Explanipedia

Supergranulation and Poleward Migration of the Magnetic Field at High Latitudes of the Sun Open

L. P. Chitta, D. Calchetti, J. Hirzberger, G. Valori, E. R. Priest , et al. · 2025

Magnetoconvection at the solar surface governs the dynamics in the upper solar atmosphere and sustains the heliosphere. Properties of this fundamental process are poorly described near the solar poles. Here we report the first out-of-eclip…

Formation of chromospheric Fe I lines in the near-ultraviolet in 1D atmospheres Open

Edvarda Harnes, H. N. Smitha, A. Lagg, Damien Przybylski, S.K. Solanki · 2025

In the near-ultraviolet part of the solar spectrum lie several Fe I lines with very broad profiles that are typical of chromospheric lines. These lines are largely unexplored because high-resolution data in this region were lacking. This c…

TuMag: The Tunable Magnetograph for the Sunrise III Mission Open

J. C. del Toro Iniesta, D. Orozco Suárez, A. Álvarez‐Herrero, E. Sanchis-Kilders, Isabel Pérez-Grande , et al. · 2025

Sunrise iii is a balloon-borne solar observatory dedicated to the investigation of the processes governing the physics of the magnetic field and the plasma flows in the lower solar atmosphere. The gondola hosts a 1-m aperture telescope tha…

Formation of chromospheric Fe I lines in the near ultraviolet in 1D atmospheres Open

Edvarda Harnes, H. N. Smitha, A. Lagg · 2025

In the near ultraviolet (NUV) part of the solar spectrum, there are several Fe I lines with very broad profiles, typical of chromospheric lines. These lines are largely unexplored due to the lack of high-resolution data in this region. Thi…

The Gondola for the Sunrise iii Balloon-Borne Solar Observatory Open

P. N. Bernasconi, M. P. Carpenter, H. Eaton, Erich Schulze, Bliss G. Carkhuff , et al. · 2025

Magnetic properties of orphan penumbrae Open

J. S. Castellanos Durán, B. Löptien, A. Lagg, S. K. Solanki, M. van Noort · 2025

Orphan penumbrae (OPU) are features resembling sunspot penumbrae, but are not connected to an umbra. Here we compare OPUs and sunspot penumbrae, including their filaments. We also identify and describe the main mechanisms for the formation…

Sunrise iii: Overview of Observatory and Instruments Open

A. Lagg, A. Gandorfer, S. K. Solanki, J. C. del Toro Iniesta, Yukio Katsukawa , et al. · 2025

In July 2024, Sunrise completed its third successful science flight. The Sunrise iii observatory had been upgraded significantly after the two previous successful flights in 2009 and 2013, to tackle the most recent science challenges conce…

The Sunrise Ultraviolet Spectropolarimeter and Imager: Instrument Description Open

A. Feller, A. Gandorfer, B. Grauf, J. Hölken, F. A. Iglesias , et al. · 2025

The third science flight of the balloon-borne solar observatory Sunrise carries three entirely new post-focus science instruments with spectropolarimetric capabilities, concurrently covering an extended spectral range from the near ultravi…

The Sunrise Ultraviolet Spectropolarimeter and Imager: Standalone Polarimetric Calibration Open

F. A. Iglesias, A. Feller, A. Gandorfer, T. L. Riethmüller, A. Lagg , et al. · 2025

Sunrise is a 1-m optical solar observatory carried aloft by a stratospheric balloon. It was developed to study magnetic fields and plasma flows in the solar atmosphere with very high spatial resolution and sensitivity. The Sunrise UV Spect…

The Sunrise Ultraviolet Spectropolarimeter and Imager: Instrument description Open

A. Feller, A. Gandorfer, B. Grauf, A. Lagg, J. Staub , et al. · 2025

The third science flight of the balloon-borne solar observatory Sunrise carries three entirely new post-focus science instruments with spectropolarimetric capabilities, concurrently covering an extended spectral range from the near ultravi…

