Annual report 2018 Contents 1 06 From the Director

2 Annual report 08 Presentation of RoCS 08 What is the Sun? 10 Towards understanding: RoCS goals 2018 11 Advanced numerical simulations – 12 High quality observations 3 16 2018 activities by theme

18 Simulations 20 Observations with SST/IRIS 22 Observations with ALMA 26 New code developments

4 28 International Rosseland Visitor Programme

Contact 5 30 Members of the centre Svein Rosselands hus Sem Sælands vei 13 NO-0371 Oslo 6 Norway 38 Appendices

P.O box 1029 Blindern 38 Talks and presentations 2018 NO-0315 Oslo Norway 40 Papers in refereed journals 2018 To understand the origin and evolution of the solar 1 magnetic field on spatial scales ranging from the Rosseland Centre for smallest observable (<100 km) to the size of active Solar Physics (RoCS) regions (100,000 km). To understand the dynamic structuring and mass – 2 and energy transfer in the solar atmosphere from the relatively cool (6,000 K) surface to the multi- million degree corona.

To understand which configurations of the magnetic 3 field, ambient and emerging, lead to the develop- ment of dynamic phenomena such as surges, jets Our vision is and flares of all sizes that permeate the active solar atmosphere. understanding the workings of the To go beyond the single-fluid magnetohydrodynamic 4 energetic Sun. (MHD) paradigm, which breaks down in the nearly neutral chromosphere and the almost collisionless coronal plasma. We will do this by applying multi-­ fluid and particle-in-cell techniques, providing new understanding of heating and particle acceleration in both quiet and active solar environments. 6 RoCS Annual report 2018 1 From the Director 7

Simulation of the solar dynamo that generates the magnetic field (left, simulation by the group in Paris) and a simulation of the outer solar atmosphere (right, simulation by RoCS) where the emerging field interacts with pre-existing field creating explosions and jets.

leaders got the information just after the attended and the four members gave their A new international project got selected for board meeting. I was in Boulder, Colorado, view on the way forward for RoCS. The funding in 2018: a very prestigious synergy at the time and because of the time-zone starting two months were also used to grant from the European Research Council difference I got the excellent news in the select the first employees of the centre (ERC). In this project, called WHOLE SUN, morning and was dying to send around and for preparing for the adaption of new we work with groups in Paris, Göttingen, the message to the whole team and the rooms in the Svein Rosseland building. St. Andrews and Tenerife. The WHOLE supporting people at the University of Oslo. SUN project attempts to link the eruptive I almost sent off the email one hour too In 2018 the ramp-up of activities continued. phenomena observed in the solar atmos- early because the time-zone difference Two faculty positions were filled with par- phere to the motions of plasma deep in the was one hour less than normal (daylight tial funding from RoCS: Sven Wedemeyer interior of the Sun, where its magnetic field savings time in the USA but not in Europe) and Tiago Pereira. Three postdoctoral re- is generated. One of the goals is to develop From the opening of RoCS November 1 2017. but realised just in time. The message was searchers and four PhD students started a new code that can treat this whole region From left: Boris Gudiksen (PI), Sven Wedemeyer sent off on the minute 02:00 and all PIs re- in 2018. We also completed a contract with as one system. Computationally, this is very (PI), Mats Carlsson (director), Viggo Hansteen sponded within minutes so all were waiting the University of Glasgow enabling pro- challenging and in need of exascale class From the Director (PI), Luc Rouppe van der Voort (PI) for the news. Lots of champagne followed. fessor Lyndsay Fletcher to work 20% for capacity (about 100 times more powerful RoCS from December 1st 2018. The possi- computers than the top computers today). – But the reward of hard work is more hard bility through a centre to attract leading work – much remained before the official scientists to come for shorter or longer A number of exciting results have been start of the centre on November 1st 2017: visits have often been highlighted as one obtained in 2018. A selection of these are This is the first annual report of the Rosseland Centre for Solar final adjustments for the contract, making of the most important aspects by other reported on in this annual report in Section Physics (RoCS). The centre is one of the 10 centres of excellence plans for the renovation of the Svein Ros- centres of excellence. We are ramping up 3 with a full list of papers published in selected by the Research Council of Norway in the fourth round seland building that houses the Institute this activity and are in the final stages of refereed journals in Appendix 2. of the centres of excellence scheme. As this is the first report, of Theoretical Astrophysics to make room signing several 20% contracts with leading for the expansions, announcements of po- experts, thus expanding the knowledge A large number of exciting projects are well we have taken the opportunity to have a presentation of the sitions and selections of candidates, etc, base of the centre. Another important ac- under way. The ramping up of activities vision and scientific programme of the centre and also of all etc. Throughout the application process tivity here is our International Rosseland continues with more people coming on the people working at RoCS. I would also like to give some and up to the starting date and this first Visitor Programme, which is described in board all the time. Together we are making year of ramping up, lots of persons have more detail in Section 4. a difference! background from how the centre came into realisation. been involved – the current RoCS team, the leadership, administrative staff and During 2018 we have also worked to technical staff of the Institute of Theoretical strengthen internal collaboration within March 2019 The process towards establishing a Centre but we got the positive message two days comments on the report. The proposed Astrophysics, support personnel at the the centre. Our first retreat was in March of Excellence is long and full of hard work. before and we then had two months of directors of all 34 finalists were asked to Faculty of Mathematics and Natural Sciences 2018 and the emphasis was on synergy Mats Carlsson, The deadline for phase I of the proposal intensive work to finish the full proposal give a five-minute presentation in front of and the University of Oslo. They are all between existing activities when planning Director of RoCS (a project description limited to five pag- before the deadline May 25th 2016. We the expert panel followed by a twenty-min- thanked. for the future. We also took an active part es) was November 25th 2015 and the PI got the report from the expert referees in ute interview. This happened on January in a pilot project on career development for team and Bart De Pontieu worked most October (with an overall rating of seven, 24 2017. The final, official decision from the Project start was November 1st 2017 and temporary researchers. This is in collabo- of October and November that year on the exceptional) but since the report invited Research Council was taken by the board that day we had an opening seminar with ration with other centres of excellence in proposal. The verdict from the evaluation comments on some unclear parts, we used on March 14 but with an embargo until presentations of the research plan of the Oslo, after the initiative from the Hylleraas was expected on March 17th (my birthday) the opportunity to send in one page with 02:00 at night on March 15. The centre centre. The Scientific Advisory Committee Centre for Molecular Quantum Chemistry. 8 RoCS Annual report 2018 2 What is the Sun? 9

The different atmospheric layers of the Sun and the height ranges sampled by the instruments to be used by RoCS. What is the Sun? –

Sufficiently stable to nurture life during the last 4 billion years, and modern humans the last 100,000 years, the Sun is neverthe- less a variable star. While the total solar irradiance only varies about 0.1% during the 11-year solar cycle, the high-energy portion of the solar output can vary by several orders of magnitude on timescales of minutes.

Solar activity - sunspots and active regions, convection becomes more efficient than The solar magnetic field, generated in the UV and X-ray emission, the million degree radiative diffusion so that in the top layer convection zone and photosphere, is at the corona, flares, coronal mass ejections, the of the solar interior mass motions carry heart of these thorny problems. In the solar acceleration of energetic particles - is in- energy towards the solar surface. It is these photosphere the plasma dominates the creasingly interfering with human activity convective motions, combined with the magnetic field, forcing the field to continual as our society’s dependence on sensitive Sun’s enigmatic differential rotation, that motion. The emergence and displacement electronic equipment grows and as we generate the magnetic field and drive the of magnetic flux at photospheric heights venture beyond the Earth’s magnetosphere large range of phenomena we call solar as the plasma does work on the field imply and into the solar system proper. There is a activity. an upwardly propagating energy flux. The pressing need to understand the workings magnetic field is also the primary agent of the energetic Sun; such understanding is At the top of the convection zone lies the for transporting this “mechanical” energy now within reach, and is the goal of RoCS. solar surface, the photosphere, comprised from the convection zone into the outer of convection cells and threaded with mag- solar atmosphere, where it is dissipated. The Sun is a glowing ball of gas with a netic fields. Above the photosphere we A wide variety of physical mechanisms surface temperature of 6000 K. Its struc- find the outer solar atmosphere where, have been proposed, but the complexity of ture is determined by the forces of gravi- astonishingly, the temperature starts to the atmosphere has precluded consensus tational contraction and pressure-driven rise; the chromosphere with temperatures on which of these mechanisms dominate expansion. These forces are in an exquisite around 10,000 K, the transition region, the heating of the solar atmosphere and balance that requires the solar centre to the hot (> 1 MK) corona, the solar wind, drive violent eruptions. be extremely hot, hot enough for fusion and the outer heliosphere, extending out of hydrogen atoms to occur in the core, to more than twice the distance of Pluto. releasing prodigious amounts of energy. Understanding the non-intuitive rise in This energy is steadily diluted as it dif- temperature and the processes driving the fuses away, and the temperature of the supersonic solar wind outflow that inflates solar envelope decreases with increasing the solar heliosphere has been a central distance from the site of nuclear burning. goal of solar physics since the discovery Two thirds of the way out from the core, that the corona is hot in the late 1930’s. 10 RoCS Annual report 2018 2 Towards understanding: RoCS goals 11

From the simulation output we calculate synthetic observables. For optically thick lines formed in the chromosphere, this is a complicated task since the Local Thermodynamic Equilibrium (LTE) approxima- tion breaks down and strong lines are also affected by 3D effects and by partial frequency redistribution of photons (PRD). The figure shows synthetic Towards understanding: intensities in the H-alpha line from neutral hydrogen calculated from a simulation of an explosion RoCS goals in the upper photosphere. –

