bluuebunny/crossref_metadata_2025 huggingface dataset:
Four Jovian extrasolar planets detected with CORALIE
Authors: Queloz D. , Mayor M. , Naef D. , Pepe F. , Santos N. C. , Udry S. , Burnet M.
Published: July 2016

We present radial-velocity data measurements for 4 solar-type stars (HD 6434, HD 19994, HD 92788 and HD 121504) harboring new detected planetary companions. The measurements were obtained with the CORALIE echelle spectrograph mounted on the 1.2–m “Leonard Euler” Swiss telescope at ESO–LaSilla Observatory (Chile). The minimum masses inferred for the planets are m2 sin i = 0.48, 2.0, 3.81 and 0.89MJup, respectively.
Infrared spectroscopic search for short-period giant extrasolar planets
Authors: Wiedemann Günter , Deming L. Drake , Bjoraker Gordon L. , Goukenleuque Cedric
Published: July 2016

IR spectroscopy with a resolution ⋋/△⋋ ≳ 10, 000 is a powerful technique for the investigation of short-periodic giant extra-solar planets. For an unambiguous direct detection attempt one exploits the large-amplitude Doppler modulation of the planet's IR spectrum. A successful measurement of the planet's radial velocity amplitude would yield directly the planet-star mass ratio. Spectral information can be extracted if high per-pixel S/N levels are achieved.
Terrestrial Planet Formation: The Solar System and Other Systems
Authors: Ida Shigeru , Kokubo Eiichiro
Published: July 2016

Accretion of terrestrial planets and solid cores of jovian planets is discussed, based on the results of our N-body simulations. Protoplanets accrete from planetesimals through runaway and oligarchic growth until they become isolated. The isolation mass of protoplanets in terrestrial planet region is about 0.2 Earth mass, which suggests that in the final stage of terrestrial planet formation giant impacts between the protoplanets occur. On the other hand, the isolation mass in jovian planet region is about a few to 10 Earth masses, which may be massive enough to form a gas giant. Extending the above arguments to disks with various initial masses, we discuss diversity of planetary systems. We predict that the extrasolar planets so far discovered may correspond to the systems formed from disks with large initial masses and that the other disks with smaller masses, which are the majority of the disks, may form Earth-like planets.
Migration of Celestial Bodies in the Solar System
Authors: Ipatov S. I.
Published: July 2016

Migration of planetesimals and embryos of forming planets was investigated on the basis of computer runs of the evolution of disks of gravitating bodies orbiting the Sun. Our results obtained earlier with the use of the spheres' method are close to the results obtained recently by other authors by numerical integration. Due to the interaction with migrating planetesimals, the embryos of Uranus and Neptune, which acquired most of their masses near the orbit of Saturn, could migrate to the present distances from the Sun moving all time in nearly circular orbits. Each of the terrestrial planets incorporated planetesimals from all feeding zones of these planets.
Stable mass ranges of ν Andromedae planetary system
Authors: Ito Takashi , Miyama Shoken M.
Published: July 2016

Doppler observation of extrasolar planets through the radial velocity displacement of their host stars can only determine lower limits of planetary masses. We numerically integrate ν Andromedae planetary orbits with various initial conditions of masses and angle variables to investigate which initial configuration produces stable orbits during the timescale of host star's age. According to our preliminary results starting from Lick dataset, ν Andromedae planetary system seems to remain stable over the timescale of its host star's age if sin i > 0.7 where i is the unknown line-of-sight inclination of planetary orbits. In this case we may estimate that the upper limit masses of ν Andromedae planets in our model is about 1/0.7 ∽ 1.43 times larger than its minimum.
Terrestrial planet orbits in the habitable zones of exoplanetary system
Authors: Jones B. W. , Sleep P. N.
Published: July 2016

We have investigated whether terrestrial planets can exist in orbits in known exoplanetary systems such that life could have emerged on those planets. We have shown that Rho CrB and 47 UMa could have terrestrial planets in orbits that remain confined to their habitable zones for biologically significant lengths of time. We have also shown that the Gliese 876 and Ups And systems are very unlikely to have such orbits.
Observations of Binary Systems Found in Numerical Simulations
Authors: Nelson Andrew F.
Published: July 2016

I present a two dimensional hydrodynamic simulation of a binary system consisting of two stars, each with a circumstellar disk, using a Smoothed Particle Hydrodynamic (SPH) code. I model the luminous output of this system in various millimeter and sub-millimeter wavelength bands appropriate for several new and soon to be on line interferometric telescopes and find that spiral structure present in the density structure of the disks will be difficult or impossible to observe in the observed emission from the system, due to the fact that disk photosphere temperatures are not very sensitive to the underlying density distribution.
Existence of Asteroids in the Inner Solar System
Authors: Tabachnik S. A. , Evans N. W.
Published: July 2016

Ensembles of in-plane and inclined orbits in the vicinity of the Lagrange points of the terrestrial planets are integrated for up to 100 million years. Mercurian Trojans probably do not exist, although there is evidence for long-lived, corotating horseshoe orbits with small inclinations. Both Venus and the Earth are much more promising, as they possess rich families of stable tadpole and horseshoe orbits. Our survey of in-plane test particles near the Martian Lagrange points shows no survivors after 60 million years. Low inclination test particles do not persist, as their inclinations are quickly increased until the effects of a secular resonance with Jupiter cause de-stabilisation. Numerical integrations of inclined test particles for timespans of 25 million years show stable zones for inclinations between 14° and 40°. Both Martian Trojans 5261 Eureka and 1998 VF31 lie deep within the stable zones, which suggests they may be of primordial origin.
Atmospheric Circulation of Hot Jupiters
Authors: Guillot Tristan
Published: July 2016

