1st Open Sunrise III Science Meeting: Data Release and Science Projects

Jun 1, 2026, 9:00 AM → Jun 3, 2026, 6:00 PM Europe/Berlin

KIS, Freiburg

During its 6.5-day-long journey through the stratosphere, Sunrise III recorded excellent-quality seeing-free data in the near-UV, visible, and near-IR spectral regions. Almost 2 years after the flight, the first round of scientific papers is close to being submitted. These papers are mainly based on early data reduction levels; by the time of the meeting, fully reduced datasets will be publicly available to the solar community for scientific analysis. The increased data quality in terms of spatial resolution and polarimetric accuracy will allow exploring the solar photosphere and chromosphere in great depth.

The meeting will focus on presenting the results from the early science papers, presenting the newly reduced data and providing information on how to access them. Most importantly, everyone will have the opportunity to propose  new science projects based on Sunrise III data and on the co-observations recorded by space- and ground-based observatories during the Sunrise III flight. There will be time to discuss these projects with other participants and to form new collaborations.

Registration and abstract submission will be open from March 15 to April 30 2026.

 

Save the date and stay tuned for updates!

Mon, June 1

Technical Meeting: Afternoon Session

Sunrise III team internal meeting

1 Data reduction status: SUSI

Speaker: SUSI Team

2 Data reduction status: TuMag

Speaker: TuMag Team

3 Data reduction status: SCIP

Speaker: SCIP Team

3:30 PM Coffee break

4 Data Release Website: internal review

• test access
• identify issues
• check information (data usage policy, acknowledgments, ...)

Speakers: Dr Andreas Lagg (MPS), Johannes Hoelken (MPAE)

5 Update on Sunrise IV - What can be improved?

Speaker: Sami Solanki (MPAE)

6 CWS Improvements for Sunrise IV

Speaker: Thomas Berkefeld (KIS)

7 Discussion

• How to handle the existing Science Project List? (Smitha)
• Future of monthly online science meetings
• Future of online data reduction meetings
• Next in-person meeting
• Plans for future in-person meetings

Speakers: Dr Andreas Lagg (MPS), Sami Solanki (MPAE), Smitha Narayanamurthy (MPAE)

Tue, June 2

Day 1: Session 1

Convener: Ivan Milic (KIS)

8 Welcome

Speakers: Hardi Peter (MPS), Sami Solanki (MPS)

9 SCIP Data Reduction Status

10 SUSI Data Reduction Status

11 TuMag Data Reduction Status

12 Introduction to data release website

Speaker: Johannes Hoelken (MPS)

13 Polarized point spread functions of an instrument

Studies of image formation in astronomical instruments are often conducted under the assumption that light polarization has no significant influence. When diffraction effects are considered, they are typically treated using scalar point spread functions. This contribution aims to address the general problem by highlighting the potential impact of polarization and assessing it for a specific instrument through the estimation of point spread functions for all four Stokes parameters. Using dedicated partial occulters and pinholes installed as calibration tools for the TuMag instrument (Del Toro Iniesta et al. 2025) aboard the Sunrise III mission (Korea-Lagg et al. 2025), we derive polarized point response functions by exploiting two mathematical properties. A new description of the response of an optical instrument under polarized illumination and a description of its determination in the laboratory are proposed. An application to the TuMag instrument is presented.

Speaker: Jose Carlos del Toro Iniesta (Instituto de Astrofísica de Andalucía (IAA-CSIC))

14 Field-dependent spectral properties of TuMag instrument

Solar magnetographs are often equipped with Fabry–Pérot etalons to sample spectral lines that are sensitive to the magnetic field. Typically, two etalons with different optical thicknesses and reflectivities are used to reduce unwanted light from secondary orders while improving the spectral resolution. However, using two etalons in spaceborne or balloon-borne applications is usually prohibitive in terms of mass, power consumption and cost. Forcing light to pass through a single etalon twice (double pass) can therefore be preferable in these instruments.

We investigate the effects of a double-pass configuration on the instrument's effective transmission profile and compare the results with those obtained from in-flight calibrations of the double-pass TuMag instrument on board Sunrise.

We assess the spectral performance of double-pass configurations, considering intentional etalon tilts introduced to deal with ghost images in the detector. We evaluate the spectral response and its impact on the effective transmission and the shift in wavelength sampling across the field of view. Our findings show that the predictions are in excellent agreement with the blueshift maps and flat field images calibrated for TuMag during the sunrise flight.

Speaker: Francisco Javier Bailen (IAA-CSIC)

10:35 AM Coffee break

Day 1: Session 2

Convener: Takayoshi Oba (Advanced Research Center for Space Science and Technology (ARC-SAT), Institute of Science and Engineering, Kanazawa University)

15 Waves and oscillations in the lower solar atmosphere with Sunrise III: first results and future opportunities

The seeing-free, multi-line, high-cadence observations delivered by Sunrise III provide a uniquely powerful new framework for studying waves and oscillations in the lower solar atmosphere. In this talk, I will present first results from our early-science investigations of active-region targets in the 327–329 nm near-UV window observed by SUSI, including line-dependent frequency structuring in a sunspot umbra, the spatial redistribution of oscillatory power across a magnetically diverse sunspot–plage–pore system, and MHD wave-mode identification and propagation in a pore. I will also discuss broader science opportunities enabled by the Sunrise III datasets, including current and future studies of wave propagation, mode conversion, magnetic structuring, and multi-height coupling in the lower solar atmosphere, particularly when the three Sunrise III science instruments are used together to provide broader coverage across atmospheric heights and diagnostics.

Speaker: Dr Shahin Jafarzadeh (Queen's University Belfast, UK)

16 Vector Magnetic Field of an Active Region Filament Observed by SUNRISE III/SCIP in the Ca II 8542 {\AA} Line

We report high-spatial-resolution spectropolarimetric observations of a solar filament and its surrounding region, obtained with the Sunrise Chromospheric Infrared spectro-Polarimeter (SCIP) onboard the SUNRISE III balloon-borne observatory on 15 July 2024.
The target, a filament located near the disk center adjacent to an active region, was monitored for over two hours.
SCIP recorded full Stokes profiles in the Ca II 8542 \AA line, providing, to our knowledge, the first unambiguous detection of linear polarization in a solar filament within this wavelength.
The detected linear polarization signals exceeded the 2$\sigma$ noise level and exhibited characteristic Zeeman double-lobe profiles, distinguishing them from scattering-induced polarization.
Using the weak field approximation, we derived a magnetic field strength of approximately $-80$ G along the line of sight and 300–500 G in the transverse direction.
The magnetic field vector appears nearly parallel to the filament axis in the northeastern portion, while the southeastern part extends beyond the field of view.
Furthermore, we present preliminary analysis of the magnetic structure in the neighboring plage region.
We find intriguing Stokes $V$ sign reversals that appear to be intrinsically linked to the spatial coexistence of emission and absorption components in the Ca II line core, probably reflecting complex chromospheric heating.
These results demonstrate that SCIP opens a new diagnostic window on the vector magnetic structure of the lower chromosphere, complementing existing He I-based observations of the upper chromosphere and providing new insights into the coupling between thermal and magnetic properties in both filaments and active regions.