New hardware and novel techniques, both computational and observational, promise to revolutionise our understanding of the workings of the entire coupled solar atmosphere. The solar physics group of the Institute of Theoretical Astrophysics at the University of Oslo has played a central role in these developments and has also exploited them to make significant contributions at the forefront of solar physics. Advanced numerical simulations – The Rosseland Centre for Solar Physics RoCS is in a unique position to capitalise In order to unravel the workings of the As one proceeds towards the outer layers Multi-fluid methods. We are developing a (RoCS), named after the founder of the on these exciting developments and drive outer solar atmosphere, it is necessary to of the solar atmosphere the assumptions multi-fluid extension of Bifrost, designed Institute of Theoretical Astrophysics (ITA) major breakthroughs in understanding take into account many different physical underlying the MHD description become to study partial ionization in the upper who initiated solar physics research in the interplay between the magnetic field processes. Because of the inherent com- invalid under certain conditions. The chromosphere where collisional processes Norway, dramatically expands these efforts and the plasma in the outer solar atmos- plexity of the Sun’s atmosphere, the only density drops very rapidly with height are slow enough to invalidate even the to build a comprehensive understanding phere, and the deeply rooted connections way forward is through numerical simula- above the photosphere and collisions be- generalised Ohm’s law. This code devel- of chromospheric and coronal heating and between convective motions in the Sun’s Our primary objective tions that are compared with observations. come so infrequent that the plasma is no opment builds on our previous experience violent solar activity. interior and the structuring and activity is understanding The “Bifrost” code developed at ITA is de- longer in statistical equilibrium. Some of with multi-fluid solar wind models and will of the corona. The investigations are two- the workings of the signed to treat the physics of the photo- these effects, such as the non-equilibrium also be of great interest for coronal studies, Several recent developments have made pronged: advanced 3D numerical simu- sphere, chromosphere and corona in a re- ionization of hydrogen and helium, are including the long-standing problem of the complex physics of the outer solar at- lations, which can be directly compared energetic Sun. alistic manner, and is currently state of the already included in the current Bifrost species fractionation (so called FIP-effect), mosphere tractable to quantitative analy- to high-resolution observations from the art. Bifrost allows one to construct “box in implementation. As collision rates drop which has wide-ranging astrophysical im- sis. In particular, the development of high ground and from space. Synthetic diag- a star” models, in which a certain portion even further when approaching smaller plications. performance computers has allowed us to nostics are computed from the models and of the Sun, from convection zone to corona, physical scales or proceeding further up build 3D radiative MHD codes designed compared with high-resolution observa- spanning horizontal scales commensurate into the upper chromosphere, transition Hybrid methods. Great progress has re- to treat the physics of the chromosphere tions. The similarities and discrepancies with solar magnetic scales is evolved for- region and corona, the approximation of cently been made in understanding the and corona as well as software capable of are used to investigate the role of vari- ward in time. Constructing such models is MHD is no longer valid and a different microphysics of particle acceleration and converting simulation output into synthetic ous physical mechanisms that have been time consuming; generating a typical model approach is needed. We have completed magnetic reconnection using particle and/ observables. Similarly, the last few years proposed as drivers of the energetics and consumes several months computing time an implementation of generalised Ohm’s or hybrid codes but with simplifying as- have seen major progress in extremely high dynamics of the active solar atmosphere, on massively parallel computers, and the law in Bifrost with promising first results. sumptions and limited spatial extent. We resolution imaging spectroscopy, enabled such as shocks, magneto-acoustic waves, production of synthetic diagnostics will To go beyond MHD, a multi-fluid or particle- are implementing a particle-based model by adaptive optics and image reconstruc- magnetic reconnection and various plasma take at least an equal amount of time. In based treatment is necessary to model the that can be run in conjunction with or tion techniques, as well as novel diagnos- instabilities. RoCS we plan to construct a variety of such plasma. This is especially the case for vi- “inside” a Bifrost simulation. Of special tics from space-based observatories. models spanning a large parameter space of olent episodic phenomena such as flares interest in this context is to consider the spatial size, horizontal extent and magnetic and micro-flares, which produce non-Max- structure of current sheets, reconnec- field configurations. Both the construction wellian particle distributions and copious tion, and the acceleration of particles in and the subsequent analysis of a model amounts of highly energetic particles. the complex chromospheric and coronal run require several years of continuous environment that Bifrost uniquely models. effort from highly skilled researchers. This In RoCS we address this issue by expanding approach, guided by observational input, our computational capabilities beyond the will yield considerable insight. state of the art: 12 RoCS Annual report 2018 2 High quality observations 13

Jim Dowdall/Lockheed Martin NASA’s Interface Region High quality observations Imaging Spectrograph – (IRIS) Since its launch in June 2013, NASA’s It is first when coupled and confronted with the observational Interface Region Imaging Spectrograph ground truth that models come alive. Coverage of the entire solar (IRIS) satellite is obtaining unique views atmosphere, from photosphere to corona, requires both ground- of the solar atmosphere from high resolu- tion ultraviolet images and spectra at high based and space-borne instruments. The team is closely involved cadence (down to 0.5s). The UV provides as core members of instrument teams and scientific working diagnostics on the upper chromosphere and groups in several world class observatories that, when combined, transition region that were never before will provide an unprecedented view of the entire solar atmosphere: observed at this high spatial and temporal resolution. The combination of SST and IRIS now covers, at high resolution, the full pathway from the photosphere through the chromosphere and transition region into the corona. The RoCS team includes The Swedish 1-m Solar the principal investigator of IRIS, professor Telescope (SST) Bart De Pontieu. NASA The Swedish 1-m Solar Telescope (SST) on La Palma is a world-leading facility for high-resolution observations of the Sun. It continues to rival contemporary larger aperture telescopes because of its unique combination of extraordinary site characteristics, optical design, adaptive optics and advanced image restoration techniques. Furthermore, it utilises pio- neering instrumentation such as the CRISP imaging spectro-polarimeter, a versatile tunable filtergraph that allows fast spectral imaging in the red part of the electromag- netic spectrum.

The new CHROMIS instrument, the short-wavelength companion of CRISP, became available for use in 2017. CHROMIS provides diffraction-limited spectral imag- ing in the blue/violet including the potent Ca H and K lines. This means resolving spatial scales below 100 km and thereby Hinode The Solar Dynamics Observatory (SDO) providing an unprecedented window on chromospheric heating at the smallest Hinode is a Japanese solar satellite that The Solar Dynamics Observatory (SDO) context information on the history and resolvable scales. carries three telescopes; a 50 cm Solar is a NASA solar satellite launched in 2010 large-scale connectivity of the plasma Optical Telescope (SOT), where the spec- that observes the whole Sun continuously. in the high-resolution SST/IRIS fields of tropolarimeter currently sets the standard The Atmospheric Imaging Assembly (AIA) view. Furthermore, it serves as an excel- for high-sensitivity measurements of the provides whole-disk imaging with 12s ca- lent reference for co-alignment between photospheric magnetic field, an Extreme dence in an extended range of filters that different instruments. The Helioseismic and ultraviolet Imaging Spectrograph (EIS) and cover the chromosphere to the corona. Its Magnetic Imager (HMI) provides full-disk an X-ray telescope. The Institute of Theoret- continuous operation provides valuable magnetic field measurements. ical Astrophysics, UiO, operates the Science Data Centre Europe with a complete set of all the data from Hinode. 14 RoCS Annual report 2018 2 High quality observations 15 NSO/AURA/NSF

“If the Sun did not have a magnetic field, it would be as boring a star as most astronomers believe it to be” Attributed to R.B.Leighton Clem & Adri Bacri-Normier (wingsforscience.com)/ESO).

enormous leap in capabilities compared The Daniel K Inoue Solar with the largest current solar telescopes (1.6 m aperture). The RoCS team has been Telescope (DKIST) involved in DKIST at several levels from the design phase into construction and we The Daniel K Inoue Solar Telescope (DKIST) expect to benefit from access to very high currently under construction in the USA is quality observations from DKIST from first the first in the next generation of 4-m class light (end of 2019) and onwards. aperture solar telescopes, representing an

The Atacama Large Millimetre/sub-millime- observations of our Sun, opening up new Strategic Forum on Research Infrastruc- The Atacama Large tre Array (ALMA) in the Chilean Andes is complementary ways to look at the solar The European Solar tures (ESFRI) Roadmap 2016. An infrastruc- currently the world’s largest astronomical chromosphere at high spatial, temporal ture application has been submitted to the Millimetre/sub-millimetre facility. It consists of 66 telescopes, most and spectral resolution. Most importantly, Telescope (EST) Research Council of Norway to enable a of them with a diameter of 12m, which are ALMA can provide temperature maps of strong Norwegian contribution to EST. The Array (ALMA) distributed across the Chajnantor plateau the observed chromospheric gas. This new The European Solar Telescope (EST) is European Solar Telescope has a symmetric in the Atacama Desert at an altitude of scientific opportunity laid the foundation the next generation 4-m solar telescope design with a minimum of instrumental 5000m. ALMA observes at wavelengths for related research activities at RoCS. See in Europe. EST is the top-ranked mid-size polarisation making it complementary to between 0.3mm and 3.6mm (to be extended https://www.almaobservatory.org for more project in the ASTRONET roadmap for in- the off-axis DKIST telescope and ideal for to 8.6mm). Since 2016, ALMA offers regular information about ALMA. frastructures in Astronomy 2010-2030 and measuring chromospheric magnetic fields. has recently been included in the European First light for EST is expected in 2027. 16 RoCS Annual report 2018 3 2018 activities by theme 17

2018 Activities by theme – 18 RoCS Annual report 2018 3 Simulations 19

Synthetic observables from an Ellerman bomb/ UV-burst simulation. Note the disturbed granulation pattern in the photosphere, the cool surge in the line wing of Ca II 854.2 nm, the strong emission in the Si IV 139.4 nm line, and the lack of emission in the hot Fe XII 19.51 nm line. Simulations Synthetic image of a proxy for the 19.5 nm Fe XII line from a deep, large simulation. This line is formed at – temperatures > 1 million K. Note the plethora of long loop like structures. The Bifrost code is designed to model the outer layers of the solar (or stellar) atmosphere and aims to include all the relevant physics needed to interpret and understand the observations.

