Different from previous triennial reports, this report covers the activities of IAU Commission 36 ‘Theory of Stellar Atmospheres’ over the past six years†, and will be the last report from the ‘old’ Commission 36. After the General Assembly in Honolulu (August 2015), a new Commission ‘Stellar and Planetary Atmospheres’ (C.G5, under Division G, ‘Stars and Stellar Physics’) has come into life, and will continue our work devoted to the outer envelopes of stars, as well as extend it to the atmospheres of planets (see Sect. 4).

The business meeting of IAU Commission 36 took place during the GA in Beijing on August 27th, and its major topic was the re-structuring of the IAU Divisions and consequences for our Commission. The meeting was conducted by the new president, Joachim Puls, since the past president (still in charge during the GA), Martin Asplund, could not participate.

SICStus Prolog has evolved for nearly 25 years. This is an appropriate point in time for revisiting the main language and design decisions, and try to distill some lessons. SICStus Prolog was conceived in a context of multiple, conflicting Prolog dialect camps and a fledgling standardization effort. We reflect on the impact of this effort and role model implementations on our development. After summarizing the development history, we give a guided tour of the system anatomy, exposing some designs that were not published before. We give an overview of our new interactive development environment, and describe a sample of key applications. Finally, we try to identify key good and not so good design decisions.

We present the first center-to-limb G-band images synthesized from high resolution simulations of solar magneto-convection. Towards the limb the simulations show “hilly” granulation with dark bands on the far side, bright granulation walls and striated faculae, similar to observations. At disk center G-band bright points are flanked by dark lanes. The increased brightness in magnetic elements is due to their lower density compared with the surrounding intergranular medium. One thus sees deeper layers where the temperature is higher. At a given geometric height, the magnetic elements are cooler than the surrounding medium. In the G-band, the contrast is further increased by the destruction of CH in the low density magnetic elements. The optical depth unity surface is very corrugated. Bright granules have their continuum optical depth unity 80 km above the mean surface, the magnetic elements 200-300 km below. The horizontal temperature gradient is especially large next to flux concentrations. When viewed at an angle, the deep magnetic elements optical surface is hidden by the granules and the bright points are no longer visible, except where the “magnetic valleys” are aligned with the line of sight. Towards the limb, the low density in the strong magnetic elements causes unit line-of-sight optical depth to occur deeper in the granule walls behind than for rays not going through magnetic elements and variations in the field strength produce a striated appearance in the bright granule walls.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

We present observations of the dynamic evolution of photospheric magnetic elements in the G-band, magnetograms and Dopplergrams. The observations were obtained with the Swedish 1m Solar Telescope on La Palma at close to the diffraction limit of $0{\hbox{.\!\!^{\prime\prime}}}1$. In the most quiet regions we observe individual bright points in the G-band with corresponding magnetic signal in the magnetograms. Where the filling factor of the magnetic field is larger, the bright points interact when advected by the granular and super-granular flow-fields, flux sheets form and fragment. The plage region of the decaying active region is filled with more complex topologies like ribbon structures with darker interior and bright, knotted edges. These change into flower-like shape when small in extent and into micro-pores when the flux region is larger in extent. The magnetic elements in the plage region are associated with upflows with strong downflows in the immediate vicinity in the low-field region.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html

The current status and future prospects for methods of 3D NLTE radiative transfer are reviewed. Scaling properties and parallelization issues are discussed. Codes of today are capable of solving the diagnostic problem (given model atmosphere) with atomic models of 20-100 levels making possible detailed 3D NLTE determinations of abundances employing 3D LTE model atmospheres. Calculating consistent 3D NLTE radiation hydrodynamic models is orders of magnitude more demanding computationally but methods exist that give a reasonably correct description of the radiation interactions in a statistical sense.

Ceramic composites containing 2 and 5vol. % of nanosized commercially available TiN and SiC particles in alumina were prepared via a water based slurry processing route followed by spark plasma sintering (SPS) at 75 MPa in the temperature range 1200–1600°C. Some of the samples could be fully densified by use of SPS already after five minutes at 1200°C and 75 MPa. The aim was to control the alumina grain growth and thus obtain different nano-structure types. The microstructures have been correlated to some mechanical properties; e.g. hardness and fracture toughness.

The natural state of the Solar chromosphere is very dynamic. Any photospheric disturbance will grow and naturally form shocks over the twenty scale-heights in density between the photosphere and the corona. Observations in the resonance lines from singly ionized calcium and recently in the ultraviolet region of the spectrum observed with the Solar and Heliospheric Observatory satellite also show a very dynamic chromosphere. This dynamic picture is further supported by numerical simulations. Static and dynamic pictures of the chromosphere are fundamentally different. The simulations also show that time variations are crucial for our understanding of the chromosphere itself and for the spectral features formed there.

We have investigated the photoluminescence emission energy of InP dots as a function of cap layer thickness. We find a strong blue-shift with increasing cap layer thickness. The strain tensor in the dot as well as in the surrounding matrix has been modelled using finite element methods and the band-gap has been calculated using deformation potential theory. We find good agreement between calculation and experiment. For uncapped dots we find that the emission energy is lower than for biaxially strained InP, and is indeed close to unstrained InP.

We compare infrared hydrogen lines observed with ATMOS with computations for two models of the solar atmosphere, one without and one with a chromosphere. The weaker H I lines are formed in the photosphere. Proper evaluation of Stark broadening is required to reproduce their profiles; the heavy ion contribution is most important. The cores of the stronger lines are sensitive to the structure of the chromosphere, but detailed NLTE modeling is needed for diagnostic applications.

We review the formation of infrared solar spectral lines from highly excited levels in neutral atoms. The lines of Mg I and H I are the most interesting ones. We explain the NLTE processes by which they are affected and we study the sensitivity of the Mg I 12 μm lines to granulation and to flux tubes.