A Tale of Two Emergences: Sunrise II Observations of Emergence Sites in a Solar Active Region

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

doi:10.3847/1538-4365/229/1/3

Cited by 35 publications

(35 citation statements)

References 47 publications

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“…During the flux emergence process, bald patches are often associated with the serpentine field lines formed due to the development of Parker magnetic buoyancy instability (e.g., Pariat et al 2004Pariat et al , 2009Xu et al 2010;Cheung et al 2014;Schmieder et al 2014;Danilovic et al 2017;Danilovic 2017). Previous studies tend to suggest that many EBs are associated with these bald patches (e.g., Georgoulis et al 2002;Schmieder et al 2004;Pariat et al 2004;Centeno et al 2017;Yang et al 2016). Since the curvature of the magnetic field line on the bald patch is positive, we can identify the locations of bald patches in the photosphere based on the following condition (Pariat et al 2004):…”

Section: Magnetic Field Topologiesmentioning

confidence: 99%

Magnetic Reconnection at the Earliest Stage of Solar Flux Emergence

Tian

Zhu

Peter

et al. 2018

ApJ

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On 2016 September 20, the Interface Region Imaging Spectrograph observed an active region during its earliest emerging phase for almost 7 hours. The Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory observed continuous emergence of small-scale magnetic bipoles with a rate of ∼10 16 Mx s −1 . The emergence of magnetic fluxes and interactions between different polarities lead to frequent occurrence of ultraviolet (UV) bursts, which exhibit as intense transient brightenings in the 1400Å images. In the meantime, discrete small patches with the same magnetic polarity tend to move together and merge, leading to enhancement of the magnetic fields and thus formation of pores (small sunspots) at some locations. The spectra of these UV bursts are characterized by the superposition of several chromospheric absorption lines on the greatly broadened profiles of some emission lines formed at typical transition region temperatures, suggesting heating of the local materials to a few tens of thousands of kelvin in the lower atmosphere by magnetic reconnection. Some bursts reveal blue and red shifts of ∼100 km s −1 at neighboring pixels, indicating the spatially resolved bidirectional reconnection outflows. Many such bursts appear to be associated with the cancellation of magnetic fluxes with a rate of the order of ∼10 15 Mx s −1 . We also investigate the three-dimensional magnetic field topology through a magneto-hydrostatic model and find that a small fraction of the bursts are associated with bald patches (magnetic dips). Finally, we find that almost all bursts are located in regions of large squashing factor at the height of ∼1 Mm, reinforcing our conclusion that these bursts are produced through reconnection in the lower atmosphere.

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Section: Magnetic Field Topologiesmentioning

confidence: 99%

Magnetic Reconnection at the Earliest Stage of Solar Flux Emergence

Tian

Zhu

Peter

et al. 2018

ApJ

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“…Magnetic reconnection in the lower solar atmosphere can easily occur at bald patches. It is commonly believed that EBs are produced by magnetic reconnection at bald patches [16,51,57,58,59]. Peter et al [2] also explained the formation of UV bursts using a magnetic field configuration of bald patches.…”

Section: Magnetic Field Topologies Around the Uv Burstsmentioning

confidence: 99%

Solar ultraviolet bursts in a coordinated observation of IRIS, Hinode and SDO

Chen

Zhu

Samanta

et al. 2019

Sci. China Technol. Sci.

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Solar ultraviolet (UV) bursts are small-scale compact brightenings in transition region images. The spectral profiles of transition region lines in these bursts are significantly enhanced and broadened, often with chromospheric absorption lines such as Ni ii 1335.203 and 1393.330 Å superimposed. We investigate the properties of several UV bursts using a coordinated observation of the Interface Region Imaging Spectrograph (IRIS), Solar Dynamics Observatory (SDO), and Hinode on 2015 February 7. We have identified 12 UV bursts, and 11 of them reveal small blueshifts of the Ni ii absorption lines. However, the Ni ii lines in one UV burst exhibit obvious redshifts of ∼20 km s −1 , which appear to be related to the cold plasma downflows observed in the IRIS slit-jaw images. We also examine the three-dimensional magnetic field topology using a magnetohydrostatic model, and find that some UV bursts are associated with magnetic null points or bald patches. In addition, we find that these UV bursts reveal no obvious coronal signatures from the observations of the Atmospheric Imaging Assembly (AIA) on board SDO and the EUV Imaging Spectrometer (EIS) on board Hinode.

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“…The observations were obtained between 23:39UT on 2013 June 12 and 00:38UT on 2013 June 13 with a cadence of 7 s. These observations covered a part of NOAA AR 11768, mainly its following polarity that was dominated by a series of pores, some of which lie at least partly within the SUFI field ofview (FOV). The FOV also contained a number of plage elements and two granulation-scale flux emergences (e.g., Centeno et al 2017). The FOV was centered at cos 0.93 m q = = , where θ is the heliocentric angle.…”

Section: Observationsmentioning

confidence: 99%

Oscillations on Width and Intensity of Slender Ca ii H Fibrils from Sunrise/SuFI

Gafeira

Jafarzadeh

Solanki

et al. 2017

ApJS

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We report the detection of oscillations in slender Ca II H fibrils (SCFs) from high-resolution observations acquired with the SUNRISE balloon-borne solar observatory. The SCFs show obvious oscillations in their intensity, but also their width. The oscillatory behaviors are investigated at several positions along the axes of the SCFs. A large majority of fibrils show signs of oscillations in intensity. Their periods and phase speeds are analyzed using a wavelet analysis. The width and intensity perturbations have overlapping distributions of the wave period. The obtained distributions have median values of the period of 32±17 s and 36±25 s, respectively. We find that the fluctuations of both parameters propagate in the SCFs with speeds of 11 11 49 -+ km s −1 and 15 15 34 -+ km s −1 , respectively. Furthermore, the width and intensity oscillations have a strong tendency to be either in anti-phaseor, to a smaller extent, in phase. This suggests that the oscillations of both parameters are caused by the same wave mode and that the waves are likely propagating. Taking all the evidence together, the most likely wave mode to explain all measurements and criteria is the fast sausage mode.

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A Tale of Two Emergences: Sunrise II Observations of Emergence Sites in a Solar Active Region

Abstract: reconnection enables the field to release itself from its photospheric anchors, allowing it to continue its voyage up to higher layers. This process releases energy that lights up the arch-filament systems and heats the surrounding chromosphere.

Cited by 35 publications

References 47 publications

Magnetic Reconnection at the Earliest Stage of Solar Flux Emergence

Magnetic Reconnection at the Earliest Stage of Solar Flux Emergence

Solar ultraviolet bursts in a coordinated observation of IRIS, Hinode and SDO

Oscillations on Width and Intensity of Slender Ca ii H Fibrils from Sunrise/SuFI

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