Modelling the energetic Sun values similar to those encountered in non-equilibrium simulation (Carlsson et al the interaction of emerging fields as they The input parameters to simulations are, sunspots. Additionally, the year has been 2016) but with double the resolution (24 form the active chromosphere and corona. roughly speaking, the entropy flux needed spent exploring the importance of spatial km horizontally) has also been started. These simulations show synthetic diagnos- in the convection zone to maintain a giv- resolution in determining the dynamics of tics that are remarkably similar to what is en effective temperature, and the initial the chromosphere and corona; previous In the same vein, but also to better un- observed. Amongst other results we find magnetic field configuration and/or the simulations have shown that the solar at- derstand the corrugation of the transition that Ellerman bombs and UV-bursts are magnetic field to be injected at the bot- mosphere may be more dynamic and more region, 2D numerical experiments have formed naturally and sometimes co-located tom boundary. Simulations are run over magnetically dominated, even in the quiet been computed of a coronal-hole-like and co-temporally as a result of large angle one to several hours solar time, typically or semi-quiet Sun, than thought earlier. atmosphere in a box with 16 Mm in the reconnection in emerging flux regions. producing a snapshot of containing all the horizontal direction and [-2.6, 14] Mm ver- magnetohydrodynamic variables every 10 Importance of resolution tically. There are four experiments of this Nevertheless, there are still open questions seconds. There are indications that increased numer- kind with increasing numerical resolution; concerning the flux emergence process ical resolution would increase the dynamics from horizontal resolution of 31 km to 4 km itself, also because of the challenge posed These snapshots are the basis for computing found in the chromosphere in the simula- and vertical resolutions from 20 km to 2.5 by out-of-equilibrium ionisation throughout detailed synthetic diagnostics of spectral tion. Since one of the major shortcomings km. The results are not yet fully analysed, the outer atmosphere. Therefore, 2D flux lines that can, at least statistically, be com- of the current generation of simulations is but a first look at the experiments shows emergence experiments that combine the pared with actual observations from the too narrow spectral lines compared with potentially interesting features in terms non-equilibrium ionisation of hydrogen and solar atmosphere. the observations, increased numerical res- of the generation of spicules. These snap- including the effects of ambipolar diffusion olution could be important for the creation shots have a cadence of 2 seconds, which have been run. Hitherto these simulations have been of more realistic simulations. To investigate increases the possibilities of analysing the concentrated on sections of the solar at- this further, a number of simulations have more dynamical structures and to carry out Several of the results of the simulations mosphere best characterised as “quiet been started – a series of simulations with Lagrangian tracing to study them in detail. described above are under investigation and Sun” with relatively weak magnetic fields hydrogen ionisation in equilibrium, a re- will be presented at the Flux Emergence compared to sites of emerging flux or fully stricted height range and a small box (to Flux emergence Workshop in Tokyo in mid-March of 2019. developed active regions. However, the have short wall clock times for the runs): The interaction of magnetic flux recently premise of RoCS is to study “the active 6 Mm x 6 Mm horizontal box and [-2.5,7.5] emerged from the solar interior with the Deep models, large models Sun” and the simulations carried out in Mm vertically with horizontal resolutions pre-existing coronal magnetic field is of Finally, a number of “deep” models, ex- 2018 have focused on the dynamics and of 40, 20, 10, and 5 km. The results are special interest: many prominent features tending to 8 Mm or more below and up energetics that ensue when the magnetic under investigation. A large simulation in the solar atmosphere are related to this to 50 Mm above the photosphere and field becomes stronger and approaches corresponding to the published hydrogen 72 Mm wide horizontally are being run. These models should allow the study of the formation and evolution of the chro- mospheric network and most ambitious- ly the formation of strong photospheric fundamental process. A number of sim- A number of studies with horizontal res- fields such as sunspots and the study of ulations have been run both in 3D and in olution of 31 km and vertical resolution of the chromosphere and corona above these. 2D in which fields are injected at the lower 12 km have been run. These simulations These models have so far been run with boundary and are allowed to propagate have several goals: To see whether the quiet a relatively coarse horizontal resolution of up through the convection zone. The field Sun magnetic field is maintained by a local 100 km, but it is planned to refine this to breaks through the photosphere and emerg- shallow dynamo or requires the injection 50 km now as the models have achieved es into the outer atmosphere interacting of field from the deeper convection zone. close to steady-state conditions where the with the pre-existing ambient field as large- To understand the formation of strong chro- dynamics of the deep convection zone are scale magnetic structures are built up in mospheric fields in a nascent active region. mirrored in the topology of the chromo- the chromosphere and corona. To study the observational consequences of sphere and corona.

Current sheet in the photosphere through the chromosphere that generates both Ellerman bombs and UV bursts. These snapshots show how emerging flux leads to violent reconnection in the outer solar atmosphere. 20 RoCS Annual report 2018 3 Observations with SST/IRIS 21

Observations with SST and IRIS –

The RoCS group is the largest external user of the Swedish 1-m Solar Telescope (SST) at La Palma in the Canary Islands. All obser­ vations are coordinated with the IRIS satellite so that we have dense coverage of the solar atmosphere from the photosphere up through the chromosphere and transition region into the corona.

The observing time at SST is usually spread We have close collaboration with the group With image restoration, high data quality over three 2-week campaigns. In 2018, these at the Lockheed Martin Solar and Astro- can be achieved over a larger field of view campaigns were in May, September and physics Laboratory (LMSAL) in Palo Alto and over longer periods of time. Besides October. These campaigns are very much (USA). The LMSAL group has one 2-week considerable computing power and data a team effort and this year 8 RoCS members observing campaign at the SST and we are storage capacity, data reduction requires participated in the observations. The ob- involved in the planning, IRIS coordina- a fair amount of manpower and is handled servations involved daily interaction with tion and data reduction. For most of their as a team effort. We collaborate with the the IRIS planners to decide what target campaign, they supported a multi-day IRIS SST staff in Stockholm and La Palma to to observe and which observing program program to track one of the rare magneti- improve, optimise and further develop the to run. The Sun is currently in the quiet cally active regions during its passage over data processing pipelines for the CRISP and Region with enhanced magnetic field observed with CHROMIS (25-May-2017). Sunspot observed with CHROMIS (22-Sep-2017). The top panel shows the phase of its 11-year magnetic activity cycle, the disk. This program resulted in a few CHROMIS instruments. The top panel shows the photosphere as imaged with the CHROMIS wideband photosphere as imaged with the CHROMIS wideband channel (wavelength channel (wavelength 395 nm), the bottom panel is recorded with CHROMIS 395 nm), the bottom panel shows the chromosphere as imaged with CHROMIS and most of the observed targets were in interesting data sets of the active region in the blue wing of the Calcium K line at a Doppler offset of 20 km/s. in the Calcium K line (wavelength 393.3 nm). quiet regions. filament above the polarity inversion line One of the highlights of the reduction ef- in the centre of the active region. They fur- forts in 2018 is an enhanced network data Special focus of this year was to do ex- ther managed to acquire a high quality set acquired in May 2017. This is a time periments to improve the data quality of coronal hole time series during one of the series of more than 2 hours duration and observations at the solar limb. Observations best seeing periods of 2018. covers a region close to disk centre with are added through alignment with data being investigated. We have been involved in ground-based hydrogen alpha spectral at the limb are challenging since both the extended patches with mixed magnetic from NASA’s Solar Dynamics Observatory in a comprehensive review paper with Dr. imaging. With this recipe, Ellerman Bombs, adaptive optics system and image restora- Data reduction field polarities. The seeing was excellent (SDO). Several science projects are planned Young from George Mason University and and with them sites of significant photo- for this dataset, for example related to the NASA as lead author. The review provides spheric reconnection, can be detected in tion have difficulties with the sharp drop Besides planning and acquiring new obser- and stable for long duration. Instrumen- generation and evolution of spicules. a full observational characterisation of UV the full-disk and continuous database of in light level at the edge of the solar disk. A vations, the reduction and data processing tation at the SST worked flawlessly and bursts and addresses their relation to so- SDO, bypassing the inherent intemittency strong motivation to try limb observations of current and earlier observations is one of the coordination and co-pointing with Ellerman Bombs and UV bursts called explosive events, known from low of ground-based observations. To devise this this year is the use of the new CHROMIS the other main activities of the observations IRIS was optimal. After all processing and spatial resolution UV spectroscopy from recipe, active regions from 10 different SST instrument and the potential to get unique group. We employ image restoration tech- co-alignment we have now a unique dataset Magnetic reconnection in the solar atmos- earlier space missions before IRIS. data sets, acquired between 2010 and 2015, high-spatial-resolution observations of jets niques to mitigate the effect of atmospheric with chromospheric spectral imaging in phere is one of the main topics of research were aligned to SDO imaging and analysed. and spicules in the calcium K spectral line. turbulence (so-called “seeing”) on the data calcium K (from CHROMIS) and hydrogen of RoCS. Observationally, magnetic recon- Our extensive database with SST active While the weather conditions were not quality. Like all modern telescopes, the alpha (CRISP) and photospheric magneto- nection is manifested in so-called Ellerman region observations has been exploited of the desired quality and stability, we SST employs an adaptive optics system to metry from Fe 6302 spectropolarimetry Bombs in the lower solar atmosphere and for a paper by Dr. Vissers from Stockholm managed to get very good results. We are correct for seeing in real time during the ob- (CRISP). IRIS provides upper chromospheric UV bursts in the upper chromosphere and University as the lead author. This study planning to pursue these new directions servations. Adaptive optics provides a sig- and transition region diagnostics from a transition region. Several aspects in the presents a recipe for detecting Ellerman and discuss with the institute in Stockholm nificant improvement of the data quality but high-cadence spatial raster that runs right relation between Ellerman Bombs and UV Bombs in the AIA 1700Å channel of SDO. to make a more permanent solution for post-facto image restoration is mandatory through the center of the SST field-of-view. bursts have been addressed with coordinat- Ellerman Bombs are normally detected limb observations. to attenuate residual seeing deformations. Upper transition region and coronal images ed SST and IRIS observations and are still 22 RoCS Annual report 2018 3 Observations with ALMA 23

