The theoretical community is beginning to appreciate (and predict) the potential diversity of explosive outcomes from stellar evolution, while the supernovæ surveys are finding new kinds of supernovæ. This talk described two such new supernovæ. The first are ultraluminous core collapse supernovæ with radiated energies approaching 1051 ergs. The talk went on to present our recent work that explains these events with late-time energy deposition from rapidly rotating, highly magnetized neutron stars: magnetars. It concluded with our theoretical work on helium shell detonations on accreting white dwarfs that predict a new class of supernovæ called “.Ia's”. The first such candidate may well have been found by the Palomar Transient Factory.

The interstellar medium constitutes a physically and chemically complex component of galaxies and is important in the cycle of matter and the evolution of stars. From various spectroscopic clues we now know that the interstellar medium is rich in organic compounds. However, identifying the exact nature of all these components remains a challenge. In particular the identification of the so-called diffuse band carriers has been alluding astronomers for almost a century.

In recent decades, observational, experimental and theoretical advances have rapidly lead to renewed interest in the diffuse interstellar bands (DIBs). This has been instigated partly by their perceived relation to the infrared aromatic emission bands, the UV extinction bump and far-UV rise, and the growing number of (small) organic molecules identified in space.

This chapter gives an overview of the observational properties and behaviour of the DIBs, and their presence throughout the Universe. I will highlight recent progress in identifying their carriers and discuss their potential as tracers and probes of (extra)-Galactic ISM conditions.

The Christmas burst, GRB 101225A, was one of the most controversial bursts in the last few years. Its exceptionally long duration but bright X-ray emission showing a thermal component followed by a strange afterglow with a thermal SED lead to two different interpretations. We present here our model ascribing this strange event to a new type of GRB progenitor consisting of a neutron star and an evolved main-sequence star in a very faint galaxy at redshift 0.33 while Campana et al. (2011) proposed a Galactic origin. New observations at several wavelengths might resolve the question between the two models in the near future.

Differential emission measure tomography (DEMT) makes use of extreme ultraviolet (EUV) image series to deliver two products: a) the three-dimensional (3D) reconstruction of the coronal emissivity in the instrumental bands, and b) the 3D distribution of the local differential emission measure (LDEM). The LDEM allows, in turn, construction of 3D maps of the electron density and temperature distribution. DEMT is being currently applied to the space-based EUV imagers, allowing reconstruction of the inner corona in the height range 1.00 to 1.25 R⊙. In this work we applied DEMT to different Carrington Rotations corresponding to the last two solar Cycle minima. To reconstruct the 2008 minimum we used data taken by the Extreme UltraViolet Imager (EUVI), on board the Solar TErrestrial RElations Observatory (STEREO) spacecraft, and to reconstruct the 1996 minimum we used data taken by the Extreme ultraviolet Imaging Telescope (EIT), on board the Solar and Heliospheric Observatory (SOHO). We show here comparative results, discussing the observed 3D density and temperature distributions in the context of global potential magnetic field extrapolations. We also compare the DEMT results with other observational and modeling efforts of the same periods.

Recent studies show that an old stellar population with high metallicity in the monolithic paradigm can explain the UV upturn. Numerical simulations and empirical studies however point out that massive early-type galaxies have evolved hierarchically with an extended star formation history. This obviously has an impact on our traditional understanding on the UV upturn and requires a new investigation on its origin. We report on our investigation on the evolutionary history of model galaxy SEDs in the hierarchical scenario. The use of conventional population models (calibrated to the monolithic picture) in combination with merger trees and extended star formation fails to reproduce the observed UV upturn. If a hierarchical picture is thought to be more realistic than a monolithic one, new calibration on the population models is required.