About 40% of the extrasolar giant planets discovered so far have orbital distances smaller than 0.2 AU. These “hot Jupiters” are expected to be in synchronous rotation with their star. The ability to measure their radii prompts a careful reexamination of their structure. I show that their atmospheric structure is complex and that thermal balance cannot be achieved through radiation only but must involve heat advection by large-scale circulation. A circulation model inspired from Venus is proposed, involving a relatively strong zonal wind (with a period that can be as short as 1 day). It is shown that even this strong wind is incapable of efficiently redistributing heat from the day side to the night side. Temperature variations of 200 K or more are to be expected, even at pressures as large as 10 bar. As a consequence, clouds should be absent on the day side, allowing more efficient absorption of the stellar light. The global chemical composition of the atmosphere should also be greatly affected by the presence of large temperature variations. Finally, stellar tides may also be important in their ability to deposit heat at levels untouched by stellar radiation, thereby slowing further the cooling of the planets.
Can D-D fusion contribute to Jupiter's excess heat?
Authors: Ouyed Rachid
Published: July 2016

We explore the highly speculative idea of Deuterium - Deuterium (D-D) fusion inside Jupiter as an internal heating source. We suggest that D could have been brought deep inside the planet by planetesimals (during the process of planet formation) and deposited through planetesimal/ices vaporization. Here, the general aspects of the model are presented.
Possible in situ Formation of Close Giant Planets in a Passive Quiescent Nebula
Authors: Nakagawa Yoshitsugu
Published: July 2016

Formation of giant planets along the standard model is considered in the innermost region of protoplanetary nebulae where turbulence has already decayed. Preference of quiescent nebulae is discussed. It is shown that if dust material enough to form a core with about ten times Earth mass and the corresponding amount of gas exist in the innermost region, a giant planet with mass somewhat larger than our Jupiter can form there.
Visions of Nature's Planet Foundry: Images of Circumstellar Disks
Authors: Stapelfeldt Karl
Published: July 2016

As the number of detected extrasolar planetary systems has steadily grown over the past five years, so too has the number of circumstellar disks with resolved images. In this contribution, I take stock of the current inventory of disk images at various wavelengths; summarize the results of a new disk imaging survey conducted with the Hubble Space Telescope; review the major inferences that can be drawn about disk structure from the extant images; and suggest areas for future progress.
β Pictoris and other star spectra, in connection with planet formation
Authors: Lagrange Anne. M. , Beust Herve
Published: July 2016

We review here the present knowledge on the gaseous phases of debris disks found around MS and old PMS stars, and make an attempt to connect them with planetary system activity.
Toward Consistent Models of Protoplanetary Discs
Authors: Reyes-Ruiz Mauricio
Published: July 2016

In this paper we present results on the effect of the vertical stratification of magnetic diffusivity, expected in current models of protoplanetary discs, on the development of the magnetorotational instability. Specifically, on the basis of a quasi-global, linear analysis we study the operation of the magnetorotational instability across the so-called dead zone of protoplanetary discs. Our results indicate that the predicted strong vertical diffusivity gradients can damp the instability in such regions. This suggests the necessity of a revision of current models for the structure and evolution of protoplanetary discs.
Dust Particle Settling in Protoplanetary Disks around Young Stars in Binary Systems
Authors: Sato Y. , Nakagawa Y.
Published: July 2016

We calculate the SEDs of young stars accompanied by protoplanetary disks, taking into account the effect of the settling of dust particles. Observed disk candidates contain significant number of binary or multiple systems. We compare our results with observed data and obtain many excellent fittings. From the results, it is found that in close binary systems the disk masses are relatively low and dust particles is hard to settle as compared with the cases of disks in wide binaries or around isolated stars. This is attributable to gravitational perturbation from the companion stars, which will disturb formation of planetary systems in close binary systems.
Mid-IR Spectroscopy of the Debris Disks in the TW Hydrae Association
Authors: Sitko Michael L. , Lynch David K. , Russell Ray W. , Grady Carol A.
Published: July 2016

Spectroscopic observation between 3-14 μm of 3 stars in the TW Hya Association were obtained using the Aerospace Corporation Broadband Array Spectrograph System (BASS) on the NASA IRTF telescope. The targets observed were TW Hya, HR 4796A, and HD 98800. Both of the late-type stars, TW Hya and HD 98800, exhibit a strong 10 μm silicate emission band. The strong emission indicates the presence of small dust grains close to the star, at angular distances not currently accessible to coronagraphic techniques. The spectral structure due to crystalline material that is present in some young early-type stars (HD 163296, HD 31648, etc.) is not apparent in these two objects. For HR 4796A, the dust emission is weak.
The 3.3 micron PAH feature in Vega-type stars
Authors: Walther Dolores M. , Coulson Iain M. , Greaves Jane , Holland Wayne , Dent William R.F.
Published: July 2016

We present spectroscopic data of 3 isolated Vega-type systems which exhibit the 3.3 μm‘PAH’ feature ascribed to stretching of the C-H bonds in aromatic hydrocarbons. These are part of a sample of mainly hot stars. We discuss the implications of Vega-type stars having an organic component to their surroundings and compare them with the unique star, HD135344 (SAO 206462).
Formation of protoplanetary with radiation of SiO maser from Orion-IRC2
Authors: Yu Zhi-Yao
Published: July 2016