One of the first ALMA Band 3 images produced with the data processing pipeline SoAP. The circular map has a diameter 66 arcseconds, which corresponds to 48000 km on the Sun and thus covers only a small region of it. The brightness temperature (colour-coded, see legend to the right) range from 5700 K to about 9000 K. The image illustrates the complicated structure of the solar chromosphere on a large range of spatial scales. Observations A typical data set contains time series of such images for up to an hour and for different frequencies. with ALMA –

The capability of measuring the temperatures of the gas in the Sun’s chromosphere with the Atacama Large Millimetre/sub- millimetre Array (ALMA) opened new scientific avenues that laid the foundation for a new branch of research activities at RoCS. Access project (2017-18), the performance second meeting and created a plan for how announced observing cycle 6. The Solar of ART was increased substantially, mak- to review the phenomenon of solar and Simulations for the Atacama Large Milli- ing it the future workhorse for producing stellar activity with the new observational meter Observatory Network (SSALMON) synthetic observations that are a crucial possibilities provided by ALMA. In Decem- continued its work and launched a new ALMA-related science at RoCS sphere are ready for scientific analys­ ­is. how the observed structure of the sunspot component of the envisaged processing ber 2018, a FRINATEK project was granted expert team tasked to find a common stand- The complexity and novelty of these ob- and its surrounding change with height. tests and for comparisons between obser- by the Research Council of Norway, named ard for data processing of solar ALMA data. The backbone of all ALMA-related activ- vations and simulations. EMISSA (Exploring Millimeter Indicators of ities at RoCS is the Solar ALMA project*, servations makes the processing a very The analysis of early data from ALMA challenging task. The main focus of the Band 3 and Band 6, which cover different Solar-Stellar Activity). The EMISSA project Public outreach and networking which is funded by a Consolidator Grant Reaching for the stars will start at RoCS in 2019 and will comple- ALMA team at RoCS in 2018 has therefore wavelength ranges and thus map different The SolarALMA project was presented at from the European Research Council. The ment ongoing research. project started in 2016. After a second PhD been the development and optimisation heights, has begun with the aim to study In the future, the ALMA-related activities at public outreach events at the University research fellow joined in 2018, the project of calibration and processing software for the small-scale structure and dynamics of RoCS will be extended to the study of other of Oslo for teachers (“Faglig pedagogisk Networking currently employs two researchers and ALMA data, resulting in a first version of the the solar chromosphere by making use of stars, providing wider parameter ranges dag) and for school classes (“Ungforsk”). 2 PhD research fellows in addition to the Solar ALMA Pipeline (SoAP). The processing the remarkably high cadence of 2s. to which the Sun as a reference star can The Norwegian ALMA Day 2018 was held The project was also featured in the arti- PI Sven Wedemeyer. The scientific goal is also includes the co-alignment of ALMA be compared to. In 2018, the internation- on March 21, 2018, in cooperation with cle “Sun like it hot” in EU’s research and to constrain heating processes in the solar observations with space-borne co-obser- Developing new scientific tools al team “A New View of the Solar-stellar the Nordic ALMA Regional Center node, innovation magazine Horizon. atmosphere with ALMA observations of the vations with the IRIS and SDO satellites. The ALMA team at RoCS continues to Connection with ALMA”, led by S. Wede- Onsala Space Observatory, Sweden. As in Sun, whereas the broader technical goal Many challenges of interferometric imaging contribute to the further development of meyer (RoCS), T. Bastian and H. Hudson and the year before, the aim was to attract new is to develop the necessary observational of our Sun have been overcome so that the the solar observing modes as part of the funded by the International Space Science potential ALMA users from Norway and to and simulation tools for fully exploiting quality of the resulting image series was international ALMA solar development Institute (ISSI), Bern, Switzerland, had its inform about new possibilities in the then ALMA’s diagnostic potential. improved significantly in 2018. Regular group, gradually expanding the scientific data processing with SoAP started with the possibilities. The year 2018 also marks the first observational data sets from earlier Marinkovic/X-Cam/ALMAA. (ESO/NAOJ/NRAO) ALMA (ESO/NAOJ/NRAO) Observations in 2018 official start of an ESO-funded ALMA de- test observations and regular observations velopment study in co-operation with the Applying for observation time with ALMA from 2016/17 so that an increasing number Nordic ALMA Regional Center node at the is a competitive process. In 2018, several of data sets now becomes ready for scien- Onsala Space Observatory and Stockholm proposals for ALMA observations of the tific analysis. The long-term aim of RoCS’ University, Sweden. In the course of three Sun and other stars have been submitted ALMA efforts is to provide such processed years, simulation tools will be developed by RoCS staff of which one has been ap- data sets to the wider solar community. that will allow to quantitatively test, opti- proved with a PI from RoCS. The proposed mise and further develop the data process- observations of the Sun in ALMA Band 3 First scientific results ing pipeline (SoAP) and thus increase the and Band 6 have been carried out success- quality and scientific impact of ALMA ob- fully in December 2018. Among the first applications of SoAP-pro- cessed data was the detailed comparison of servations of the Sun. Initial tests have been carried out in 2018. An important requisite From measurement to science- sunspot observations with ultraviolet ob- for the study was the development of the ready data servations from IRIS. For that purpose, the ALMA data was split into frequency sub- Advanced Radiative Transfer code (ART), The observational data delivered by ALMA bands that are formed at slightly different based on an initial version by Jaime de la needs to be processed before the resulting heights and thus give a first impression of Cruz Rodriguez (Stockholm University). time series of images of the solar chromo- In the framework of a PRACE Preparatory The ALMA 12m antennas can be relocated in different array configurations with ALMA combines different types of antennas, which have been developed and different sizes and resulting angular resolution. On this picture, a 12m antenna produced by Europe, North America, and Japan. For observations of the Sun, is transported to its new location. more than 50 antennas are connected in order to mimic a telescope with a diameter of up to 500m. The number of the involved antennas and the resulting *The SolarALMA project has received funding from the European Research Council (ERC) under the size of this array will be increased in the future. European Union’s Horizon 2020 research and innovation programme (grant agreement No. 682462). A. Marinkovic/X-Cam/ALMA (ESO/NAOJ/NRAO) 25

Observations with ALMA with Observations 3 RoCS 2018 Annual report 24 Four antennas of the Atacama Large Millimeter/ submillimeter Array (ALMA) at Four (OSF), 2900 m above sea level. The three larger the Operations Support Facility antennas have a diameter of 12m whereas the smaller one measures 7m. The different sizes and flexible locations within the array enable unprecedented including our Sun. observations of a multitude of different objects on the sky, The ALMA project is an international collaboration between Europe, East Asia and North America in cooperation with the Republic of Chile. 26 RoCS Annual report 2018 3 New code developments 27

Test of the PIC and MHD running in the same simulation with shared boundaries, and the ability to transfer information correctly across boundaries. Here a vertical flux tube is simulat- ed with MHD in the lower and upper third of the simulation domain, while the central domain is simulated with a PIC code. The images show a cut through the center of the flux tube. Gyration of the particles modelled with the PIC code is New code not modelled by MHD and is absent in the MHD domains. developments –

To reach the ambitious goal of modelling the active sun, we need of such a system needed integration. The simulate the not so deep layers correctly. new codes that are radically different from the codes that have main MHD solver of Bifrost has now been In the end we have a simulation where implemented in the DISPATCH framework, the deep layers are well modelled as well so far been used in the investigation of the solar atmosphere. and initial testing results are being pro- as the photosphere, without wasting too duced, with the goal of running further much computational time. We have run two more complex setups during 2019. simulations which are 72 Mm square and 9 The end goal is to produce a code that tromagnetic environment of the constituent Bifrost & DISPATCH Mm deep. Both are running and producing Magnetogram created from a high magnetic flux is able to handle the different physical particles in the coronal plasma to provide Regime switching interesting science already. We can inves- simulation including 9 Mm of the convection zone, Bifrost is at the moment one of the leading to produce supergranular-like structures in the regimes and the different resolution re- the correct answers to how solar flares are tigate the formation of magnetic structures numerical codes for simulating the solar This path has been developing in sequence granulation pattern. and sunspots through these models and quirements needed in different regions of produced and in which way they release atmosphere from the upper convection zone with the integration path, and should allow have a basis for later simulations. the active sun. Examples of very different the large amount of energy we observe to the lower corona. Due to the inherently us to seamlessly switch from one physical physical regimes could be the deep con- from our solar observatories. modular structure of Bifrost, the integration regime to another. The borders between vection zone where the typical time scale of Bifrost into DISPATCH can be done in the physical regimes will naturally be a and length scale are hours and several Mm Three development paths steps. After the initial step of settling on difficult problem, so it has been prioritised respectively and the relevant physics can be The numerical tools being developed un- a plan for the integration, we have also to be one of the first to be handled and work handled (almost) as simple hydrodynamics. der RoCS have in 2018 been focused on been working on a self-contained testing has started on the boundaries between a Conversely, the inner parts of a solar flare three aspects: The integration of Bifrost strategy which make it possible to stop bugs PIC description and MHD description of involve magnetic instabilities than cannot into the DISPATCH framework, the ability from infecting the production version of the the physics of the solar corona. Since the be well simulated by MagnetoHydroDy- of DISPATCH to seamlessly switch between code and should make it possible for us to PIC description provides a distribution of namics(MHD) because the diffusion length different types of physics and finally run- evaluate implementation strategies much particle velocities and masses in a cell, it is on the order of the mean free path of ning simulations spanning, large physical faster. This automatic testing regime was is important to find the correct location the ions and electrons in the solar corona. volumes and including large amounts of only partially implemented in Bifrost and where a fluid, as in MHD, is again a suf- Consequently, we now need to employ a magnetic flux. existing in DISPATCH, so the two versions ficient description of the physics and in Particle In Cell (PIC) code to treat the elec- that case, how to translate the distributed values of the particles into the single valued fluid variables.

