bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemical Composition of the Pole-On Be Star HD 120991
Authors: Frémat Y. , Zorec J. , Hubert A.-M.
Published: July 2016

In the present work, we propose a study performed on a pole-on Be star using its IUE and FUSE spectra that we showed only slightly affected by circumstellar emission. All our computations take into account the effects of fast rotation on the spectra (differential Doppler broadening + deformation and gravitational darkening). Using the line profiles of several well known transitions and a least squares method, we determine the abundance of light elements in the photosphere of HD 120991 and compare them to the chemical composition of the interstellar medium seen in the line of sight.
X–Ray Activity and Rotation on Bright Late–Type Giants and Supergiants
Authors: Covino Stefano , Tagliaferri Gianpiero , de Medeiros José Renan
Published: July 2016

We present and discuss statistical relation between rotation and X-ray activity for giant and supergiant stars.”
DISCUSSION: Rotation in Relation with Abundances and Magnetic Fields
Authors: Vauclair Sylvie
Published: July 2016

This general discussion was open on the papers presented in oral session II and related posters.
The Internal Solar Rotation from Helioseismology
Authors: Christensen-Dalsgaard Jørgen
Published: July 2016

Helioseismology has provided detailed inferences about the internal rotation of the Sun, and hence stringent constraints on any attempt to understand the properties and evolution of stellar rotation. Here I briefly discuss the techniques used in the analysis and review the results that have been obtained. Strikingly, these results are markedly different from the predictions made before the helioseismic data became available, emphasizing the difficulties in the modelling of phenomena as complex as stellar internal rotation.
Rotational Transport Processes
Authors: Talon Suzanne
Published: July 2016

In this review, I discuss physical mechanisms leading to momentum and chemical transport in stars. Various instabilities leading to turbulence are discussed. I then present a self-consistent description of rotational mixing under the action of turbulence and meridional circulation in 1D models. Limitations of the model are discussed, both in terms of an extra mechanism for momentum transport in the Sun and solar-type stars (magnetic field and/or gravity waves) and in terms of our understanding of turbulent properties.
Evolution of Rotation in Binaries: Physical Processes
Authors: Rieutord Michel
Published: July 2016

In this review, we describe the physical processes driving the dynamical evolution of binary stars, namely the circularization of the orbit and the synchronization of their spin and orbital rotation. We also discuss the possible role of the elliptic instability which turns out to be an unavoidable ingredient of the evolution of binary stars.
Interactions between Rotation and Pulsation
Authors: Townsend Rich
Published: July 2016

In this contribution, I will examine the interaction between stellar rotation and pulsation. I begin with a brief review of the non-rotating case, emphasizing the character of pulsations as azimuthally-propagating waves. I then go on to discuss how these waves are modified under the influence of the centrifugal and Coriolis forces. Through simple arguments, I outline the conditions under which each force can become significant in determining the wave dynamics. Particular attention is paid to the Coriolis force, since it is responsible for the formation of a waveguide, which confines the pulsation to a narrow band centered on the stellar equator. Using the example of a prograde sectoral pulsation mode, I explain the basic physical principles underlying this trapping.

The Coriolis force is also responsible for the existence of Rossby waves, which are not found in non-rotating stars. I demonstrate how these waves may be understood in terms of a conservation law for angular momentum, and review their most important characteristics. I then examine how rotation modifies the frequencies of pulsation, and explain how observations of such modifications can provide information regarding a star's rotation rate. To conclude, I focus on the converse of the pulsation-rotation interaction: how the transport of angular momentum by pulsation might be important in determining the evolution of a star's rotation profile.
Angular momentum evolution in M67
Authors: Melo C. , Pasquini L. , de Medeiros J.R.
Published: July 2016

We present nearly 70 new observations for M67 members at the main-sequence (MS), turn-off (TO) and post-turn-off (PTO) in addition to those already published in Melo, Pasquini & De Medeiros (2001). These additional v sin i measurements confirm that most of stars are experiencing a strong braking as they pass the turn-off. In contrast to our previous results, some spread in the v sin i is observed among the TO and PTO stars.
Mass Loss and Stellar Rotation
Authors: Lamers Henny J.G.L.M.
Published: July 2016

The observational evidence for non-spherical winds of rapidly rotating hot and cool stars is presented. Models to explain equatorially enhanced winds of AGB stars and of hot B[e]-supergiants are discussed. We distinguish between models with a disk due to an increased equatorial mass flux and those with a disk due to spherical mass loss with a wind flowing towards the equatorial plane.
Effects of Rotation on Helium Accreting White Dwarf
Authors: Yoon S.-C. , Langer N.
Published: July 2016

Classical studies of accreting white dwarfs have assumed spherical symmetry. However, it is believed that in close binary systems the transfered matter carries angular momentum to spin up the accreting star. Here, we present preliminary results of CO white dwarf models which accrete helium rich matter with effects of rotation considered, in the context of the Sub-Chandrasekhar mass scenario for Type Ia supernovae.
Studies of an Intergalactic HI Cloud
Authors: English Jayanne , Koribalski B. , Freeman K. C.
Published: July 2016

