Gavin Rowell, Matthieu Renaud, Phoebe de Wilt, Fabien Voisin, Yasuo Fukui, Michael Burton, Andrew Walsh, Akiko Kawamura, Andrew Walsh, Akiko Kawamura, Felix Aharonian

We present the results of molecular spectral line observations towards Supernova Remnants such as W28, RX J1713.7-3946 and HESS J1731-347. These remnants exhibit TeV gamma-ray emission, beacons for the presence of enhanced populations of high energy particles. It follows that these objects may accelerate Galactic cosmic-ray protons via the diffusive shock mechanism, but knowledge of the environment local to such remnants is required to constrain such scenarios. The Mopra radio telescope is ideal for probing the interstellar environments of HESS gamma-ray sources through large-scale molecular line surveys. Mopra can be employed to hunt for dense gas-tracing CS and NH3 transitions to identify potential cosmic-ray target material, while simultaneously searching for shock-tracing SiO emission lines which can directly highlight shock-disrupted gas. Furthermore, spectral line width gives an insight into gas dynamics and Mopra is capable of measuring this at a ~1' resolution over degree-scale regions. We present results from recent 7 and 12mm surveys towards the above-mentioned TeV-emitting Supernova Remnants and discuss the implications for distance, the diffusion of cosmic-rays and the high energy gamma-ray spectrum.

Magnetic flux emergence from the solar convection zone into the atmosphere drives dynamic phenomena observable over a range of temperatures and spatiotemporal scales. In this talk, we review the fundamental physical processes important for flux emergence and relate these processes to observables accessible to ground-based and space borne observatories. We illustrate how continuous spectropolarimetric observations enabled the recent development of data-driven simulations of emerging flux, and how such simulations will improve our understanding of the solar atmosphere. We give suggestions for coordinated studies involving observations by existing and next generation solar telescopes (European Solar Telescope, Daniel K. Inouye Solar Telescope, ALMA and future space missions) and data-driven models. We also explore how machine learning techniques can be applied to perform physical diagnostics of the solar atmosphere.

Ariane Schad, Guy Davies, Markus Roth

Context. The Sun and solar-like stars undergo activity cycles for which the underlying mechanisms are not well understood. The oscillations of the Sun are known to vary with activity cycle and these changes provide diagnostics on the conditions below the photosphere. Kepler has detected oscillations in hundreds of solar-like stars but as of yet, no widespread detection of signatures of magnetic activity cycles in the oscillation parameters of these stars have been reported. Aims. We analyse the photometric short cadence Kepler time series of a set of 24 solar-like stars, which were observed for at least 960 days each, with the aim to find signatures of stellar magnetic activity in the oscillation parameters. Methods. We analyse the temporal evolution of oscillation parameters by measuring mode frequency shifts and changes in the height of the p-mode envelope. Results. For 22 of the 24 investigated stars, we find significant frequency shifts in time, indicating stellar magnetic activity. For the most prominent example, KIC 8006161, we find that, similar to the solar case, frequency shifts are smallest for the lowest and largest for the highest p-mode frequencies. Conclusions. These findings show that magnetic activity can be routinely observed in the oscillation parameters for solar-like stars. The large proportion of stars for which this is the case opens up the possibility to place the Sun and its activity cycle in the context of other stars.

Helicities as well as the turbulent energies are key players of the dynamo process. From viewpoint of turbulent transport, helicities mainly suppress the effective transports. In the presence of inhomogeneous large-scale flow, the turbulent cross helicity (cross-correlation between the velocity and magnetic-field fluctuations) enters the turbulent electromotive force and its suppression/generation effect tends to be balanced with the turbulent magnetic diffusivity. At the same time, the turbulent cross helicity coupled with the mean magnetic strain affects the momentum transport. In addition to these effects of helicities, in strong compressible magnetohydrodynamic (MHD) turbulence, the density variance contributes to the turbulent electromotive force as the coupling coefficient of the obliqueness of the mean magnetic field to the density gradient. This means that the density variance as well as the helicities alters the turbulent transport. This density-variance effect is expected to enhance the intensity of turbulence across the slow MHD shock, which may contribute to the realization of a localized fast magnetic reconnection.