Magnetic reconnection test Large dimensions and magnetic flux experiment with the main Bifrost To run a simulation large enough to in- MHD solver implemented in the clude supergranules one needs a domain DISPATCH framework. that goes down to at least 9 Mm below the photosphere. Here the time scale and length scale are so much larger than in the photosphere that we can neglect the details of the photosphere to a first approxima- tion until the deeper layers have adjusted to the radiative losses and the injection of enthropy at the bottom of the box. By having a resolution only good enough to resolve the deepest layers, the computa- tional time remains short. By gradually increasing the resolution when the deeper layers have adjusted, means we start to 28 RoCS Annual report 2018 4 International Rosseland Visitor Programme 29

"Looking in the rear mirror and questioning myself what made the biggest change with the creation and the operation of CIR, I am tempted to say the Visiting Professor programme."

Ludvig M. Sollid, director of Centre for Immune Regulation (CIR). From CIR final report 2007-2017.

Rajashik Tarafder, final year master student Lyndsay Fletcher, professor at University at IISER-Kolkata, India. He did his master of Glasgow, and Christopher Osborne, PhD internship at RoCS January-March 2018 student, visited in May, working with Mats with Mats Carlsson. He was studying beam- Carlsson on understanding radiative trans- heating during flares using the RADYN fer under flare conditions. radiation hydrodynamics code. Patrick Antolin visited RoCS in June 2018 Baptiste Pellorce, first-year master student and worked with Clara Froment on the at Claude Bernard University Lyon 1, France. analysis of a coronal rain event observed He did his master internship from March with the SST and SDO. This visit initiat- to June 2018 with Tiago Pereira. He worked ed the development of a new code for the on the open source IRISpy and NDcube spectral characterisation of coronal rain. projects, developing Python tools to read He also worked with Sven Wedemeyer and and visualise IRIS observations. Shahin Jafarzadeh in connection with ALMA observations. Alberto Sainz Dalda, researcher at Bay Area Environmental Research Institute and Lock- Juan Martínez Sykora, researcher at Bay International Rosseland heed Martin Solar and Astrophysics Labo- Area Environmental Research Institute and ratory, visited in April, working with Tiago Lockheed Martin Solar and Astrophysics Pereira on synthesis of chromospheric lines Laboratory, visited in February-March, with the RH 1.5D code. August and September. He is working on Visitor Programme a multi fluid multi species code designed Marouchka Froment, first-year master at to study how the various elements and ENS Paris-Saclay, France. She did her master ions move in relation to each other in the internship from April, 16 to July, 27 2018 collision poor chromosphere and the effects – with Clara Froment. She analysed SDO and this has on heating and dynamics in the STEREO data in connection with coronal outer atmosphere. heating events. In particular, she performed Many previous centres of excellence have concluded that visits thermal diagnostics of the coronal plasma Ineke De Moortel, professor at University from internationally leading scientists have been among the for a combined event showing coronal rain of St.Andrews, visited in August. She is an and periodic prominence eruptions. expert on waves using both mathematical most valuable outcomes of having a centre. The International and numerical approaches to study their in- Rosseland Visitor Programme takes the international exchange Åke Nordlund, professor at Copenhagen teraction and influence on the solar corona. even further by including funds for visits by researchers at University. He visited in April and is work- ing on implementing our codes within the Jiajia Liu, postdoctoral research associate professor, post-doctoral and PhD level to be used for shorter DISPATCH framework. at the University of Sheffield. He visited or longer visits to RoCS. in September-October working with Mats Carlsson on automatic detection of vortices in Bifrost simulations. 30 RoCS Annual report 2018 5 Members of the centre 31

Members of Phd the centre –

The main resource of RoCS and its most important Helle Bakke Souvik Bose Frederik Clemmensen Ainar Drews contributor is our staff. Everyone at our centre, Helle Bakke is a doctoral research fellow Souvik Bose is a doctoral research fellow Frederik Clemmensen is a doctoral research Ainar Drews is a doctoral research fellow scientific, administrative and technical, is handpicked at RoCS. Helle is at the interface between at RoCS. Souvik’s research mainly focuses fellow at RoCS. The primary topic of Fred- at RoCs and his research is focused on ob- observations and numerical models, and is on the dynamics of the solar atmosphere, erik's research is the processes in the solar servations of the Sun. Some of his earlier because of their excellent qualifications and expertise. focusing on the effect of accelerated par- in particular the origin and the evolution atmosphere that leads to highly energetic, work is dedicated to partial automation of During 2018 we had eight doctoral research fellows, five ticles in the solar atmosphere. She enjoys of spicules in the solar chromosphere. He accelerated particles. For this purpose, he solar observations using simple machine postdocs, five researchers, two associate professors, three outreach and social activities, and one is mainly an observer and uses the data uses new methods of numerical modelling learning. Ainar's research revolves around professors and one centre coordinator. In addition we had of her favourite parts of the job is being from both ground and space-based solar which he is involved in developing. In gen- the investigation of primarily chromospher- a teaching assistant. telescopes for his research. In addition he eral, Frederik is interested in programming ic objects in the penumbrae of sunspots two adjunct professors, as well as six associated members makes use of numerical radiative transfer and developments in computing. called Penumbral Microjets, employing in the administrative and technical staff. Our Scientific codes for reproduction of synthetic data to both ground- and space- based instruments. Advisory Committee consisted of 4 members. Owing to compare with the observations. our privileged position as a centre of excellence, we are able to grow in numbers, hiring talented and exceptional researchers of a large number of nationalities. All our members are putting their best efforts into strengthening our scientific achievements, set forward new goals and reach even higher standards for our research.

Henrik Eklund Lars Frogner Juan Camilo Guevara Gómez Charalambos Kanella Henrik Eklund is a doctoral research Lars Frogner is a doctoral research fellow Juan Camilo Guevara Gómez is a doctoral Charalambos Kanella is a doctoral research fellow at RoCS. His research is focused on at RoCS. Lars' research is mainly concerned research fellow at RoCS. Juan is mainly ana- fellow interested in the solar coronal heat- determining optimal ways to utilise inter- with numerical modelling of the solar at- lysing observational data taken by ALMA ing problem, magnetic topology, heating ferometric ALMA observations to study the mosphere, in particular the origin, behavior aimed to reveal further details of the phys- mechanisms, magnetic reconnection, joule solar atmosphere. A strong combination of and effect of accelerated particles. He is ical processes contributing to the coronal heating and generally the solar atmosphere. numerical simulations and observations is generally interested in a range of topics in heating as well as to understand and to Besides that, he shows strong interest in used in this work. Henrik is also studying software development, including numerical describe the chromospheric dynamics at space weather, astrophysical plasma and planetary formation through both simu- simulations and computer graphics. millimeter/submillimeter wavelengths. He planetary science. He also likes to be up- lations and interferometric observations. also enjoys contributing in computational dated on aurora activities. Charalambos focused projects. Juan is also active in out- Kanella successfully defended his PhD on reach activities and enjoys communicating October 10 2018. science to the public. 32 RoCS Annual report 2018 5 Members of the centre 33

