Code ROCHE is devoted to modeling multi-dataset observations of close eclipsing binaries such as radial velocities, multi-wavelength light curves, and broadening functions. The code includes circular surface spots, eccentric orbits, asynchronous or/and differential rotation, and third light. The program makes use of synthetic spectra to compute observed UBVRIJHK magnitudes from the surface model and the parallax. The surface grid is derived from a regular icosahedron to secure more-or-less equal (triangular) surface elements with observed intensities computed from synthetic spectra for supplied passband transmission curves. The limb-darkening is automatically interpolated from the tables after each computing step. All proximity effects (tidal deformation, reflection effect, gravity darkening) are taken into account. Integration of synthetic curves is improved by adaptive phase step (important for wide eclipsing systems).

The code is still under development. It is planned to extend its capabilities towards low mass ratios and widely different radii of components to facilitate modeling of extrasolar planet transits. Another planned extension of the code will be modeling of spatially-resolved eclipsing binaries using relative visual orbits and/or interferometric visibilities.

The BINSYN program suite has been ported to a Linux-based operating system. The new program structure is a major revision from the original version and a public version is nearing completion. This paper describes research areas where the program suite is particularly applicabile.

Recent PIC simulations of relativistic electron-positron (electron-ion) jets injected into a stationary medium show that particle acceleration occurs in the shocked regions. Simulations show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields and for particle acceleration. These magnetic fields contribute to the electron's transverse deflection behind the shock. The “jitter” radiation from deflected electrons in turbulent magnetic fields has properties different from synchrotron radiation calculated in a uniform magnetic field. This jitter radiation may be important for understanding the complex time evolution and/or spectral structure of gamma-ray bursts, relativistic jets in general, and supernova remnants. In order to calculate radiation from first principles and go beyond the standard synchrotron model, we have used PIC simulations. We present synthetic spectra to compare with the spectra obtained from Fermi observations.

Astronomical transients are intrinsically interesting objects to study. However, fast optical transients (μs time-scales) are a largely unexplored field of optical astronomy. Most optical observations use instruments that have integration times of the order of seconds and are thus unable to resolve fast transients. Current-generation atmospheric Cherenkov gamma-ray telescopes such as Veritas, which consists of four 12-m telescopes, have huge collecting areas, much larger than those of any existing optical telescopes. This paper outlines the benefits of using a Cherenkov telescope to detect optical transients, and the implementation of the Veritas Transient Detector (TRenDy), a dedicated multi-channel photometer based on field-programmable gate arrays which can be used on Veritas for such studies without interfering with gamma-ray observations.

We present very deep spectroscopic observations of the rich optical recombination line (ORL) spectrum of the bright Saturn nebula NGC 7009. Detailed spectral analyses, combined with systematic emission line identifications, in the whole optical range (3040–11 000 Å) give more than 1000 emission lines, over 80% of which are ORLs. New calculations of the N ii effective recombination coefficients in intermediate coupling scheme are carried out. These N ii atomic data, together with the most recent O ii and Ne ii effective recombination coefficients, are utilized in the spectral analyses of NGC 7009. Departure from LS coupling is noticed. Agreement is found between the observed and predicted relative intensities of ORLs. The elemental abundances of C, N, O, and Ne deduced from ORLs are systematically higher than those from collisionally excited lines (CELs) by a factor of 5–7.

The role interstellar turbulence plays in regulating star formation is a much debated research topic. In this paper, I take an observational view point in presenting observations of H2 line emission from extragalactic sources. I highlight key results from these observations. (1) H2 line emission is a main cooling channel of molecular gas. It is a tracer of mechanical energy dissipation complementing mass tracers in describing the dynamical state of molecular gas in galaxies. (2) Spectroscopy of warm H2 observations with the Spitzer Space Telescope and the SINFONI spectro-imager at ESO provide evidence of shock excited H2 line emission in galaxies that exemplify the main agents of galaxy evolution. (3) The dissipation of mechanical energy involves a turbulent energy cascade and the cycling of interstellar matter across ISM phases, including the formation of H2 gas from warm atomic gas. (4) In Stephan's Quintet and the radio galaxy 3C326, two sources with a high H2 luminosity to mass ratio (i.e. a high dissipation rate per unit mass), turbulence is observed to quench star formation. In the Antennae merger, star formation is observed to proceed where the turbulent kinetic energy is being dissipated.