An intergalactic HI cloud of a few x109M⊙, previously detected using the Parkes Radio Telescope and the Australia Telescope Compact Array (ATCA) (English 1994; Freeman et al. 1996), has been confirmed in further ATCA observations of the NGC 3256 galaxy group. The group contains the prominent merging galaxy NGC 3256, which is surrounded by a number of HI fragments (English et al. 2003), the tidally disturbed galaxy NGC 3263 (Koribalski et al., in prep.), and several other galaxies. Using ATCA HI data we examine the nature of this massive gas cloud and its relationship to the neighbouring galaxies. This could be a primordial “galaxy building block”. However the cloud's properties, in conjunction with the spatial extents and velocity behaviours of the group's major galaxies, may indicate that it originated out of tidal debris.
Intracluster Stellar Population
Authors: Arnaboldi Magda
Published: July 2016

I shall review the latest results for the presence of diffuse light in nearby clusters, and the evidence of ongoing star formation in an intracluster Virgo field. I shall discuss how intracluster planetary nebulae (ICPN) can be used as excellent tracers of the diffuse stellar population in nearby clusters. Their number density distribution, density profile and radial velocity distribution provide observational constraints to models for cluster formation and evolution. The preliminary comparison of the available ICPN samples with high resolution N-body models of a Virgo-like cluster in a Lambda CDM cosmology supports “harassment” as the most likely mechanism for the origin of diffuse stellar light in clusters.
Galaxy Threshing and the Origin of Intracluster Stellar Objects
Authors: Bekki Kenji , Couch Warrick J. , Drinkwater Michael J. , Shioya Yasuhiro
Published: July 2016

We numerically investigate the dynamical evolution of non-nucleated dwarf elliptical/spiral galaxies (dE) and nucleated ones (dE,Ns) in clusters of galaxies in order to understand the origin of intracluster stellar objects, such as intracluster stars (ICSs), GCs (ICGCs), and “ultra-compact dwarfs” (UCDs) recently discovered by all-object spectroscopic survey centred on the Fornax cluster of galaxies. We find that the outer stellar components of a nucleated dwarf are removed by the strong tidal field of the cluster, whereas the nucleus manages to survive as a result of its initially compact nature. The developed naked nucleus is found to have physical properties (e.g., size and mass) similar to those observed for UCDs. We also find that the UCD formation process does depend on the radial density profile of the dark halo in the sense that UCDs are less likely to be formed from dwarfs embedded in dark matter halos with central ‘cuspy’ density profiles. Our simulations also suggest that very massive and compact stellar systems can be rapidly and efficiently formed in the central regions of dwarfs through the merging of smaller GCs. GCs initially in the outer part of dE and dE,Ns are found to be stripped to form ICGCs.
Multifrequency Study of the Blue Compact Dwarf Haro 2
Authors: Bravo-Alfaro H. , Coziol R. , Brinks E. , Baker A. J. , Walter F. , Kunth D.
Published: July 2016

We present VLA HI imaging of the blue compact dwarf (BCD) galaxy Haro 2 and a map of its CO(1-0) distribution obtained with the OVRO millimeter array. In addition we obtained NIR JH images with the 2.1m telescope of Mexico's National Optical Observatory (OAN) and derived surface brightness profiles. Combining all these results we find an intriguing picture: the HI reveals that the kinematical major axis lies perpendicular to the photometric major axis. Our observations support the suggestion that this configuration is due to recent capture of an important quantity of gas of external origin.
The Fuse Survey of O VI in and near the Milky Way
Authors: Savage B. D. , Wakker B. P. , Sembach K. R. , Richter P. , Meade M.
Published: July 2016

We summarize the results of the Far-Ultraviolet Spectroscopic Explorer (FUSE) program to study O VI in the Milky Way halo. Spectra of 100 extragalactic objects and two distant halo stars are analyzed to obtain measures of O VI absorption along paths through the Milky Way thick disk/halo and beyond. Strong O VI absorption over the velocity range from −100 to 100 km s−1 reveals a widespread but highly irregular distribution of O VI, implying the existence of substantial amounts of hot gas with T~3×105 K in the Milky Way thick disk/halo. The overall distribution of O VI can be described by a plane-parallel patchy absorbing layer with an average O VI mid-plane density of no(O VI) = 1.7×10−8 cm−3, an exponential scale height of ~2.3 kpc, and a ~0.25 dex excess of O VI in the northern Galactic polar region. Approximately 60 percent of the sky is covered by high velocity O VI with |vLSR|>100 km s−1. This high velocity O VI traces a variety of phenomena in and near the Milky Way including outflowing material from the Milky Way, tidal interactions with the Magellanic Clouds, accretion of gas onto the Milky Way, and warm/hot gas interactions in a highly extended (>70 kpc) Galactic corona or with hot intergalactic gas in the Local Group.
Do Halo Red Giant Stars Contribute to the High-Velocity Gas Falling onto the Milky Way Disk?
Authors: de Boer Klaas S.
Published: July 2016