Here we report a study of formation of protoplanetary with radiation of SiO maser from Orion-IRC2 using a new model, i.e. the distinct multiple rotating and expanding disc-rings of Orion-IRC2 SiO (ν =1, J-2-1) maser for explanation of the fact that the several small peaks superposed the double-peaked spectral profile and the relative position map.
Detecting Earth-Uranus Class Planets with the Space Mission COROT
Authors: Léger A. , Baglin A. , Barge P. , Bordé P. , Defaÿ C. , Deleuil M. , Rouan D. , Schneider J. , Vuillemin A.
Published: July 2016

The space mission COROT can be considered as a DARWIN/TPF precursor, since it will contribute to the pre-DARWIN/TPF effort with its dedicated exoplanet program. COROT will survey more than 50 thousands stars, each one during five months, in order to detect transits of planets. Despite of the modest size of the telescope, the photon-noise limited performances may lead to the detection of several tens of “hot jupiters” and, more important, of a few planets of the Earth-Uranus class, i.e. with a size of typically 1.5 to 4 Earth radius. In the basic mode of operation (characterization of a planet by at least 3 detected transits), only planets with a short orbital period, and thus rather “hot” ones (T = 600K), should be discovered. However, one of the COROT's features is its capability to provide a wavelength dependent information, thanks to a prism in the optical path.
Planet Detection Capabilities of the Eddington Mission
Authors: Deeg Hans J. , Horne Keith , Favata Fabio , Aerts C. , Antonello E. , Badiali M. , Catala C. , Christensen-Dalsgaard J. , Gimenez A. , Grenon M. , Penny A. , Rauer H. , Roxburgh I. W. , Schneider J. , Waltham N. R.
Published: July 2016

Eddington is a space mission for extrasolar planet finding and for asteroseismic observations. It has been selected by ESA as an F2/F3 reserve mission with a potential implementation in 2008-13. Here we describe Eddington's capabilities to detect extrasolar planets, with an emphasis on the detection of habitable planets. Simulations covering the instrumental capabilities of Eddington and the stellar distributions in potential target fields lead to predictions of about 10,000 planets of all sizes and temperatures, and a few tens of terrestrial planets that are potentially habitable. Implications of Eddington for future larger scale missions are briefly discussed.
Sgr A*: Observations, Models, and Imaging of the event horizon with VLBI
Authors: Falcke Heino , Markoff Sera , Biermann Peter L. , Krichbaum Thomas P. , Melia Fulvio , Agol Eric , Bower Geoffrey
Published: July 2016

We show and discuss results and prospects of high-resolution imaging of the supermassive black hole candidate Sgr A*. We also briefly review the latest observational and theoretical progress for this source. The latest millimeter-VLBI observations show compact radio emission from within a region of about 15 Schwarzschild radii. This compact component is most likely responsible for the so-called sub-mm bump in the spectrum and perhaps even for the recently discovered circular polarization discovered up to 43 GHz and some X-ray emission through synchrotron self-Compton emission. Most importantly, however, the sub-mm emission from Sgr A* opens the door to observe, for the first time, the event horizon of a black hole directly with VLBI at sub-mm wavelengths.
Chandra Observations of M31
Authors: Garcia M.R. , Murray S.S. , Primini F.A. , Forman W.R. , Jones C. , McClintock J.E.
Published: July 2016

As part of the Chandra GTO program we are monitoring and surveying M31 using the HRC and ACIS cameras. These observations have resolved the nuclear X-ray source into five separate sources, one of which is very soft and may (or may not!) be associated with the central super-massive black hole. In addition, the superb spatial resolution and low scattering of the Chandra telescope allows us to unambiguously resolve the diffuse emission from the point sources. This emission is clearly softer than the point sources, and also increases with temperature radially. The monitoring nature of the observations allows detailed study of the variability of the point sources.
Parsec-Scale Jets and Tori in Seyfert Galaxies
Authors: Roy A.L. , Wrobel J.M. , Wilson A.S. , Ulvestad J.S. , Norris R.P. , Mundell C.G. , Krichbaum T.P. , Falcke H. , Colbert E. J. M.
Published: July 2016

What causes the dichotomy between very powerful and very weak radio emission from AGNs? Perhaps the engines are the same but the jets get disrupted by dense ISM in radio-quiet objects, or else the engines are intrinsically different with jet power scaling with, say, black hole spin. To distinguish, one can look for interaction between the jets and the NLR and measure the jet speed close to the core using VLBI, before environmental effects become important. We find that in radio-quiet AGN, the jets appear slower and have a greater tendency to bend, and that one-sidedness and flat-spectrum cores are probably due to obscuration.
Effect of an Attenuated Continuum in the BLR of AGNs
Authors: Nazarova L.S.
Published: July 2016

The possibility of an attenuated continuum for the gas ionization in the BLR is discussed. It is shown that “line ratio” problem for the low ionization lines in NGC 5548 could be successfully solved when the attenuation by the column density Nh = 1022 cm−2 are taken into consideration.
Multiband CCD Photometry of BL Lacertae
Authors: Kurtanidze Omar M. , Richter Gotthard M. , Nikolashvili Maria G.
Published: July 2016

We present CCD opbservations of BL Lacertae obtained from August 1997 to August 1998. The maximum amplitudes in BVRI bands during observing period included most part of great ouburst and second one are equal to 3.00 (rms=0.03), 2.71 (0.02), 2.53 (0.01) and to 1.25 (0.040), 1.11 (0.03), 1.02 (0.01) 0.91 (0.03), respectively. The amplitude for variability is larger toward the blue end of the spectrum.
The Microarcsecond Quasar J1819+3845
Authors: Dennett-Thorpe J. , de Bruyn A. G.
Published: July 2016