Jack Harvey

SOLIS stands for Synoptic Optical Long-term Investigations of the Sun. Daily fulldisk magnetic fields measurements of the Sun are being done for several decades at NSO Kittpeak. The SOLIS/VSM instrument replaced earlier instruments at Kitt Peak. The current SOLIS/VSM instrument has capability to make full Stokes polarimetry in photospheric lines, however, for chromosphere only longitudinal polarimetry exists. With the recent progress in non-LTE inversions of the chromospheric spectra it was decided that a full Stokes polarimeter needs to be developed. Based on similar design to photospheric modulator we have developed a separate modulator for chromospheric full Stokes measurements using Ca II 854.2 nm line. We will present design and performance of the new modulator and possibly sample observations.

P. Schwartz^1, P. Heinzel^2, S. Jejcic^3, J. Rybak^1, P. Kotrc^2, F. Farnik^2, Yu. A. Kupryakov^{2,4}, E. E. DeLuca^5, L. Golub^5, P.R. Jibben^5, U. Anzer^6, A.G. Tlatov^7, S.A. Guseva^7; 1 Astronomical Institute of Slovak Academy of Sciences, 05960 Tatranska Lomnica, Slovak Republic; 2 Astronomical Institute, Czech Academy of Sciences, 25165 Ondrejov, Czech Republic; 3 University of Ljubljana, Faculty of Mathematics and Physics, 1000 Ljubljana, Slovenia,; 4 Sternberg Astronomical Institute, 119899 Moscow, Russia; 5 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MA 02138 Cambridge, USA; 6 Max-Planck-Institut fur Astrophysik, Karl-Schwarzschild-Strasse 1, 85740 Garching, Germany; 7 Kislovodsk Mountain Astronomical Station of the Pulkovo observatory, Kislovodsk 357700, Russia

Total masses of six quiescent prominences observed from April through June 2011 were estimated using multi-spectral observations (in EUV, X-rays, H alpha,and Ca ii H) and method based on work of Heinzel et al. (2008). The method uses the fact that intensity of the EUV solar corona at wavelengths below 912 Å is reduced at a prominence by the absorption in resonance continua (photoionisation) of hydrogen and possibly by helium and subsequently an amount of absorbed radiation is proportional to the column density of hydrogen and helium plasma. Moreover, the deficit of the coronal emissivity in volume occupied by the cool prominence plasma also contributes to the intensity decrease. The observations in X-rays which are not absorbed by the prominence plasma, allow us to separate these two mechanisms from each other. The X-ray observations of XRT onboard the Hinode satellite made with the Al-mesh focal filter were used because the X-ray coronal radiation formed in plasma of temperatures of the order of 10^6 K was registered and EUV spectral lines occurring in the 193, 211 and 335 A channels of the Atmospheric Imaging Assembly of the Solar Dynamics Observatory satellite are also formed at such temperatures. Unfortunately, the Al-mesh filter has a secondary peak of the transmittance at around 171 A what causes a contribution from the EUV corona to the measured data of up to 10 % in the quiet corona. Thus, absorption in prominence plasma influences XRT X-ray data when using the Al-mesh filter. On the other hand, other X-ray XRT filters are more sensitive to plasma of much higher temperatures (log T of the order of 7), thus observations using these filters cannot be used together with the AIA observations in the method for mass estimations. This problem could be solved using observations in the green coronal line instead of X-rays. Absorption of the green coronal line by a prominence plasma is negligible and this line is formed at temperatures of the order of 10^6 K. We compare values of the total mass of the prominence observed on 20 October 2012 on SE limb estimated when using XRT X-ray observations and observations in the green coronal line obtained at Kislovodsk Mountain Astronomical Station of the Pulkovo observatory (Russia).

R.H. Cameron

Hale’s polarity laws for sunspot groups, the helioseismic determination of differential rotation in the convection zone, and the success of surface flux transport models in reproducing the observed evolution of large-scale solar surface fields, together with a simple mathematical argument, yield compelling evidence that the large-scale solar dynamo operates according to the scenario originally envisaged by H.W. Babcock and R. Leighton in the 1960s. The polar fields represent THE poloidal flux from which the toroidal flux emerging in sunspot groups is wound up by (mainly latitudinal) differential rotation. The polar fields themselves result from tilted sunspot groups while small-scale magnetic features ("turbulence") do not provide a significant contribution.