Postdocs and Professor II’s and researchers adjunct professors

Clara Froment Vasco Henriques Jayant Joshi Shahin Jafarzadeh Petra Kohutova Lyndsay Fletcher Clara Froment is a researcher at RoCS: Vasco Henriques is a researcher at RoCS. Jayant Joshi is a postdoctoral researcher at Shahin Jafarzadeh is a researcher at RoCS. Petra Kohutova is a postdoctoral researcher Lyndsay Fletcher is adjunct professor at Clara is mainly investigating the process- Vasco investigates poorly understood dy- RoCS. Jayant’s research is mostly focused Shahin's main studies concern the lower-to- at RoCS. Petra studies processes responsible RoCS. Her main research interest is so- es that heat the outer layer of the Solar namic processes at small-scales in our on measuring the magnetic field in the solar mid atmosphere of the Sun, regarding how for matter and energy transfer between lar flares, specifically the transport of -en atmosphere, the Corona. She is using both star, especially in active regions. For this, lower atmosphere. He is mainly an observer, magnetic fields structure dynamics of those different layers of solar atmosphere. She ergy through the flare atmosphere, the observations and numerical simulations he primarily observes using the Swedish and he makes use of both, ground-based layers — toward understanding the mys- uses a technique called coronal seismol- energisation of the chromosphere and the to study the thermodynamics of active 1-meter Solar Telescope and then uses su- and spaceborne solar telescopes. terious heating of the Sun's atmosphere. ogy, which is based on using the proper- interpretation of radiation signatures to regions. Her main research topic focus- percomputers to find models that reproduce He is predominantly interested in charac- ties of waves in the solar atmosphere for help us understand this process. She works es on the characterisation of evaporation those observations. He is also working on terisation of wave activities in the lower diagnostics of coronal parameters. To do mostly on data analysis, figuring out ways and condensations cycles in coronal loops, the connection across multiple layers in solar atmosphere. To this end, he works this, she combines high-resolution solar to confront data with flare models. She which are the signature of a steady heating the Sun's atmosphere via jet-like features, within the WaLSA international science observations with numerical simulations. teaches students at all levels in her home mainly concentrated in the lower atmos- which are ever-present but difficult to team (https://WaLSA.team), of which, he institute (University of Glasgow, UK) and phere of the Sun. For that, Clara is using a observe, especially in satellite data. Vasco is a coordinator. Shahin is an experienced leads efforts to increase the fraction of combination of satellites and ground-based has had a passion for astronomy since he observer and passionately engages in var- women and girls participating in physics observations that span the different layer would bring his small telescope to astrono- ious public outreach activities. and astronomy. She was a member of RoCS’ of the solar atmosphere. On top of that, she my festivals in the Portuguese countryside Scientific Advisory Committee until the enjoys very much participating in public as a teenager, and has a passion for new 30th of November 2018. outreach activities. technologies for and beyond science.

Daniel Nóbrega Siverio Ada Ortiz-Carbonell Tiago M. D. Pereira Andrius Popovas Mikolaj Szydlarski Bart De Pontieu Daniel Nóbrega-Siverio is a postdoctoral Ada Ortiz-Carbonell is a researcher at RoCS. Tiago M. D. Pereira is a researcher at RoCS Andrius Popovas, postdoctoral research- Mikolaj Szydlarski is a researcher at RoCS. Bart De Pontieu is adjunct professor at researcher at RoCS. He studies eruptive She studies the process of magnetic flux (PI and associate professor from February er at RoCS: numerical simulations of the Physicist and Mathematician by education, RoCS. His main research interest lies in phenomena in the solar atmosphere as- emergence from the interior of the Sun 1st 2019). He studies dynamic processes Solar atmosphere are his working horse. but Computer Scientist by heart. Mikolaj the heating of the outer solar atmosphere. sociated with magnetic flux emergence into the outer solar atmosphere. She also in stellar atmospheres. In particular, he is He is upgrading the code Bifrost to make is interested in the application of high-per- He is an expert in interpreting high reso- processes, like surges, and the magnetic studies the process known as reconnection. working on the solar chromosphere, the it exascale-ready and be able to work with formance computing (HPC) to challenging lution observational data, both from space flux emergence process itself. In addition, She is an observer with a big data analy- interface between the hot corona and the many additional features, like adaptive problems in solar astrophysics. His fields and from the ground, in the context of he is very interested in unraveling the role sis component, and uses a combination of dense surface. Tiago leverages space and mesh refinement, independent time-step- of expertise include MHD simulations and numerical models. Amongst many other of nonequilibrium and partial ionization ground-based and space-borne observations ground-based observations with detailed ping, multi-solver-multi-physics, etc. Solar ALMA data reduction. topics he has done ground breaking work effects in the chromosphere. His main ap- in order to cover a wider range of layers radiative transfer calculations from 3D on the importance of spicules to our under- proach is theoretical, through numerical in the solar atmosphere. She is involved models. With an interest in computational standing of the energetics and dynamics experiments carried out using the state-of- in the European Solar Telescope project, astrophysics, data analysis and visualis- of the chromosphere and corona. Bart is the-art Bifrost code, combined with forward participating in the Science Advisory Group ation, he works with high-performance the PI of the IRIS satellite and manages a modeling to compare with observations. and being the EST Norwegian Communi- computing and big data problems. large group at Lockheed Martin Solar and cations officer. Astrophysical Laboratory. 34 RoCS Annual report 2018 5 Members of the centre 35

Centre leadership Technical and administrative and administration associated staff

Mats Carlsson Boris Gudiksen Viggo Hansteen Martina D’Angelo Terje Fredvik Stein Vidar Haugan Mats Carlsson is a professor and the director Boris Gudiksen is an associate professor Viggo Hansteen is a professor and PI at Martina D’Angelo is the communication Terje Fredvik is an engineer in the insti- Stein Vidar Haugan is the lead engineer in of RoCS. Main interests include chromo- and PI at RoCS with focus on the devel- RoCS. He works both on simulations and advisor and press contact at the Institute tute’s Project Related IT Services Group. the institute's Project Related IT Services spheric physics and radiation MHD. He opment of numerical codes used to run observations, from the ground and from of Theoretical Astrophysics (ITA) and RoCS. Terje is the lead of the development of the Group. Stein is the main contributor to the is working with both large-scale simula- simulations of the solar atmosphere. His space. He is interested in how the magnetic Martina’s main responsibilities are internal data pipeline for the SPICE instrument on architecture and operations of the Hinode tions and observations from the ground main interest is the solar corona and how field is formed in the deep convection zone, communication, creating and coordinating Solar Orbiter. He is also a contributor to Science Data Centre Archive Europe, which and from space. it maintains its high temperature. how it rises to the photosphere, and how it outreach activities, writing popular science the operations of the Hinode Science Data also serves IRIS data and will later on also forms the outer solar atmosphere. Coronal articles about the ongoing research and Centre Europe, a member of the ITA FITS serve other data sets, from e.g. ALMA. He heating and chromospheric dynamics and news at ITA and RoCS, web editor of ITA's Working Group, and assists in the adap- is also a member of the ITA FITS Working energetics seen by numerical models and and RoCS' web pages and related social tation of the SOLARNET FITS mechanisms Group, acts as a liaison between RoCS and comparisons with high resolution, high media channels. for both observational and simulated data. the SOLARNET project, and contributes to quality, diagnostics are keywords. the development of the data pipeline for the SPICE instrument on Solar Orbiter.

Benedikte Fagerli Karlsen Luc Rouppe van der Voort Sven Wedemeyer Kristine Aa. S. Knudsen Torben Leifsen Martin Wiesmann Benedikte Fagerli Karlsen is the centre Luc Rouppe van der Voort is a professor Sven Wedemeyer is an associate professor Kristine Aa. S. Knudsen is the Head of Office Torben Leifsen is the head of IT at the insti- Martin Wiesmann is an engineer in the coordinator at RoCS. She is responsible and PI at RoCS. Luc’s main area of research and PI at RoCS. Sven leads the research at the Institute of Theoretical Astrophysics. tute. He is responsible for planning, build- institute’s Project Related IT Services Group: for the administration of the centre and is high-resolution observations of the Sun. activities related to solar observations with She is the head of our administration, and ing and running the IT systems together Martin is responsible for part of the IRIS takes care of all practical tasks related to He is a veteran observer at the Swedish 1-m ALMA and supporting simulations, which cooperates closely with both the scientific, with the IT-group at the institute. We are pipeline as well as the adaptation of AIA the centre’s activity. Among her tasks are Solar Telescope on the island of La Palma. involves the ERC-funded SolarALMA pro- technical and administrative staff at RoCS currently operating one server room and and Hinode data to IRIS data. He also con- new employments, visitors, contracts, re- After years of main focus on the lower parts ject, an ESO-funded development study, and and the Institute. are in the process of building a second to tributes to the Solar Orbiter SPICE pipeline porting and logistics at events. of the solar atmosphere, he is extending his the SSALMONetwork. His research mostly accomodate the needs of RoCS and other and quicklook software. He is mainly a interest up into the transition region and focuses on the small-structure, dynamics projects. Torben has a background in solar programmer, implementing requests and corona through coordinated observations and energy balance of the solar atmosphere physics, and is a member of the Virgo team wishes from various scientists into the with the IRIS satellite. with implications for other stellar types. on the ESA spacecraft SOHO doing research pipeline or as separate programs. in helioseismology in his spare time. 36 RoCS Annual report 2018 5 Members of the centre 37

Scientific Advisory Committee

Tony Arber Lyndsay Fletcher Tony Arber is a computational plasma Professor Lyndsay Fletcher was a part of physicist whose interests span solar RoCS’ Scientific Advisory Committee from physics, space weather, laser-plasmas and the 1st of November 2017 until the 30th QED-plasmas. He has been responsible for of November 2018, after which she took developing MHD codes for both solar phys- up an adjunct professor position at RoCS. ics and laser-driven fusion as well as kinetic Her main position is as a professor at the codes for high-power plasma interactions. University of Glasgow. More information For all codes, he is interested in software about professor Fletcher may be found un- development methods and uncertainty der “Professor II’s and adjunct professors”. quantification.