We present new WSRT observations of the micro-arcsecond quasar J1819+3845. All short term variations are attributed to interstellar scintillation of a source which is at most 30 micro-arcseconds in diameter. The timescale of the modulations changes over the year, which we interpret as due to a peculiar velocity of the scattering medium. The scintillation behaviour can be used to determine sub-structure in the source.
Extreme Examples of Intraday Variability - Search for Diffractive Scintillation in the Smallest Quasar, PKS 0405-385
Authors: Kedziora-Chudczer Lucyna , Macquart Jean-Pierre , Jauncey David L.
Published: July 2016

We discuss conditions which have to be satisfied for observable signatures of diffractive scintillation in intraday variable (IDV) sources. We apply this discussion to the quasar PKS 0405-385 which had a scintillating component with angular size of 5 μas (Kedziora-Chudczer et al. 1997).
High Resolution Studies of mJy and μJy Radio Sources
Authors: Garrington S. , Muxlow T. , Garrett M.
Published: July 2016

VLBI observations can now be used to examine the milliarcsecond properties of mJy and sub-mJy radio sources. Here we describe a snapshot survey of compact mJy sources selected from the FIRST survey and the first EVN observations of a 6 arcmin square field centred on the Hubble Deep Field. At the few mJy level, a significant number of steep-spectrum sources appear to be very young low-luminosity radio galaxies. Older and fainter examples of this type of source are seen in the HDF, and are detected by the EVN. The VLBI observations of the HDF support the view that at least one of the putative distant, dusty starbursts harbours an AGN.
VLBI Observations of a Sample of 15 EGRET-detected AGNs at 5 GHz
Authors: Hong X. Y. , Jiang D.R. , Schilizzi R. T. , Nicolson G. , Shen Z.-Q. , Wang W. H.
Published: July 2016

We report VLBI observations of 15 EGRET-detected AGNs with European VLBI Network (EVN) at 5 GHz. All sources in the sample display core-jet structures.
The “Number — Flux Density” Relation for Milliarcsecond Structures in Extragalactic Radio Sources
Authors: Gurvits L.I.
Published: July 2016

“Number - flux density” distributions for total and correlated flux densities at various interferometer spacings in 355 extragalactic radio sources are analysed. Qualitative conclusions on the population of milliarcsecond components in these sources are presented.
Merging Galaxies with Multiple Nuclei from HST ULIRGs Snapshot Survey
Authors: Cui J. , Xia X.-Y. , Deng Z.-G. , Mao S. , Zou Z.-L.
Published: July 2016

We perform photometric measurements on a large HST snapshot imaging survey sample of 97 ultraluminous infrared galaxies (ULIRGs). We classify all the sources into three categories with multiple, double and single nucleus/nuclei, mainly based on a quantitative criterion of I-band luminosity. The resultant fractions of multiple, double and single nucleus/nuclei ULIRGs are 18%, 39% and 43%, respectively. This supports the multiple merger scenario as a possible origin of ULIRGs, in addition to the commonly-accepted pair merger model. Further statistical studies indicate that the fraction of AGN increases from multiple (18%) to double (39%) and then to single (43%) nucleus/nuclei ULIRGs. For the single nucleus category, there is a high luminosity tail in the luminosity distribution, which corresponds to a Seyfert 1/QSO excess. This supports the statement that active galactic nuclei tend to appear at final merging stage. For multiple and double mergers, we also find a considerably high fraction of very close nucleus pairs (e.g., 2/3 for those separated by less than 5 kpc). This strengthens the conclusion that systems at late merging phase preferentially host ULIRGs.
Subparsec-scale HI in the Nucleus of NGC 4151
Authors: Mundell C.G. , Wrobel J.M. , Pedlar A. , Gallimore J.F.
Published: July 2016

We present sensitive, high-resolution λ21-cm VLBA+VLA observations of the radio jet and nuclear HI absorption in NGC 4151. The 25-mas (1.6-pc) resolution continuum image reveals a highly collimated radio jet, underlying the discrete components seen previously with MERLIN and the VLA. Spatially and kinematically complex HI absorption is detected against the whole 3-pc extent of the continuum component predicted by Ulvestad et al. to contain the AGN. Instead, we suggest the component against which the absorption is detected is part of the eastern counterjet, ruling it out as the location for the AGN.
Atomic and Molecular Gas in the Merger Arp 299
Authors: Polatidis A.G. , Aalto S.
Published: July 2016

We present MERLIN observations of the atomic and molecular gas of IC 694 a member of the merger system Arp 299. The radio continuum of IC 694 is consistent with a disk of synchrotron emission powered by supernovae remnants. The atomic and molecular gas are located in a similarly orientated 250 pc large disk.
Chandra Observations of The Antennae Galaxies (NGC 4038/39)
Authors: Fabbiano G.
Published: July 2016

A deep (∼ 70ks) Chandra ACIS pointing at the merging system NGC 4038/39 gives us an exceptional detailed view of its X-ray emission and demonstrates the capabilities of Chandra's sub-arcsecond resolution. We detect an extraordinarily luminous population of pointlike sources, that may suggest 10-100M⊙ Black Hole counterparts. We also detect a luminous hot ISM, with features ranging to large scale outflows to hot superbubbles.
Gas and Stellar Kinematics in NGC 6240
Authors: Tecza Matthias , Tacconi Linda , Genzel Reinhard
Published: July 2016

