The variation in solar irradiance is commonly assumed to be driven by its surface magnetism. Until recently, this assumption could not be verified conclusively as models of solar irradiance variability based on solar surface magnetism have to be calibrated to solar irradiance measurements. Making use of realistic three-dimensional magnetohydrodynamic simulations of the solar atmosphere and state-of-the-art full-disk magnetograms from SDO, we developed a model of total solar irradiance (TSI) that does not require any such calibration. The modelled TSI variability is therefore, unlike preceding models, independent of TSI measurements. The model replicates over 95% of the observed variability over the lifetime of SDO, confirming the relationship to solar surface magnetism and leaving limited scope for alternative drivers of solar irradiance variability (at least over the time scales examined, that is, days to the solar cycle).

With its unprecedented capabilities, the Solar Dynamics Observatory has brought into our view a full range of dynamics in the Sun's atmosphere. For the first time, we have been able to monitor, continuously and in great details, evolution of the magnetic field and plasma properties prior to Coronal Mass Ejections, the most spectacular form of energy release in the heliosphere. Some CMEs, when finally reaching 1 AU and measured by satellites near Earth, are found to be magnetic flux ropes. We still do not know the exact origin of these structures. Are all CMEs flux ropes at their birth? How do they form on the Sun? What are the plasma signatures and magnetic properties of flux ropes in the corona prior to their eruption? What is the magnetic environment that leads to formation and eruption of a flux rope? How are CMEs and their magnetic configuration related to other energetic events, e.g. flares and energetic particles? This talk will review some significant progress in the SDO era to help answer these questions using observations as well as advanced MHD models.

Jiong Qiu is an associate professor of Physics at Montana State University. Her research focuses on understanding magnetic reconnection and subsequent energy release in solar eruptive events. She analyzes observational signatures of magnetic reconnection, diagnose plasma heating in solar flares, and study the evolution and structure of CMEs in the corona. She works with graduate and undergraduate students, and has managed the NSF-sponsored Research Experiences for Undergraduates program at MSU since 2008. Previously, she has also conducted earthshine measurements of global atmosphere properties at Big Bear Solar Observatory, New Jersey Institute of Technology. She earned her PhD in astrophysics from Nanjing University in China.

Helioseismology has had great success in determining the solar interior rotation profile, its dependence on the solar cycle and its temporal variation. After reviewing these results, I will turn to two less understood phenomena in the solar interior, namely meridional circulation and the nature of convective flows in the deep interior. I will argue that both of these phenomena can be brought to a similar understanding. Helioseismic inversions for the deep solar meridional flow have not yet come to a consistent picture, for which there are several possible reasons. A number of systematic effects have been shown to be present in the data. Among those is a spurious center-to-limb effect. Although progress has been made to characterize this effect, its origin is not yet understood. Furthermore, it was shown that inferences of the meridional flow are ambiguous in the lower half of the convection zone for two years of data. In addition, several results suggest a time dependence of the deep meridional flow. An even larger discrepancy exists in measurements of the spectrum of convective velocities at depth. Here, I will present a new approach to reexamine one of the conflicting studies that is based on a more accurate model for the observations. Finally, I will close with a short review of a few interesting recent results, among which are the detection of equatorial Rossby waves and a study of wave-like properties of supergranulation. Both of these results imply that helioseismology agrees with surface observations such as correlation tracking. These are good news for tackling the challenges ahead.

Vincent Böning is a postdoctoral researcher at the Max Planck Institute for Solar System Research in Göttingen, Germany, and works on helioseismology of meridional circulation and subsurface convection. He received his Ph.D. in 2017 from University of Freiburg, Germany, with a project on deep meridional flow at the Kiepenheuer Institute for Solar Physics. As a main result of his thesis, he found that the detection of the meridional flow is ambiguous for flows below about 0.85 solar radii when a time series of about 2 years of GONG data is used.

