There is a general agreement that Type Ia supernovae correspond to the thermonuclear runaway of a white dwarf (WD) in a compact binary. The details of these progenitor systems are still unclear. Using the population synthesis code SeBa and several assumption for the WD retention efficiency, we estimate the delay times and supernova rates for the single degenerate scenario.

Accretion disks around some white dwarfs in Cataclysmic Variables are thought to tilt around the line of nodes by the lift force acting at the disk's center of pressure. We investigate whether protoplanetary disks can also experience disk tilt. We find that lift may be possible by an asymmetric, net uni-directional, in-falling gas/dust stream overflowing a bluff body (e.g., Class I sources) or inner annuli of young Class II sources if gas/dust is still in-falling and the aspect ratio and disk surface area are large enough. However, inner disks of Class II sources LkCa 15, UX Tau A, and Rox 44 are not large enough, and therefore disk tilt is not likely.

We present a general three-dimensional model of multipolar planetary nebulae (PNe). By rotating to different viewing angles and adjusting the angles between the multiple lobes, we demonstrate that the model is able to reproduce HST Hα images of 20 multipolar young PNe. Though this model only considers the geometrical projection effects, it significantly unifies the selected PNe and can be considered as a first-order fundamental model of the “multipolar” morphological class. This kind of model reduces complexity and is essential to pursuing of the shaping mechanism. In addition, we illustrate that under some special conditions, i.e. in certain viewing angles, or with low sensitivity, it will be hard to imagine that the projected image originates from a multipolar-lobed model.

Among the possible progenitor scenarios considered for Type Ia supernovae, those that involve a carbon–oxygen white dwarf (CO WD) accreting stably towards the Chandrasekhar mass should undergo a phase of hydrostatic carbon burning under high densities and strong convection: the simmering or carbon–flash phase, which can extend for a few hundred years before explosion. During this phase the progenitor CO WD can burn a small fraction of its carbon hydrostatically, releasing energy and ashes that make the star convective and able to capture electrons from the degenerate plasma. In this work we present simplified pre–supernova evolution models of CO WDs growing towards the Chandrasekhar mass accreting matter stably and evolving through the simmering phase towards ignition in order to explore the effects of different initial masses and cooling times in the final chemical composition of the WD before explosion. Preliminary results show that, as expected, denser systems at the start of the simmering phase undergo stronger neutronization. The amount of neutronization is less than what is found in the one–zone models of Chamulak et al. (2008), about a third, and can vary by about a factor of two depending on the exact path to explosion.

High velocity jets are among the most prominent features of a wide class of planetary nebulae, but their origins are not understood. Several different types of physical models have been suggested to power the jets, but there is no consensus or preferred scenario. We compare current theoretical ideas on jet formation with observations, using the best studied pre–planetary nebulae in millimeter CO, where the dynamical properties are best defined. In addition to the mass, velocity, momentum, and energy of the jets, the mass and energetics of the equatorial mass-loss that typically accompanies jet formation prove to be important diagnostics. Our integrated approach provides estimates for some key physical quantities – such as the binding energy of the envelope when the jets are launched – and allows testing of model features using correlations between parameters. Even with a relatively small sample of well-observed objects, we find that some specific scenarios for powering jets can be ruled out or rendered implausible, and others are promising at a quantitative level.

The 2D and 3D Doppler tomograms of X-ray binary system Cyg X-1 (V1357 Cyg) were reconstructed from spectral data for the line HeII 4686Å obtained with 2-m telescope of the Peak Terskol Observatory (Russia) and 2.1-m telescope of the Mexican National Observatory in June, 2007. Information about gas motions outside the orbital plane, using all of the three velocity components Vx, Vy, Vz, was obtained for the first time. The tomographic reconstruction was carried out for the system inclination angle of 45°. The equal resolution (50 × 50 × 50 km/s) is realized in this case, in the orbital plane (Vx, Vy) and also in the perpendicular direction Vz. The checkout tomograms were realized also for the inclination angle of 40° because of the angle uncertainty. Two versions of the result showed no qualitative discrepancy. Details of the structures revealed by the 3D Doppler tomogram were analyzed.

The spectral disentangling technique makes possible separation of individual component spectra in binary or multiple systems, and determination of the orbital elements in a self-consistent way. Since its introduction, a number of variants of their basic idea have been implemented. We present yet another ‘direct’ approach using optimization by genetic algorithm. Starting with an initial random flux distribution representing individual spectra, genetic optimization returns both individual component spectra and an optimal set of orbital parameters only constrained by time-series of the observed composite spectra of the binary system. Benchmark tests on V453 Cyg, which is an eclipsing binary with total eclipse, as well as tests on the artificial time-series spectra, have proven that ‘constrained genetic disentangling’ is performing correctly and efficiently, albeit with high demand on CPU time. Since genetic optimization can be easily parallelized, we expect our second release to run on cluster in a less time-consuming way.