We present the results of a study by Dessart et al. (2012), where we performed stellar collapse simulations of proposed long-duration γ-ray burst (LGRB) progenitor models and assessed the prospects for black hole formation. We find that many of the proposed LGRB candidates in Woosley & Heger (2006) have core structures similar to garden-variety core-collapse supernova progenitors and thus are not expected to form black holes, which is a key ingredient of the collapsar model of LGRBs. The small fraction of proposed progenitors that are compact enough to form black holes have fast rotating iron cores, making them prone to a magneto-rotational explosion and the formation of a proto-magnetar rather than a black hole. This leads us to our take-home message, that one must consider the iron-core structure (eg. ρ(r), Ω(r)) of evolved massive stars before making assumptions on the central engine of LGRBs.

We developed a self-consistent stellar-nebular model for NGC 7009. This model reproduces the available observations ranging from optical to UV. The combined approach to the modeling process produces more constraints and thus more trustworty results. After obtaining the model, we perform a comparative study of the chemical composition of He, N, O, Ne, Cl, and S in the nebula and its central star. Concluding that the stellar composition agrees with the nebular composition with t2 ≠ 0.00.

We analysed the Spitzer maps of Stephan's Quintet in order to investigate the nature of the dust emission associated with the X-ray emitting regions of the large scale intergalactic shock and of the group halo. This emission can in principle be powered by dust-gas particle collisions, thus providing efficient cooling of the hot gas. However the results of our analysis suggest that the dust emission from those regions is mostly powered by photons. Nonetheless dust collisional heating could be important in determining the cooling of the IGM gas and the large scale star formation morphology observed in SQ.

We describe the La Silla-QUEST (LSQ) Variability Survey. LSQ is a dedicated wide-field synoptic survey in the Southern Hemisphere, focussing on the discovery and study of transients ranging from low redshift (z < 0.1) SN Ia, Tidal Disruption events, RR Lyræ variables, CVs, Quasars, TNOs and others. The survey utilizes the 1.0-m Schmidt Telescope of the European Southern Observatory at La Silla, Chile, with the large-area QUEST camera, a mosaic of 112 CCDs with field of view of 9.6 square degrees. The LSQ Survey was commissioned in 2009, and is now regularly covering ~1000 square deg per night with a repeat cadence of hours to days. The data are currently processed on a daily basis. We present here a first look at the photometric capabilities of LSQ and we discuss some of the most interesting recent transient detections.

The precision of observations using observatories in space exceeds by a factor of 100 the accuracy of the light curve and line profile synthesis methods developed decades ago. Furthermore, physical effects too small to detect using ground based observations, such as aberration and Doppler beaming, become important when observing from space.

The GDDSYN method, developed by Hendry and Mochnacki, is both accurate and efficient, and is useful in the new context of space-based observations. Using a geodesic distribution of triangular surface elements varying little in size, it provides an alternative to the Wilson-Devinney code used at the heart of PHOEBE, and is adaptable to the new physical effects which are now observable. Tests and improvements are discussed.

A review of some earlier exact analytic solutions of monochromatic stationary vector radiative transfer equation in homogeneous infinite medium is given. It is stressed that Green's functions for plane-parallel, spherical and cylindrical symmetry are expressed through derivatives and integrals from basically one and the same set of functions.

We report on the type-Ic SN 2010bh associated with XRF 100316D at z = 0.059, which is among the latest spectroscopically confirmed GRB-SNe (Bufano et al. 2012). This supernova proves to be the most rapidly evolving GRB-SN to date.

Program SHELLSPEC is designed to calculate light-curves, spectra and images of interacting binaries and extrasolar planets immersed in a moving circumstellar environment which is optically thin. It solves simple radiative transfer along the line of sight in moving media. The assumptions include LTE and optional known state quantities and velocity fields in 3D. Optional (non)transparent objects such as a spot, disc, stream, jet, shell or stars may be defined (embedded) in 3D and their composite synthetic spectrum calculated. The Roche model can be used as a boundary condition for the radiative transfer. Recently, a new model of the reflection effect, dust and Mie scattering were incorporated into the code.