Oskar Steiner Francesca Zuccarello Oskar Steiner is a senior researcher at the Francesca Zuccarello is an associate pro- Leibniz-Institut für Sonnenphysik (KIS) fessor at the University of Catania (Italy). in Freiburg, Germany and at the Istituto Francesca is involved in the study of emer- Ricerche Solari Locarno (IRSOL) in Switzer- gence, evolution and decay of solar active land. His research focusses on the numer- regions, as well as in research related to ical simulation of magnetohydrodynamic solar eruptive events. Francesca is mainly processes in the solar and stellar atmos- an observer. She participated in several pheres. He is also interested in polarim- Coordinated Observational Campaigns. etry and numerical methods of radiative transfer. 38 RoCS Annual report 2018 6 Talks and presentations 2018 39

Talks and presentations 2018 –

Carlsson, Mats.: Rosseland Senter Carlsson, Mats.: Chromospheric Struc- Fredvik, Terje.: Oslo SPICE Status. Hansteen, Viggo.: Ion neutral effects Jafarzadeh, Shahin.: Fibrillar Structures Jafarzadeh, Shahin.: Kahoot quiz with for Solfysikk. Foredrag, Matematisk ture, Heating and Dynamics. Workshop SPICE Consortium Meeting 2; 2018-11-13 in the solar chromosphere and type II in the Solar Chromosphere. European a focus on Earth and Mars. Astronomy Naturvitenskapelig fakultet; 2018-01-18 on modern methods in Solar Physics; - 2018-11-14 spicules. Dynamic Sun II: Solar Mag- Week of Astronomy and Space Science on Tap Oslo; 2018-11-26 2018-08-29 - 2018-08-30 netism from the interior to the corona; (EWASS) 2018; 2018-04-03 - 2018-04-06 2018-02-12 - 2018-02-16 Carlsson, Mats.: More realistic starting Fredvik, Terje.: SPICE FITS Hardcore. Mendes Domingos Pereira, Tiago.: solutions for Radyn. ISSI meeting; Carlsson, Mats.: Solfysikk. Foredrag, SPICE Operations Consortium Meeting 3; Jafarzadeh, Shahin.: Propagation of Thermal coupling through the atmos- 2018-02-12 - 2018-02-16 Nærings og fiskeridepartementets 2018-11-13 - 2018-11-14 Hansteen, Viggo.: The Heating of the transverse waves in small-scale mag- phere. 9th IRIS workshop; 2018-06-25 forsknings og innovasjonsavdeling; Solar Chromosphere and Corona, What netic elements through the lower solar - 2018-06-29 2018-10-22 can "realistic" 3D Numerical Models atmosphere. DKIST Critical Science Plan Carlsson, Mats.: Solen - din nærmeste Fredvik, Terje.: SPICE FITS 101. SPICE teach us?. 17th Annual International Workshop on Wave Generation and stjerne. Åpen dag; 2018-03-08 Operations Consortium Meeting 3; Astrophysics Conference; 2018-03-05 - Propagation; 2018-04-09 - 2018-04-11 Rouppe van der Voort, Luc.: Alignment Carlsson, Mats.: Gode forskningsresulta- 2018-11-13 - 2018-11-14 2018-03-09 between IRIS and ground-based data. ter og ERC SyG. Foredrag, SFF samling IRIS-9; 2018-06-25 - 2018-06-29 Carlsson, Mats.: Modelling of the i Norges forskningsråd; 2018-11-22 - Jafarzadeh, Shahin.: Kahoot quiz on Chromosphere. ISSI meeting; 2018-11-22 Froment, Clara.: Evaporation and conden- Hansteen, Viggo.: Chromospheric Dynam- Solar System. Astronomy on Tap Oslo; 2018-03-13 - 2018-03-16 sation cycles in coronal loops and heat- ics and Heating Processes Ion-Neutral 2018-06-11 Rouppe van der Voort, Luc.: Spicules with ing of the solar corona. Seminar at IAS Effects in the Solar Chromosphere and SST. Modern techniques in solar physics; Carlsson, Mats.: Recent developments Type II Spicules. Triannual Earth Sun 2018-08-29 - 2018-08-30 Carlsson, Mats.: Chromospheric in modelling of the chromosphere. Summit; 2018-05-20 - 2018-05-24 Jafarzadeh, Shahin.: Transverse kink Dynamics and Magnetism. EWASS; Seminar, Yunnan Solar Observatory; Froment, Clara.: Long-period EUV Pulsa- waves in the solar chromosphere. ISSI 2018-04-03 - 2018-04-06 2018-12-04 tions & Coronal Rain : Manifestations of Meeting on Towards Dynamic Solar Wedemeyer, Sven.: Experiences from Solar Coronal Loops Heating Properties. Hansteen, Viggo.: Modeling chromo- Atmospheric Magneto-Seismology with applying for an ERC Consolidator Grant. Seminar at the LPC2E spheric heating and dynamics: What do New Generation Instrumentation; ERC Consolidator seminar; 2018-01-19 Carlsson, Mats.: SRD: Report from WG2. Carlsson, Mats.: Recent developments we understand?. EST Science Meeting; 2018-07-02 - 2018-07-06 EST Science Meeting; 2018-06-11 - in modelling of the chromosphere. 2018-06-11 - 2018-06-15 2018-06-15 Seminar, National Astronomical Froment, Clara.: Long-period intensity Wedemeyer, Sven.: Solar Observations Observatories of China; 2018-12-06 pulsations in coronal loops. BUKS Jafarzadeh, Shahin.: Kinematics of with ALMA. Imaging of Stellar Surfaces; workshop; 2018-09-03 - 2018-09-07 Hansteen, Viggo.: Ellerman bombs and Magnetic Bright Features in the Solar 2018-03-05 - 2018-03-09 Carlsson, Mats.: Optically thick diagnos- UV bursts: reconnection at different Photosphere. XXXth General Assembly tics. IRIS-9; 2018-06-25 - 2018-06-29 Carlsson, Mats.: Solar Radiation MHD, atmospheric layers?. IRIS 9 konferanse; of the International Astronomical Union; part I. Lecture, NAOC; 2018-12-06 Froment, Clara; Antolin, Patrick; Henriques, 2018-06-25 - 2018-06-29 2018-08-20 - 2018-08-24 Wedemeyer, Sven.: Sola, din nærmeste Carlsson, Mats.: Solar Radiation MHD, V. M. J.; Rouppe van der Voort, Luc.: Mul- stjerne. Ungforsk 2018; 2018-09-26 - Carlsson, Mats.: Radiative transfer. part II. Lecture, NAOC; 2018-12-07 ti-scale observations of thermal nonequi- 2018-09-27 IRIS-9; 2018-06-25 - 2018-06-29 librium cycles in coronal loops. Hinode Hansteen, Viggo.: Ellerman bombs and Jafarzadeh, Shahin.: Instrumentation 12 conference; 2018-09-10 - 2018-09-13 UV bursts: reconnection at different for observing waves and instabilities, Carlsson, Mats.: Recent developments atmospheric layers?. SDO 2018 Science especially ALMA. BUKS2018: Waves and Wedemeyer, Sven.: Oppvarming av solens Carlsson, Mats.: An IRIS optically thin in modelling of the chromosphere. Workshop; 2018-10-29 - 2018-11-02 instabilities in the solar atmosphere: atmosfære & solfysikkforskning i dag. view of the dynamics of the solar Seminar, Kavli Institute for Astronomy Froment, Clara; Antolin, Patrick; Henri- Confronting the current state-of-the-art; Faglig-pedagogisk dag; 2018-10-31 chromosphere. IRIS-9; 2018-06-25 - & Astrophysics; 2018-12-10 ques, V. M. J.; Rouppe van der Voort, Luc.: 2018-09-03 - 2018-09-07 2018-06-29 Multi-scale observations of thermal Hansteen, Viggo.: Mass and energy flows nonequilibrium cycles in coronal loops. between the solar chromosphere, transi- Fredvik, Terje.: SPICE Data Pipeline and Colloque Programme National Soleil- tion region and corona. AGU; 2018-12-11 Jafarzadeh, Shahin.: Observing the Data Products. SPICE Consortium Terre; 2018-11-19 - 2018-11-21 - 2018-12-15 dynamic chromosphere. Solar Activity, Meeting 3; 2018-04-19 - 2018-04-20 Magnetism and Irradiance; 2018-10-16 - 2018-10-18 40 RoCS Annual report 2018 6 Papers in refereed journals 2018 41

