranule-scale motions inferred from TRACE ultraviolet observations of the chromosphere

Horizontal supergranule-scale motions inferred from TRACE ultraviolet observations of the chromosphere

Motions of IsolatedG‐Band Bright Points in the Solar Photosphere

Phase diversity restoration of sunspot images

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