Speaker: Takuma Matsumoto (Nagoya University)

17 Three-dimensional Magnetic Structures of Ellerman Bombs revealed by SUNRISE III/SCIP

Ellerman bombs (EBs) are transient brightenings in the wings of chromospheric lines, recognized as signatures of magnetic reconnection in the lower solar atmosphere. However, the three-dimensional (3D) magnetic topology of EBs has remained elusive due to the lack of seamless height coverage in spectropolarimetric observations.

We present initial results from SUNRISE III/SCIP observations of an emerging flux region obtained on 2024 July 15. SCIP performed simultaneous full-Stokes spectropolarimetry in Fe I 846.8 nm, K I D1/D2 (769.8/766.4 nm), and Ca II infrared triplet lines (849.8/854.2 nm), providing seamless diagnostics from the photosphere to the chromosphere with diffraction-limited spatial resolution. By applying the Weak Field Approximation to the multi-line dataset, we reconstructed three-dimensional line-of-sight magnetic field.

We identify two distinct classes of reconnection events.
In Event 1, the bipolar magnetic structure is confined to the lower layers (K I and Ca II wing heights), while a unipolar field configuration and no significant core intensity enhancement are found in the Ca II 854.2 nm core. These results indicate the low-altitude reconnection and heating.
In Event 2, the bipolar structure persists up to the Ca II 854.2 nm core formation height, accompanied by clear core brightening, indicating that the current sheet extends to higher altitudes and drives chromospheric heating. These contrasting behaviors were predicted by MHD-based synthetic observations (Kawabata et al. 2024, ApJ), and the SCIP observations now provide direct observational confirmation.

These results demonstrate that SCIP has successfully resolved the 3D structure of magnetic reconnection at different atmospheric heights. Future work will employ Non-LTE inversions to derive the thermal structure.

Speaker: Yusuke Kawabata (National Astronomical Observatory of Japan)

18 An assessment of the Weak Field Approximation using Response Functions

The weak-field approximation (WFA) is extensively used to infer solar magnetic fields due to its simplicity and low computational cost, often being applied beyond its formal range of validity. In this work, we reassess its limitations using Generalized Response Functions (GRFs), which quantify the sensitivity of WFA-derived magnetic fields to atmospheric parameters. We derive analytical expressions for these GRFs and evaluate them using synthetic Stokes profiles for representative spectral lines.
Our analysis shows that the WFA depends strongly on the atmospheric magnetic structure (strenght and inclination). We find that the approximation departs from the true magnetic field well below the nominal saturation limit, primarily due to the breakdown of the linear relation between Stokes $V$ and the intensity derivative. Revisiting the original perturbative formulation clarifies that this loss of linearity and the impact of inclination are intrinsic limitations, indicating that the WFA is often applied outside its domain of validity.

Speaker: David Arroyo Caballero (IAA-CSIC)

19 Three-dimensional magnetic field structure of a quiet Sun region with Sunrise III/SCIP

Sunrise III/SCIP acquired a unique, high-precision spectropolarimetric dataset for a quiet Sun region near the disk center on 2024 July 11 with the full field of view of 58" x 58". With an integration time of 10 s per slit position, the scan was completed in 107 minutes without interruption, achieving a polarimetric precision of 0.03-0.04% (1$\sigma$). The multi-wavelength SCIP observations, covering both photospheric and chromospheric spectral lines in the 850 nm and 770 nm bands, reveal that the chromospheric line-of-sight magnetic field exhibits thread-like elongated structures over the internetwork regions of the quiet Sun. No clear photospheric counterpart is detected directly beneath these chromospheric thread-like structures. The threads are typically narrower than 1” and are embedded within the canopy fields extending from nearby network regions. Their line-of-sight field strengths derived from the weak-field approximation are typically 10-20 G weaker than the surrounding canopy fields. In particularly clear cases, the magnetic polarity of thread-like structures is opposite to that of the adjacent canopy field. These findings suggest that the canopy field is not a simple expanding structure originating from network regions but instead has a complex three-dimensional configuration containing numerous local dip structures. These observations provide new constraints on the three-dimensional magnetic topology of the photosphere and chromosphere in quiet-Sun regions.
In addition, we detect the blue and red excursions in the wing of the Ca II 854 nm line. These excursions sometimes coexist with the thread-like chromospheric magnetic field structures near network boundaries. We also discuss the relationship between the thread-like magnetic field structures and dynamics in the chromosphere.

Speaker: Masahito Kubo (National Astronomical Observatory of Japan)

20 Interpreting high-resolution Sunrise III / SCIP observations with the MURaM-ChE code

The SCIP instrument on board Sunrise III observed the solar chromosphere at high spectral and spatial resolution through the Ca II 854.2 nm line. Kubo et al. (2026) present quiet Sun observations that reveal fine-structured network magnetic fields at chromospheric heights. By using the recently developed chromospheric extension of the MURaM code in combination with radiative transfer computations we were able to find similar fine-structured network magnetic fields in an enhanced network simulation. In the model atmosphere, opposite magnetic field polarities can be found as elongated structures close to the otherwise expanding main network polarity. At these locations, the magnetic field is twisted in the simulation, similar to twisted flux ropes. In this work we present the comparison between the observation and simulation and the evolution of such “opposite-polarity-intrusions”. We additionally provide possible future topics for interpreting Sunrise III data with the help of forward-modeled synthetic spectra.

