Petra Kohutova

• Poirier, Nicolas Aurelien Corentin; Danilovic, S.; Kohutova, Petra; Baso, Carlos José Díaz; Voort, Luc Rouppe van der & Calchetti, D. [Vis alle 7 forfattere av denne artikkelen] (2025). Coronal kink oscillations and photospheric driving: Combining SolO/EUI and SST/CRISP high-resolution observations. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 696. doi: 10.1051/0004-6361/202453025. Fulltekst i vitenarkiv Vis sammendrag

  Context. The driving and excitation mechanisms of decay-less kink oscillations in coronal loops remain under active debate. The photospheric dynamics may provide the continuous energy supply required to sustain these oscillations. Aims. We aim to quantify and provide simple observational constraints on the photospheric driving of coronal loops in a few typical active region configurations: sunspot, plage, pores, and enhanced-network regions. We then aim to investigate the possible interplay between the photospheric driving and the properties of kink oscillations in the connected coronal loops. Methods. We analysed two unique datasets of the corona and photosphere taken at a high spatial and temporal resolution during the first coordinated observation campaign between Solar Orbiter and the Swedish 1-m Solar Telescope (SST). We applied a local correlation tracking method on the SST/CRISP data to quantify the photospheric motions at the base of coronal loops. The same loops were then analysed in the corona by exploiting data from the Extreme Ultraviolet Imager (EUI) on Solar Orbiter and by using a wavelet analysis to characterise the detected kink oscillations. Results. Each type of photospheric region shows varying dynamics but with an overall increase in strength going from pore to plage to enhanced-network to sunspot regions. Differences can also be seen in the amplitudes of the fundamental kink mode measured in the corresponding coronal loops. This suggests the photosphere is involved in the driving of coronal kink oscillations. However, the few samples available do not allow the excitation mechanism to be further established yet. Conclusions. Despite oscillating coronal loops being anchored in seemingly “static” strong magnetic field regions, as seen from coronal EUV observations, photospheric observations provide evidence for a continuous and significant driving at their base. The precise connection between photospheric driving and coronal kink oscillations remains to be further investigated. Upcoming coordinated observations between Solar Orbiter and ground-based telescopes will provide crucial additional observational constraints, with this pilot study serving as a baseline for future works. Finally, this study provides critical constraints on both the quasi-steady and broadband photospheric driving that can be tested in existing numerical models of coronal loops.

• Kohutova, Petra; Antolin, Patrick; Szydlarski, Mikolaj & Poirier, Nicolas Aurelien Corentin (2024). Can we rely on EUV emission to identify coronal waveguides? Astronomy and Astrophysics (A & A). ISSN 0004-6361. 690. doi: 10.1051/0004-6361/202451196. Fulltekst i vitenarkiv Vis sammendrag

  Context. Traditional models of coronal oscillations rely on a modelling of the coronal structures that support them as compact cylindrical waveguides. An alternative model of the structure of the corona has recently been proposed, in which the thin strand-like coronal loops, that are observed in the extreme-UV (EUV) emission are the result of the line-of-sight integration of warps in more complex coronal structures. This is referred to as the coronal veil model. Aims. We extend the implications of the coronal veil model of the solar corona to models of coronal oscillations. Methods. Using convection-zone-to-corona simulations with the radiation-magnetohydrodynamics (rMHD) code Bifrost, we analysed the structure of the self-consistently formed simulated corona. We focused on the spatial variability of the volumetric emissivity of the Fe IX 171.073 Å EUV line and on the variability of the Alfvén speed, which captures the density and magnetic structuring of the simulated corona. We traced features associated with large magnitudes of the Alfvén speed gradient, which trap MHD waves and act as coronal waveguides. We searched for the correspondence with emitting regions, which appear as strand-like loops in the line-of-sight-integrated EUV emission. Results. We find that the cross sections of the waveguides bounded by large Alfvén speed gradients become less circular and more distorted with increasing height in the solar atmosphere. The waveguide filling factors corresponding to the fraction of the waveguides filled with plasma that emits in the given EUV wavelength range from 0.09–0.44. This suggests that we can only observe a small fraction of the waveguide. Similarly, the projected waveguide widths in the plane of the sky are several times larger than the widths of the apparent loops that are observed in the EUV. Conclusions. We conclude that the coronal veil structure is independent of the model. As a result, we find a lack of straightforward correspondence between peaks in the integrated emission profile that constitute apparent coronal loops and regions of plasma bound by a large Alfvén speed gradient that act as waveguides. Coronal waveguides cannot be reliably identified based on emission in a single EUV wavelength is not reliable in the simulated corona formed in convection-zone-to-corona models.