The amount of gas shed by red giant stars in the halo is assessed to find its contribution to the long known infall of high-b gas. The infall rate due to RG star mass loss equals 3 · 10−6 M⊙ kpc−1 y−1.
Gas Mixing, Gas Cycles and the Chemical Evolution of Dwarf Irregular Galaxies
Authors: Hensler Gerhard , Köppen Joachim , Pflamm Jan , Rieschick Andreas
Published: July 2016

Dwarf galaxies are ideal laboratories to study influential effects on galaxy evolution. In particular, their gas-rich variant with very active star formation, starbursting dwarf irregulars, shows chemical and structural signatures that lead unambiguously to the conclusion that they are standing in a vital contact with their surroundings. Gas infall cannot only trigger star formation but also allows for a reduction of the metal content. on the other hand, active star formation ignites numerous supernovae type II which accumulate and can produce a galactic wind. This again depletes the metals pushing them into a gas mixing cycle with different timescales, locally of about 10 Myrs, but an galactic scales of at least 1 Gyr. This paper illuminates the different processes like gas infall and outflow and their effects on the chemical evolution, the star formation, and the gas mixing in dwarf irregular galaxies.
Flux Ratio [Ne v] 14.3/24.3 as a Test of Collision Strengths
Authors: Rubin R.H.
Published: July 2016

From ISO [Ne v] 14.3/24.3 μm line flux ratios, we find that 10 out of 20 planetary nebulae (PNs) have measured ratios below the low-electron density (Ne) theoretical predicted limit. Such astronomical data serve to provide important tests of atomic data, collision strengths in this case. In principle, well-calibrated measurements of the [Ne v] 14.3/24.3 flux ratio could improve upon the existing atomic data.
Chemical and Dynamical Evolution of IZw18
Authors: Recchi Simone
Published: July 2016

We study the effect of different star formation regimes on the dynamical and chemical evolution of the Dwarf Galaxy IZw18. To do that, we make use of a 2-D hydrocode coupled with detailed chemical yields originating from SNeII, SNeIa and low- and intermediate-mass stars. The results of our simulations are that IZw18 is a pretty young galaxy (we do not need to invoke stars older than 300 Myr in order to reproduce the chemical properties of this object) and the last burst of star formation occurred at most 15 Myr ago.
Investigation of the UV Radiation Process in NGC 2023
Authors: Dae-Hee Lee , Kwang-Il Seon , Kyoung-Wook Min
Published: July 2016

We observed the H2 absorption lines in the far-UV band toward HD 37903, which is the central star of the reflection nebula NGC 2023, and ran the radiative-collisional equilibrium program CLOUDY to simulate the UV radiation process of NGC 2023. The input parameters are chosen to generate the same ionization and excitation distribution of atoms and molecules as observed, so that we can create a physical model for NGC 2023.
Model for Infrared Properties of Extremely Young Galaxies
Authors: Takeuchi T. T. , Hirashita H. , Ishii T. T. , Hunt L. K. , Ferrara A.
Published: July 2016

We constructed a model of the infrared spectral energy distribution for very young galaxies by taking into account the dust size distribution in the early stage of galaxy evolution.
The Effect of Cosmic-Ray Diffusion for Parker Instability
Authors: Kuwabara Takuhito , Nakamura Kenji , Ko Chung-Ming
Published: July 2016

We studied the effect of anisotropic cosmic-ray (CR) diffusion for Parker instability by two-dimensional magnetohydrodynamic (MHD) simulation. We investigated two cases: a mechanical perturbation case and an explosional perturbation case. In the former case, the growth rate is proportional to the value of the diffusion coefficient of the CR. In the latter case, the growth rate becomes large in the early stages as the value of diffusion coefficient of the CR is getting small. But, after all, the result becomes the same as the former case in the late stages.
H2-Bearing Damped Lyman-α Systems as Tracers of Cosmological Chemical Evolution
Authors: Murphy M. T. , Curran S. J. , Webb J. K.
Published: July 2016

The chemical abundances in damped Lyman-α systems (DLAs) show more than 2 orders of magnitude variation at a given epoch, possibly because DLAs arise in a wide variety of host galaxies. This could significantly bias estimates of chemical evolution. We explore the possibility that DLAs in which H2 absorption is detected may trace cosmological chemical evolution more reliably since they may comprise a narrower set of physical conditions. The 9 known H2 absorption systems support this hypothesis: metallicity exhibits a faster, more well-defined evolution with redshift than in the general DLA population. The dust-depletion factor and, particularly, H2 molecular fraction also show rapid increases with decreasing redshift. We comment on possible observational selection effects which may bias this evolution. Larger samples of H2-bearing DLAs are clearly required and may constrain evolution of the UV background and DLA galaxy host type with redshift.
IR Mergers/Qsos with Galactic Winds
Authors: Lípari S. , Dottori H. , Mediavilla E. , Terlevich R. , Diaz R. , Taniguchi Y. , Garcia-Lorenzo B. , Acosta-Pulido J. , Zheng W.
Published: July 2016

