Magnetic helicity is a quantity that describes the linkage and twistedness/shear in the magnetic field. It has the unique feature that it is probably the only physical quantity which is approximately conserved even in resistive MHD. This makes magnetic helicity an ideal tool for the exploration of the physics of eruptive events. The concept of magnetic helicity can be used to monitor the whole history of a CME event from the emergence of twisted magnetic flux from the convective zone to the eruption and propagation of the CME into interplanetary space. In this article, I discuss the sources of the magnetic helicity injected into active regions and the role of magnetic helicity in the initiation of solar eruptions.

Magnetic fields are believed to play an important role in star formation. We observed M42 and Mon R2 massive star forming regions using the wide-field (8′ × 8′) near-infrared imaging polarimeter SIRPOL in South Africa. Magnetic fields are mapped on the basis of dichroic polarized light from hundreds of young stars embedded in the regions. We found “hourglass shaped” magnetic field structure toward OMC-1 region, which is very consistent with magnetic fields traced by using dust emission polarimetry at sub-mm to FIR wavelengths. In the Mon R2 region, we found “S-shaped” magnetic field structure across the massive protostar IRS 1 and IRS 2. We will present the results of comparison of magnetic fields at NIR with those at other wavelengths.

The HST proper motion (PM) measurements of the Clouds have severe implications for their interaction history with the Milky Way (MW) and with each other. The Clouds are likely on their first passage about the MW and the SMC's orbit about the LMC is better described as quasi-periodic rather than circular. Binary L/SMC orbits that satisfy observational constraints on their mutual interaction history (e.g., the formation of the Magellanic Bridge during a collision between the Clouds ~300 Myr ago) can be located within 1σ of the mean PMs. However, these binary orbits are not co-located with the Magellanic Stream (MS) when projected on the plane of the sky and the line-of-sight velocity gradient along the LMC's orbit is significantly steeper than that along the MS. These combined results ultimately rule out a purely tidal origin for the MS: tides are ineffective without multiple pericentric passages and can neither decrease the velocity gradient nor explain the offset stream in a polar orbit configuration. Alternatively, ram pressure stripping of an extended gaseous disk may naturally explain the deviation. The offset also suggests that observations of the little-explored region between RA 21h and 23h are crucial for characterizing the full extent of the MS.

Open clusters have long been objects of interest in astronomy. As a good approximation of essentially pure stellar populations, they have proved very useful for studies in a wide range of astrophysically interesting questions, including stellar evolution and atmospheres, the chemical and dynamical evolution of our Galaxy, and the structure of our Galaxy. Of fundamental importance to our understanding of open clusters is accurate determinations of cluster ages. Currently there are two main techniques for independently determining the ages of stellar populations: main sequence evolution theory (via cluster isochrones) and white dwarf cooling theory. We will provide an overview of these two methods, the current level of agreement between them, as well as a look to the current state of increasing precision in the determination of each. Particularly I will discuss the comprehensive data set collection that is being done by the WIYN Open Cluster Study, as well as a new Bayesian statistical technique that has been developed by our group and its applications in improving and determining white dwarf ages of open clusters. I will review the so-called bright white dwarf technique, a new way of measuring cluster ages with just the bright white dwarfs. I will discuss the first application of the Bayesian technique to the Hyades, also demonstrating the first successful application of the bright white dwarf technique. These results bring the white dwarf age of the Hyades into agreement with the main sequence turn off age for the first time.

Radial Velocity follow-up is essential to establish or exclude the planetary nature of a transiting companion as well as to accurately determine its mass. Here we present some elements of an efficient Doppler follow-up strategy, based on high-resolution spectroscopy, devoted to the characterization of transiting candidates. Some aspects and results of the radial velocity follow-up of the CoRoT space mission are presented in order to illustrate the strategy used to deal with the zoo of transiting candidates.

Commission 12 encompasses investigations on the internal structure and dynamics of the Sun, mostly accessible through the techniques of local and global helioseismology, the quiet solar atmosphere, solar radiation and its variability, and the nature of relatively stable magnetic structures like sunspots, faculae and the magnetic network. A revision of the progress made in these fields is presented. For some specific topics, the review has counted with the help of experts outside the Commission Organizing Committee that are leading and/or have recently presented relevant works in the respective fields. In this cases the contributor's name is given in parenthesis.