We present results from sub-arcsecond near infrared integral field spectroscopy and millimeter IRAM-interferometry of the interacting galaxy NGC 6240. Using stellar absorption features in the NIR we determined the stellar velocity field and dispersion in NGC 6240. The two NIR emission peaks show rapid rotation and indicate a prograde encounter of the two progenitor galaxies. From the velocity dispersion an excess mass between the two nuclei is detected. This mass can be attributed to a massive rotating disk of cold CO gas located between the nuclei.
The Youngest Star-Forming Regions in Galaxies: Giant Compact HII Regions and Protoglobular Clusters?
Authors: Turner Jean L.
Published: July 2016

Subarcsecond radio and infrared observations reveal a class of luminous, obscured, optically thick HII regions associated with extremely large young clusters in nearby starburst galaxies. VLA images show bright radio nebulae with ne ∼ 104 cm−3, densities characteristic of young Galactic compact HII regions. Excitation of the nebulae requires the presence of several thousand O stars within regions of 1-10 pc extent, corresponding to clusters containing 105–106 stars. The compact nebulae are also bright in the mid-infrared, and can for significant fractions of not only the total IR luminosity, but also the total bolometric luminosity, of the parent galaxies. The prototype for these “supernebulae” is the large, obscured cluster in the dwarf galaxy NGC 5253.
Rapidly Evolving Structures in the Photosphere of the Mira Variable TX Cam
Authors: Diamond P. J. , Kemball A. J.
Published: July 2016

44 VLBA observations of the 43 GHz SiO masers in the circumstellar envelope surrounding the Mira variable TX Cam reveal dramatic structural variations over the 80 week stellar cycle. The dominant dynamical mode is one of expansion although other complex motions are visible. The gravitational field of the star does not have a significant effect on the dynamics observed, these are probably governed more by the magnetic field and the effects of the shock waves resulting from the pulsation of the Mira itself.
High Angular Resolution Studies of Stellar Atmospheres
Authors: Haniff Chris A.
Published: July 2016

The advent of long-baseline optical and infrared interferometers has meant that spatially resolved studies of stellar atmospheres have now become routinely possible. While prototype arrays, which have typically operated with short baselines and limited sensitivity, have produced exciting preliminary results, it is the development of larger dedicated facility arrays, such as the CHARA, Keck, and VLT interferometers, that offer the best prospects for advancing astrophysics. In this paper I review the possibilities and limitations of interferometric studies of stellar atmospheres, and highlight some recent results from optical/IR spatial interferometry.
HST & VLA Imaging of the Symbiotic Star HM Sge
Authors: S. Eyres S.P. , Bode M.F.
Published: July 2016

Symbiotic stars are a heterogenous group of interacting binaries, where the combination of a mass-losing giant and a hot compact companion create conditions ideal for studying interacting winds, dust formation, nebular shaping and accretion phenomena. We present HST and VLA observations of the symbiotic nova HM Sge as an example of our work. In this case, we characterise hot and cool parts of the extended nebula, determine the angular binary separation to be 40±9 milli-arcsec, and the interstellar reddening to be no more than E(B-V) = 0.35. Comparison with a suggested binary separation of 50 au gives a distance of 1250±280 pc, consistent with the sparsely-sampled distance-extinction mapping in the direction of HM Sge. A number of other observations of additional high spatial-resolution observations of symbiotic stars have been completed or are being planned.
An Analysis of HST/FOS Spectra of Spatially Resolved Compact OB Systems in the LMC
Authors: Niemczura E. , Cugier H.
Published: July 2016

An analysis of the spatially resolved (0.1) main-sequence stars of four compact multiple systems located in the Large Magellanic Cloud (LMC) is given. For this purpose we compared theoretical synthetic spectra with the observations obtained by means of the Faint Object Spectrograph (FOS) aboard the Hubble Space Telescope (HST).
Supernova 1993J in M81
Authors: Bietenholz M. F. , Bartel N. , Rupen M. P. , Beasley A. J. , Graham D. A. , Altunin V. I. , Venturi T. , Umana G. , Cannon W. H. , Conway J. E.
Published: July 2016

Twenty-two consecutive VLBI images of supernova 1993J in the galaxy M81 taken over 7 years show, in unprecedented detail, the dynamic evolution of the expanding radio shell of an exploded star. High precision astrometry using phase-referencing shows that the supernova expands isotropically, and that its geometric center has a formal proper motion of 190±110 km s−1 w.r.t. the core of M81. Systematic changes in the images most likely reflect a pattern of inhomogeneities in the medium left over from the progenitor star, or possibly instabilities in the expanding shell. As the shockfront sweeps up the medium, it is progressively decelerated, and after 7 years it has slowed to less than 1/2 its original expansion velocity. SN1993J is likely now entering the early stages of the adiabatic phase common in much older supernova remnants.
Late Radio Emission from SN 1993J: Evidence for Synchrotron Self-Absorption
Authors: Perez-Torres M.A. , Alberdi A. , Marcaide J.M.
Published: July 2016

The standard model for radio supernovae considers the synchrotron radio emission to be only partially absorbed by ionized thermal electrons in the circumstellar wind of the progenitor star. However, for the best studied radio supernova, SN 1993J, we present evidence of synchrotron self-absorption based on modelfits to all available radio data. We show that while external absorption is the main absorption mechanism at early times, synchrotron self-absorption is the dominant mechanism at late epochs.
The Time Evolution of the Radio Supernovae in Arp 220
Authors: Lonsdale Colin J. , Diamond Philip J. , Lonsdale Carol J. , Smith Harding E.
Published: July 2016

