We modeled the broad wings of the OVI 1032,1038Å resonance lines and HeII 1640Å line in the spectra of some symbiotic stars by the electron-scattering process. We determined an empirical relationship between the emission measure of the symbiotic nebula and the electron optical depth. This allowed us to determine a contribution from the electron-scattering also to emission lines, which originate in a more extended, low density part of the nebula. For example, subtracting the electron-scattering contribution from the Hα line profile makes it possible to determine more precisely the mass loss rate via the wind from the hot star in symbiotic binaries.

We develop a new numerical code of the multi-energy and multi-angle neutrino-radiation transfer in three dimensions (3D) for core-collapse supernovae. Our 3D code to solve the Boltzmann equations is based on the discretized-ordinate (SN) method with a fully implicit differencing for time advance. A basic set of neutrino reactions is implemented in the collision terms together with a realistic equation of state. By following the time evolution of neutrino distributions in six dimensions (3 spatial and 3 momentum-space) by the 3D Boltzmann solver, we study the 3D feature of neutrino transfer for given background models of supernova cores in order to understand the explosion mechanism through neutrino heating in multi dimensions.

V393 Scorpii is a bright Galactic Double Periodic Variable showing a long photometric cycle of ≈253 days. The ASAS V-band light curve has been disentangled into an orbital and long cycle component. The orbital light curve was modeled with two stellar components and a circumprimary accretion disk. Based on this model, and the careful choice of a template spectrum for the donor, the contribution of the donor to the line+continuum spectrum was removed at every orbital phase. The remaining residual spectra were analyzed. Notable findings are the larger line emissivity observed during the long cycle maximum that is concentrated to low velocities and the presence of discrete absorption components in the wings of the OI 7773 line, whose visibility strongly depends on the orbital phase. In addition, weak emission is observed in donor metallic absorption lines. Finally, we present the first Hα Doppler map for V 393 Scorpii. A modulated wind explains many observational features.

An automated rapid classification of the transient events detected in modern synoptic sky surveys is essential for their scientific utility and effective follow-up when resources are scarce. This problem will grow by orders of magnitude with the next generation of surveys. We are exploring a variety of novel automated classification techniques, mostly Bayesian, to respond to those challenges, using the ongoing CRTS sky survey as a testbed. We describe briefly some of the methods used.

We present XMM-Newton and Chandra observations of the born-again planetary nebula A 30. These X-ray observations reveal a bright unresolved source at the position of the central star whose X-ray luminosity exceeds by far the model expectations for photospheric emission and for shocks within the stellar wind. We suggest that a “born-again hot bubble” may be responsible for this X-ray emission. Diffuse X-ray emission associated with the petal-like features and one of the H-poor knots seen in the optical is also found. The weakened emission of carbon lines in the spectrum of the diffuse emission can be interpreted as the dilution of stellar wind by mass-loading or as the detection of material ejected during a very late thermal pulse.

We present two-dimensional numerical simulations of core-collapse supernova including multi-energy neutrino radiative transfer. We aim to examine the influence of the equation of state (EOS) for the dense nuclear matter. We employ four sets of EOSs, namely, those by Lattimer and Swesty (LS) and Shen et al., which became standard EOSs in the core-collapse supernova community. We reconfirm that not every EOS produces an explosion in spherical symmetry, which is consistent with previous works. In two-dimensional simulations, we find that the structure of the accretion flow is significantly different between LS EOS and Shen EOS, inducing an even qualitatively different evolution of the shock wave, namely, the LS EOS leads to shock propagation beyond 2000 km from the center, while the Shen EOS shows only oscillations within 500 km. The possible origins of the difference are discussed.

Galactic-scale studies of γ-rays and sub-mm radiation suggest that a significant amount of neutral interstellar medium is not detectable either in CO or HI (Grenier et al. 2005; Ade et al. 2011). This component is called “dark gas”. Here we argue that cool and dense atomic gas without molecules is responsible for the dark gas. This interpretation is supported by a recent finding of cool HI gas corresponding to the TeV γ-ray shell in the SNR RX J1713.7-3946 (Fukui et al. 2011). Such HI gas is not recognized under a usual assumption of optically thin HI emission but is identified by a careful analysis considering optically thick HI. The typical column density of such HI gas is a few times 1021 cm−2 and is also identified as visual extinction.

The nearby starburst galaxies M82 and NGC 253 are now detected in GeV and TeV γ-rays, allowing us to directly study cosmic rays (CRs) in starburst galaxies. Combined with radio observations, the detections constrain the propagation and density of CRs in these starbursts. We discuss the implications for “proton calorimetry”, whether CR protons cool through pion losses before escaping these galaxies. The ratio of γ-ray and radio luminosities constrains how much of the CR electron cooling is due to synchrotron losses. As for leptonic emission, we predict that synchrotron and Inverse Compton emission make up ~1–10% of the unresolved hard X-ray emission from M82, and a few percent or less of the total X-ray emission from starbursts. A detection of these components would inform us of the magnetic field strength and 10 – 100 TeV electron spectrum. We conclude by discussing the prospects for detecting leptonic MeV γ-rays from starbursts and the cosmic γ-ray background.