We report, as a part of a long-term study of IR mergers and IR QSOs, detailed spectroscopic evidences for outflow (OF) features in nearby IR mergers/QSOs (with low and extreme velocity OF, LVOF and EVOF, respectively). We found EVOF in IRAS 01003-2238, 11119+3257, 13218+0552, 14394+5332, 15130-1958 and 15462-0450. The low velocity OF components were detected mainly in objects with starburst processes. Meanwhile the EVOF were found mainly in objects with obscured IR QSOs plus strong starbursts.

HST images of IR+BAL+Fe II QSOs show in practically all of these objects “arc or shell” features probably associated to galactic winds (GW) and/or merger processes. We present also new results of a study of the morphology, kinematics and ionized structure of IR mergers/QSOs with GW. This new study is based mainly in INTEGRAL two-dimensional (2D) fibre spectroscopy (obtained at La Palma 4.2 m telescope).
Massive Stellar Clusters and Superwind Engines in the Antennae
Authors: Gilbert Andrea M. , Graham James R.
Published: July 2016

The youngest super star clusters (SSCs) in the Antennae Galaxies (NGC 4038/39) drive supersonic mass-loaded outflows. High-resolution Keck/NIRSPEC spectroscopy reveals broad, spatially extended Brγ emission lines that are well-fit by simple wind models. Cluster mass-loss rates are up to 1.5 M⊙ yr−1 and terminal velocities are up to 205 km s−1. These emission-line clusters (ELCs) constitute at least 15% of the star formation rate in the Antennae, and their high star formation efficiencies imply that they will probably evolve into bound SSCs. The youngest ELC outflows are driven primarily by stellar winds, and they efficiently entrain ambient matter. They transfer or dissipate most of their energy and momentum in a hot or cool medium that does not emit Brγ. ELCs are the individual engines that power galactic-scale superwinds, viewed in their earliest evolutionary stage.
Mass Spectrum of a Starburst
Authors: Palouš Jan , Wünsch Richard , Ehlerová Soňa
Published: July 2016

The fragmentation of supershells and filaments driven by a superwind in a starburst region produces clumps with a mass spectrum approximated by a power law. Its spectral index is close to −2.3. We present results of computer simulations using the thin shell approximation, which are compared to 3D hydrodynamical simulations with self-gravity using the ZEUS computer code. In a low density medium the fragmentation time-scale is comparable to the collisional time-scale, and consequently collisions change the mass spectra of fragments to less steep values. In high density environments collisional time-scales are much longer and the mass spectrum results from gravitational fragmentation of expanding sheets and filaments.
Gas Outflows in Radio Galaxies
Authors: Morganti R. , Oosterloo T. , Emonts B.H.C. , Tadhunter C. N. , Holt J.
Published: July 2016

We present a summary of our recent results on gas outflows in radio galaxies. Fast outflows (up to 2000 km s−1) have been detected both in ionized and neutral gas. The latter is particularly surprising as it shows that, despite the extremely energetic phenomena occurring near an AGN, some of the outflowing gas remains, or becomes again, neutral. These results are giving new and important insights on the physical conditions of the gaseous medium around an AGN.
Stars and Gas in the Large Interacting Galaxy NGC 6872
Authors: Horellou Cathy , Koribalski Bärbel
Published: July 2016

The luminous barred galaxy NGC 6872 is one of the largest spiral galaxies known. Star formation occurs all along the arms, which extend over more than 100 kpc. The galaxy experiences tidal perturbations from the nearby companion IC 4970 passing by on a low-inclination, prograde orbit. We have mapped the large-scale distribution and kinematics of the atomic gas (HI) in the NGC 6872/IC 4970 system and carried out N-body simulations with stars and gas. HI is absent from the central region; on the other hand, large gas concentrations are found at the tip of the tidal arms, spatially coincident with the blue stellar clusters and with the peaks of the Hα distribution. We use that remarkable system to investigate the evolution of gas and stars in a close prograde encounter, examine the influence of a dark matter halo on the length of the tidal tails, and test models of collisionally induced star formation.
Double Nuclei and “TDGs”: Colliding or Activity of Nucleus Monster?
Authors: Khachikian Edward , Terzian Yervant
Published: July 2016