Speaker: Patrick Ondratschek (MPS)

12:30 PM Lunch break

Day 1: Session 3

Convener: Dusan Vukadinovic (Institute of Physics, University of Graz)

21 Probing High-frequency Wave Propogation into the Chromosphere with Sunrise III

Speaker: Momchil Molnar (GNOI)

22 Multi-line Diagnostic of Very Quiet Sun Brightening Events Detected by SUNRISE III/SUSI

We describe transient brightenings in a very quiet Sun region detected with SUNRISE III/SUSI spectroscopic observations covering the Ca II K at 3933.663 Angstrom. The Ca II K line is one of the strongest lines in the solar spectrum and serves as a key diagnostic of the solar atmosphere. On its wings there are plenty of absorption lines that originate from various atmospheric heights. At some locations in the QS region, some of these lines exhibit Line Excesses (LEs), with several of them even appearing in emission. All of them are accompanied by Ca II K wing enhancements while only part of them are also associated with Ca II K core brightenings. These LEs show red/blue asymmetries, providing evidence for energy and mass flows in the solar lower atmosphere. In addition, we find that this type of brightenings is ubiquitous in the QS, even in the seemingly quietest regions.

Speaker: Shihao Rao (MPS)

23 3D modeling of Ca II emission above the limb

Sunrise III identified extended Ca II K emission above the limb. In a recently submitted letter, we described this emission and performed a simple radiative transfer modeling to compare emission properties with 1D and 3D models of the solar atmosphere. Here, we present more detailed modeling, including the 3D scattering in the upper chromosphere, as well as the discussion on the intensity of the emission above the limb and its implications.

Speaker: Ivan Milic (KIS)

24 Characterization of a solar pore from photosphere to chromosphere with SCIP@Sunrise

In this talk we aim at deepening our understanding of pores with particular focus on their characterization at middle atmospheric layers (upper photosphere / lower chromosphere). Pores are small and dark magnetic features observed in the photosphere that are composed of only an umbral core, i.e. they do not have penumbral structure, and have short lifetimes compared to larger sunspots. The absence of penumbra has been explained by a simple model: they are a magnetic flux tube whose magnetic field does not reach the inclination threshold required for penumbral formation. However, there are not many works addressing their vertical structure and thermodynamic coupling up to chromospheric heights. Understanding the stratification of physical parameters above pores is essential for clarifying how magnetic flux concentrations interact with the surrounding plasma, how energy is transported and dissipated, and how a magnetic canopy can develop above these structures.
Here we take advantage of the full spectropolarimetric capabilities of the SCIP instrument onboard the balloon mission Sunrise. The dataset corresponds to observations taken on 2024, July 10th between 19:14 UT and 21:05 UT, targeting a pore embedded in a flux emergence region. The simultaneous acquisition of spectral lines sensitive to both photospheric and chromospheric layers enables a consistent multi-height analysis of the atmospheric structure. We have inverted the observations in the Ca II 8542 Å spectral window using the coupled version of the STiC inversion code, which performs non-LTE inversions to retrieve the stratification of temperature, line-of-sight velocity, and the magnetic field vector from the photosphere up to the middle chromosphere (log τ ≈ −4.5). The coupled inversion scheme ensures a physically consistent solution across multiple spectral diagnostics, allowing us to infer vertical gradients and identify signatures of magnetic field expansion and thermodynamic structuring.
We investigate the thermal and magnetic structure of the pore in the upper photosphere and chromosphere and complement it with radiative losses in the Mg II and Ca II lines as well as determination of the excess thermal energy identified for mid-high photospheric temperature enhancements
Our results reveal an expansion of the magnetic field with height consistent with the development of a magnetic canopy. Thermodynamically, the pore is cooler at photospheric heights but presents similar temperatures at the mid-chromosphere. All around the pore boundary (as determined from intensity threshold) we infer temperature enhancements in the upper photosphere (up to 300K) that require approximately $5kJ/m^2$. This is likely a consequence of heating in the canopy boundary but, due to the observational setup, we could not determine the actual heating mechanism. These regions exhibit increased radiative losses mostly associated with the CaII.

Speaker: Ana Belen Grinon-Marin (Institute for Solar Physics / Stockholm University)

25 Magnetic Connectivity and Chromospheric Acceleration in an Arch Filament System Observed with Sunrise III

Emerging flux regions (EFRs) are highly dynamic environments where magnetic fields rise through the solar atmosphere, often giving rise to arch filament systems (AFSs) and filamentary structures. We present high-resolution, multi-line observations of an EFR obtained during the Sunrise III mission, combining spectropolarimetric measurements from TuMag and SCIP with EUV observations from SDO. The dataset provides continuous temporal coverage over nearly four hours, allowing us to follow the evolution of plasma and magnetic fields across multiple atmospheric layers.
We find strong and highly variable plasma motions within the AFS, including both upflows and downflows, with line-of-sight downflow velocities derived from the Mg I b₂ line reaching up to ~17 km s⁻¹ at the footpoints. These high-velocity episodes are co-temporal with brightenings observed in AIA 171 Å and 304 Å channels. The multi-line inversions and magnetic field extrapolations reveal a complex and evolving magnetic topology, including regions where field lines from different domains converge.
The observed dynamics occurs in close temporal proximity to a partial filament eruption,
suggesting a possible relationship between the filament evolution and the AFS dynamics.
While the exact mechanism cannot be uniquely identified, the results point to a strong
coupling between plasma flows and changes in magnetic connectivity. This study highlights the diagnostic potential of high-resolution, multi-line observations for investigating the dynamics of emerging flux regions.

Speaker: Sergio Javier González Manrique (Instituto de Astrofisica de Canarias)

26 Light in the darkness: uncovering hidden features near the solar limb using Sunrise III/SUSI

Sunrise III/SUSI conducted observations at the 409 nm spectral window, capturing an exceptional scan from near the disk up to 7 Mm above it. Ground-based acquisition of such data is hindered by foreshortening, low contrast, and variable atmospheric conditions. Over one hundred spectral transitions were detected, including Hydrogen (H$\delta$), Sr II, rare-earth elements such as La, Dy, and Hf, and molecular transitions of CH and CN. Weak lines of rare-earth elements and blends, typically undetectable on the disk, are now observable off-limb. These observations also reveal that the spicule forest appears in spectral lines that normally probe photospheric heights at the disk centre, as well as the small-scale structure of the surface-parallel chromospheric velocity field.

