Kinematics of Magnetic Bright Features in the Solar Photosphere

Jafarzadeh, S.; Solanki, S. K.; Cameron, R. H.; Barthol, P.; Rodríguez, J. Blanco; Iniesta, J. C. del Toro; Gandorfer, A.; Gizon, Laurent; Hirzberger, J.; Knölker, M.; Pillet, V. Martı́nez; Suárez, D. Orozco; Riethmüller, T. L.; Schmidt, W.; Noort, M. van

doi:10.3847/1538-4365/229/1/8

Cited by 18 publications

(10 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…On the contrary, the fibrils look shorter and more clustered on the east side. In the blue wing of Ca ii K ( Figure 2f) we observe bright and thin fibrils, which are known as straws (Rutten 2007) or slender Ca ii H fibrils (Jafarzadeh et al 2017). In our observations, these fibrils are rooted exactly above the bright granules of the AR (Figure 2a), in agreement with previous publications (Rutten 2007;Pietarila et al 2009;Jafarzadeh et al 2017).…”

Section: Resultssupporting

confidence: 92%

“…In the blue wing of Ca ii K ( Figure 2f) we observe bright and thin fibrils, which are known as straws (Rutten 2007) or slender Ca ii H fibrils (Jafarzadeh et al 2017). In our observations, these fibrils are rooted exactly above the bright granules of the AR (Figure 2a), in agreement with previous publications (Rutten 2007;Pietarila et al 2009;Jafarzadeh et al 2017). Moving towards the line centre, the straws progressively lose their sharpness and become partially covered by dark and opaque fibrils.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Chromospheric observations and magnetic configuration of a supergranular structure

Robustini

Pozuelo

Leenaarts

et al. 2018

A&A

View full text Add to dashboard Cite

Context. Unipolar magnetic regions are often associated with supergranular cells. The chromosphere above these regions is regulated by the magnetic field, but the field structure is poorly known. In unipolar regions, the fibrillar arrangement does not always coincide with magnetic field lines, and polarimetric observations are needed to establish the chromospheric magnetic topology. Aims. In an active region close to the limb, we observed a unipolar annular network of supergranular size. This supergranular structure harbours a radial distribution of the fibrils converging towards its centre. We aim to improve the description of this structure by determining the magnetic field configuration and the line-of-sight velocity distribution in both the photosphere and the chromosphere. Methods. We observed the supergranular structure at different heights by taking data in the Fe i 6301-6302 Å, Hα, Ca ii 8542 Å and the Ca ii H&K spectral lines with the CRISP and CHROMIS instruments at the Swedish 1-m Solar Telescope. We performed Milne-Eddington inversions of the spectropolarimetric data of Fe i 6301-6302 Å and applied the weak field approximation to Ca ii 8542 Å data to retrieve the magnetic field in the photosphere and chromosphere. We used photospheric magnetograms of CRISP, HINODE/SP and HMI to calculate the magnetic flux. We investigated the velocity distribution using the line-of-sight velocities computed from the Milne-Eddington inversion and from Doppler shift of the K 3 feature in the Ca ii K spectral line. To describe the typical spectral profiles characterising the chromosphere above the inner region of the supergranular structure, we performed a K-mean clustering of the spectra in Ca ii K. Results. The photospheric magnetic flux shows that the supergranular boundary has an excess of positive polarity and the whole structure is not balanced. The magnetic field vector at chromospheric heights, retrieved by the weak field approximation, indicates that the field lines within the supegranular cell tend to point inwards, and might form a canopy above the unipolar region. In the centre of the supergranular cell hosting the unipolar region, we observe a persistent chromospheric brightening coinciding with a strong gradient in the line-of-sight velocity.

show abstract

Section: Resultssupporting

confidence: 92%

Section: Resultsmentioning

confidence: 99%

Chromospheric observations and magnetic configuration of a supergranular structure

Robustini

Pozuelo

Leenaarts

et al. 2018

A&A

View full text Add to dashboard Cite

show abstract

“…The more vertical chromospheric field depicted can be explained with the presence of magnetic canopy at different heights. In detail, when comparing photospheric and chromospheric estimates of the field inclination at the same disc position, we are considering field lines connected to different foot-points in the penumbra (Jafarzadeh et al 2017). The photospheric pattern of the field inclination along A1 in the outer penumbra corresponds well to that ob-served for the inclination in the middle chromosphere.…”

