Oskar von der Lühe Kiepenheuer-Institut für Sonnenphysik, Freiburg

The first modern solar physicist: Galileo proposed the solar origin of sunspots Sunspot drawings by Galileo from 1613 (Rice Galileo Project)

Time-resolved measurements of a physical characteristic of the Sun – with a scope of the entire solar disk and the solar space environment – with a scope of long time periods – often with high cadence (minutes) Similar paradigms – repeated measurements of large volumes of targeted and untargeted astrophysical quantities with long duration and high cadence - now enter nighttime astronomy where they are called “time domain astrophysics” and create billion-$ projects

NSO/GONG Udaipur H  Intensity 2012/02/14 GONG, MDI, AIA, MSFC, SOLIS, LASCO, PMOD, SWPC

Distinct field of research since the introduction of stellar spectroscopy in the 19 th century – Leading stellar spectroscopy for many decades, still leading in polarimetry – Leading in theoretical understanding of stellar atmospheres – Only discipline in astrophysics which has direct impact on modern civilization The “Easy Experiments” have mostly already been done Big steps of discovery and understanding of the Sun which result from simple experiments require new technologies Nobel Prize level discoveries are not likely Progress means hard and tedious work – Advanced technology, techniques and methods in theoretical and experimental solar physics

Solar Physics Stellar Physics (non-stellar) Astrophysics Terrestrial Physics Fundamental Physics Stellar dynamos Stellar structure Exoplanets Particle physics General relativity Cosmic magnetic fields Abundances Flares and CMEs Solar „constant“

Stellar physics has reached a similar level of maturity as has solar physics Currently active links are stellar magnetic activity and asteroseismology Stellar physics has experienced a tremendous boost since the discovery of exoplanets Advances in Stellar physics reflect back on Solar physics C. Schrijver / LMSARL

Monitoring of solar activity and energetic events is essential for spacecraft operations Impact of solar activity on the Earth‘s magnetic field may impact large infrastructures Predicting solar activity, solar energetic events and their impact in Earth is the bread-and-butter raison d'être for solar research Stereo A WSA-Enlil (NOAA)

How is the solar magnetic field generated, maintained and dissipated? – Discriminate solar dynamo models – Determine the role of induction effects near the surface for the global field – Determine the characteristics of angular momentum transport inside the Sun – Observe, identify and characterize magnetic reconnection How does solar magnetism influence the internal structure and the luminosity of the Sun? – Compare the Sun with stars with differ in magnetic activity through asteroseismology – Determine impact on exoplanet detection and characterization How are the solar corona and the solar wind maintained and what determines their properties? – Observe, identify and characterize acoustic and magneto-acoustic waves in the upper atmosphere What triggers transient energetic events? – Determine the role of the interaction of interior flow and magnetic fields – Establish reliable space weather prediction

11 Detailed studies of magnetic field and plasma physics processes in the solar atmosphere including the corona – Consistently highest spatial, temporal and spectral resolution – High sensitivity, very high SNR – Modest fields of view and temporal coverage – Access to a large part of the electromagnetic spectrum Comprehensive studies of large to medium scale processes in the solar interior and atmosphere including the corona – Medium/high spatial resolution, limited spectral resolution and/or coverage, selected spectral lines – Full solar disk, entire electromagnetic spectrum – Long term uninterrupted temporal coverage Several large aperture telescopes on the ground and in space Small to medium aperture ground based networks and space facilities

Numerical simulation (M. Rempel, HAO)Observations with GREGOR (v. d. Lühe, KIS)

13 Advanced Technology Solar Telescope 4m USA BBSO New Solar Telescope 1.6m USA Design Construction Commissioning Yunnan Obs. Solar Telescope 1m China National Large Solar Telescope 2m India Gregor 1.5m D/ES European Solar Telescope 4m EUR

How is the solar magnetic field generated, maintained and dissipated? – Discriminate solar dynamo models – Determine the role of induction effects near the surface for the global field – Determine the characteristics of angular momentum transport inside the Sun – Observe, identify and characterize magnetic reconnection How does solar magnetism influence the internal structure and the luminosity of the Sun? – Compare the Sun with stars with differ in magnetic activity through asteroseismology – Determine impact on exoplanet detection and characterization How are the solar corona and the solar wind maintained and what determines their properties? – Observe, identify and characterize acoustic and magneto-acoustic waves in the upper atmosphere What triggers transient energetic events? – Determine the role of the interaction of interior flow and magnetic fields – Establish reliable space weather prediction

Space missions offer unique opportunities – Access to the entire e. m. spectrum – Absence of detrimental impact of the Earth‘s atmosphere – Stable conditions and very consistent data Stereo SoHO Hinode Solar Dynamics Observatory

Ground based observatories offer unique opportunities: – Large telescopes and instruments – Flexibility – High data rates GREGOR/KIS

There is no synoptic measurement which cannot in principle be done from space – many measurements can only be done from space Limiting factors for space missions are cost and telemetry – ground missions are required to get the complete picture Solar physics has a fair share of space missions Scientific goals and data products of space and ground missions must complement and be well aligned – Redundancy is part of that Solar Dynamics Observatory PMOD/WRC

Synoptic Realm

19 GONG BiSON SOON

Future solar networks should provide: – Velocity maps at different heights – Maps of vector magnetic fields at different heights – Maps of quantities relevant for space weather – At multiple wavelengths – With high cadence, duty cycle and lifetime – With high sensitivity to velocity and magnetic fields – Complement space missions

Operating even a small network (BISON, GONG) is a big effort for a national community Designing, deploying and operating a distributed, comprehensive, ground based network requires a new level of international collaboration – SOLARNET - SPRING Opportunity to involve and sustain smaller research groups in solar physics

Synoptic facilities on the ground and in space produce large amounts of data which must be digested to produce useful products Procedures for data calibration, reduction and archiving are similar, if not the same – MDI and GONG share a lot of data reduction procedures Space projects come with data management funding Ground facilities share these needs and also require adequate funding

Solar physics is relevant because of its societal impact Synoptic solar observations are essential for answering relevant key questions – Both space and ground facilities are indispensible. They must be complementary – Future ground based networks should be an international endeavor The importance of synoptic observations is veiled by the visibility of large projects which has adverse effects on funding