• Kohutova, Petra; Antolin, Patrick; Szydlarski, Mikolaj & Carlsson, Mats (2023). Damping of coronal oscillations in self-consistent 3D radiative magnetohydrodynamics simulations of the solar atmosphere. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 676. doi: 10.1051/0004-6361/202346671. Fulltekst i vitenarkiv Vis sammendrag

  Context. Oscillations are abundant in the solar corona. Coronal loop oscillations are typically studied using highly idealised models of magnetic flux tubes. In order to improve our understanding of coronal oscillations, it is necessary to consider the effect of a realistic magnetic field topology and the density structuring. Aims. We analyse the damping of coronal oscillations using a self-consistent 3D radiation-magnetohydrodynamics simulation of the solar atmosphere spanning from the convection zone into the corona, the associated oscillation dissipation and heating, and finally, the physical processes that cause the damping and dissipation. The simulated corona that forms in this model does not depend on any prior assumptions about the shape of the coronal loops. Methods. We analysed the evolution of a bundle of magnetic loops by tracing the magnetic field. Results. We find that the bundle of magnetic loops shows damped transverse oscillations in response to perturbations in two separate instances, with oscillation periods of 177 s and 191 s, velocity amplitudes of 10 km s −1 and 16 km s −1 , and damping times of 176 s and 198 s. The coronal oscillations lead to the development of velocity shear in the simulated corona, which results in the formation of vortices seen in the velocity field that are caused by the Kelvin-Helmholtz instability. This contributes to the damping and dissipation of the transverse oscillations. Conclusions. The oscillation parameters and evolution we observed are in line with the values that are typically seen in observations of coronal loop oscillations. The dynamic evolution of the coronal loop bundle suggests that the models of monolithic and static coronal loops with constant lengths might need to be re-evaluated by relaxing the assumption of highly idealised wave guides.

• Kohutova, Petra & Popovas, Andrius (2021). Excitation and evolution of coronal oscillations in self-consistent 3D radiative MHD simulations of the solar atmosphere. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 647. doi: 10.1051/0004-6361/202039491. Fulltekst i vitenarkiv Vis sammendrag

  Context. Solar coronal loops are commonly subject to oscillations. Observations of coronal oscillations are used to infer physical properties of the coronal plasma using coronal seismology. Aims. Excitation and evolution of oscillations in coronal loops is typically studied using highly idealised models of magnetic flux tubes. In order to improve our understanding of coronal oscillations, it is necessary to consider the effect of realistic magnetic field topology and evolution. Methods. We study excitation and evolution of coronal oscillations in three-dimensional (3D) self-consistent simulations of solar atmosphere spanning from the convection zone to the solar corona using the radiation-magnetohydrodynamic (MHD) code Bifrost. We use forward-modelled extreme-ultraviolet emission and 3D tracing of magnetic field to analyse the oscillatory behaviour of individual magnetic loops. We further analyse the evolution of individual plasma velocity components along the loops using wavelet power spectra to capture changes in the oscillation periods. Results. Various types of oscillations commonly observed in the corona are present in the simulation. We detect standing oscillations in both transverse and longitudinal velocity components, including higher-order oscillation harmonics. We also show that self-consistent simulations reproduce the existence of two distinct regimes of transverse coronal oscillations: rapidly decaying oscillations triggered by impulsive events and sustained small-scale oscillations showing no observable damping. No harmonic drivers are detected at the footpoints of oscillating loops. Conclusions. Coronal loop oscillations are abundant in self-consistent 3D MHD simulations of the solar atmosphere. The dynamic evolution and variability of individual magnetic loops suggest that we need to re-evaluate our models of monolithic and static coronal loops with constant lengths in favour of more realistic models.