Since our unexpected discovery of 12 compact radio sources in one of the nuclei of Arp220 we have been monitoring the structure using global VLBI and the VLBA. With several epochs of data we can now demonstrate that the fluxes of the radio sources are, in general, decreasing sytematically but not smoothly. The sources also have steep spectra. Both facts support our earlier supposition that these are highly luminous radio supernovae. We initially predicted a radio supernova rate of approximately 2yr−1 Our most recent observations indicate that the occurrence rate of luminous RSN is several times lower than predicted, thus our model of the Arp220 starburst must be revised.
VLBI Pulsar Astrometry
Authors: Campbell R.M.
Published: July 2016

I briefly review the means by which VLBI observations can determine the position, proper motion, and parallax of a pulsar, consider a subset of the applications of such results, and highlight recent developments in pulsar gating at JIVE.
Prospect for VLBI Network Extension: the First Results of an Ad-hoc S2 Array Experiments
Authors: Molotov Igor , Likhachev Sergey , Chuprikov Andrey , Lipatov Boris , Dementiev Alexander , Cannon Wayne , Dougherty Sean , Del Rizzo David , Stanghellini Carlo , Trigilio Corrado , Hong Xiaoyu , Huang Xinyong , Shiguang Liang , Quick Jonathan , Nicolson George
Published: July 2016

The Canadian S2 system gives a chance for Russian and some other radio telescopes in the world to be involved into international VLBI programs. Brief descriptions of previous S2 experiments and future possibilities are presented.
Conference Summary
Authors: Wilkinson Peter N.
Published: July 2016

A personal view of the conference highlights.
The Formation of Close Binary Stars
Authors: Bonnell Ian A.
Published: July 2016

I review the possible formation mechanisms of close binary stars. The formation of close binary systems is problematic in that there is no theory that does not encounter significant difficulties or unknowns. Fission does not appear to occur in stars. Capture is unlikely to form many close binary systems except possibly amongst massive stars. Fragmentation can form close binary systems but these need to accrete the majority of their eventual mass. Furthermore, there appears to be a limited window in initial conditions that may preclude forming sufficient systems in this way. Possible alternatives include the orbital migration of a binary due to its circumbinary disk and the disintegration of a non-hierarchical multiple system.
An Update on Binary Formation by Rotational Fission
Authors: Tohline Joel E. , Durisen Richard H.
Published: July 2016

During the 1980s, numerical simulations showed that dynamic growth of a barlike mode in initially axisymmetric, equilibrium protostars does not lead to prompt binary formation, i.e., fission. Instead, such evolutions usually produce a dynamically stable, spinning barlike configuration. In recent years, this result has been confirmed by numerous groups using a variety of different hydrodynamical tools, and stability analyses have convincingly shown that fission does not occur in such systems because gravitational torques cause nonlinear saturation of the mode amplitude. Other possible routes to fission have been much less well scrutinized because they rely upon a detailed understanding of the structure and stability of initially nonaxisymmetric structures and/or evolutions that are driven by secular, rather than dynamic processes. Efforts are underway to examine these other fission scenarios.
Multiplicity of Massive Stars
Authors: Preibisch Thomas , Weigelt Gerd , Zinnecker Hans
Published: July 2016

We discuss the observed multiplicity of massive stars and implications on theories of massive star formation. After a short summary of the literature on massive star multiplicity, we focus on the O-and B-type stars in the Orion Nebula Cluster, which constitute a homogenous sample of very young massive stars. 13 of these stars have recently been the targets of a bispectrum speckle interferometry survey for companions. Considering the visual and also the known spectroscopic companions of these stars, the total number of companions is at least 14. Extrapolation with correction for the unresolved systems suggests that there are at least 1.5 and perhaps as much as 4 companions per primary star on average. This number is clearly higher than the mean number of ∼ 0.5 companions per primary star found for the low-mass stars in the general field population and also in the Orion Nebula cluster. This suggests that a different mechanism is at work in the formation of high-mass multiple systems in the dense Orion Nebula cluster than for low-mass stars.
Fragmentation of a Protostellar Core: The Case of CB 230
Authors: Launhardt Ralf
Published: July 2016

The Bok globule CB230 (L1177) contains an active, low-mass star-forming core which is associated with a double NIR reflection nebula, a collimated bipolar molecular outflow, and strong mm continuum emission. The morphology of the NIR nebula suggests the presence of a deeply embedded, wide binary protostellar system. High-angular resolution observations now reveal the presence of two sub-cores, two distinct outflow centers, and an embedded accretion disk associated with the western bipolar NIR nebula. Judging from the separation and specific angular momentum, the CB230 double protostar system probably results from core fragmentation and will end up at the upper end of the pre-main sequence binary separation distribution.
Interferometric Observations of Disks around PMS Binary Stars
Authors: Dutrey Anne
Published: July 2016

Current millimetre arrays are well suited to study the gas and dust distribution around young binary systems of separation ∼ 0.3–3″. In particular, they clearly demonstrate that disks around binary systems are tidally truncated. I review here the observed properties at mm wavelengths of the gas and dust around the best known multiple systems. I also discuss the limitations of current mm interferometers.
A Detailed Study of the GG Tau Circumbinary Disk
Authors: McCabe Caer-Eve , Ghez Andrea M.
Published: July 2016