Current numerical studies suggest that the first protogalaxies formed a few stars at a time and were enriched only gradually by the first heavy elements. However, these models do not resolve primordial supernova (SN) explosions or the mixing of their heavy elements with ambient gas, which could result in intervening, prompt generations of low-mass stars. We present multiscale 1D models of Population III supernovae in cosmological minihalos that evolve the blast from its earliest stages as a free expansion. We find that if the star ionizes the halo, the ejecta strongly interacts with the dense shell swept up by the H II region, potentially cooling and fragmenting it into clumps that are gravitationally unstable to collapse. If the star fails to ionize the halo, the explosion propagates metals out to 20 - 40 pc and then collapses, heavily enriching tens of thousands of solar masses of primordial gas, in contrast to previous models that suggest that such explosions ‘fizzle’. Rapid formation of low-mass stars trapped in the gravitational potential well of the halo is unavoidable in these circumstances. Consequently, it is possible that far more stars were swept up into the first galaxies, at earlier times and with distinct chemical signatures, than in present models. Upcoming measurements by the James Webb Space Telescope (JWST) and Atacama Large Millimeter Array (ALMA) may discriminate between these two paradigms.

In recent years buckyonions have been suggested as a carrier of the 2175 Å interstellar extinction feature, based on the close similarity between the electronic transition spectra of buckyonions and the 2175 Å interstellar extinction feature. We examine this hypothesis by calculating the interstellar extinction with buckyonions as a dust component. It is found that dust models containing buckyonions (in addition to amorphous silicates, PAHs, graphite or amorphous carbon) can closely reproduce the observed interstellar extinction curve. However, a more severe challenge to the buckyonion hypothesis is provided by the non-detection of the ~7–8 μm C–H stretching bands expected from buckyonions in the diffuse interstellar medium. This will allow us to place an upper limit on the abundance of buckyonions.

I will first discuss abundance gradients in the Milky Way and nearby disk galaxies, then the problem of substructures in the Galactic Disk, and finally some new opportunities for investigating substructure in disks.

Thermohaline mixing has recently been proposed to occur in low mass red giants, with large consequences for the chemical yields of low mass stars. We investigate the role of thermohaline mixing during the evolution of stars between 1 M⊙ and 3 M⊙, in comparison to other mixing processes acting in these stars. We confirm that thermohaline mixing has the potential to destroy most of the 3He which is produced earlier on the main sequence during the red giant stage. In our models we find that this process is working only in stars with initial mass M ≲ 1.5 M⊙. Moreover, we report that thermohaline mixing can be present during core helium burning and beyond in stars which still have a 3He reservoir. While rotational and magnetic mixing is negligible compared to the thermohaline mixing in the relevant layers, the interaction of thermohaline motions with differential rotation and magnetic fields may be essential to establish the time scale of thermohaline mixing in red giants.

We present a new iodine cell based approach that allows one to obtain radial velocities of the components of double-lined spectroscopic binary stars (SB2s) with a precision reaching 5 m/s. Such an RV precision is up to 100 times better than what is currently available in the literature for the SB2s. We discuss the applications of our method to the radial velocity searches for circumbinary planets and spectroscopic follow-up of transiting planet candidates around eclipsing binary stars.

I discuss the following five selected topics on formation and evolution of the LMC and the SMC based on fully self-consistent chemodynamical simulations of the Magellanic Clouds (MCs): (1) formation of bifurcated gaseous structures and young stars in the Magellanic bridge (MB), (2) formation of the Magellanic stream (MS) due to the tidal interaction between the LMC, the SMC, and the Galaxy within the last 2 Gyrs, (3) origin of the observed kinematical differences between H i gas and stars in the SMC, (4) formation of stellar structures dependent on their ages and metallicities in the LMC, and (5) a new common halo model explaining both the latest HST ACS observations on the proper motions of the LMC and the SMC and the presence of the MS in the Galactic halo. I focus exclusively on the latest developments in numerical simulations on formation and evolution of the Magellanic system.

Commission 49 covers research on the solar wind, shocks and particle acceleration, both transient and steady-state, e.g., corotating, structures within the heliosphere, and the termination shock and boundary of the heliosphere.