• Kohutova, Petra; Antolin, Patrick; Popovas, Andrius; Szydlarski, Mikolaj Marcin & Hansteen, Viggo (2020). Self-consistent 3D radiative magnetohydrodynamic simulations of coronal rain formation and evolution. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 639. doi: 10.1051/0004-6361/202037899. Fulltekst i vitenarkiv Vis sammendrag

  Context. Coronal rain consists of cool and dense plasma condensations formed in coronal loops as a result of thermal instability. Aims. Previous numerical simulations of thermal instability and coronal rain formation have relied on the practice of artificially adding a coronal heating term to the energy equation. To reproduce large-scale characteristics of the corona, the use of more realistic coronal heating prescription is necessary. Methods. We analysed coronal rain formation and evolution in a three-dimensional radiative magnetohydrodynamic simulation spanning from convection zone to corona which is self-consistently heated by magnetic field braiding as a result of convective motions. Results. We investigate the spatial and temporal evolution of energy dissipation along coronal loops which become thermally unstable. Ohmic dissipation in the model leads to the heating events capable of inducing sufficient chromospheric evaporation into the loop to trigger thermal instability and condensation formation. The cooling of the thermally unstable plasma occurs on timescales that are comparable to the duration of the individual impulsive heating events. The impulsive heating has sufficient duration to trigger thermal instability in the loop but does not last long enough to lead to coronal rain limit cycles. We show that condensations can either survive and fall into the chromosphere or be destroyed by strong bursts of Joule heating associated with a magnetic reconnection events. In addition, we find that condensations can also form along open magnetic field lines. Conclusions. We modelled, for the first time, coronal rain formation in a self-consistent 3D radiative magnetohydrodynamic simulation, in which the heating occurs mainly through the braiding and subsequent Ohmic dissipation of the magnetic field. The heating is stratified enough and lasts for long enough along specific field lines to produce the necessary chromospheric evaporation that triggers thermal instability in the corona.

• Kohutova, Petra; Verwichte, Erwin & Froment, Clara (2020). First direct observation of a torsional Alfvén oscillation at coronal heights. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 633. doi: 10.1051/0004-6361/201937144. Fulltekst i vitenarkiv Vis sammendrag

  Context. Torsional Alfvén waves are promising candidates for the transport of energy across different layers of the solar atmosphere. They have been predicted theoretically for decades. Previous detections of Alfvén waves so far have however mostly relied on indirect signatures. Aims. We present the first direct observational evidence of a fully resolved torsional Alfvén oscillation of a large-scale structure occurring at coronal heights. Methods. We analysed IRIS imaging and spectral observation of a surge resulting from magnetic reconnection between active region prominence threads and surrounding magnetic field lines. Results. The IRIS spectral data provide clear evidence of an oscillation in the line-of-sight velocity with a 180° phase difference between the oscillation signatures at opposite edges of the surge flux tube. This together with an alternating tilt in the Si IV and Mg II k spectra across the flux tube and the trajectories traced by the individual threads of the surge material provide clear evidence of torsional oscillation of the flux tube. Conclusions. Our observation shows that magnetic reconnection leads to the generation of large-scale torsional Alfvén waves.

• Voort, Luc Rouppe van der; Pontieu, Bart Walter De; Carlsson, Mats; Rodriguez, Jaime de la Cruz; Bose, Souvik & Chintzoglou, Georgios [Vis alle 33 forfattere av denne artikkelen] (2020). High-resolution observations of the solar photosphere, chromosphere, and transition region: A database of coordinated IRIS and SST observations. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 641. doi: 10.1051/0004-6361/202038732. Fulltekst i vitenarkiv Vis sammendrag

  NASA’s Interface Region Imaging Spectrograph (IRIS) provides high-resolution observations of the solar atmosphere through ultraviolet spectroscopy and imaging. Since the launch of IRIS in June 2013, we have conducted systematic observation campaigns in coordination with the Swedish 1 m Solar Telescope (SST) on La Palma. The SST provides complementary high-resolution observations of the photosphere and chromosphere. The SST observations include spectropolarimetric imaging in photospheric Fe  I lines and spectrally resolved imaging in the chromospheric Ca  II 8542 Å, H α , and Ca  II K lines. We present a database of co-aligned IRIS and SST datasets that is open for analysis to the scientific community. The database covers a variety of targets including active regions, sunspots, plages, the quiet Sun, and coronal holes.