We discuss two approaches to searches for gravitational-wave (GW) and electromagnetic (EM) counterparts of binary neutron-star mergers. The first approach relies on triggering archival searches of GW detector data based on detections of EM transients. Quantitative estimates of the improvement to GW detector reach due to the increased confidence in the presence and parameters of a signal from a binary merger gained from the EM transient suggest utilizing other transients in addition to short gamma-ray bursts. The second approach involves following up GW candidates with targeted EM observations. We argue for the use of slower but optimal parameter-estimation techniques and for a more sophisticated use of astrophysical prior information, including galaxy catalogues to find preferred follow-up locations.

There are several types of binary stars which show non-periodical radial velocity variations with the amplitude larger than those connected with the orbital motion. The non-periodical changes have to be removed in order to study the orbital ones. We propose three removal techniques, two of which are based on the trend modeling with continuous functions and the third one that takes the orbital motion into account.

We present luminosity and temperature light curves following supernova shock breakouts through a thick wind. These events are very luminous and their spectrum may contain both an X-ray and a UV/optical component. For breakout pulse durations between a week and a month, the X-ray component luminosity peaks 100-500 days after the explosion, respectively.

We present new observations in the radio continuum of 31 planetary nebulae at 5 and 8 GHz with the Australian Telescope Compact Array. The observations are used to invesigate properties of the interstellar extinction toward Galactic Bulge.

We present detailed analysis of mid-infrared (MIR) data for 9 type II-P supernovae from the public Spitzer database. Spectral energy distributions (SEDs) from observed fluxes are fitted with simple models to get basic information about the dust as the presumed source of MIR radiation. We found two SNe, 2005ad and 2005af, which likely have newly-formed dust in their environment, while in the other seven cases the observed MIR flux may originate from pre-existing circumstellar or interstellar dust.

Modern time-domain surveys have demonstrated that finding variable objects is relatively straightforward. The problem now is one of selecting and following up discoveries. With even larger-scale surveys on the horizon, the magnitude of the problem will inevitably increase. One way to prepare for the coming deluge is to have realistic estimates of the numbers of potential detections so that resources can be developed to meet that need. To that end, astronomers at the National Optical Astronomy Observatory (NOAO) have begun a project to characterize the variable sky in terms of type of objects, distribution on the sky and range of variation.

We discuss the results of the search for [WR] central stars in binary systems. GLMP 160 is the first [WR] central star in a binary system known. We analyze photometry, spectroscopy and imaging of this system.

Thanks to OGLE, Kepler, CoRoT and planned new ambitious survey projects, the eclipsing binary (EB) community is beginning to experience a long-predicted data deluge. Beyond the analysis of the many fascinating individual objects yielded by these programs, these complete datasets themselves should yield further insights. Because objects in such datasets are characterized by many parameters, tools that assist in understanding high-dimensional data are acquiring increasing relevance. Chiefly among these are new Advanced Visualization (AV) tools and various methods of clustering data, both approaches complementing each other naturally. We illustrate the use of these tools as applied to OGLE II LMC EB data and respective EBAI light curve solutions.

Starting from first principles, we construct a simple model for the evolution of energetic particles produced by supernovae in the starburst galaxy M82. The supernova rate, geometry, and properties of the interstellar medium are all well observed in this nearby galaxy. Assuming a uniform interstellar medium and constant cosmic-ray injection rate, we estimate the cosmic-ray proton and primary & secondary electron/positron populations. From these particle spectra, we predict the gamma ray flux and the radio synchrotron spectrum. The model is then compared to the observed radio and gamma-ray spectra of M82 as well as previous models by Torres (2004), Persic et al. (2008), and de Cea del Pozo et al. (2009). Through this project, we aim to build a better understanding of the calorimeter model, in which energetic particle fluxes reflect supernova rates, and a better understanding of the radio-FIR correlation in galaxies.

We studied optical and near-infrared (NIR) light curves, and optical spectra of Supernovae (SNe) 2006V and 2006au, two objects monitored by the Carnegie Supernova Project (CSP) and displaying remarkable similarity to SN 1987A, although they were brighter, bluer and with higher expansion velocities. SN 2006au also shows an initial dip in the light curve, which we have interpreted as the cooling tail of the shock break-out. By fitting semi-analytic models to the UVOIR light curve of each object, we derive the physical properties of the progenitors and we conclude that SNe 2006V and 2006au were most likely Blue Supergiant (BSG) stars that exploded with larger energies as compared to that of SN 1987A. We are currently investigating the host galaxies of a few BSG SNe, in order to understand the role played by the metallicity in the production of these rare exploding BSG stars.

We carefully consider numerous explanations for the sulfur abundance anomaly in planetary nebulae. No one rationale appears to be satisfactory, and we suggest that the ultimate explanation is likely to be a heretofore unidentified feature of the nebular gas which significantly impacts the sulfur ionization correction factor.

Recent studies of the Algol-type binary RY Per presented strong evidence that there is an accretion disk around the primary in the system. We used new UBV photometry from Hvar Observatory and the BINSYN software package in order to determine the basic parameters of the disk. The search for the best parameter set was performed with a fully automated steepest descent method. The resulting disk is large and visible at all orbital phases. Somewhat surprising is the large mass transfer rate which should be tied with, currently unreported, secular period changes.