Speaker: Juan Sebastian Castellanos Duran (MPS)

3:30 PM Coffee break

Day 1: Session 4

Convener: Johannes Hoelken (MPAE)

27 Unlocking small-scale solar physics with Sunrise III: From magnetic building blocks to energy transport

Speaker: Santiago Vargas-Domínguez (Universidad Nacional de Colombia - Observatorio Astronómico Nacional)

28 Direct Measurement of the Height Dependence of $p$-mode Propagation in the Lower Solar Atmosphere with Sunrise III

In this presentation I summarize my early-science paper, where we report on the direct measurement of the height dependence of $p$-mode phase shifts in the lower solar atmosphere.
The line-core positions of 19 spectral lines in a 2 nm-wide window around the Ca II H line (396.8 nm) were used to determine the vertical oscillations at their respective formation heights. We find that the phases of the oscillations of the line core positions are roughly ordered according to the computed formation heights of the respective spectral lines. A statistical study of the phase shifts using the 1-hour-long sit-and-stare observation reveals that waves propagating upwards from the photosphere to heights of approximately 500--700 km are most common, with average time lags of 20--30 s. Also present are evanescent waves with zero phase shifts, predominantly above intergranular lanes and areas of enhanced magnetic activity. Additionally, downward propagating waves with negative time lags of 10--15 s are seen, mostly above areas of enhanced magnetic activity. A common feature of all the observed $p$-mode waves is that in the lower 250 km they show small time lags of zero to a few seconds, and only at higher layers the propagating waves become more dominant.

Speaker: Andreas Lagg (MPS)

29 Reconstructing vector magnetic fields evolution in an emerging flux region observed by TuMag/Sunrise III in the Photosphere and Chromosphere

We present our first result on the reconstruction of vector magnetic fields in the emerging flux region labeled 02_EMEF from vector polarimetric data acquired by TuMag/Sunrise III on July 10, 2024 from 19:14 to 21:47 UT. The full dataset is composed of a time series of 97 sets of vector polarimetric spectral images taken across the Fe I 5250.2 A (a photospheric line) and Mg I b2 5172.7 A (a low chromospheric line) spectral lines. The images cover a region of ~ 60 x 60 arcseconds at with pixel size of 0.037 arcsec. The time series covers a span of 2.5 hours with a mean cadence of 83 seconds between vector polarimetric sets.
We apply the Weak Field Approximation (WFA) to both the photospheric and chromospheric Stokes data to extract the full magnetic vector, and qualitatively compare the magnetic topology between photosphere and low chromosphere. We discuss limitations, successes and challenges in obtaining the reconstruction using the WFA. We also provide initial results in analyzing the time evolution of the photospheric and chromospheric magnetic fields in this emerging flux region across the entire observation time span.

Speaker: Pietro Bernasconi (JHU/APL)

30 Preliminary Magnetic Field Components and Analysis for TuMag Data

Following an effort (see abstract by P. Bernasconi et al.) to infer the magnetic field components of TuMag sample 02_EMEF (emerging flux region) in the absence of a full inversion process, we present a preliminary magnetic field analysis of this dataset. We possess 97 sets of Fe I and Mg I Stokes profiles at Levels 1.0 and 1.1, with a mean cadence of 82.8 sec, taken roughly between 19:14 and 21:47 on July 10,2024. Inference of magnetic field components has led to simultaneous and co-aligned photospheric and chromospheric configurations with linear dimensions of ~60”.1 (1644^2 and a pixel size of ~0”.037). On the line-of-sight field data, we analyze and compare the photospheric and chromospheric signed and unsigned fluxes. We further apply a recently published methodology to identify apparent magnetic energy release episodes due to magnetic flux cancellation and, again, compare between the photosphere and the chromosphere. On vector magnetic field data, we make an effort to obtain an azimuth disambiguation solution and we assess its quality and credibility. Given the continuing progress and work underway, we reserve presentation of findings and conclusions for the time of the meeting. The Sunrise III data analysis presented receives partial support by NASA Cooperative Agreement #80NSSC24M0024.

Speaker: Manolis Georgoulis (Johns Hopkins APL)

31 Transition probabilities of atomic lines in SCIP observing window

To fully exploit the rich SCIP observations, it is important to update the atomic data of observed lines. In this contribution, I will discuss the procedure to identify lines with poorly constrained parameters, such as the transition probability, and how these are inferred from observations, self-consistently with the physical parameters. For this purpose I use SCIP observations of an emerging flux region from the 10th of July consisting of the quiet sun and a few pores. The diverse features in the observed FOV allow us to disentangle blends and thus improve the inference of atomic parameters. The uncertainties in the inferred parameters are determined using a Bayesian method. The improvements in atomic parameters permit inference of complex atmospheric models, further revealing finer scales of the solar atmosphere through many-line inversions.

Speaker: Dusan Vukadinovic (Institute of Physics, University of Graz)

32 Morphological analysis of magnetic bright points in high-resolution SUSI images

We present an analysis of magnetic bright points (BPs) using high-resolution images from the SUSI instrument. We built a neural network to detect automatic BPs in thousands of reconstructed SJ images, and from this, a morphological analysis is performed to characterise properties such as area, length, and proper motion velocities.

Speaker: Daniel Ramos (GNOI)

6:00 PM Meeting dinner

Wed, June 3

Day 2: Session 1

Convener: Edvarda Harnes (MPS)

33 Beyond Intensity: Linear Polarization as a Proxy for Solar Vortices1

Vortex motions in the solar atmosphere play a crucial role in energy transport and plasma heating. Current observational methods for detecting vortices rely primarily on intensity morphology, which is limited in sensitivity and often fails to capture the full vortex population. In this Letter, we propose linear polarization (LP) as a novel diagnostic for identifying vortices in spectropolarimetric observations. Using a single snapshot of a MURaM magnetoconvection simulation of an enhanced network region, we synthesize full Stokes profiles across various spectral lines. We develop a dual-criterion detection algorithm based on the Laplacian curvature of the LP degree and the perpendicularity of the Stokes Q and U spatial gradients. Detected LP swirl regions are found to be co-spatial with vortices identified independently through swirling strength, as well as with coherent rotational patterns in both the velocity and magnetic field vectors, validating the proposed diagnostic.

Speaker: Nitin Yadav (Indian Institute of Technology Delhi)

34 Observational Evidence of Directed Information Transfer by Solar Vortices

We analyse high-resolution data from the TuMag instrument aboard the Sunrise III balloon mission. Vortices are identified using a velocity-independent approach that detects their signatures directly in intensity patterns, combining morphological identification of vortex structures with Spectral Proper Orthogonal Decomposition to extract coherent dynamical patterns imprinted by vortices in Mg I $b_2$ time series. This spectral line allows us to probe both the photosphere and the low chromosphere. Our results show that approximately $8.5\times10^4$ vortices are present on the Sun at any given time, with typical lifetimes of around 27 minutes. Inter-layer coupling is quantified using Granger causality, which tests whether variations in one atmospheric layer statistically predict future changes in another, making it sensitive to both energy and momentum transport. Within vortices, this coupling is not spatially uniform: parts of the vortex region show the lower layer driving the upper one, while other parts show the reverse, producing a characteristic dipolar, "yin-yang" pattern of directional influence. Notably, the same dipolar pattern is recovered in numerical simulations when examining vertical energy transport measured by the Poynting flux in vortex regions. Our results show that lower-atmospheric fluctuations more effectively predict upper-atmospheric variations within vortices than in control regions, with predictive coupling approximately 27% stronger inside vortices. This provides the first observational indication that solar vortices are capable of organising and enhancing transport between atmospheric layers.