We present near-infrared images of the circumbinary disk surrounding the pre–main-sequence binary star, GG Tau A, obtained with NICMOS aboard the Hubble Space Telescope. These images have a SNR ∼25 times higher than previous ground-based measurements, which allows the spatially resolved disk to be explored in detail. The geometry of the ring implies that the circumbinary disk is not intrinsically circular, possibly due to interactions with the central binary star. Overall, the circumbinary disk is redder than the central binary, with the amount of red excess increasing with wavelength. Significant variations in color over the 13 arcsec2 covered by the disk are also observed, raising the possibility that disk inhomogeneities are present.
The Infrared Companions of T Tauri Stars: Clues to the Formation and Early Evolution of Binaries
Authors: Koresko Chris D. , Leinert Christoph
Published: July 2016

Infrared companions are young stellar objects with unusual properties gravitationally bound to more or less typical T Tauri stars. As such they promise to be the source of information on either a particular phase in the development of young stars or on a particular mode of development. We discuss the observed properties of infrared companions as well as attempts to explain their physical status with the aim to see how much of solid conclusion has been obtained so far.
Disk Clearing in the Young Binary AK Sco
Authors: Jensen Eric L. N.
Published: July 2016

The pre–main-sequence spectroscopic binary AK Sco is surrounded by a circumbinary disk. Yet while this disk must be somewhat disturbed by the binary at its center, there is no evidence from current data that it has a cleared central hole like those seen in some young binaries, nor that accretion from the outer disk has been cut off. Indeed, most of its spectral and photometric diagnostics are indistinguishable from those of young single stars. Why doesn't this system show any evidence of disturbance of its disk? It may be that the center of the disk is indeed largely cleared, but that a small amount of dust in this region supplies the observed near-infrared excess.
Outflow from Protostars and Angular Momentum Transfer
Authors: Tomisaka Kohji
Published: July 2016

Dynamical contraction of a slowly-rotating magnetized cloud is studied using 2D magnetohydrodynamical (MHD) simulations. In the isothermal stage (n ≲ nA ∼ 1010cm−3), the cloud evolves similarly to that expected from the Larson-Penston self-similar solution and experiences a run-away collapse. However, after the central density exceeds ∼ nA, an accretion disk is formed around an adiabatic core. Just outside the core, an outflow is ejected by the effect of magnetic torque (magneto-centrifugal wind). Since ∼ 10% of the mass is ejected with almost all the angular momentum, the specific angular momentum of the protostellar core reduces to that observed in pre-main-sequence stars.
Optical and Infrared Long–Baseline Interferometry: Application to Binary Star Science
Authors: Quirrenbach Andreas
Published: July 2016

Interferometric observations of binary stars have a profound impact on many areas of stellar astrophysics. This article gives a brief review of interferometric techniques applied to binaries, and of orbit determination and binary surveys with optical and infrared interferometers.
Numerical Hydrodynamics: SPH versus AMR
Authors: Plewa Tomek
Published: July 2016

The advantages and disadvantages of two approaches to astrophysical hydrodynamics, Smoothed Particle Hydrodynamics (SPH) and Adaptive Mesh Refinement (AMR), are briefly discussed together with some current problems of computational hydrodynamics.
Impressions of IAU-Symposium 200
Authors: Ebert Rolf
Published: July 2016

Hans Zinnecker has asked me to express my impressions of this conference. My first impression here was this very modern lecture room. It contains no blackboard any more, and instead very modern tools for projecting slides and films. The room also has a supply of fresh air at EVERY seat of this room, so nobody has an excuse any more to fall asleep. When I heard the lectures on Monday, I had the feeling the whole universe was made out of binaries only. This impression reminds me of a story I have heard about Bohr and Pauli: Pauli visited Bohr at his summer cottage one day for a discussion on Quantum Theory. When Pauli approached the cottage, he saw a horse-shoe over the entrance door - a sign of good luck as you may know. Pauli, a very critical person, asked Bohr: “Do you believe in it, and that it will bring luck to you?” Bohr answered: “No, I don't believe in it. But I was told that it helps even if one does not believe in it.” This story shows you the deeply positive way of how physicists think, and may therefore also encourage us to solve our problem.
Introductory Remarks
Authors: Peebles P. J. E.
Published: July 2016

I review the assumptions and observations that motivate the concept of the extragalactic cosmic background radiation, and the issues of energy accounts and star formation history as a function of galaxy morphological type that figure in the interpretation of the measurements of the extragalactic infrared background.
Physical Modeling of the Zodiacal Dust Cloud
Authors: Ozernoy Leonid M.
Published: July 2016