This paper presents high resolution spectroscopy of the HX Vel (IDS 08390-4744 AB) multiple system. New spectroscopic observations of the system were made at Mt. John University Observatory in 2007 and 2008. Radial velocities of both components of HX Vel A were measured using gaussian fitting. The spectroscopic mass ratio of the close binary was determined as 0.599±0.052, according to a Keplerian orbital solution. The resulting orbital elements are a1sini=0.0098±0.0003 AU, a2sini=0.0164±0.0003 AU, M1sin3i=1.19±0.07 M⊙ and M2sin3i=0.71±0.04 M⊙.

We present a complete study of the morphology of post-Asymptotic Giant Branch (post-AGB) stars. The post-AGB stage is a very short evolutionary phase between the end of the AGB and the beginning of the Planetary Nebula (PN) stage (between 100 and 10,000 yrs). Post-AGB stars do not show variability and are not hot enough to fully ionize the hydrogen envelope. We have defined the end of the post-AGB phase and the beginning of the PN phase when the star has a temperature of 30000 K. Post-AGB stars have a circumstellar shell that is illuminated by the central stars or partially ionized. However, this circumstellar shell is too small to be resolved by ground-based observations. Thus, we have used the Hubble Space Telescope (HST) database to resolve these shells. 117 post-AGBs were found in this database. Here we present the preliminary results on their morphological classification and the correlation with the galactic latitude. Our preliminary results show that 38% of the sample are stellar-like (S), 31% bipolar (B), 12% multipolar (M) and 19% elliptical (E).

HD 49798/RX J0648.0-4418 is the only known X-ray binary composed of a hot subdwarf and a massive white dwarf (M=1.28 ± 0.05 M⊙). This system, with an orbital period of 1.55 days, is the outcome of a common envelope evolution, most likely of a pair of stars with initial masses of ~8–10M⊙. When the hot subdwarf, currently in a He-burning phase, will expand again and fill its Roche-lobe, the enhanced mass transfer can rapidly bring the already massive white dwarf above the Chandrasekhar limit. The possible final fate, either a Type Ia supernova explosion or an accretion induced collapse, is particularly interesting in view of the high rotational velocity of this star, which has the shortest spin period (13s) observed in a white dwarf.

The authors have shown previously that, as viewed from an evident observing point to the west, and a plausible observing point to the east, the Thirteen Towers of Chankillo formed an artificial ‘toothed’ horizon that spanned the annual rising and setting arcs of the sun and provided a means to identify each day in the seasonal year by observing the position of sunrise or sunset against them. The Thirteen Towers thus constitute a unique solar observation device that is still functioning, and a remarkable example of a native form of landscape timekeeping that preceded similar facilities in imperial Cusco by almost two millennia. Yet the social, political, and ritual contexts in which Chankillo's astronomical alignments operated deserve further exploration. In this paper, we present new archaeoastronomical evidence that not only clarifies some aspects of the solar observation device but suggests a wider range of alignments visible from more publicly accessible parts of the ceremonial complex, and also suggests a possible interest in marking lunar alignments as well as solar ones. We also bring together archaeological evidence to suggest that the society that built Chankillo was differentiated. The Thirteen Towers may have served to regulate the calendar, solar and ritual, while the solar cult centred on them may have lent legitimacy and authority to a rising warrior elite through ceremony in an impressive sacred setting that brought society together while reproducing its growing inequality.

Commission 49 (Interplanetary Plasma and Heliosphere) is part of IAU Division II (Sun and Heliosphere). The research topics include large-scale solar disturbances such as coronal mass ejections (CMEs), shocks, and corotating interaction regions (CIRs) propagating into the heliosphere. The disturbances propagate through the solar wind, which essentially defines the heliosphere. The solar disturbances provide large-scale laboratory to study plasma processes over various time and spatial scales, the highest spatial scale being the size of the heliosphere itself (~100 AU). These solar disturbances are related to solar activity in the form of active regions and coronal holes. Solar eruptions are accompanied by particle acceleration and the particles can be hazardous to life on earth in various ways from modifying the ionosphere to damaging space technology and increasing lifetime radiation dosage to astronauts and airplane crew. Particle acceleration in solar eruptions poses fundamental physics questions because the underlying mechanisms are not fully understood. One of important processes is the particle acceleration by shocks, which occurs throughout the heliosphere. The heliosphere has both neutral and ionized material, with interesting interaction between the two components.