Speaker: Suzana de Souza e Almeida Silva (University of Sheffield)

35 SCIP multi-line inversions in the 850 nm window: height stratification of solar magnetic fields in a pore

We analyze spectropolarimetric observations acquired with the SCIP instrument in the near-infrared spectral window CH1 around 850 nm. This wavelength range contains a total of 12 spectral lines sampling different layers of the solar atmosphere. In this work, we focus on a subset of seven Fe and Ca lines, spanning photospheric, upper-photospheric, and chromospheric heights, including the Ca II 854.2 nm and Ca II 849.8 nm lines. We perform simultaneous multi-line full-Stokes inversions using the NLTE DeSIRe inversion code. The inversion strategy takes into account the spectral PSF, computed specifically for these SCIP observations, and includes an unpolarized stray light correction of the spectral profiles, which improves the quality of the fits. We carried out multiple inversion cycles with up to 11 nodes in optical depth and included spatial straylight correction in the modeling, resulting in good fits and a reliable inference of the height-dependent atmospheric parameters.

Our analysis focuses on an emerging flux region containing pores, observed in four consecutive SCIP maps. This allows us to investigate both the vertical structure and the temporal evolution of the magnetic field in pores. The inferred stratification shows a clear expansion of the magnetic field with height, as represented as a function of optical depth. TuMag images are used for context.

The results show the potential of combining multiple spectral lines in the 850 nm wavelength range and demonstrate the capabilities of multi-line inversion techniques to study the vertical and temporal evolution of solar magnetic fields.

Speaker: Christoph Kuckein (Instituto de Astrofisica de Canarias (IAC))

36 Analysis of extremely asymmetric Stokes $V$ profiles in quiet Sun regions with the Sunrise/SCIP instrument

We investigate small-scale magnetic features in the quiet solar photosphere through high-resolution multi-wavelength spectropolarimetric observations taken by the Sunrise Chromospheric Infrared spectro-Polarimeter on board the Sunrise-III stratospheric balloon-borne solar observatory. The instrument allows for high signal-to-noise observations of multiple spectral lines.
Our analysis focuses on Stokes $V$ profiles exhibiting a larger blue lobe. We detect asymmetries in such profiles across various spectral lines forming at different atmospheric heights, from the lower to the upper photosphere. The observations show that spectral lines formed in the higher photosphere, such as Fe I 8468 Å and K I 7698Å, exhibit strong line asymmetries. In contrast, the asymmetries are significantly weaker for lines formed in the lower photosphere, such as Fe I 8471 Å and Fe I 8526 Å.
By comparing spectral lines with different formation heights, we find that the degree of Stokes $V$ asymmetry tends to increase with formation height, and the magnetic polarity remains consistent across all analyzed lines, including the K I line and the chromospheric Ca II lines. In addition, the Stokes $V$ zero-crossing velocity measured directly from these profiles systematically decreases (i.e., becomes less blueshifted) with increasing formation height. This indicates that the overall upward line-of-sight velocity of the magnetic features is lower in the upper photosphere than in the lower layers.

Speaker: Shujun CAI (National Astronomical Observatory of Japan)

37 3D magnetic structures triggering an M-class flare observed with SUNRISE III

SUNRISE III observed an M5.3-class flare on July 13th. The 3-hour observation began at 11:44 UT, one hour before the GOES X-ray flux peaked at 12:40 UT. SCIP obtained full Stokes profiles in the 770 nm and 850 nm range, covering the photospheric Fe I 849 nm, the upper photospheric K I 766 nm and 770 nm, and the chromospheric Ca II 849 nm and 854 nm lines. The FOV of SCIP covered a part of the polarity inversion line (PIL) in the active region, where complex Stokes V profiles appeared in the photospheric lines. The Stokes inversion found that these profiles can be explained by a two-component atmosphere with both magnetic polarities. The non-linear force-free-field extrapolation suggests that the magnetic fields have a bold patch structure on the PIL. We also discuss the chromospheric magnetic field structures associated with the flare activity.

Speaker: Ryohtaroh Ishikawa (National Institute for Fusion Science)

38 High resolution spectropolarimetric analysis of a flare

Speaker: Lakshmi Pradeep Chitta (MPS)

10:30 AM Coffee break

Day 2: Session 2

Convener: Ryohtaroh Ishikawa (National Institute for Fusion Science)

39 Toward understanding magneto-convective regimes in active regions

The solar photosphere is shaped by the interplay between convection and magnetic fields, producing a rich variety of structures in active regions. While granulation represents the fundamental convective pattern of the quiet Sun, magnetic field in active regions gives rise to distinct magneto-convective regimes, each defined by a different balance between plasma motions and magnetic forces. Observations and MHD simulations suggest that these regimes are organized around key magnetic field thresholds, which govern the morphology, brightness, and dynamics of features such as umbrae and penumbrae. However, our current understanding relies largely on analyses of observations with limited spatial and temporal resolution, restricting us to statistical descriptions of stable structures and obscuring the dynamic transitions between observed regimes. These transient processes—where convection rapidly reorganizes under evolving magnetic conditions—are fundamental to understand evolution of structures in active regions and the fine-scale interplay between magnetic and kinetic forces. In this talk, I will highlight some of the Sunrise III datasets offering a promising opportunity to understand more details about magneto-convective regimes.

Speaker: Jan Jurcak (Astronomical Institute of the CAS)

40 Chromospheric Dynamics of an Umbral Flare Kernel - Based on Coordinated SUNRISE III SCIP and Domeless Solar Telescope Observations

We report imaging spectroscopic observations of an M1.4 solar flare obtained during a coordinated observation between SUNRISE-III/SCIP and Domeless Solar Telescope (DST) at Hida Observatory, Kyoto University.
The flare that occurred on 2024 July 13 in NOAA Active Region 13738 exhibited a compact flare kernel located within a sunspot umbra.
SCIP performed rapid slit-scan observations over a 58" x 58" field of view around the umbra at a cadence of 40 s, covering infrared chromospheric lines, including Ca II 8498/8542 Å and K I D1.
At the same time, DST observed a wider (300" x 120") surrounding region with a cadence of 25 s in H$\alpha$, Ca II 8542 Å, and Na I D1/D2.
We investigate the temporal evolution and spectral characteristics of the umbral flare kernel by using simultaneous spectroscopic observations in multiple chromospheric lines.
Clear flare-related brightenings are detected in all chromospheric lines observed by SCIP and DST, while no significant enhancement is found in photospheric lines.
The high spatial resolution of SCIP reveals fine substructures within the kernel on spatial scales of order 1 Mm that are largely smeared out in ground-based observations alone.
The spectral profiles exhibit temporally and spatially varying Doppler shifts and line broadenings, indicating complex, fine-scale plasma motions in the chromosphere.