Section: Resultsmentioning

confidence: 98%

Height Dependence of the Penumbral Fine-scale Structure in the Inner Solar Atmosphere

Murabito

Ermolli

Giorgi

et al. 2019

ApJ

Self Cite

View full text Add to dashboard Cite

We studied the physical parameters of the penumbra in a large and fully-developed sunspot, one of the largest over the last two solar cycles, by using full-Stokes measurements taken at the photospheric Fe I 617.3 nm and chromospheric Ca II 854.2 nm lines with the Interferometric Bidimensional Spectrometer. Inverting measurements with the NICOLE code, we obtained the three-dimensional structure of the magnetic field in the penumbra from the bottom of the photosphere up to the middle chromosphere. We analyzed the azimuthal and vertical gradient of the magnetic field strength and inclination. Our results provide new insights on the properties of the penumbral magnetic fields in the chromosphere at atmospheric heights unexplored in previous studies. We found signatures of the small-scale spine and intra-spine structure of both the magnetic field strength and inclination at all investigated atmospheric heights. In particular, we report typical peak-to-peak variations of the field strength and inclination of ≈ 300 G and ≈ 20 • , respectively, in the photosphere, and of ≈ 200 G and ≈ 10 • in the chromosphere. Besides, we estimated the vertical gradient of the magnetic field strength in the studied penumbra: we find a value of ≈ 0.3 G km −1 between the photosphere and the middle chromosphere. Interestingly, the photospheric magnetic field gradient changes sign from negative in the inner to positive in the outer penumbra.

show abstract

“…The contribution function of the Ca ii H bandpass, computed from an atmospheric model corresponding to AR plages and showing a mean formation height of 550 km (Jafarzadeh et al 2017a), implies that this line has a contribution from the photosphere, but also from the low-to-mid chromosphere. The fishhook shape in the scatterplot of Figure 6 is gone, due to the absence of granulation at the larger formation height of this line compared to the 300 nm bandpass and the 525 nm continuum.…”

Section: Resultsmentioning

confidence: 99%

Intensity contrast of solar plage as a function of magnetic flux at high spatial resolution

Kahil

Riethmüller

Solanki

2019

A&A

Self Cite

View full text Add to dashboard Cite

Magnetic elements have an intensity contrast that depends on the type of region they are located in (e.g. quiet Sun, or active region plage). Observed values also depend on the spatial resolution of the data. Here we investigate the contrast-magnetic field dependence in active region plage observed near disk center with Sunrise during its second flight in 2013. The wavelengths under study range from the visible at 525 nm to the near ultraviolet (NUV) at 300 nm and 397 nm. We use quasi-simultaneous spectropolarimetric and photometric data from the Imaging Magnetograph eXperiment (IMaX) and the Sunrise Filter Imager (SuFI), respectively. We find that in all wavelength bands, the contrast exhibits a qualitatively similar dependence on the line-of-sight magnetic field, B LOS , as found in the quiet Sun, with the exception of the continuum at 525 nm. There, the contrast of plage magnetic elements peaks for intermediate values of B LOS and decreases at higher field strengths. By comparison, the contrast of magnetic elements in the quiet Sun saturates at its maximum value at large B LOS . We find that the explanation of the turnover in contrast in terms of the effect of finite spatial resolution of the data is incorrect with the evidence provided by the high-spatial resolution Sunrise data, as the plage magnetic elements are larger than the quiet Sun magnetic elements and are well-resolved. The turnover comes from the fact that the core pixels of these larger magnetic elements are darker than the quiet Sun. We find that plages reach lower contrast than the quiet Sun at disk center at wavelength bands formed deep in the photosphere, such as the visible continuum and the 300 nm band. This difference decreases with formation height and disappears in the Ca ii H core, in agreement with empirical models of magnetic element atmospheres.

show abstract

Kinematics of Magnetic Bright Features in the Solar Photosphere

Cited by 18 publications

References 42 publications

Chromospheric observations and magnetic configuration of a supergranular structure

Chromospheric observations and magnetic configuration of a supergranular structure

Height Dependence of the Penumbral Fine-scale Structure in the Inner Solar Atmosphere

Intensity contrast of solar plage as a function of magnetic flux at high spatial resolution

Contact Info

Product

Resources

About