• Kohutova, Petra; Verwichte, Erwin & Froment, Clara (2019). Formation of coronal rain triggered by impulsive heating associated with magnetic reconnection. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 630. doi: 10.1051/0004-6361/201936253. Fulltekst i vitenarkiv Vis sammendrag

  Context. Coronal rain consists of cool plasma condensations formed in coronal loops as a result of thermal instability. The standard models of coronal rain formation assume that the heating is quasi-steady and localised at the coronal loop footpoints. Aims. We present an observation of magnetic reconnection in the corona and the associated impulsive heating triggering formation of coronal rain condensations. Methods. We analyse combined SDO/AIA and IRIS observations of a coronal rain event following a reconnection between threads of a low-lying prominence flux rope and surrounding coronal field lines. Results. The reconnection of the twisted flux rope and open field lines leads to a release of magnetic twist. Evolution of the emission of one of the coronal loops involved in the reconnection process in different AIA bandpasses suggests that the loop becomes thermally unstable and is subject to the formation of coronal rain condensations following the reconnection and that the associated heating is localised in the upper part of the loop leg. Conclusions. In addition to the standard models of thermally unstable coronal loops with heating localised exclusively in the footpoints, thermal instability and subsequent formation of condensations can be triggered by the impulsive heating associated with magnetic reconnection occurring anywhere along a magnetic field line.

• Froment, Clara; Antolin, Patrick; Henriques, Vasco Manuel de Jorge; Kohutova, Petra & Voort, Luc Rouppe van der (2019). Multi-scale observations of thermal non-equilibrium cycles in coronal loops. Astronomy and Astrophysics (A & A). ISSN 0004-6361. 633. doi: 10.1051/0004-6361/201936717. Fulltekst i vitenarkiv Vis sammendrag

  Context. Thermal non-equilibrium (TNE) is a phenomenon that can occur in solar coronal loops when the heating is quasi-constant and highly-stratified. Under such heating conditions, coronal loops undergo cycles of evaporation and condensation. The recent observations of ubiquitous long-period intensity pulsations in coronal loops and their relationship with coronal rain have demonstrated that understanding the characteristics of TNE cycles is an essential step in constraining the circulation of mass and energy in the corona. Aims. We report unique observations with the Solar Dynamics Observatory (SDO) and the Swedish 1-m Solar Telescope (SST) that link the captured thermal properties across the extreme spatiotemporal scales covered by TNE processes. Methods. Within the same coronal loop bundle, we captured 6 h period coronal intensity pulsations in SDO/AIA and coronal rain observed off-limb in the chromospheric Hα and Ca II K spectral lines with SST/CRISP and SST/CHROMIS. We combined a multi-thermal analysis of the cycles with AIA and an extensive spectral characterisation of the rain clumps with the SST. Results. We find clear evidence of evaporation-condensation cycles in the corona which are linked with periodic coronal rain showers. The high-resolution spectroscopic instruments at the SST reveal the fine-structured rain strands and allow us to probe the cooling phase of one of the cycles down to chromospheric temperatures. Conclusions. These observations reinforce the link between long-period intensity pulsations and coronal rain. They also demonstrate the capability of TNE to shape the dynamics of active regions on the large scales as well as on the smallest scales currently resolvable.