Speaker: Ayumi Asai (Astronomical Observatory, Kyoto University)

41 Chromospheric Spectropolarimetric Evidence of Magnetic Portals in Quiet-Region Flux Tubes Revealed by SUNRISE-3/SCIP

Acoustic waves propagate into the chromosphere and upper atmosphere, contributing significantly to energy transport and dynamics. Their upward propagation, however, is restricted to frequencies above the acoustic cutoff frequency, which depends on atmospheric conditions. In particular, the magnetic field configuration plays a key role, as the cutoff frequency is reduced in regions where the field is inclined with respect to gravity, forming so-called magnetic portals. Previous studies reported links between magnetic fields and oscillations in quiet regions, but these analyses were based on photospheric magnetic field information, leaving the chromospheric structure unconstrained. This study investigates the coupling between acoustic waves and magnetic topology using photospheric and, for the first time, chromospheric spectropolarimetry in a quiet region, obtained with the infrared instrument onboard the balloon-borne observatory SUNRISE-3/SCIP.

LOS magnetic fields reveal that photospheric magnetic fluxtubes expand into the chromosphere. In the chromospheric velocity field, these fluxtubes exhibit large-amplitude 5-minute oscillations, while the surrounding regions show small-amplitude 3-minute oscillations. The enhanced oscillations are pronounced in fluxtubes that not only expand but also suggest a tilt of their tube axes toward the chromosphere. In these regions, sawtooth temporal velocity variations are associated with strong intensity enhancement, suggesting steepened shocks. Flux tubes with low-frequency, large-amplitude oscillations are identified in network regions and also in internetwork regions, where they are barely detectable in SDO/HMI magnetograms. These results provide direct observational evidence that expanding fluxtubes, possibly with tilted axes, act as magnetic portals in both network and internetwork regions, allowing low-frequency waves to propagate into the chromosphere and driving dynamics via shock formation.

Speaker: Takayoshi Oba (Advanced Research Center for Space Science and Technology (ARC-SAT), Institute of Science and Engineering, Kanazawa University)

42 Exploring spatially highly resolved Stokes V profiles from Sunrise-III/SUSI

High-resolution broad-band observations of the Sun reveal a multitude of small-scale structures, everywhere in the photosphere. The increase in resolution usually comes with the cost of increased noise and decreased polarimetric signal.
In this contribution we present an approach inspired by stellar astrophysics, in particular the study of stellar magnetism. We use least-squares deconvolution (LSD) of spectro-polarimetric data to combine the signal from many simultaneously observed spectral lines in spatially highly resolved (∼ 0.07”) Sunrise-III/SUSI observations into a single combined profile. As first results we obtain high-resolution high-contrast Stokes V/I maps that allow for the spatial resolution of weak signals against a 2.5e−4 root-mean-square (RMS) continuum noise background.
In these maps we find patches of both magnetic polarities with a range of Stokes V signal levels, as well as parasitic opposite polarity signals at the border of patches with stronger Stokes V signals. Further analysis of these signals is ongoing.

Speaker: Johannes Hoelken (MPS)

43 Sunspot structure across photospheric and low chromospheric layers

We analyze high-resolution spectropolarimetric observations from TuMag/SUNRISE III in the Fe I 5250.2 Å and Mg I b2 5173 Å lines to investigate how sunspot properties change from the photosphere to the low chromosphere, a transition layer characterized by key changes in the thermal, dynamic, and magnetic structure of the solar atmosphere.
We perform a comparative analysis using both spectral lines to study how the velocity and magnetic field structures vary across this interface in sunspot environments, with particular emphasis on the penumbral region.

Speaker: Azaymi L. Siu-Tapia (Instituto de Astrofísica de Andalucía (IAA-CSIC))

44 High-order hydrogen Paschen emission lines observed with SCIP

We report the detection of high-order hydrogen Paschen emission lines (Pa~15, Pa~16, and Pa~17) in the quiet-Sun chromosphere off the solar limb using the Chromospheric Infrared SpectroPolarimeter (SCIP) on board the SUNRISE balloon telescope. These lines reveal thread-like structures resembling spicules and exhibit systematically smaller Doppler velocities than Ca II 854.2 nm, indicating that they are optically thinner and more affected by line-of-sight averaging. Radiative transfer simulations using the spherical code rhsphere reproduce the overall spectral properties and support a recombination-driven formation mechanism. The observed ratios show significant dispersion and systematic deviations from one-dimensional model predictions. These results suggest that multi-dimensional and inhomogeneous plasma conditions play an important role in the formation of high-order Paschen lines, and demonstrate their potential as a new diagnostic of optically thin, recombination-dominated plasma in the off-limb chromosphere.

Speaker: Haocheng Yu (NAOJ)

12:30 PM Lunch

Day 2: Session 3

Convener: Christoph Kuckein (Instituto de Astrofisica de Canarias (IAC))

45 Height-dependent magnetic topology of quiet-Sun network element revealed by Sunrise III/SCIP

We present an analysis of high-resolution multi-line spectropolarimetric observations of quiet-Sun network elements obtained with the Sunrise III Chromospheric Infrared SpectroPolarimeter (SCIP). Using simultaneous photospheric Fe I and chromospheric Ca II diagnostics, we examine the magnetic structure of a network element across optical depth. We find a coherent transverse magnetic structure with pronounced lateral variation in azimuth across the feature. At the network boundary, we identify localised pixels exhibiting complex Stokes $V$ profiles and opposite-polarity line-of-sight magnetic fields, in some cases changing sign between photospheric depths. In addition, we report a distinct example showing opposite-sign Stokes $V$ profiles between photospheric and chromospheric lines, indicative of a height-dependent reversal of the line-of-sight magnetic field. These observations highlight the complexity of quiet-Sun network boundaries and provide constraints on the three-dimensional magnetic structure of small-scale solar magnetic fields.