Martínez-Sykora, J., De Pontieu, B., De Popovas, A., Nordlund, Å., Ramsey, J. P., Trujillo Bueno, J., Stěpán, J., Belluzzi, L., Papers in refereed Moortel, I., Hansteen, V. H., & Carlsson, & Ormel, C. W.: 2018, Monthly Notices Asensio Ramos, A., Manso Sainz, R., del M.: 2018, The Astrophysical Journal of the Royal Astronomical Society 479, Pino Alemán, T., Casini, R., Ishikawa, R., 860, 116, Impact of Type II Spicules in 5136, Pebble dynamics and accretion Kano, R., Winebarger, A., Auchère, F., the Corona: Simulations and Synthetic on to rocky planets - I. Adiabatic and Narukage, N., Kobayashi, K., Bando, T., journals 2018 Observables convective models Katsukawa, Y., Kubo, M., Ishikawa, S., Giono, G., Hara, H., Suematsu, Y., Shimi- zu, T., Sakao, T., Tsuneta, S., Ichimoto, – Moreno-Insertis, F., Martínez-Sykora, J., Quintero Noda, C., Uitenbroek, H., K., Cirtain, J., Champey, P., De Pontieu, Hansteen, V. H., & Muñoz, D.: 2018, The Carlsson, M., Orozco Suárez, D., B., Carlsson, M.: 2018, The Astrophysi- Astrophysical Journal 859, L26, Small- Katsukawa, Y., Shimizu, T., Ruiz Cobo, B., cal Journal 866, L15, CLASP Constraints scale Magnetic Flux Emergence in the Kubo, M., Oba, T., Kawabata, Y., Hasega- on the Magnetization and Geometrical Quiet Sun wa, T., Ichimoto, K., et al.: 2018, Monthly Complexity of the Chromosphere- Antolin, P., Schmit, D., Pereira, T. M. D., Bose, S., & Nagaraju, K.: 2018, IAU Hong, J., Ding, M. D., Li, Y., & Carlsson, Notices of the Royal Astronomical Soci- Corona Transition Region De Pontieu, B., & De Moortel, I.: 2018, Symposium 340, 85, Role of the back- M.: 2018, The Astrophysical Journal 857, ety 481, 5675, Study of the polarization The Astrophysical Journal 856, 44, ground regimes towards the Solar Mean L2, Non-LTE Calculations of the Fe I 6173 Nindos, A., Alissandrakis, C. E., Bas- produced by the Zeeman effect in the Transverse Wave Induced Kelvin-Helm- Magnetic Field (SMMF) A Line in a Flaring Atmosphere tian, T. S., Patsourakos, S., De Pontieu, solar Mg I b lines von Essen, C., Ofir, A., Dreizler, S., Agol, holtz Rolls in Spicules B., Warren, H., Ayres, T., Hudson, H. S., E., Freudenthal, J., Hernández, J., Wede- Shimizu, T., Vial, J.-C., Wedemeyer, S., meyer, S., Parkash, V., Deeg, H. J., Hoyer, Brajša, R., Sudar, D., Benz, A. O., Skokić, Joshi, J., & de la Cruz Rodríguez, J.: 2018, & Yurchyshyn, V.: 2018, Astronomy and Reid, A., Henriques, V. M. J., Mathiouda- S., Morris, B. M., Becker, A. C., et al.: Auchère, F., Froment, C., Soubrié, E., I., Bárta, M., De Pontieu, B., Kim, S., Astronomy and Astrophysics 619, A63, Astrophysics 619, L6, First high-resolu- kis, M., & Samanta, T.: 2018, The Astro- 2018, Astronomy and Astrophysics 615, Antolin, P., Oliver, R., & Pelouze, G.: 2018, Kobelski, A., Kuhar, M., Shimojo, M., Magnetic field variations associated with tion look at the quiet Sun with ALMA physical Journal 855, L19, Penumbral A79, Kepler Object of Interest Network. The Astrophysical Journal 853, 176, The Wedemeyer, S., White, S., et al.: 2018, umbral flashes and penumbral waves at 3mm Waves Driving Solar Fan-shaped I. First results combining ground- and Coronal Monsoon: Thermal Nonequilibri- Astronomy and Astrophysics 613, A17, Chromospheric Jets space-based observations of Kepler um Revealed by Periodic Coronal Rain First analysis of solar structures in 1.21 systems with transit timing variations mm full-disc ALMA image of the Sun Kanella, C., & Gudiksen, B. V.: 2018, Panesar, N. K., Sterling, A. C., Moore, R. Astronomy and Astrophysics 617, A50, L., Tiwari, S. K., De Pontieu, B., & Norton, Stěpán, J., Trujillo Bueno, J., Belluzzi, Bakke, H., Frogner, L., & Gudiksen, B. Investigating 4D coronal heating events A. A.: 2018, The Astrophysical Journal L., Asensio Ramos, A., Manso Sainz, R., Wülser, J.-P., Jaeggli, S., De Pontieu, B., V.: 2018, Astronomy and Astrophysics Chintzoglou, G., De Pontieu, B., Martín- in magnetohydrodynamic simulations 868, L27, IRIS and SDO Observations del Pino Alemán, T., Casini, R., Kano, R., Tarbell, T., Boerner, P., Freeland, S., Liu, 620, L5, Non-thermal electrons from ez-Sykora, J., Pereira, T. M. D., Vourlidas, of Solar Jetlets Resulting from Winebarger, A., Auchère, F., Ishikawa, W., Timmons, R., Brannon, S., Kankel- solar nanoflares. In a 3D radiative MHD A., & Tun Beltran, S.: 2018, The Astro- Network-edge Flux Cancelation R., Narukage, N., Kobayashi, K., Bando, borg, C., Madsen, C., McKillop, S., et al.: simulation physical Journal 857, 73, Bridging the Kianfar, S., Jafarzadeh, S., Mirtorabi, M. T., Katsukawa, Y., Kubo, M., Ishikawa, S., 2018, Solar Physics 293, 149, Instrument Gap: Capturing the Ly Counterpart of a T., & Riethmüller, T. L.: 2018, Solar Phys- Giono, G., Hara, H., Suematsu, Y., Shimi- Calibration of the Interface Region Imag- Type-II Spicule and Its Heating Evolution ics 293, 123, Linear Polarization Features Pereira, T. M. D.: 2019, Advances in zu, T., Sakao, T., Tsuneta, S., Ichimoto, ing Spectrograph (IRIS) Mission Bastian, T. S., Chintzoglou, G., with VAULT2.0 and IRIS Observations in the Quiet-Sun Photosphere: Structure Space Research 63, 1434, The dynamic K., Cirtain, J., Champey, P., De Pontieu, De Pontieu, B., Shimojo, M., Schmit, D., and Dynamics chromosphere: Pushing the boundaries B., Carlsson, M.: 2018, The Astrophysical Leenaarts, J., & Loukitcheva, M.: 2018, of observations and models Journal 865, 48, A Statistical Inference Young, P. R., Tian, H., Peter, H., Rutten, The Astrophysical Journal 860, L16, Freudenthal, J., von Essen, C., Dreizler, Method for Interpreting the CLASP R. J., Nelson, C. J., Huang, Z., Schmieder, Erratum: A First Comparison of Millime- S., Wedemeyer, S., Agol, E., Morris, B. Klevas, J., Kučinskas, A., Wedemeyer, S., Observations B., Vissers, G. J. M., Toriumi, S., Rouppe ter Continuum and Mg II Ultraviolet Line M., Becker, A. C., Mallonn, M., Hoyer, & Ludwig, H.-G.: 2018, Contributions of Pereira, T. M. D., Rouppe van der Voort, van der Voort, L. H. M., Madjarska, M. S., Emission from the Solar Chromosphere S., Ofir, A., Tal-Or, L., Deeg, H. J., et al.: the Astronomical Observatory Skalnate L., Hansteen, V. H., & De Pontieu, B.: Danilovic, S., et al.: 2018, Space Science 2018, Astronomy and Astrophysics 618, Pleso 48, 280, Impact of magnetic fields 2018, Astronomy and Astrophysics 611, Stangalini, M., Jafarzadeh, S., Ermolli, I., Reviews 214, 120, Solar Ultraviolet Bursts A41, Kepler Object of Interest Network. on the structure of convective atmos- L6, Chromospheric counterparts of Erdélyi, R., Jess, D. B., Keys, P. H., Giorgi, Bjørgen, J. P., Sukhorukov, A. V., II. Photodynamical modelling of Kepler-9 pheres of red giant stars solar transition region unresolved fine F., Murabito, M., Berrilli, F., & Del Moro, Leenaarts, J., Carlsson, M., de la Cruz over 8 years of transit observations structure loops D.: 2018, The Astrophysical Journal 869, Zacharias, P., Hansteen, V. H., Leenaarts, Rodríguez, J., Scharmer, G. B., & 110, Propagating Spectropolarimetric J., Carlsson, M., & Gudiksen, B. V.: 2018, Hansteen, V. H.: 2018, Astronomy and Kuridze, D., Henriques, V. M. J., Disturbances in a Large Sunspot Astronomy and Astrophysics 614, A110, Astrophysics 611, A62, Three-dimension- Froment, C., Auchère, F., Mikić, Z., Mathioudakis, M., Rouppe van der Voort, Polito, V., Testa, P., Allred, J., De Pontieu, Disentangling flows in the solar al modeling of the Ca II H and K lines Aulanier, G., Bocchialini, K., Buchlin, L., de la Cruz Rodríguez, J., & Carlsson, B., Carlsson, M., Pereira, T. M. D., Gošić, transition region in the solar atmosphere E., Solomon, J., & Soubrié, E.: 2018, The M.: 2018, The Astrophysical Journal 860, M., & Reale, F.: 2018, The Astrophysi- Tiwari, S. K., Moore, R. L., De Pontieu, Astrophysical Journal 855, 52, On the 10, Spectropolarimetric Inversions of the cal Journal 856, 178, Investigating the B., Tarbell, T. D., Panesar, N. K., Wine- Occurrence of Thermal Nonequilibrium Ca II 8542 ̊A Line in an M-class Solar Response of Loop Plasma to Nanoflare barger, A. R., & Sterling, A. C.: 2018, The Bose, S., & Nagaraju, K.: 2018, The Astro- in Coronal Loops Flare Heating Using RADYN Simulations Astrophysical Journal 869, 147, Evidence physical Journal 862, 35, On the Varia- of Twisting and Mixed-polarity Solar bility of the Solar Mean Magnetic Field: Photospheric Magnetic Field in Large Contributions from Various Magnetic Gošić, M., de la Cruz Rodríguez, J., De Leenaarts, J., de la Cruz Rodríguez, J., Popovas, A., Nordlund, Å., & Ramsey, Penumbral Jets: IRIS and Hinode Features on the Surface of the Sun Pontieu, B., Bellot Rubio, L. R., Carlsson, Danilovic, S., Scharmer, G., & Carlsson, J. P.: 2019, Monthly Notices of the Royal Observations M., Esteban Pozuelo, S., Ortiz, A., & M.: 2018, Astronomy and Astrophysics Astronomical Society 482, L107, Pebble Polito, V.: 2018, The Astrophysical 612, A28, Chromospheric heating during dynamics and accretion on to rocky Journal 857, 48, Chromospheric Heating flux emergence in the solar atmosphere due to Cancellation of Quiet Sun planets - II. Radiative models Internetwork Fields Design: Anagram design, Trykk: Konsis

O Sun of Real Peace

O so amazing and broad—up there resplendent, darting and burning!

O vision prophetic, stagger’d with weight of light! with pouring glories!

Walt Whitman 44 NCMM Annual Report 2017

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