We present multifrequency VLBI observations of the blazars 3C273 and 3C279 after detecting strong γ-ray flares in both of them. 3C273 exhibited a prominent flare in γ-rays in September 2009 which was followed by a strong flare in the 7 mm VLBI core and emergence of a new feature in the parsec scale jet. We have used time delay between flares in different wavebands together with kinematic analysis to determine that the γ-ray emission zone in 3C273 is located 3.6-5.3 pc upstream from the apparent 7 mm core. We have also analyzed frequency dependent core position to measure a deprojected distance between 7 mm core and the true base of the jet: 1-6 pc for 3C273 and 1-3 pc for 3C279, depending on observing epoch. For 3C279 light curve analysis did not give a robust γ-radio delay because there were too many overlapping flares in this source during considered period.

The triennial meeting of Commission 4 was attended by 16 people. All of the presentations from the meeting are provided on the commission website at http://www.iaucom4.org/c4docs.html, so this report provides only summaries.

We propose a Bayesian method to measure the total Galactic extinction parameters, RV and AV. Validation tests based on the simulated data indicate that the method can achieve the accuracy of around 0.01 mag. We apply this method to the SDSS BHB stars in the northern Galactic cap and find that the derived extinctions are highly consistent with those from Schlegel et al. (1998). It suggests that the Bayesian method is promising for the extinction estimation, even the reddening values are close to the observational errors.

We use radar images with decameter resolution to measure the sizes, shapes, spin states, mutual orbits, masses, and densities of components of asteroid binaries and triples. We simulate the spin-orbit dynamics of these systems and map the possible spin configurations of the satellites on surface of section plots. The presence of chaotic regions in the phase space has important consequences for the evolution of binary asteroids. It may substantially increase spin synchronization timescales, delay BYORP-type evolution, and extend the lifetime of binaries.

We discuss some results for mass profiles that we have obtained from hydrostatic studies of the hot gas in isolated, massive elliptical galaxies.

Supermassive black hole binaries (SMBHBs) are the products of frequent galaxy mergers. It is very hard to be detected in quiescent galaxy. By using one million particle direct N-body simulations on special many-core hardware (GPU cluster), we study the dynamical co-evolution of SMBHB and its surrounding stars, specially focusing on the evolution of stellar tidal disruption event (TDE) rates before and after the coalescence of the SMBHB. We find a boosted TDE rate during the merger of the galaxies. After the coalescence of two supermassive black holes (SMBHs), the post-merger SMBH can get a kick velocity due to the anisotropic GW radiations. Our results about the recoiling SMBH, which oscillates around galactic center, show that most of TDEs are contributed by unbound stars when the SMBH passing through galactic center. In addition, the TDE light curve in SMBHB system is significantly different from the curve for single SMBH, which can be used to identify the SMBHB.

Here I present results from individual galaxy studies and galaxy surveys in the Local Universe with particular emphasis on the spatially resolved properties of neutral hydrogen gas. The 3D nature of the data allows detailed studies of the galaxy morphology and kinematics, their relation to local and global star formation as well as galaxy environments. I use new 3D visualisation tools to present multi-wavelength data, aided by tilted-ring models of the warped galaxy disks. Many of the algorithms and tools currently under development are essential for the exploration of upcoming large survey data, but are also highly beneficial for the analysis of current galaxy surveys.

We summarise the motivations and main results of the joint discussion “3D Views of the Cycling Sun in Stellar Context”, and give credit to contributed talks and poster presentations, as due to the limited number of pages, this proceedings could only include contributions from the keynote speakers.

The role of magnetic fields in late type stars, such as Asymptotic Giant Branch stars (AGBs), Post-AGBs and Planetary Nebulae (PNe), is poorly known from an observational point of view. Magnetic fields are however believed to have a non-negligible influence on the dynamics (via mass loss control, outflows shaping) and even on the chemistry (e.g. extra mixing) of these stellar objects. We are therefore presenting two different types of investigation, both based on the use of polarimetry, which aim at filling the gap between the observations on the one hand and the theoretical predictions on the other hand.

In this contribution talk we summarize the results of our ongoing project of detailed analysis of the chemical content (chemical tagging) as a promising powerful method to provide clear constraints on the membership of FGK kinematic candidates to stellar kinematic groups of different ages that can be used as an alternative or complementary to the methods that use kinematics, photometry or age indicators. This membership information is very important to better understand the star formation history in the solar neighborhood discerning between field-like stars (associated with dynamical resonances (bar) or spiral structure) and real physical structures of coeval stars with a common origin (debris of star-forming aggregates in the disk). We have already applied the chemical tagging method to constrain the membership of FGK candidate stars to the Hyades supercluster and the Ursa Major moving group and in this contribution we present the preliminary results of our study of the Castor moving group.

We model numerically the evolution of 104M⊙ turbulent molecular clouds in near-radial infall onto 106M⊙, equal-mass supermassive black hole binaries, using a modified version of the SPH code gadget-3. We investigate the different gas structures formed depending on the relative inclination between the binary and the cloud orbits. Our first results indicate that an aligned orbit produces mini-discs around each black hole, almost aligned with the binary; a perpendicular orbit produces misaligned mini-discs; and a counter-aligned orbit produces a circumbinary, counter-rotating ring.

I present an overview of new observations of atomic and molecular gas in early-type galaxies, focusing on the Atlas3D project. Our data on stellar kinematics, age and metallicity, and ionized gas kinematics allow us to place the cold gas into the broader context of early-type galaxy assembly and star formation history. The cold gas data also provide valuable constraints for numerical simulations of early-type galaxies.

