The photospheric structure of a solar pore with light bridge

Giordano, Silvia; Berrilli, F.; Moro, D. Del; Penza, V.

doi:10.1051/0004-6361:20077928

Cited by 30 publications

(32 citation statements)

References 40 publications

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“…This corresponds to the magnetic canopy above the LB, which was observationally confirmed by Jurčák et al (2006). The magnetic field from the surrounding umbral cores is expanding above the LB's weaker field, forming a cusp-like structure at the height h 220 km (Giordano et al 2008). Note that the central part of the LB is almost field-free at the lowest photospheric layer.…”

Section: Structure and Widthmentioning

confidence: 66%

“…Pores contain a wide variety of fine bright features, such as umbral dots and light bridges, which may be signs of a convective energy transportation mechanism (e.g. Sobotka et al 1999;Keil et al 1999;Hirzberger 2003;Giordano et al 2008;Sobotka & Jurčák 2009;Ortiz et al 2010). The simple magnetic structure of pores provides an opportunity to study the interaction of plasma with the magnetic field.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of the solar atmosphere above a pore with a light bridge

Sobotka

Švanda

Jurčák

et al. 2013

A&A

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Context. Solar pores are small sunspots lacking a penumbra that have a prevailing vertical magnetic-field component. They can include light bridges at places with locally reduced magnetic field. Like sunspots, they exhibit a wide range of oscillatory phenomena. Aims. A large isolated pore with a light bridge (NOAA 11005) is studied to obtain characteristics of a chromospheric filamentary structure around the pore, to analyse oscillations and waves in and around the pore, and to understand the structure and brightness of the light bridge. Methods. Spectral imaging observations in the line Ca II 854.2 nm and complementary spectropolarimetry in Fe I lines, obtained with the DST/IBIS spectrometer and HINODE/SOT spectropolarimeter, were used to measure photospheric and chromospheric velocity fields, oscillations, waves, the magnetic field in the photosphere, and acoustic energy flux and radiative losses in the chromosphere. Results. The chromospheric filamentary structure around the pore has all important characteristics of a superpenumbra: it shows an inverse Evershed effect and running waves, and has a similar morphology and oscillation character. The granular structure of the light bridge in the upper photosphere can be explained by radiative heating. Acoustic waves leaking up from the photosphere along the inclined magnetic field in the light bridge transfer enough energy flux to balance the entire radiative losses of the light-bridge chromosphere. Conclusions. A penumbra is not a necessary condition for the formation of a superpenumbra. The light bridge is heated by radiation in the photosphere and by acoustic waves in the chromosphere.

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Section: Structure and Widthmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Dynamics of the solar atmosphere above a pore with a light bridge

Sobotka

Švanda

Jurčák

et al. 2013

A&A

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“…HINODE -The active region NOAA 10977 was observed by the Solar Optical Telescope (SOT; Tsuneta et al 2008) onboard the Hinode satellite (Kosugi et al 2007) The time interval between two successive spectral series was ∼20 s. Data reduction, which includes standard CCD response calibration and correction for systematic blueshift of the instrument profile, was performed as described by Giordano et al (2008).…”

Section: Observations and Data Reductionmentioning

confidence: 99%

Observation of bipolar moving magnetic features streaming out from a naked spot

Zuccarello¹,

Romano

Guglielmino³

et al. 2009

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Context. Mechanisms responsible for active-region formation, evolution, and decay have been investigated by many authors and several common features have been identified. In particular, a key element in the dispersal of the magnetic field seems to be the presence of magnetic elements, called moving magnetic features (MMFs). Aims. We analyze the short-lived sunspot group NOAA 10977, which appeared on the solar disk between 2 and 8 December 2007, to study the details of its emergence and decay phases.Methods. We performed a multi wavelength analysis of the region using images at visible (G band and H α ) and near-IR (Ca ii) wavelengths acquired by both the IBIS instrument and SOT/HINODE, EUV images (17.1 nm) acquired by TRACE, and MDI and SOT magnetograms. Results. The observed region exhibits some peculiarities. During the emergence phase the formation of the f-pore was initially observed, while the p-polarity later formed a naked spot, i.e., a sunspot without a penumbra. We measured a moat flow around this spot, and observed some MMFs streaming out from it during the decay phase. The characteristics of these MMFs allowed us to classify them as type I (U-shaped) MMFs. They were also cospatial with sites of increased brightness both in the photosphere and the chromosphere. Conclusions. The presence of bipolar MMFs in a naked spot indicates that current interpretation of bipolar MMFs, as extensions of the penumbral filaments beyond the sunspot outer boundaries, should be revised, to take into account this observational evidence. We believe that our results provide new insights into improving models of sunspot evolution.

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“…However, high spatial-resolution observations indicate that pores contain a wide variety of fine bright features, such as umbral dots or light bridges that may be signs of a convective energy transportation mechanism (e.g. Sobotka et al 1999;Keil et al 1999;Hirzberger 2003;Giordano et al 2008;Sobotka & Jurčák 2009;Ortiz et al 2010).…”

Section: Introductionmentioning

confidence: 99%

Magnetic and velocity fields of a solar pore

Sobotka

Moro

Jurčák

et al. 2012

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Context. Solar pores are intermediate-size magnetic flux features that emerge at the surface of the Sun. The absence of a filamentary penumbra indicates that there is a relatively simple magnetic structure with a prevailing vertical magnetic field. Aims. Relations between the magnetic field components, line-of-sight velocities, and horizontal motions in and around a large pore (D eff = 8. 5) are analysed to provide observational constraints on theoretical models and numerical simulations. Methods. Spectropolarimetric observations in Fe I 617.3 nm of the pore NOAA 11005 with the IBIS spectrometer attached to the Dunn Solar Telescope are inverted into series of maps of thermal, magnetic, and velocity parameters using the SIR code. Horizontal velocities are obtained from series of white-light images by means of local correlation tracking. Results. The magnetic field B extends from the visible pore border of more than 3. 5 and has a radial structure in a form of spines that are co-spatial with dark intergranular lanes. The horizontal component B hor is more extended than the vertical component B z . The temperature linearly decreases with increasing B z , by about −300 K kG −1 in the photosphere and −800 K kG −1 in the umbra. The temperature contrast of granulation increases with increasing magnetic field strength and is then suppressed for B z > 1200 G. Granular upflows dominate in regions with B z < 600-700 G. Line-of-sight velocities are lower in stronger fields, except for fast isolated downflows at the pore's border. The velocity signature of granulation is suppressed completely for B hor > 1000 G. Horizontal motions of granules start to be damped for B z > 500 G and recurrently exploding granules appear only in magnetic fields comparable to or weaker than the equipartition field strength 400 G.

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The photospheric structure of a solar pore with light bridge

Cited by 30 publications

References 40 publications

Dynamics of the solar atmosphere above a pore with a light bridge

Dynamics of the solar atmosphere above a pore with a light bridge

Observation of bipolar moving magnetic features streaming out from a naked spot

Magnetic and velocity fields of a solar pore

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