It is known that among active galaxies (AG) with strong emission lines (UV-galaxies, Sy 1 and Sy2, Markarian and Kazarian galaxies, Radio-galaxies, QSO's host galaxies and so on) there are large per cent of objects with double and multiple nucleus. The common sizes and volumes of these nuclei are on the order of a few hundred parsecs or kilo-parsecs. In fact these are not double galaxies or clusters of galaxies as many of astronomers believe, but just the complicated nucleus of AG. The problem is:what are the nature and the birth of these objects?There are in fact two basic suppositions in the subject: (a) The complicated nuclei are the result of merging or colliding of two or more galaxies, or: (b) They are the results of nuclear activity. The results of detailed spectroscopic observations of a number of ”tidal galaxies”, carried out with the 5m Palomar telescope, 2.6m telescope of Ambartsumian Byurakan astrophysical observatory (multi-pupil spectroscopy with Tiger receiver) and 6m telescope of Special Astrophysical observatory of Russia are presented. It is shown that in many cases the ”tidal dwarf galaxies ”(or actually complicated nucleus) are the result of galactic nuclear activity.
Jet-Induced Star Formation
Authors: van Breugel Wil , Fragile Chris , Anninos Peter , Murray Stephen
Published: July 2016

Jets from radio galaxies can have dramatic effects on the medium through which they propagate. We review observational evidence for jet-induced star formation in low (‘FR-I’) and high (‘FR-II’) luminosity radio galaxies, at low and high redshifts respectively. We then discuss numerical simulations which are aimed to explain a jet-induced starburst (‘Minkowski's Object’) in the nearby FR-I type radio galaxy NGC 541. We conclude that jets can induce star formation in moderately dense (10 cm−3), warm (104 K) gas; that this may be more common in the dense environments of forming, active galaxies; and that this may provide a mechanism for ‘positive’ feedback from AGN in the galaxy formation process.
Star Formation in Virgo Intracluster Space
Authors: Gerhard Ortwin
Published: July 2016

A number of candidate isolated compact HII regions have been discovered on combined Hα, [OIII], and broadband images in the Virgo cluster. One point-like source was spectroscopically confirmed as an HII region; this object is powered by a small starburst with an estimated mass of ~ 400 M⊙ and age of ~ 3 Myr. The object is located in the diffuse outer halo of NGC 4388, or could possibly be in intracluster space. Several resolved HII candidates are seen in the extended (~ 35 kpc) emission line region north-east of NGC 4388, perhaps triggered by the jet from the galaxy's nucleus. Star formation can thus take place far outside the main star forming regions of galaxies. The origin of the gas, the star formation, and some implications are discussed.
Discovery of Intergalactic H II Regions
Authors: Ryan-Weber E. V. , Putman M. E. , Freeman K. C. , Meurer G. R. , Webster R. L.
Published: July 2016

We have discovered a number of very small isolated H II regions 20-30 kpc from their nearest galaxy. The H II regions appear as tiny emission line dots (ELdots) in narrow band images obtained by the NOAO Survey for Ionization in Neutral Gas Galaxies (SINGG). We have spectroscopic confirmation of 5 isolated H II regions in 3 systems. The Hα luminosities of the H II regions are equivalent to the ionizing flux of only 1 large or a few small OB stars each. These stars appear to have formed in situ and represent atypical star formation in the low density environment of galaxy outskirts. In situ star formation in the intergalactic medium offers an alternative to galactic wind models to explain metal enrichment. In interacting systems (2 out of 3), isolated H II regions could be a starting point for tidal dwarf galaxies.
Superwind and Chain Galaxy Formation at High Redshift
Authors: Shioya Yasuhiro , Taniguchi Yoshiaki
Published: July 2016

We propose a possible new model for the formation of chain galaxies at high redshift.
Hα Kinematics of Tidal Tails in Interacting Systems: Projection Effects and Dark Matter in TDGs
Authors: Amram Philippe , Bournaud Fréderic , Duc Pierre-Alain
Published: July 2016

Several interacting systems exhibit at the tip of their long tidal tails massive condensations of atomic hydrogen, which may be the progenitors of Tidal Dwarf Galaxies. Because, quite often, these tails are observed edge-on, projection effects have been claimed to account for the large HI column densities measured there. Here we show that determining the velocity field all along the tidal features, one may disentangle projection effects along the line of view from real bound structures. Due to its large field of view, high spectral and 2D spatial resolutions, Fabry-Perot observations of the ionized gas are well adapted to detect a kinematical signature of either streaming motions along a bent tidal tail or of in-falling/rotating material associated with a forming TDG. Spectroscopic observations also allow to measure the dynamical masses of the TDGs that are already relaxed and check their dark matter content.
Stellar Populations of a Sample of Tidal Dwarf Galaxies
Authors: Weilbacher Peter M. , Alvensleben Uta Fritze-V. , Duc Pierre-Alain
Published: July 2016

We investigate the stellar populations of a sample of Tidal Dwarf Galaxies, combining observations and evolutionary synthesis models to try and reveal their formation mechanism. on optical images we select a first sample of TDGs for which optical spectroscopy is used to measure metallicities and velocity structure. Finally, we estimate ages, burst strengths, and stellar masses from near-infrared imaging in comparison with a dedicated grid of evolutionary synthesis models, to assess if Tidal Dwarfs are formed out of collapsing gas clouds or by an accumulation of old stars from the parent galaxy or by a combination of both.
Kinematics of the LMC CH-stars
Authors: Hartwick F.D.A. , Cowley A. P.
Published: July 2016