Sunrise III: Overview of Observatory and Instruments Open

A. Lagg, A. Gandorfer, S. K. Solanki, J. C. del Toro Iniesta, Yukio Katsukawa , et al. · 2025

In July 2024, Sunrise completed its third successful science flight. The Sunrise III observatory had been upgraded significantly after the two previous successful flights in 2009 and 2013. Three completely new instruments focus on the smal…

The Sunrise Ultraviolet Spectropolarimeter and Imager: Standalone polarimetric calibration Open

F. A. Iglesias, A. Feller, A. Gandorfer, T. L. Riethmüller, A. Lagg , et al. · 2025

Sunrise is a 1-m optical solar observatory carried aloft by a stratospheric balloon. It was developed to study magnetic fields and plasma flows in the solar atmosphere with very high spatial resolution and sensitivity. The Sunrise UV Spect…

Superstrong Magnetic Fields in Sunspot Bipolar Light Bridges Open

J. S. Castellanos Durán, A. Lagg, S. K. Solanki, M. van Noort, N. Milanović · 2025

Recent solar observations of bipolar light bridges (BLBs) in sunspots have, in a few individual cases, revealed magnetic fields up to 8.2 kG, which is at least twice as strong as typical values measured in sunspot umbrae. However, the smal…

The MODEST catalog of depth-dependent spatially coupled inversions of sunspots observed by Hinode/SOT-SP Open

J. S. Castellanos Durán, N. Milanović, A. Lagg, B. Löptien, M. van Noort , et al. · 2024

We present a catalog that contains depth-dependent information about the atmospheric conditions inside sunspot groups of all types. The catalog, which we named MODEST, is currently composed of 944 observations of 117 individual active regi…

globin: A spectropolarimetric inversion code for the coupled inference of atomic line parameters Open

Dušan Vukadinović, H. N. Smitha, A. Lagg, M. van Noort, J. S. Castellanos Durán , et al. · 2024

Context. The reliability of physical parameters describing the solar atmosphere inferred from observed spectral line profiles depends on the accuracy of the involved atomic parameters. For many transitions, atomic data, such as the oscilla…

Comparison of magnetic data products from Solar Orbiter SO/PHI-FDT and SDO/HMI Open

A. Moreno Vacas, D. Orozco Suárez, H. Strecker, J. C. del Toro Iniesta, J. M. Borrero , et al. · 2024

Context. The Polarimetric and Helioseismic Imager (SO/PHI), on board the Solar Orbiter mission, is the first photospheric magnetograph and tachograph to observe the Sun from outside the Sun-Earth line. The Full Disc Telescope (FDT) of SO/P…

Determination of the SO/PHI-HRT wavefront degradation using multiple defocused images Open

F. J. Bailén, D. Orozco Suárez, J. Blanco Rodríguez, J. C. del Toro Iniesta, H. Strecker , et al. · 2023

Context. The Polarimetric and Helioseismic Imager on board the Solar Orbiter mission (SO/PHI) offers refocusing capabilities to cope with the strongly varying thermal environment of the optical system along the spacecraft’s elliptical orbi…

A first rapid synoptic magnetic field map using SDO/HMI and SO/PHI data Open

P. Loeschl, G. Valori, J. Hirzberger, J. Schou, S. K. Solanki , et al. · 2023

Context. Traditionally, the observation time needed to build synoptic maps of the solar magnetic field is bound to the 27 days of a full Carrington rotation due to the single viewpoint from Earth. Aims. Our aim is to reduce this observatio…

Reconstruction of total solar irradiance variability as simultaneously apparent from Solar Orbiter and Solar Dynamics Observatory Open

K. L. Yeo, N. A. Krivova, S. K. Solanki, J. Hirzberger, D. Orozco Suárez , et al. · 2023

Solar irradiance variability has been monitored almost exclusively from the Earth's perspective. {We present a method to combine the unprecedented observations of the photospheric magnetic field and continuum intensity from outside the Sun…

Reconstruction of total solar irradiance variability as simultaneously apparent from Solar Orbiter and Solar Dynamics Observatory Open