We present our analysis of the spectra of NGC 7027 taken with the PACS and SPIRE instruments of the Herschel satellite.

The San Pedro Mártir kinematic catalogue of galactic planetary nebulae provides spatially resolved, long-slit, Echelle spectra for about 600 planetary nebulae, representing 55 observing runs and about 4000 individual integrations to date in this first release. The project is ongoing and will continue adding spectra to the database. The data are presented wavelength calibrated and corrected for heliocentric motion. This is the most extensive and homogeneous single source of data concerning the internal kinematics of the ionized nebular material in planetary nebulae. The catalogue is available through the world wide web at http://kincatpn.astrosen.unam.mx and an article will a full description of the catalogue will soon appear in the RevMexAA.

Recurrent novae (RNe) belong to the group of cataclysmic variables that exhibit nova outbursts at intervals on the order of decades. They are rare, with 10 Galactic RNe known to date. Two are known in the LMC, while there are a few suspected RNe in M31. Nova outburst models require a high accretion rate on a massive white dwarf to explain the recurring nova outbursts, making this class of objects one of the most likely progenitor binary systems of Type Ia supernovae. The observational properties of the known Galactic recurrent novae are presented here, together with some discussion on the recent outbursts of RS Ophiuchi (2006), U Scorpii (2010), and T Pyxidis (2011).

Current and planned telescope systems (both on the ground and in space) as well as new technologies will be discussed with emphasis on their impact on the studies of binary star and exoplanet systems. Although no telescopes or space missions are primarily designed to study binary stars (what a pity!), several are available (or will be shortly) to study exoplanet systems. Nonetheless those telescopes and instruments can also be powerful tools for studying binary and variable stars. For example, early microlensing missions (mid-1990s) such as EROS, MACHO and OGLE were initially designed for probing dark matter in the halos of galaxies but, serendipitously, these programs turned out to be a bonanza for the studies of eclipsing binaries and variable stars in the Magellanic Clouds and in the Galactic Bulge. A more recent example of this kind of serendipity is the Kepler Mission. Although Kepler was designed to discover exoplanet transits (and so far has been very successful, returning many planetary candidates), Kepler is turning out to be a “stealth” stellar astrophysics mission returning fundamentally important and new information on eclipsing binaries, variable stars and, in particular, providing a treasure trove of data of all types of pulsating stars suitable for detailed Asteroseismology studies. With this in mind, current and planned telescopes and networks, new instruments and techniques (including interferometers) are discussed that can play important roles in our understanding of both binary star and exoplanet systems. Recent advances in detectors (e.g. laser frequency comb spectrographs), telescope networks (both small and large – e.g. Super-WASP, HAT-net, RoboNet, Las Combres Observatory Global Telescope (LCOGT) Network), wide field (panoramic) telescope systems (e.g. Large Synoptic Survey Telescope (LSST) and Pan-Starrs), huge telescopes (e.g. the Thirty Meter Telescope (TMT), the Overwhelming Large Telescope (OWL) and the Extremely Large Telescope (ELT)), and space missions, such as the James Webb Space Telescope (JWST), the possible NASA Explorer Transiting Exoplanet Survey Satellite (TESS – recently approved for further study) and Gaia (due for launch during 2013) will all be discussed. Also highlighted are advances in interferometers (both on the ground and from space) and imaging now possible at sub-millimeter wavelengths from the Extremely Long Array (ELVA) and Atacama Large Millimeter Array (ALMA). High precision Doppler spectroscopy, for example with HARPS, HIRES and more recently the Carnegie Planet Finder Spectrograph, are currently returning RVs typically better than ~2-m/s for some brighter exoplanet systems. But soon it should be possible to measure Doppler shifts as small as ~10-cm/s – sufficiently sensitive for detecting Earth-size planets. Also briefly discussed is the impact these instruments will have on the study of eclipsing binaries, along with future possibilities of utilizing methods from the emerging field of Astroinformatics, including: the Virtual Observatory (VO) and the possibilities of analyzing these huge datasets using Neural Network (NN) and Artificial Intelligence (AI) technologies.