Velocities have been measured for 74 CH stars in the direction of the Large Magellanic Cloud (LMC). These have been used to study the kinematics of the oldest stellar population. Velocities of these objects appear to reflect two distinct subgroups - one associated with the old globular cluster population and a second with the LMC disk.
HII regions and young star clusters in the Magellanic Clouds
Authors: Lee Myung Gyoon
Published: July 2016

Using U BV CCD photometry, the stellar content of HII regions and young star clusters in the Magellanic Clouds has been studied: (1) the reddenings have been determined, and ages of OB associations and young star clusters have been measured; (2) the stellar initial mass functions have been determined by using the main-sequence luminosity functions; and (3) U BV CCD surface photometry of nine young star clusters has been obtained and their structural properties investigated.
Dynamical study of the LMC globular cluster NGC 1978 from core velocity dispersion
Authors: Meylan G. , Dubath P. , Mayor M.
Published: July 2016

The projected velocity dispersion in the core of the Large Magellanic Cloud (LMC) intermediate-age globular cluster NGC 1978 is deduced from integrated light spectra. A numerical cross-correlation technique gives a projected velocity dispersion σp(core) = 5.8±1.2 km s−1. Multimass anisotropic King-Michie dynamical models are applied to the observational constraints given by the surface brightness profile and the above central projected velocity dispersion. Depending on the model, the values obtained for the total mass of the cluster range from 0.36 to 1.44 106M⊙, corresponding to mass-to-light ratios M/LV ranging from 1.2 to 4.2 (M/LV)⊙, values typical of galactic globular clusters.
An X-ray survey of OB associations in the Large Magellanic Cloud
Authors: Wang Qingde , Helfand David J.
Published: July 2016

Based on Einstein IPC data, we have completed a census of X-ray emission from and around OB associations in the LMC. In addition to an apparent correlation of young, X-ray bright supernova remnants with recent star formation regions, we detect diffuse X-ray emission from over two dozen other associations; luminosities in the 0.16–3.5 keV band range from ˜ 3 × 1034 (the detection threshold) to ˜ 1036erg s−1. The mean X-ray luminosity of the ˜ 50 undetected associations is ˜ 1034erg s−1 and the emission from all associations contributes ˜ 4% to the total diffuse X-ray emission from the galaxy. Implications of this survey for ISM bubble evolution is discussed.
N159A: a region of active star formation in the LMC
Authors: Deharveng L. , Caplan J.
Published: July 2016

The Large Magellanic Cloud (LMC) HII region N159A is shown to be a group of ionized regions, some of which overlap, rather than a single HII region. There are at least 11 stars earlier than B2 in this region
Planetary nebulae in the Magellanic Clouds
Authors: Dopita M. A.
Published: July 2016

We present a simple two-wind model for the evolution of the Magellanic Cloud planetary nebulae (PN) which reproduces the observed density / radius / ionised mass relationships, and serves to define the geometrical relationship between the ionised nebula and the star. From self-consistent photoionisation modelling of 78 Magellanic Cloud PN, we have constructed the H-R Diagram for the central stars, and have derived both the chemical abundances and the nebular parameters. We find that the central stars have masses generally between 0.55 and 0.7 M⊙. Type I PN have more massive precursors, and show clear evidence for the Third dredge-up episode and for the dredge-up of ON processed material. The expansion velocity of the nebula is closely correlated with the position of the central star on the H-R Diagram, proving that the nebula undergoes continuous acceleration. Excluding Type I PN, the mean abundances derived for the LMC and the SMC agree with those derived from H II regions and evolved, radiative SNR.
Effects of envelope overshoot on the bump of the Red Giant Branch luminosity function
Authors: Alongi M. , Bertelli G. , Bressan A. , Chiosi C.
Published: July 2016

We show that a certain amount of non-local overshoot at the base of the outer convective envelop of low mass stars, while climbing along the RGB toward central He-ignition, explains the shift of about 0.4V mag required to bring the luminosity of the bump predicted in the theoretical RGB luminosity functions into agreement with the observational one.
Metal abundances of Magellanic Cloud clusters
Authors: Geisler D. , McWilliam A. , Suntzeff N. , Mateo M. , Graham J. , Pasquini L.
Published: July 2016

We have obtained Washington CCD photometry with the CTIO 4m and 1.5m for ˜50 intermediate-to-old age star clusters in the Clouds. The data extend to near or below the main sequence and provide excellent photometry for the giants, from which precise (internal errors <0.1 dex) mean cluster abundances can be determined. We present data for several of the clusters and discuss the results. Intermediate resolution spectra have also been obtained for some 16 clusters with the CTIO 4m ARGUS multiple-object fibre-fed spectrograph. Finally, we have also obtained high dispersion (R˜20,000) échelle spectra for several of the brighter giants in a small sample of Large Magellanic Cloud (LMC) clusters. Detailed elemental abundances derived from these spectra will be presented. These data will help refine our knowledge of the age-metallicity relation in the Clouds.
Two more Magellanic Cloud CM diagrams
Authors: Mould J.R. , Jensen J. B. , Da Costa G.S. , Kristian J. , Nemec J.M.
Published: July 2016