ϵ Aurigae is one of the most mysterious objects on the sky. Prior modeling of its light-curve assumed a dark, inclined, disk of dust with a central hole to explain the light-curve with a sharp mid-eclipse brightening. Our model consists of two geometrically thick flared disks: an internal optically thick disk and an external optically thin disk which absorbs and scatters radiation. Shallow mid-eclipse brightening may result from eclipses by nearly edge-on flared (dusty or gaseous) disks. Mid-eclipse brightening may also be due to strong forward scattering and optical properties of the dust which can have an important effect on the light-curves.

There are many similarities between interacting binary stars and transiting extrasolar planets. The reflection effect which is briefly reviewed is one of them. The exact Roche shape and temperature distributions over the surface of all currently known transiting extrasolar planets have been determined. In some cases (HAT-P-32b, WASP-12b, WASP-19b), departures from the spherical shape can reach 7-15%.

Using known distributions for the periods, amplitudes and light-curve shapes of young stars, we examine how well one could measure periods of these objects in the upcoming era of large synoptic surveys. Surveys like the LSST should be able to recover accurate rotation periods for over 90% of targets of interest in regions near to massive-star formation. That information will usher in a new era in our understanding of how the angular momentum of a young star/disk system evolves with time.

Stephan's Quintet (SQ, HCG92) is a well studied compact group of galaxies with a disturbed intergalactic medium (IGM). An “intruder” galaxy NGC 7318b is currently colliding with the IGM at a relative velocity of 1000 km s−1, causing a large-scale shock front. We observed SQ with the Far-Infrared Surveyor (FIS) aboard AKARI in four far-infrared (far-IR) bands at 65, 90, 140, and 160μm. The 160μm image clearly shows an additional peak of emission overlying structure extending in the North-South direction along the shock ridge seen in the 140μm band, and in H2 and X-ray emission. Whereas most of the far-IR emission in the shocked region is from cold dust (20 K), the [CII]158μm emission - whose luminosity is comparable to that of the warm H2 gas - can significantly contribute to the single peak emission in the 160μm band. We conclude that the [CII] line emission comes from the warm H2 gas in the shock. Our result represents the first detection of shock-excited [CII] line emission.

We perform hydrodynamical simulations of core collapse supernovae (CCSNe) with a cylindrically-symmetrical numerical code (FLASH) to study the inflation of bubbles and the initiation of the explosion within the frame of the jittering-jets model. We study the typical time-scale of the model and compare it to the typical time-scale of the delayed neutrino mechanism. Our analysis shows that the explosion energy of the delayed neutrino mechanism is an order of magnitude less than the required 1051 erg.

The gravitational waves radiated from explosions of compact objects are expected to be accompanied by other astronomical radiation such as radio flares, neutrinos and gamma-rays. In order to improve the detection of gravitational waves, mutual follow-up observations have been proposed between gravitational wave telescopes and other astronomical telescopes, known as “multi-messenger” observations. We propose multi-messenger observations using the LIGO, Virgo and Nasu Radio Telescopes.

The LITTLE THINGS project† has compiled multi-wavelength data (including VLA hi-line emission maps, GALEX FUV/NUV imagery, UBV, narrow-band Hα, and Spitzer images) for a representative sample of nearby dwarf irregular (dIrr) galaxies. The broadband data are used to constrain the radial variations of the star formation (SF) rate (SFR) averaged over the past 0.1 Gyr, 1 Gyr and a Hubble time, with a complete library of model SF histories (SFHs). The recent SF of more than ~ 80% of the dIrrs in our sample has been concentrated in the inner disk, and the SF in the outer disk has been markedly suppressed. This outside-in shrinking of the star-forming disk leaves a down-bending (double exponential) stellar mass surface density (Σ*) distribution. Our findings in dIrrs are in contrast to the inside-out disk growth scenario suggested for luminous spiral galaxies.