Speaker: ryan campbell (Queen's University Belfast)

46 Three-dimensional analysis of a C-class flare observed with Sunrise III/SCIP

Deciphering the physical properties of flares is crucial for understanding the nature of one of the most energetic events on the Sun. We make use of high spatial and spectral resolution observations of a flare-producing active region, focusing on a complex light bridge, to analyse the physical properties of a C-class flare. The observations show Stokes profiles with different line Doppler shifts and asymmetries between photospheric and chromospheric spectral lines, and also reveal Ca II infrared spectral lines in emission in areas where atmospheric heating is extreme. Inversion results are compatible with the mentioned spectral features, with regions where plasma flows are opposite between the photosphere and chromosphere, and areas with extreme temperature in the chromosphere despite relatively weak plasma velocities. The magnetic field configuration also show abrupt changes along the line-of-sight for the former cases while it is constant with height in latter regions. The lack of line-of-sight flows at regions of extreme heating suggests that there are no indication of chromospheric condensation or evaporation pointing towards a new physical scenario related to the flare ribbon or a complex topology that prevents the detection of the expected plasma flows from a standard flare model scenario.

Speaker: Carlos Quintero Noda (Institute of Astrophysics of the Canary Islands / La Laguna University)

47 Multi-lobed Stokes V Profiles of the Fe I 407.17 nm Line Observed by Sunrise III

The Sunrise Ultraviolet Spectropolarimeter and Imager (SUSI) instrument captured high spectral and spatial resolution observations of the strong Fe I line at 407.17 nm. We observe that within a sunspot penumbra, this line displays multi-lobed Stokes V profiles unlike other lines in the same spectrum. These multi-lobed profiles were predicted in earlier computations and are found to result from the bell-shaped Stokes I profiles of this line within the penumbra. The multi-lobed Stokes V profiles are best seen in the inner parts of the penumbra, where the Stokes V signal of the line is stronger, and the Stokes I line shape displays the characteristic flattening of the inner wing along with a steep line core. This allows us to measure magnetic field strengths at different heights in the atmosphere by applying the weak-field approximation to the line core and line wing separately. The LOS magnetic field strengths we obtain are, as expected above the inner penumbra and magnetic elements, stronger in the photosphere than higher up. Despite the blend line in the blue wing and the relatively weak Stokes V signals when compared with other lines, the Fe I 407.17 nm line could be used as an initial estimate of the magnetic field at two different height ranges, for example for initializations of inversions.

Speaker: Edvarda Harnes (MPS)

48 Magnetic Field Stratification in Active-Region Plage from Ca II K and Ca II 8542A Spectropolarimetry

We investigate the height dependence of the line-of-sight (LOS) magnetic field in an active-region (AR) plage from the upper photosphere to the upper chromosphere using co-spatial ultraviolet (UV) and infrared (IR) spectropolarimetric observations. We analyze the Stokes I and V profiles acquired during the Sunrise III stratospheric balloon flight with the SUSI and SCIP instruments. The Ca II K line observed by SUSI and the Ca II 8542A line observed by SCIP provide complementary chromospheric diagnostics, while nearby Fe I lines sample photospheric layers. The LOS magnetic field is inferred by applying the weak field approximation (WFA) within a Markov chain Monte Carlo (MCMC) framework, allowing us to obtain best-fit values and confidence intervals. The photospheric Fe I lines reveal strong, finely structured magnetic fields reaching up to ∼1.2 kG. In contrast, the chromospheric Ca II diagnostics yield systematically weaker magnetic fields, typically in the range ∼100–400 G, and with a more spatially diffuse distribution. Furthermore, magnetic-field maps inferred from the Ca II K line, formed in the upper chromosphere, appear smoother and more extended than those derived from the Ca II 8542A line, which forms lower in the chromosphere. These results provide quantitative observational evidence that AR magnetic fields weaken and expand with height, transitioning from kilogauss, highly structured photospheric concentrations to weaker, more diffuse fields in the upper chromosphere.

Speaker: Iñigo Juanikorena Berasategi (GNOI)

49 Magnetic fields distribution along spicules revealed with SUNRISE III SCIP

Understanding the magnetic field structure of spicules is essential for developing formation models of spicules, which are important for understanding mass transport to the corona and the coronal heating.
We report the spatial distribution of spicule magnetic fields along the line-of-sight ($B_{\rm{LOS}}$) from spectropolarimetric observations of the solar limb with SUNRISE-III/SCIP under seeing-free conditions, applying the Weak Field Approximation to the Stokes $\textit{I}$ and $\textit{V}$ profiles of the Ca II 8542 $\mathrm{\mathring{A}}$ line.
We find that $B_{\rm{LOS}}​$ ranges up to 20 $\rm{G}$, nearly independent of height, in the region up to 2 $\rm{Mm}$ from the limb, whereas the distribution broadens to 40 $\rm{G}$ at 2-4 $\rm{Mm}$ from the limb.
The Stokes $\textit{I}$ profiles averaged over the same distance from the limb changed from a double-peaked shape to a single-peaked one at around 2 $\rm{Mm}$ from the limb.
This suggests that the observed $B_{\rm{LOS}}$ depends on the optical thickness of the Ca II lines.
In the optically thick region with double-peaked profiles, the estimated $B_{\rm{LOS}}$ represents a superposition of few foreground spicules, whereas in the optically thin region with single-peaked profiles, the estimated $B_{\rm{LOS}}​$ reflects contribution from a prominent tall inclined spicule, leading to more dispersed $B_{\rm{LOS}}​$ values.
We further report the spatial structure of spicule magnetic fields by incorporating the $B_{\rm{LOS}}$​ spatial distribution obtained from the Ca II 8498 $\mathrm{\mathring{A}}$ line, which has a different optical thickness from the Ca II 8542 $\mathrm{\mathring{A}}$ line, and examine how the difference in optical thickness affects the inferred magnetic field structure of spicules.