Lindsay 11 and NGC 1806 are globular clusters in the Small and Large Magellanic Clouds (SMC and LMC) respectively. Both clusters have extended asymptotic giant branches with carbon stars at the tip. Colour-magnitude diagrams are fitted with appropriate isochrones which indicate that both clusters belong to the abundant population of intermediate age in the Magellanic Clouds.
A survey for RR Lyrae variables in the Large Magellanic Cloud
Authors: Reid Neill , Freedman Wendy L.
Published: July 2016

In this paper we report preliminary results from a survey of RR Lyrae variable stars in the Large Magellanic Cloud.
The chemical evolution of the Magellanic Clouds
Authors: Russell S. C.
Published: July 2016

The chemical and structural evolution of the Magellanic Clouds are compared with those of the Galaxy. Simple models with gas infall and bimodal star formation are assumed, and are constrained by the most recent observational data. The evolution of the gas content, and the He, C, O and Fe abundances are all successfully modelled. The abundance of N is, however, predicted too high, and the apparent ages of the oldest star clusters are inconsistent with the simple model.
Comparison of the abundances in the stars and in the HII regions of the Magellanic Clouds
Authors: Spite M. , Spite F.
Published: July 2016

Both HII regions and F supergiants are young objects, and are, therefore, supposed to have the same abundances for all elements, especially for C, O and S, which offer a good opportunity to check the abundance determinations made by two different techniques. For oxygen and sulfur the agreement is good but the discrepancy of the carbon abundance cannot be easily explained.
N132D: a chemical and dynamic analysis
Authors: Sutherland Ralph S. , Dopita M. A.
Published: July 2016

We have obtained 2D spectrophotometry of the LMC supernova remnant N132D, achieving a higher spatial resolution than previous studies (Lasker 1978, 1980). A model based on a simple expanding ring of oxygen rich material is shown to be inadequate. We find incomplete arcs of shocked material with individual components of differing compositions. Oxygen rich material appears as rapidly moving small knots in parts of these arcs and in a larger diffuse cloud, all in the central 6-10 pc region of the remnant. We propose a model for this remnant involving the interaction of the supernova blastwave with an incomplete ring of normal composition material to produce reflected shockwaves in the inner regions of the remnant, exciting oxygen rich material.

In the knots of more normal composition a wide range of shock conditions prevail. Apart from 'normal' fully ionized radiative shocks with velocities 100-200 km/s the very steep Balmer decrements in the filaments of some spectra are consistent with partially ionized, slower, shocks. Other spectra show very strong emission lines for the higher ionization species, OIII and NeIII, which could be explained in terms of either strong shocks with long recombination timescales or as very young shocks that have not yet achieved steady flow.
OH/IR stars in the Large Magellanic Cloud: the observations
Authors: Wood P. R. , Bessell M. S. , Hughes S.M.G. , Hyland A. R. , Whiteoak J. B. , Gardner F. F. , Otrupcek R. E.
Published: July 2016

In 1985 we began a search for OH/IR objects in the Magellanic Clouds. The first detection was reported by Wood, Bessell & Whiteoak (1986). Subsequent searches have yielded several of these objects and other highly-evolved stars obscured by thick circumstellar shells.

The 1612-MHz OH observations were made using the Parkes 64-m radio telescope. Most of the observations utilized a dual-channel cryogenic receiver providing a system temperature of around 38 K on cold sky. The OH spectra were obtained with the Parkes digital correlator split into 512-channel segments. Bandwidths of 2 MHz provided a resolution of 7.8 kHz (equivalent to 1.5 km s−1 in radial velocity) after Hanning smoothing. The mode of observation has been described by Whiteoak and Gardner (1976). Typically, an integration period of 60 minutes was used; this yielded a detection limit (3a) of around 50 mJy for an OH feature. Detected emission was reobserved with a 1-MHz bandwidth. A search was also made for 1665-MHz OH emission.
Interstellar gas around WO stars in the Galaxy and the Magellanic Clouds
Authors: Lozinskaya Tatiana A.
Published: July 2016

The four oxygen-sequence WR stars, Sand 1 in the Small Magellanic Cloud (SMC), Sand 2 in the Large Magellanic Cloud (LMC), and WR 102 and WR 142 in the Galaxy represent the latest stage of the evolution of massive stars (Sanduleak 1971, Barlow and Hummer 1982, Moffatet al.1985). We have shown WR 102 to be a stripped CO core of a supermassive star (Dopitaet al.1990), probably seen only several thousand years before a SN explosion. The four stars are characterized by extremely energetic stellar winds –Vw from 4500 to 7400 km/s (Barlow and Hummer 1982, Dopitaet al.1990, Torreset al.1986). Examination of the environments of WO stars leads to the conclusion that the four objects appear to be associated with optical and/or IR shell-like structures, although the short WO-superwind does not prevail in the shell's formation.
The interacting Magellanic System
Authors: Wayte S. R.
Published: July 2016