Se alle arbeider i NVA

• Kohutova, Petra (2026). Studying the solar atmosphere. Fulltekst i vitenarkiv
• Kohutova, Petra (2026). Spectropolarimetric Observations of the Solar Corona with DKIST/CryoNIRSP. Fulltekst i vitenarkiv
• Kohutova, Petra (2026). Spectropolarimetric observations of coronal oscillations with DKIST/Cryo-NIRSP. Fulltekst i vitenarkiv
• Kohutova, Petra (2025). Oscillations in the Structured and Dynamic Solar Corona. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Kohutova, Petra; Voort, Luc Rouppe van der & Danilovic, Sanja (2024). About the source of sustained kink oscillations in coronal loops. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Kohutova, Petra; Voort, Luc Rouppe van der & Danilovic, Sanja (2024). Photospheric driving of sustained kink oscillations in coronal loops. Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Kohutova, Petra; Voort, Luc Rouppe van der & Danilovic, Sanja (2024). About the source of sustained kink oscillations in coronal loops. Fulltekst i vitenarkiv
• Kohutova, Petra; Antolin, Patrick; Szydlarski, Mikolaj & Poirier, Nicolas Aurelien Corentin (2024). Can we rely on EUV emission to identify coronal waveguides? Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Voort, Luc Rouppe van der; Kohutova, Petra & Danilovic, Sanja (2024). About the nature of sustained kink oscillations in coronal loops: combining coronal and chromospheric diagnostics. Fulltekst i vitenarkiv
• Popovas, Andrius; Nordlund, Åke; Szydlarski, Mikolaj; Kohutova, Petra; Hansteen, Viggo Haraldson & Noraz, Quentin Jean Francois Alain [Vis alle 7 forfattere av denne artikkelen] (2023). Update on global MHD simulations of the solar convective region. Fulltekst i vitenarkiv
• Popovas, Andrius; Nordlund, Åke; Szydlarski, Mikolaj; Kohutova, Petra; Hansteen, Viggo Haraldson & Noraz, Quentin Jean Francois Alain [Vis alle 7 forfattere av denne artikkelen] (2023). Global MHD simulation of the solar convective region. Fulltekst i vitenarkiv
• Popovas, Andrius; Nordlund, Åke; Szydlarski, Mikolaj; Kohutova, Petra & Noraz, Quentin Jean Francois Alain (2023). Global MHD simulations of the solar convective zone using a volleyball mesh decomposition: Pilot. Fulltekst i vitenarkiv
• Kohutova, Petra; Antolin, Patrick; Szydlarski, Mikolaj & Carlsson, Mats (2023). Damping of Coronal Oscillations in Self-Consistent 3D Radiative MHD Simulations of the Solar Atmosphere. Fulltekst i vitenarkiv
• Kohutova, Petra; Antolin, Patrick; Szydlarski, Mikolaj & Carlsson, Mats (2023). Damping of coronal oscillations in self-consistent 3D radiative MHD simulations of the solar atmosphere. Fulltekst i vitenarkiv
• Kohutova, Petra (2023). What can coronal rain tell us about coronal heating mechanisms and the structure of the corona? Fulltekst i vitenarkiv
• Poirier, Nicolas Aurelien Corentin; Kohutova, Petra; Joshi, Reetika & Voort, Luc Rouppe van der (2023). About the source of sustained kink oscillations in coronal loops: what do we know and what do we need from future observation campaigns? Fulltekst i vitenarkiv
• Kohutova, Petra; Popovas, Andrius; Antolin, Patrick; Szydlarski, Mikolaj & Carlsson, Mats (2022). Coronal oscillations in the self-consistent 3D MHD simulations of the solar atmosphere. Fulltekst i vitenarkiv
• Kohutova, Petra; Popovas, Andrius; Antolin, Patrick; Szydlarski, Mikolaj & Carlsson, Mats (2022). Coronal oscillations in the self-consistent 3D MHD simulations of the solar atmosphere. Fulltekst i vitenarkiv
• Kohutova, Petra (2021). Formation of coronal rain and coronal heating mechanisms. Fulltekst i vitenarkiv
• Froment, Clara; Antolin, Patrick; Henriques, Vasco; Kohutova, Petra & Voort, Luc Rouppe van der (2019). Multi-scale observations of thermal nonequilibrium cycles in coronal loops (presenting author: Patrick Antolin). Fulltekst i vitenarkiv
• Froment, Clara; Antolin, Patrick; Henriques, Vasco; Kohutova, Petra & Voort, Luc H.M. Rouppe van der (2019). Multi-scale observations of thermal nonequilibrium cycles in coronal loops. Fulltekst i vitenarkiv
• Kohutova, Petra (2019). Waves in the solar atmosphere and MHD seismology. Fulltekst i vitenarkiv
• Kohutova, Petra; Verwichte, Erwin & Froment, Clara (2019). Propagating torsional oscillation of a chromospheric surge. Fulltekst i vitenarkiv
• Kohutova, Petra; Antolin, Patrick; Popovas, Andrius; Szydlarski, Mikolaj Marcin & Hansteen, Viggo (2019). 3D radiative MHD simulations of coronal rain formation and evolution. Fulltekst i vitenarkiv
• Kohutova, Petra (2019). Probing the nature of coronal heating through thermal instability and coronal rain. Fulltekst i vitenarkiv
• Kohutova, Petra (2018). Thermal instability, coronal rain and their potential for coronal seismology. Fulltekst i vitenarkiv

Se alle arbeider i NVA