The star formation history (SFH) of galaxies is a principle uncertainty in SED modeling, and simple parameterizations of the SFH in typical SED fitting techniques may introduce biases in the resulting derived parameters. It is possible to constrain the SFH of galaxies more tightly through the observations of resolved stellar colour-magnitude diagrams with HST. This work is a first attempt to combine constraints on galaxy SFH from resolved stars with broadband SED modeling from the UV to the IR. This combination allows for the effects of different realistic SFHs on the SED to be quantified.

In close eclipsing binary systems, measurements of the eclipse timing variations (ETV), obtained by means of accurate light curves, may be used to find circumbinary additional objects. The presence of these objects causes the motion of the eclipsing binary with respect to the centre of mass of the entire system and it results in advances or delays in the times of eclipses due to the light time effect. The most important issue of this project is to inspect the potential of detecting low mass substellar companions to close eclipsing binaries through the timing method. For this purpose, we use the public data from Kepler and CoRoT spacecrafts, collecting the light curves for a selected sample and analyzing the observed minus calculated (O-C) times of the eclipses in the search for ETVs and characterizing them. A large amplitude of the O-C ETVs can be explained in some cases by the presence of a third body in the system.

In the core-degenerate (CD) scenario for the formation of Type Ia supernovae (SNe Ia) the Chandrasekhar or super-Chandrasekhar mass white dwarf (WD) is formed at the termination of the common envelope phase or during the planetary nebula phase, from a merger of a WD companion with the hot core of a massive asymptotic giant branch (AGB) star. The WD is destroyed and accreted onto the more massive core. In the CD scenario the rapidly rotating WD is formed shortly after the stellar formation episode, and the delay from stellar formation to explosion is basically determined by the spin-down time of the rapidly rotating merger remnant. The spin-down is due to the magneto-dipole radiation torque. Several properties of the CD scenario make it attractive compared with the double-degenerate (DD) scenario. (1) Off-center ignition of carbon during the merger process is not likely to occur. (2) No large envelope is formed. Hence avoiding too much mass loss that might bring the merger remnant below the critical mass. (3) This model explains the finding that more luminous SNe Ia occur preferentially in star forming galaxies.

Division III, with 1126 members, is the third largest of the 12 IAU Divisions, focusing on subject matter related to the physical study of interplanetary dust, comets, minor planets, satellites, planets, planetary systems and astrobiology. Within the Division are very active working groups that are responsible for planetary system and small body nomenclature, as well as a newly created working group on Near Earth Objects which was established order to investigate the requirements for international ground-and/or space-based NEO surveys to characterize 90% of all NEOs with diameters >40m in order to establish a permanent international NEO Early Warning System.

I provide a synthetic overview of the present status of stellar models for the asymptotic giant branch phase, one of the most complex and still uncertain stages of stellar evolution. In particular I will focus on two aspects that are most relevant in the context of the planetary nebulæ progeny, namely: the chemical composition of the AGB ejecta, and the mass of the bare CO core left after the ejection of the stellar mantle at the AGB tip. Recent progress, present uncertainties, and future perspectives to constrain AGB models are briefly discussed.

Tycho Brahe's observations of a supernova in 1572 challenged the contemporaneous European view of the cosmos that the celestial realm was unchanging. 439 years later we have once again seen the light that Tycho saw, as some of the light from the 1572 supernova is reflected off dust and is only now reaching Earth. These light echoes, as well as ones detected from other transients and variables, give us a very rare opportunity in astronomy: direct observation of the cause (the supernova explosion) and the effect (the supernova remnant) of the same astronomical event. Furthermore, in some cases we can compare light echoes at different angles around a supernova remnant, and thus investigate possible asymmetry in the supernova explosion. In addition, in cases where the scattering dust is favorably positioned, the geometric distance to the SN remnant can be determined using polarization measurements. These techniques have been successfully applied to various transients in the last decade, and the talk gave an overview of the scientific results and techniques, with a particular focus on the challenges we will face in the current and upcoming wide-field time-domain surveys.