This review is based on extensive work done in collaboration with N. Gorkavyi, J. Mather, and T. Taidakova, which aimed at physical modeling of the interplanetary dust (IPD) cloud in the Solar System, i.e., establishing a link between the observable characteristics of the zodiacal cloud and the dynamical and physical properties of the parent minor bodies. Our computational approach permits one to integrate the trajectories of hundreds of particles and to effectively store up to 1010–11 positions with modest computer resources, providing a high fidelity 3D distribution of the dust. Our numerical codes account for the major dynamical effects that govern the motion of IPD particles: Poynting-Robertson (P-R) drag and solar wind drag; solar radiation pressure; particle evaporation; gravitational scattering by the planets; and the influence of mean-motion resonances. The incorporation of secular resonances and collisions of dust particles (both mutual and with interstellar dust) is underway. We have demonstrated the efficacy of our codes by performing the following analyses: (i) simulation of the distribution of Centaurs (comets scattered in their journey from the Kuiper belt inward in the Solar System) and revealing the effects of the outer planets in producing ‘cometary belts’; (ii) detailed inspection of a rich resonant structure found in these belts, which predicts the existence of gaps similar to the Kirkwood gaps in the main asteroid belt; (iii) a preliminary 3-D physical model of the IPD cloud, which includes three dust components – asteroidal, cometary, and kuiperoidal – and is consistent with the available data of Pioneer and Voyager dust detectors; (iv) modeling of the IPD cloud, which provides a zodiacal light distribution in accord, to the order of 1%, with a subset of the COBE/DIRBE observations; and (v) showing that the resonant structure in dusty circumstellar disks of Vega and Epsilon Eridani is a signature of embedded extrasolar planets. Further improvements of our modeling and their importance for astronomy and cosmology are outlined.
The Diffuse Near- and Mid-Infrared Emission from the Galaxy
Authors: Cohen Martin
Published: July 2016

Recognition of an isotropic cosmic near-infrared (NIR) and mid-infrared (MIR) background involves the removal of the zodiacal foreground (both scattered and reradiated), of the truly diffuse Galactic foreground (dominated by fluorescent bands of polcyclic aromatic hydrocarbons), and of resolved and unresolved Galactic point sources. I discuss model simulations of the near- and mid-infrared point source sky from which one can assess its particular contribution to the diffuse Galactic infrared foreground. I will also indicate the transitional stage which characterizes our knowledge of fundamental stellar parameters that are essential inputs to any such models. Using the latest version of the SKY model (Wainscoat et al. 1992; Cohen 1993; Cohen 1994; Cohen et al. 1994; Cohen 1995; Ruphy et al. 1997), I will demonstrate matches to deep point source counts for a variety of passbands and galactic latitudes, and will try to quantify the uncertainties achievable in model predictions of the integrated surface brightness due to the smearing of all these foreground point sources.
Dust in Clusters of Galaxies and the Sunyaev Zel'dovich Effect
Authors: Giard Martin
Published: July 2016

We review here the unique opportunity provided by the sub-millimeter/millimeter domain to characterize both the warm intra-cluster plasma via the Sunyaev Zel'dovich Effect (SZE) on the cosmic microwave background, and the dust within this plasma via its thermal emission. However, multi-wavelength measurements are needed in order to separate these effects from the foreground galactic dust and the background infrared galaxies.
Investigation of the Local Universe by Means of IRAS Galaxies
Authors: Mickaelian A. M.
Published: July 2016

The Byurakan-IRAS galaxy (BIG) sample is based on optical identifications of IRAS PSC sources (Beichman, C. A. et al., eds. 1988, Infrared Astronomical Satellite (IRAS) Catalogs and Atlases: The Point Source Catalog, NASA RP–1190, Washington, DC). It makes use of the IR colours, DSS images, and the First Byurakan Spectral Survey (Markarian, B. E. et al. 1989, Commun. Special Astrophys. Obs., 62, 5).

All IRAS sources in the region +61° < δ < 90° at high galactic latitudes (|b| >15°) in an area of 1487 deg2 have been revealed up to the limit of the IRAS survey. The BIG sample (Mickaelian, A. M. 2000, Afz, 43, 425 and references therein) consists of 1500 galaxies, including 870 that were previously known. A redshift survey for brighter objects is being carried out with the SAO (Russia) 6 m, Byurakan Observatory 2.6 m, and Observatoire de Haute Provence 1.93 m telescopes. Redshifts in the range of 0.009–0.173 have been measured. For fainter objects, including 30 empty fields corresponding to sources with IR colors typical of galaxies, deep imaging is being carried out to reveal faint objects and study their morphologies. These objects are candidate ULIRGs. Many are multiple galaxies and small groups. About half of the galaxies are radio sources, and a number are also X-ray sources. The IR luminosity may be due to normal star formation or triggered by interaction or active galactic nuclei (AGNs). The AGNs and interacting/merging systems among the nearest BIG objects are the most interesting cases: they provide understanding of the properties of activity, starburst, and interaction phenomena and their interrelation, thus allowing a study of the physics and evolution of galaxies in the Local Universe.
Evolution of the Extragalactic Infrared-to-Ultraviolet Background and Gamma-Ray Attenuation
Authors: Kneiske T. M. , Mannheim K.
Published: July 2016

We describe a model for the evolution of the cosmic background radiation field from infrared to ultraviolet wavelengths tuned to observations of star formation and including the effects of reprocessing by dust and gas. With this model, we can compute the attenuation of gamma rays from extragalactic sources. The attenuation length for the vast majority of extragalactic gamma-ray sources (blazars and gamma-ray bursts at redshifts of order unity) depends on the evolving optical-to-ultraviolet background, whereas gamma-ray attenuation measurements of nearby sources-such as Mrk 501 probe the infrared background. We focus on the cosmological aspects of the model and discuss the effects of changing cosmological parameters, star formation rate, initial mass function, and dust opacity on the resulting gamma-ray attenuation. A plausible choice of parameters leads to fair agreement between our model in the infrared and the observed attenuation of gamma rays from Mrk 501.
Fitting Zodiacal Models
Authors: Wright Edward L.
Published: July 2016

Models of the zodiacal light are necessary to convert measured data taken from low Earth orbit into the radiation field outside the Solar System. The uncertainty in these models dominates the overall uncertainty in determining the extragalactic background light for wavelengths λ < 100 μm.