Laure Lef\`evre, Edward W. Cliver, Leif Svalgaard

In 2015, a new entirely recalibrated version of the sunspot number and group number series has been released. Important changes, by up to 40\%, have been applied to the original historical series, leading to a new picture of the secular evolution of solar activity, without significant upward trend between the $17^{th}$ and the $20^{th}$ century. We first describe the main changes and implications of this very first revision of the sunspot number series since its creation, more than 165 years ago. We also discuss the long-term non-linear relation between the sunspot number and the group number, as it is now free from artifacts. Both series are now largely reconciled, but do not fully overlap, clearly reflecting different properties of the solar cycle. Together with this major step, several important changes were simultaneously adopted regarding past conventions. We will explain the various modifications and their motivations, in order to help users making the proper adaptations. In particular, A.Wolfer was chosen as the new reference, in place of R. Wolf, thus dropping the fixed 0.6 Z\"urich factor. For the group numbers, given the time variability of the average number of spots per group, we don't apply anymore a constant scaling factor to match the average scale of the sunspot number, in contrast with the previous series by Hoyt and Schatten (1998). Finally, we present the new data sets and data formats adopted for this revised series and for the future production of the sunspot number. The new SILSO Web portal will provide access both to current and past versions of the series, allowing to keep track of future revisions and thus giving more flexibility to follow future progresses in sunspot science. Finally, we conclude on the redefinition of the base method used to routinely produce the sunspot number from all current and future observations of the SILSO worldwide network. New tools and statistical approaches derived directly from our global recalibration work will soon be ported to our operational software, improving the quality control and the long-term stability of the sunspot number series. This will complete the necessary modernization of our only direct long-term record of solar activity.

Markus Roth, Frank Hill, Michael Thompson

Synoptic observations of the Sun are very important to understand the long term behavior of the solar activity cycle. Our current understanding solar magnetic cycle is rather in its infancy, as can be inferred from our very poor prediction for the strength of solar cycle 24, based on various dynamo models. Solar magnetism is at the heart of all solar activity and therefore it is important to understand what parameters govern the magnetic cycle in the Sun. An important parameter that is realized more recently is the internal dynamics, i.e., profile of solar internal rotation and nature of large scale meridional flows. Therefore, it is important to study the solar interior by making use of helioseismology. Ground based helioseismology networks such as GONG are now quite few decades old and its possible failure poses risk to the continuity of solar oscillation data. Hence, a next generation of synoptic network SPRING is being proposed and is currently under design study. We will present science requirements and the details of the SPRING network.

J. Jiang and R. H. Cameron

The ongoing 11-year cycle of solar activity is considerably less vigorous than the three cycles before. It was preceded by a very deep activity minimum with a low polar magnetic flux, the source of the toroidal field responsible for solar magnetic activity in the subsequent cycle. Simulation of the evolution of the solar surface field shows that the weak polar fields and thus the weakness of the present cycle 24 are mainly caused by a number of bigger bipolar regions with a ‘wrong’ (i.e., opposite to the majority for this cycle) orientation of their magnetic polarities in the North- South direction, which impaired the growth of the polar field. These reg ions had a particularly strong effect since they emerged within ±10° latitude from the solar equator.

SOLAR-C WG

Solar-C is a Japan-led international solar mission designed to investigate the magnetic activities of the Sun, focusing on the study in heating and dynamical phenomena of the chromosphere and corona, and also to develop an algorithm for predicting short and long term solar evolution.It has long been known that the interplay between magnetic fields and plasmas is at the heart of most solar phenomena, but the details of this interplay are in many cases clouded in ambiguity and uncertainty. To dramatically improve the situation, SOLAR-C will carry three dedicated instruments; the Solar UV-Vis-IR Telescope (SUVIT), the EUV Spectroscopic Telescope (EUVST) and the High Resolution Coronal Imager (HCI), to jointly observe the entire visible solar atmosphere with essentially the same high spatial resolution (0.1-0.3 arcsec), performing high resolution spectroscopic measurements over all atmospheric regions and spectro-polarimetric measurements from the photosphere through the upper chromosphere. In addition, Solar-C will contribute to our understanding on the influence of the Sun-Earth environments with synergetic wide-field observations from ground-based and other space missions. I will present some leading science objectives and the mission concept, including the current status of SOLAR-C.

S. Brun

The aim of the present study is to characterize the effect of the rotation rate in building magnetic field via dynamo action in solar-like stars. We use the code ASH to model the convective dynamo for solar-like stars at various rotation rates and hence Rossby numbers. We find that stable magnetic configuration without cycling evolution; with steady low latitude magnetic field wreaths are found for slowly rotating cases with large Rossby number. For models rotating faster with a low Rossby number, the convective dynamo shows a cycling activity, leading to systematic pole inversion. We also note that a topology change of the stellar magnetic field occurs going from a dipolar-like to a quadrupolar-like structure when the system magnetic energy drops during the cyclic activity, in good agreement with our star the Sun.