On 2009 September 21, a filament eruption and the associated Coronal Mass Ejection (CME) was observed by the STEREO spacecraft. The CME originated from the southern hemisphere and showed a deflection of about 15° towards the heliospheric current sheet (HCS) during its propagation in the COR1 field-of-view (FOV). The aim of this paper is to provide a physical explanation for the strong deflection of the CME. We first use the STEREO observations in order to reconstruct the three dimensional (3D) trajectory of the CME. Starting from a magnetic configuration that closely resembles the potential field extrapolation for that date, we performed numerical magneto-hydrodynamics (MHD) simulations. By applying localized shearing motions, a CME is initiated in the simulation, showing a similar non-radial evolution, structure, and velocity as the observed event. The CME gets deflected towards the current sheet of the larger northern helmet streamer, due to an imbalance in the magnetic pressure and tension forces and finally it gets into the streamer and propagates along the heliospheric current sheet.

An overview of the important thermal and chemical processes in “photon-dominated regions” or “photo-dissociation regions” (PDRs) and “X-ray dominated regions” (XDRs) is presented. Applications of the models are shown to observations of the ultra-luminous infrared galaxy Mrk 231, and the starburst galaxy M 82.

The past decade has seen great progress towards the unmasking of the progenitors of gamma-ray bursts, starting with the unambiguous detection of a supernova in the light of the long-GRB 030329 almost ten years ago, and the discovery of the first afterglows to short-GRBs in 2005. Here I review progress towards unveiling the progenitors of both long and short-duration GRBs. Furthermore, I examine the diverse broader population of GRBs and high energy transients, and suggest that a full consideration of this parameter space leads to the conclusion that additional progenitor models are likely to be needed, if we are to understand the complete view of GRBs and the transient high-energy sky.

The towers, plazas, and fortified temple of Chankillo are analyzed within the context of Central Andean culture. Throughout the cultural area, staircases were apparently the scenes of ritual procession, perhaps mimicking shamanic-like movement between the three worlds. The double stairways of the thirteen towers of Chankillo may have been designed for ritual movement. The gradual rotation of the successively higher towers suggests shamanic ascent between the terrestrial and solar realms. The major astronomical feature of Chankillo is its solar axis, oriented to December solstice sunrise and June solstice sunset. Along this axis, to the east and west of the towers, there are prominent plazas in which public ceremonies may have been staged, particularly at the time of June solstice sunset. Celebrants who reached the highest tower on sunset of June solstice would have been silhouetted by the setting sun as viewed by spectators in the eastern plaza just below the tower. In the large plaza west of the towers, a similar public ceremony could have been associated with setting of the June solstice sun over the Temple of the Pillars to the west of the towers. The thirteen towers may have been stations of the moon for public ceremonies during the bright half of the lunar cycle. The presence of Spondylus shells suggests lunar ritual. The duality of private/public ritual, evident at Chavín and elsewhere, may have been present at Chankillo where public ceremonies may been observed from the plazas, while more restricted ceremonies may have occurred behind the walls of the fortified temple. If a horizon calendar had been developed using the profiles of the thirteen towers, it appears to have been an unintended consequence of the initial design of the towers. The monumental size of the towers is incommensurate with the small putative observing stations. The June solstice sun misses the lowest tower by 7 solar diameters, which would have been an unacceptable error if the tower had been built originally to mark June solstice. Another unsatisfactory feature would have been the equal spacing of the towers. If a meaningful calendar had been desired that marked divisions of the year perhaps based upon the moon, it would have involve variable spacing of the towers, with the largest spacing around equinox.