We present observations of the high mass star forming region S88B taken with the VLA with the aim of measuring magnetic fields via the Zeeman effect. By observing thermal absorption lines of OH at 1665 and 1667 MHz, we obtain magnetic fields between 90 and 210 μG. We find these magnetic fields to be dynamically significant in this region.

Encircling the Milky Way at low latitudes, the Low Latitude Stream is a large stellar structure, the origin of which is as yet unknown. As part of the SEGUE survey, several photometric scans have been obtained that cross the Galactic plane, spread over a longitude range of 50° to 203°. These data allow a systematic study of the structure of the Galaxy at low latitudes, where the Low Latitude Stream resides. We apply colour-magnitude diagram fitting techniques to map the stellar (sub)structure in these regions, enabling the detection of overdensities with respect to smooth models. These detections can be used to distinguish between different models of the Low Latitude Stream, and help to shed light on the nature of the system.

For the purpose of understanding the dynamics of planetary atmospheres, we use the annular convection model to simulate the dynamics of atmospheres of Jupiter and Saturn. The model (annular channel) rotates about a vertical axis with side-walls, and it is heated from below.

We use the software NaSt3DGP (a parallel software package to solve the 3D incompressible fluid dynamic problems in Cartesian coordinates by using Finite Difference Method) for the computation. It's reliability is tested by our application to simulate fully three-dimensional nonlinear convection in a box with lateral stress-free side-walls, uniformly heated from below. We found that, at moderately large Rayleigh numbers, the complex formation of multiple-jet flows can be maintained by the traveling convective eddies; we also found that the type of the sidewall velocity condition does not play an essential role in determining the primary properties of strongly nonlinear convection.

TAUVEX is an Indo-Israeli collaborative mission to make photometric observations in the UV region. Using the narrowband filters positioned near 2175 Å feature, we plan to construct the UV bump in the extinction curve towards B type stars brighter than mv = 14. Archival data of TD1, Galex missions are used for stars brighter than mv = 10. We sample the distance to obtain the extintion at different location of the local ISM upto 2 kpc. Using a dust model having silicate, graphite and PAH as components, the extinction curve at different location of the Galaxy is fitted to constrain the dust characteristics.

The Bologna Open Cluster Chemical Evolution (BOCCE) project is a photometric and spectroscopic survey of open clusters, to be used as tracers of the Galactic disk properties and evolution. The clusters parameters (age, distance, reddening, metallicity, and detailed abundances) are derived in a precise and homogeneous way. This will contribute to a solid, reliable description of the disk: the clusters parameters will be used, for instance, to determine the metallicity distribution in the Galactic disk and how it has evolved with time. We have concentrated on old open clusters and we have presently in our hands data for about 40 open clusters; we have fully analyzed the photometric data for about one half of them and the spectra for one quarter of them.

Recent work on coronal polar plumes (Gabriel et al. 2003, 2005) has aimed at determining the outflow velocity in plume and interplume regions, using the Doppler dimming technique on oxygen VI observations by SUMER and UVCS on SOHO. By comparing observations of SOHO/EIT with plume modelling, we show that the major part of plumes is the result of chance alignments along the line-of-sight of small enhancements in intensity. This confirms the so-called curtain model. These plumes can be attributed to reconnection activity along the boundaries of supergranule cells. A second population of plumes has a lower abundance and arises from surface bright points having a particular magnetic configuration. New observations using the Hinode/EIS spectrometer are in progress, with the aim of providing further insight for this model.

We review the current state of knowledge of damped Lyα systems (DLAs) selected in absorption on quasar sightlines. These objects are extremely useful to study the interstellar medium of high-redshift galaxies and the nucleosynthesis in the early Universe. The characteristics of this galaxy population has been investigated for years and slowly we are getting information on their puzzling nature. Imaging at z <1 shows that DLAs are associated with a mixing bag of galaxies with no especially large contribution from dwarf galaxies. Evidence for a mild evolution of the cosmic mean metallicity with time is observed. The star formation histories of these high-redshift galaxies begin to be accessible and indicate that DLAs tend to be young, gas-dominated galaxies with low star formation rates per unit area. Finally, indirect estimation of the DLA stellar masses from the mass-metallicity relations observed for emission-selected star-forming galaxies at z = 2−3 points to intermediate-mass galaxies with M* < 109M⊙.