Speaker: Yoshihiro Naito (NAOJ/SOKENDAI)

50 Spectral variability of the Ca II K line core in an emerging flux region from high resolution Sunrise iii/SUSI observations

Small-scale impulsive energy events, often attributed to magnetic reconnection, are prime candidates for heating the solar corona to millions of degrees. However, the direct detection of the effect of such events in the corona remains challenging due to fast energy dissipation in the corona. These events, though faint in the corona, can drive significant chromospheric dynamics, leaving detectable imprints in strong resonance lines such as the Ca II K line, which forms over a broad height range from the lower photosphere to the chromosphere. In this study, we analyse high-resolution, full-Stokes spectropolarimetric observations from the Sunrise III/SUSI instrument, capturing an explosive event within an emerging flux region (NOAA AR 13738) on 2024 July 10. Using spectral moments, we characterise the variability of the Ca II K line core, focusing on regions exhibiting extreme line asymmetries and broadening. By comparing these moments with simultaneous photospheric and lower chromospheric observations from SUSI and SDO/AIA, we establish a multi-height context for the event. Our analysis reveals a localized, transient brightening in the AIA 17.1 nm and 9.4 nm channels, indicative of plasma temperatures reaching 1–7 MK and typically associated with coronal loop structures extending from the transition region to coronal heights of order 10 Mm. These coronal signatures are coincident with a strong, spatially-confined enhancement in the Ca II K zeroth, first and second order spectral moments. Notably, the event is associated with mixed-polarity magnetic footpoints and shows a clear loop-like connection between the SUSI field of view and the boundary of a distant sunspot penumbra in the AIA 17.1 nm, AIA 160 nm and AIA 9.4 nm channels. The spectral moment anomalies, coronal brightenings and magnetic connectivity, support the interpretation of this event as a nanoflare-like reconnection burst.

Speaker: Kunal Hardeep Singh (MPS)

3:30 PM Coffee break

Day 2: Session 4

Convener: Juan Sebastian Castellanos Duran (MPS)

51 Unveiling spectral and radial velocity signatures of solar faculae using 3D MHD simulations

Faculae are a major source of spectral and radial velocity (RV) variability in the Sun and in Sun-like stars, yet their disk-integrated spectroscopic imprint remains insufficiently constrained. We investigate how faculae modify spectral line morphology and line-of-sight velocity signatures from disk centre to the limb using a physically consistent forward model based on 3D radiative magnetohydrodynamic simulations with MURaM and spectral synthesis with MPS-ATLAS. We compute high-resolution spectra for a range of viewing angles and model the transit of a facular patch across the visible solar disk. We find that the facular signatures depend strongly on its position on the solar disk. Near disk centre, facular magnetic fields suppress the convective blueshift and produce a redshift relative to the quiet Sun. Towards the limb, faculae produce a relative blueshift, associated with the effect of faculae on the horizontal flows and the visibility of these flows. In combination with solar rotation, this centre-to-limb behaviour produces asymmetric RV profiles and a phase lag between the RV maxima and central meridian passage of the facular patch. Different spectral lines respond differently to these effects, showing that facular signatures are intrinsically line dependent. This highlights the diagnostic value of line-resolved spectroscopy for tracing facular magnetoconvection and for developing methods to mitigate their imprints in RV measurements. Observations of faculae at different disk positions from SUNRISE III provide a unique opportunity to verify this predicted centre-to-limb dependence of faculae-induced RV signals and to evaluate their relevance for stellar RV studies.

Speaker: Florian Kröll (GNOI)

52 Simulated center-to-limb variation of convective velocity shifts and their modification by faculae

Convective velocity fields in the solar photosphere are strongly modified by magnetic structures such as faculae, leading to measurable changes in spectral line shapes and shifts. These effects become increasingly complex away from the disk center. Accurately capturing this center-to-limb variation is essential for interpreting spatially resolved solar observations and for modeling unresolved stellar spectra.

In this work, we investigate the convective velocity fields in radiative magnetohydrodynamic simulations of the quiet Sun harboring a small scale dynamo and of the facular regions, computed with the MURaM code. Employing these simulated atmospheres in the MPS-ATLAS radiative transfer code, we synthesize emergent spectra for 50 selected iron lines over a range of viewing angles from disk center to the limb. From these synthetic spectra we derive the center-to-limb variation of the spectral line shifts induced by convective flows. We validate the results for the quiet Sun by comparing them to disk-resolved quiet solar spectral measurements from the Institute for Astrophysics and Geophysics (IAG). This comparison with IAG provides a quantitative assessment of how accurately the simulations represent the convective velocities in the solar photosphere.

We further explore how the modification of vertical and horizontal convective flows by facular magnetic fields impacts the resulting spectral line profiles. We show that horizontal flows play an increasingly important role towards the limb and are crucial for understanding the spectral response to magnetoconvection away from disk center. We provide detailed predictions for the center-to-limb variation of spectral line shifts and asymmetries induced by faculae. A direct validation of these predictions through comparison with disk-resolved observations from the Sunrise-III mission is planned as a next step.

Speaker: Dr Sowmya Krishnamurthy (University of Graz)

53 Interaction of magnetic fields with horizontal vortex flows at the periphery of granules.

Plasma flows in the near-surface region are thought to play an important role in replenishing the quiet Sun magnetic field. The interaction of magnetic fields with the complex flow structure causes these fields to reorganize at sub-granular scales. Horizontally aligned vortex flows near the edge of solar granules can grab magnetic fields from the interior and bring them to the visible surface. However, it is still unclear if these magnetic fields are amplified during their motion through such a turbulent environment. Here, we present results from a high-resolution radiative magnetohydrodynamic simulation carried out using the CO5BOLD code, focusing specifically on the periphery of granules. We investigate the formation and evolution of coherent vortex structures in these regions to determine if they contribute to amplifying the magnetic field to levels observable on the quiet Sun.

Speaker: Vigeesh Gangadharan (Institut für Sonnenphysik (KIS))

54 Chromospheric Heating in Solar Plage Region

The solar chromosphere is one of the most intriguing yet poorly understood regions of the solar atmosphere, and its heating remains a central problem in solar physics. Plage regions, characterized by the strong, predominantly vertical magnetic fields, show enhanced chromospheric emission, indicating localized energy deposition. The dominant
mechanisms that heat the chromosphere include waves, magnetic reconnection, and magnetic braiding. Mass motions, such as vortex flows, may also contribute to the chromospheric heating. Overall, both observations and simulations indicate that multiple processes operate simultaneously, producing a complex, spatially heterogeneous
heating pattern. The dominant process heating the chromosphere within plages remains an open question.
We plan to use multi-line, high-resolution spectropolarimetric observations from Sunrise III to investigate the processes that heat the chromosphere in plage regions. The idea is to perform spectropolarimetric inversions of the Ca II observations from SUSI and/or SCIP data using the STiC inversion code. The inversions, applied to the datasets with
high spectral resolution and coverage, will enable detailed optical-depth resolution of the inverted atmosphere, helping accurately constrain the radiative losses that will be constrained with an estimate of the Poynting flux derived from the spatio-temporally resolved TuMag observations. The comparison between the two will provide a unique, multi-instrument, multi-layered insight into energy transport within the solar plages.

Speaker: Sandeep Dubey (Udaipur Solar Observatory, PRL, India)

55 Concluding Remarks

Speaker: Sami Solanki (MPS)