President of Commission 7 Zoran Knežević opened the business meeting at 18:40 and proposed the agenda which was accepted without change.

We present a self-consistent, absolute isochronal age scale for young (≲ 200 Myr), nearby (≲ 100 pc) moving groups, which is consistent with recent lithium depletion boundary ages for both the β Pic and Tucana-Horologium moving groups. This age scale was derived using a set of semi-empirical pre-main-sequence model isochrones that incorporate an empirical colour-Teff relation and bolometric corrections based on the observed colours of Pleiades members, with theoretical corrections for the dependence on logg. Absolute ages for young, nearby groups are vital as these regions play a crucial role in our understanding of the early evolution of low- and intermediate-mass stars, as well as providing ideal targets for direct imaging and other measurements of dusty debris discs, substellar objects and, of course, extrasolar planets.

A new non-parametric method based on Gaussian Processes (GP) was proposed recently to measure the Hubble constant H0. The freedom in this approach comes in the chosen covariance function, which determines how smooth the process is and how nearby points are correlated. We perform coverage tests with a thousand mock samples within the ΛCDM model in order to determine what covariance function provides the least biased results. The function Matérn(5/2) is the best with sligthly higher errors than other covariance functions, although much more stable when compared to standard parametric analyses.

Precise data from instrumental observations of fireballs, especially those for really bright bolides, provide information about the population and physical properties of meteoroids, i.e. fragments of asteroids and comets, colliding with the Earth's atmosphere. An overview of what is known about meteoroids and their parent bodies from analysis of bolides producing meteorite falls, especially from the instrumentally observed meteorite falls, was a topic of this invited contribution. At present, atmospheric and orbital information with different degree of reliability and precision for these meteorite falls is known for only 24 cases. This topic was described in detail in the review work of Borovička, Spurný and Brown (2015) (Borovička et al., 2015). However, this work contains all instrumentally documented falls until end of 2013. To bring this work up to date, two new instrumentally observed meteorite falls in 2014, the Annama meteorite fall in Russia on 18 April 2014 and the Žďár nad Sázavou meteorite fall in the Czech Republic on 9 December 2014, are presented and commented in this paper. Especially the second case is mentioned in more detail including still unpublished data. Statistical analyses resulting from all 24 instrumentally documented falls are also mentioned.

AGN reverberate when the broad emission lines respond to changes of the ionizing thermal continuum emission. Reverberation measurements have been commonly used to estimate the size of the broad-line region (BLR) and the mass of the central black hole. However, reverberation mapping studies have been mostly performed on radio-quiet sources where the contribution of the jet can be neglected. In radio-loud AGN, jets and outflows may affect substantially the relation observed between the ionizing continuum and the line emission. To investigate this relation, we have conducted a series of multi-wavelength studies of radio-loud AGN, combining optical spectral line monitoring with regular VLBI observations. Our results suggest that at least a fraction of the broad-line emitting material can be located in a sub-relativistic outflow ionized by non-thermal continuum emission generated in the jet at large distances (> 1 pc) from the central engine of AGN. This finding may have a strong impact on black hole mass estimates based on measured widths of the broad emission lines and on the gamma-ray emission mechanisms.

In this contribution I show that by combining imaging and integral-field spectroscopy it is possible to unravel the internal structure of galaxies. In particular, I will present the photometric and kinematic evidence for discs linking them with stellar angular momentum content of early-type galaxies. Furthermore, I show that the existence of both fast rotators with core and slow rotators with core-less nuclear light profiles challenges the standard formation scenarios for fast and slow rotators and suggests new pathways of mass assembly.

The almost stately evolution of the global heliospheric magnetic field pattern during most of the solar cycle belies the intense dynamic interplay of photospheric and coronal flux concentrations on scales both large and small. The statistical characteristics of emerging bipoles and active regions lead to development of systematic magnetic patterns. Diffusion and flows impel features to interact constructively and destructively, and on longer time scales they may help drive the creation of new flux. Peculiar properties of the components in each solar cycle determine the specific details and provide additional clues about their sources. The interactions of complex developing features with the existing global magnetic environment drive impulsive events on all scales. Predominantly new-polarity surges originating in active regions at low latitudes can reach the poles in a year or two. Coronal holes and polar caps composed of short-lived, small-scale magnetic elements can persist for months and years. Advanced models coupled with comprehensive measurements of the visible solar surface, as well as the interior, corona, and heliosphere promise to revolutionize our understanding of the hierarchy we call the solar magnetic field.

Full Stokes spectropolarimetric observations of a Mira star (χ Cyg) and a RV Tauri star (R Sct) are presented and analyzed comparatively. From their Stokes V data (circular polarization), we report the detection of a weak magnetic field at the surface of these cool and evolved radially pulsating stars. For both stars, we analyse this detection in the framework of their complex atmospheric dynamics, with the possibility that shock waves may imprint an efficient compressive effect on the surface magnetic field. We also report strong Stokes U and Stokes Q signatures associated to metallic lines (as a global trend), those linear polarimetric features appear to be time variable along the pulsating phase. More surprising, in the Stokes U and Stokes Q data, we also detect signatures associated to individual metallic lines (such as Sr i 460.7 nm, Na D2588.9 nm), that are known (from the solar case) to be easily polarizable in case of a global asymmetry at the photospheric level.