K. L. Yeo, N. A. Krivova, S. K. Solanki, J. Hirzberger, D. Orozco Suárez , et al. · 2023

Solar irradiance variability has been monitored almost exclusively from the Earth’s perspective. We present a method to combine the unprecedented observations of the photospheric magnetic field and continuum intensity from outside the Sun-…

Coronal voids and their magnetic nature Open

J. D. Nölke, S. K. Solanki, J. Hirzberger, Hardi Peter, L. P. Chitta , et al. · 2023

Context. Extreme ultraviolet (EUV) observations of the quiet solar atmosphere reveal extended regions of weak emission compared to the ambient quiescent corona. The magnetic nature of these coronal features is not well understood. Aims. We…

Coronal voids and their magnetic nature Open

J. D. Nölke, S. K. Solanki, J. Hirzberger, Hardi Peter, L. P. Chitta , et al. · 2023

Extreme ultraviolet (EUV) observations of the quiet solar atmosphere reveal extended regions of weak emission compared to the ambient quiescent corona. The magnetic nature of these coronal features is not well understood. We study the magn…

Intensity contrast of solar network and faculae close to the solar limb, observed from two vantage points Open

K. Albert, N. A. Krivova, J. Hirzberger, S. K. Solanki, A. Moreno Vacas , et al. · 2023

Context. The brightness of faculae and network depends on the angle at which they are observed and the magnetic flux density. Close to the limb, the assessment of this relationship has until now been hindered by the increasingly lower sign…

Intensity contrast of solar network and faculae close to the solar limb, observed from two vantage points Open

K. Albert, N. A. Krivova, J. Hirzberger, S. K. Solanki, A. Moreno Vacas , et al. · 2023

The brightness of faculae and network depends on the angle at which they are observed and the magnetic flux density. Close to the limb, assessment of this relationship has until now been hindered by the increasingly lower signal in magneto…

Stereoscopic disambiguation of vector magnetograms: First applications to SO/PHI-HRT data Open

G. Valori, D. Calchetti, A. Moreno Vacas, É. Pariat, S. K. Solanki , et al. · 2023

Contact. Spectropolarimetric reconstructions of the photospheric vector magnetic field are intrinsically limited by the 180° ambiguity in the orientation of the transverse component. So far, the removal of such an ambiguity has required as…

Firefly: The Case for a Holistic Understanding of the Global Structure and Dynamics of the Sun and the Heliosphere Open

N. E. Raouafi, J. T. Hoeksema, Jeffrey Newmark, S. E. Gibson, Thomas Berger , et al. · 2023

International audience

Expulsion of Counter Evershed Flows from Sunspot Penumbrae Open

J. S. Castellanos Durán, A. Lagg, S. K. Solanki · 2023

In addition to the Evershed flow directed from the umbra toward the outer boundary of a sunspot, under special circumstances a counter Evershed flow (CEF) in the opposite direction also occurs. We aim to characterize the proper motions and…

Stereoscopic disambiguation of vector magnetograms: first applications to SO/PHI-HRT data Open

G. Valori, D. Calchetti, A. Moreno Vacas, É. Pariat, S. K. Solanki , et al. · 2023

Spectropolarimetric reconstructions of the photospheric vector magnetic field are intrinsically limited by the 180$^\circ$-ambiguity in the orientation of the transverse component. So far, the removal of such an ambiguity has required assu…

Wavefront error of PHI/HRT on Solar Orbiter at various heliocentric distances Open

F. Kahil, A. Gandorfer, J. Hirzberger, D. Calchetti, J. Sinjan , et al. · 2023

Aims. We use wavefront sensing to characterise the image quality of the High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager (SO/PHI) data products during the second remote sensing window of the Solar Orbiter (SO) no…

Wavefront error of PHI/HRT on Solar Orbiter at various heliocentric distances Open

F. Kahil, A. Gandorfer, J. Hirzberger, D. Calchetti, J. Sinjan , et al. · 2023

We use wavefront sensing to characterise the image quality of the the High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager (SO/PHI) data products during the second remote sensing window of the Solar Orbiter (SO) nomi…

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