Using new, high signal-to-noise CFHT ESPaDOnS visual spectrograms, and archive IUE and FUSE UV spectrograms, together with state-of-the-art non-LTE hydrodynamical model atmospheres, we have obtained accurate He, C, N, O photospheric abundance determinations in the central stars of NGC 2392, IC 4593, and NGC 6826. We compare with the corresponding nebular abundances, taken from the literature. The central star of NGC 2392 shows high He, N, and very low C, O abundances. We propose that these peculiar abundances must have originated in a common-envelope phase of interaction with a close binary companion. If we assume that the companion is more evolved than the visible central star, this offers a way of solving the old mystery of the discrepant He II Zanstra temperature of NGC 2392.

It is important to properly describe the mass-loss rate of AGB stars, in order to understand their evolution from the AGB to PN phase. The primary goal of this study is to investigate the influence of metallicity on the mass-loss rate, under well determined luminosities. The luminosity of the star is a crucial parameter for the radiative driven stellar wind. Many efforts have been invested to constrain the AGB mass-loss rate, but most of the previous studies use Galactic objects, which have poorly known distances, thus their luminosities. To overcome this problem, we have studied mass loss from AGB stars in the Galaxies of the Local Group. The distance to the stars have been independently measured, thus AGB stars in these galaxies are ideal for understanding the mass-loss rate. Moreover, these galaxies have a lower metallicity than the Milky Way, providing an ideal target to study the influence of metallicity on the mass-loss rate. We report our analysis of mass loss, using the Spitzer Space Telescope and the Herschel Space Observatory. We will discuss the influence of AGB mass-loss on stellar evolution, and explore AGB and PN contribution to the lifecycle of matter in galaxies.

An archival search for extragalactic novae was carried out using the data obtained with the Hubble Space Telescope (HST). Twenty-seven galaxies were examined where most of the targets are beyond the Local Group. Nova rates were calculated for the target galaxies and combined with other known nova rates to show dependence on galaxy types. Here we present the nova detections for six galaxies from our object list.

We examine the abundance gradient in the Milky Way disk via homogeneously determined data for 124 Galactic planetary nebulae (PNe). We present recent results from a detailed regression analysis of the O gradient. With O, Ne, S, Cl, and Ar available and a range of galactocentric distance (R g ) from 0.9 to 21 kpc, we present additional exploration of the disk radial gradient by statistically analyzing a series of short segments of increasing average R g .

The observational techniques applied to the study of binary stars, brown dwarfs, and exoplanets are summarized in this paper.

The study of the chemical composition of Planetary Nebulae in external galaxies is of paramount importance for the fields of stellar evolution and chemical enrichment history of galaxies. In recent years a number of spectroscopic studies with 6-8m-class telescopes have been devoted to this subject improving our knowledge of, among other, the time-evolution of the radial metallicity gradient in disk galaxies, the chemical evolution of dwarf galaxies, and stellar evolution at low metallicity.

We are extending our search for faint PNe in the LMC to include the outer 56 deg2 area not covered in the original UKST survey of the central 25eg2 region. Candidate PNe have been selected using the Magellanic Cloud Emission Line Survey (MCELS) and the first round of observations has yielded 93 new LMC PNe while confirming the 102 previously known PNe in the outer LMC. We plan to continue our spectroscopic object identification program until we cover all our remaining candidates in the survey area. These observations, providing medium and high resolution spectra from λ3650Å to λ6900Å will additionally be used to measure fluxes for a series of research projects including luminosity functions, abundances and LMC kinematics.

The Local Group dwarf irregular galaxy IC 10 is the nearest starburst galaxy (at 725 kpc) and presents extended and complex HI kinematics. It is believed that IC 10 is still experiencing an intense and very recent burst of star formation, likely triggered by infalling gas from an extended envelope which is counter-rotating with respect to the galaxy proper rotation. In this contribution we summarize our preliminary results (Gonçalves et al. 2011, in prep.) obtained by performing a kinematic analysis of the PN population of IC 10. Our aim is to explore the kinematic connection of its intermediate to old stellar populations with that obtained from HI observations. Some PNe were found at large galactocentric distances and could therefore represent a trace of past tidal interactions.

The ESO VLT spectrograph X-shooter is currently the only one capable of observing the range from 330 nm up to 2.5 μm in a single shot. X-shooter is very suitable for study of the many diagnostic emission lines in PN providing a uniform flux scale at medium resolution over a large instantaneous wavelength range. Spectroscopy of two contrasting PNe, NGC 6302 and M 2-9, were observed and methods explored for identification of the many fitted emission lines.