The advent of high-cadence, large-scale photospheric vector magnetic field and Doppler velocity measurements from the Solar Dynamics Observatory and progress in the computational techniques facilitated development of the time-dependent data-driven models of the coronal magnetic fields. In this talk I will first review current state and challenges of these models. I will then describe recent progress of the Coronal Global Evolutionary Model (CGEM), a collaborative effort between UC Berkeley, Lockheed Martin and Stanford University that computes electric fields in the photosphere to drive a 3D non-potential model of the solar corona magnetic fields.

The more we have learned about the Sun, the more we can appreciate its essential complexity. Telescopes confirmed that it was not an unblemished sphere. Multi-wavelength observations revealed its structured atmosphere, and ever-higher resolution exposed its spectacular dynamics. Helioseismology penetrated its depths, and STEREO views gave us our first three-dimensional perspective. With Solar Orbiter we will finally leave our ecliptic bias behind and see the Sun from high latitudes. What will we see? And what could we see if future missions dwell at near-polar vantages, providing a synoptic view from above or below? The science enabled by such viewpoints is broad and deep, with potential both to finally fill known gaps in our understanding, and to reveal hitherto undiscovered aspects of the Sun and heliosphere.

The so-called “middle corona” — the region of the corona between 1.5 and a few solar radii — is the region where CMEs are accelerated, where magnetic energy is released by reconnection during solar flares, and where the nascent solar wind begins to be accelerated as it flows out into the heliosphere. Observations of this region therefore hold much potential to address key questions in solar physics, but because observing this region is technically challenging, it remains relatively poorly explored. SWAP on PROBA2 and SUVI on GOES-R, both of which can observe the EUV corona to heights larger than 2 solar radii, have produced observations demonstrating the value of observing this region, and a new generation of instruments currently in development will push the frontiers of understanding of this region considerably farther in the coming years. In this talk I will discuss some of the key questions in solar coronal physics that we can answer by exploring the middle corona and discuss some current and future opportunities to explore the middle corona using a variety of techniques and instruments.

Over the past few years, deep learning has become the state-of-the-art technique for many problems: classification, visual recognition, speech recognition, natural language processing or even playing games. The developement of new algorithms as well as the improvment of hardware and computing capacity make these methods able to address new application fields with big data and complex problems. In this talk, I will introduce the main topics that underlie the deep learning paradigm, and then detail four possible applications that solar data processing can benefit from: classification of images or events for segmentation or semantic recognition purposes ; inverse or ill-posed problem solving, particularly focusing on image super resolution ; and data generation using generative adversarial networks.

Cooperation between solar and stellar astrophysicists opens new research avenues for both fields as well as planetary and exoplanetary science. Stellar astrophysics leverages detailed information about the Sun to add some resolution to a usually spatially-unresolved stellar picture, and observations of sun-like stars spanning the stellar lifetime inform the evolutionary history and future of the Sun. Since 2010, the Kepler/K2 satellite’s ultra-precise long-baseline photometry has greatly renewed interest in Sun-as-a-star observations via the discovery of thousands of exoplanets, superflares on Sun-like stars, unique starspot distributions, asteroseismic oscillations, and rotation periods for stars of a wide range of mass and age. Scientific resources worldwide are concentrated on finding and characterizing even more exoplanets, and as the necessary techniques and technologies are pushed to their current limits, information about stars is desperately desired with many researchers turning to solar physics for answers on topics like the origin of radial velocity jitter and the transit light source effect. Additionally, solar and planetary science provide information on phenomena that are important for exoplanet habitability and atmosphere evolution that either cannot currently be observed or are very challenging to observe from other stars. Examples include EUV radiation, CMEs, stellar winds, and multiwavelength flare energy partitions, which all could greatly impact atmospheric heating and chemistry, potentially resulting in catastrophic mass loss. In this overview, I will discuss some of the stellar and exoplanet communities’ needs from the solar community, and I will present some recent results that highlight how extreme the environments around stars other than Sun can be.