Aims. The properties of magnetic fields forming an extended plage region in AR 10953 were investigated. Methods. Stokes spectra of the Fe I line pair at 6302 Å recorded by the spectropolarimeter aboard the Hinode satellite were inverted using the SPINOR code. The code performed a 2D spatially coupled inversion on the Stokes spectra, allowing the retrieval of gradients in optical depth within the atmosphere of each pixel, whilst accounting for the effects of the instrument's PSF. Consequently, no magnetic filling factor was needed.Results. The inversion results reveal that plage is composed of magnetic flux concentrations (MFCs) with typical field strengths of 1520 G at log(τ) = −0.9 and inclinations of 10 • −15 • . The MFCs expand by forming magnetic canopies composed of weaker and more inclined magnetic fields. The expansion and average temperature stratification of isolated MFCs can be approximated well with an empirical plage thin flux tube model. The highest temperatures of MFCs are located at their edges in all log(τ) layers. Whilst the plasma inside MFCs is nearly at rest, each is surrounded by a ring of downflows of on average 2.4 km s −1 at log(τ) = 0 and peak velocities of up to 10 km s −1 , which are supersonic. The downflow ring of an MFC weakens and shifts outwards with height, tracing the MFC's expansion. Such downflow rings often harbour magnetic patches of opposite polarity to that of the main MFC with typical field strengths below 300 G at log(τ) = 0. These opposite polarity patches are situated beneath the canopy of their main MFC. We found evidence of a strong broadening of the Stokes profiles in MFCs and particularly in the downflow rings surrounding MFCs (expressed by a microturbulence in the inversion). This indicates the presence of strong unresolved velocities. Larger magnetic structures such as sunspots cause the field of nearby MFCs to be more inclined.
We present data of 10 penumbral microjets (PMJs) observed in Hα, Ca II 8542 Å, and Fe I 6302 Å line pair with the Swedish 1 m Solar Telescope (SST) with CRISP and Ca II K with SST/CHROMIS in active region NOAA 12599 on the 12 th October 2016 at µ = 0.68. All four Stokes parameters of the Ca II 8542 Å and Fe I 6302 Å lines were observed and a series of test pixels was inverted using the Stockholm inversion code. Our analysis revealed for the first time that PMJs are visible in Hα, where they appear as dark features with average line-of-sight (LOS) upflows of 1.1 ± 0.6 km/s, matching the LOS velocities from the inversions. Based on the Hα observations we extend the previous average length and lifetime of PMJs to 2815 ± 530 km and 163 ± 25 s, respectively. The plane-of-sky (POS) velocities of our PMJs of up to 17 km/s tend to give increased velocities with distance travelled. Furthermore, two of our PMJs with significant Stokes V signal indicate that the PMJs possess an increased LOS magnetic field of up to 100 G compared to the local pre-/post-PMJ magnetic field, which propagates as quickly as the PMJs' POS velocities. Finally, we present evidence that PMJs display an on average 1 minute gradual precursory brightening that only manifests itself in the cores of the Ca II lines. We conclude that PMJs are not ordinary jets but likely are manifestations of heat fronts that propagate at the local Alfvén velocity.
Aims. We compare the properties of kG magnetic structures in the solar network and in active region plage at high spatial resolution. Methods. Our analysis used six SP scans of the solar disc centre aboard Hinode SOT and inverted the obtained spectra of the photospheric 6302 Å line pair using the 2D SPINOR code. Results. Photospheric magnetic field concentrations in network and plage areas are on average 1.5 kG strong with inclinations of 10 • − 20 • , and have < 400 m/s internal and 2 − 3 km/s external downflows. At the disc centre, the continuum intensity of magnetic field concentrations in the network are on average 10% brighter than the mean quiet Sun, whilst their plage counterparts are 3% darker. A more detailed analysis revealed that all sizes of individual kG patches in the network have 150 G higher field strengths on average, 5% higher continuum contrasts, and 800 m/s faster surrounding downflows than similarly sized patches in the plage. The speed of the surrounding downflows also correlates with the patch area, and patches containing pores can produce supersonic flows exceeding 11 km/s in individual pixels. Furthermore, the magnetic canopies of kG patches are on average 9 • more horizontal in the plage compared to the network. Conclusions. Most of the differences between the network and plage are due to their different patch size distributions, but the intrinsic differences between similarly sized patches is likely results from the modification of the convection photospheric convection with increasing amounts of magnetic flux.
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