The Magellanic System is viewed focusing on the global interactions in the System. These give insight into its history and structure. The past orbits of the Magellanic Clouds (MCs) are examined. A tidal encounter between the Large and Small Magellanic Clouds (LMC, SMC) has almost certainly occurred within the last 109 yrs. This hypothesis is supported by the observed structure of the Magellanic System, and so is accepted. The Magellanic Stream is an indirect result of the tidal encounter which is crucial to understanding the Magellanic System. It is a complex interacting gas feature, bifurcated along its entire length with many anomalous velocity H I clouds alongside. The possible models for the Magellanic Stream are examined and here I propose that its origin is due to the collision of a multi-phase halo with the vast region of gas between the LMC and the SMC. In this respect the polar subsystem around our Galaxy is seen to be particularly important. The popular tidal model for the origin of the Magellanic Stream fails to satisfy key observational features, and is thus rejected.
Asymmetric distribution of gas in the LMC and dynamical condition for globular cluster formation
Authors: Fujimoto Mitsuaki , Kumai Yasuki
Published: July 2016

The Large and Small Magellanic Clouds (LMC, SMC) have been in a binary state for the last 10 Gyr, and their centre-of-mass revolves around the Galaxy with a massive dark halo of 1012Mo. The dashed line in Fig. 1 is a relative orbit of the SMC, approaching the LMC 0.2 Gyr ago with impact parameter of 0.5 to 4 kpc (Murau & Fujimoto 1980, Fujimoto & Noguchi 1990). At this close approach, their gas clouds collided hydrodynamically to make shock compressions and coalescences in various mass scale. The ribbon is a computed orbit of a huge gas complex thus generated at α=5h40m and δ=-68° and reaching the present position.
Nucleosynthesis in AGB Stars
Authors: Lattanzio John , Forestini Manuel
Published: July 2016

We give a qualitative review of the nucleosynthesis occurring in AGB stars. We summarise some new calculations of intermediate mass stars which include all thermal pulses until the star is about to leave the AGB, as well as a detailed nucleosynthesis network. We will show that hot bottom burning delays, rather than prevents, the formation of carbon stars; those that form are not optically visible.
Presolar grains from meteorites: AGB star matter in the laboratory
Authors: Zinner Ernst , Amari Sachiko
Published: July 2016

Primitive meteorites contain dust grains that predate the Solar System, formed in stellar atmospheres and thus represent samples of ancient Stardust. Among the presolar grain types identified so far, corundum (Al2O3) and silicon carbide (SiC) are inferred to originate from AGB stars. Corundum grains carry the signatures of core H burning in their O isotopes and of shell H burning during the AGB phase in the form of extinct 26Al. In presolar SiC, most of which originated from carbon stars, the C and N isotopes and 26Al reflect core and shell H burning and shell He burning. In addition, many elements that carry the isotopic signature of neutron capture have also been measured. Most individual grains show excesses in 29Si and 30Si, but the contribution from neutron capture is only a minor effect and the major effect is due to galactic heterogeneity. Noble gases and the elements Ba, Nd, Sm, and Dy are measured in ”bulk samples”, collections of many grains. Their measured isotopic patterns are well reproduced by models of the s-process in AGB stars. Recently, the isotopic analysis of Sr, Zr and Mo in single SiC grains has been made possible by resonance ionization mass spectrometry. These measurements also point to low-mass AGB stars as the most likely sources. Specifically, large 96Zr depletions in some grains indicate that the 22Ne(α, n) source was not active in the grains' parent stars.
Results on AGB stars from Infrared surveys
Authors: Epchtein N.
Published: July 2016

In the last 3 decades, infrared surveys have discovered new classes of AGB stars, and significantly improved our knowledge of their statistical and physical properties, often in conjunction with surveys in other spectral ranges (mainly OH maser lines). After a short description of the major past and present infrared surveys and their most commonly used analysis tools, their impact is illustrated by a few examples such as the characterisation of the populations of the Bulge and Magellanic Clouds and the distribution of carbon-rich stars in the galactic disc. In conclusion, further all-sky surveys in the still unexplored spectral regions between 2 and 10 μm are strongly advocated as well as the development of ground-based telescopes dedicated to deeper surveys and monitoring of the variability.
Physics and Evolution of LPVs from HIPPARCOS Kinematics
Authors: Mennessier M.O. , Alvarez R. , Luri X. , Noirhomme-Fraiture M. , Rouard E.
Published: July 2016

The HIPPARCOS satellite provides astronomical data for about one thousand Long Period Variable stars (LPVs) from which kinematics properties and luminosity calibrations in several bandpasses are deduced using an appropriate method. Several results are deduced: a classification of the LPVs and its relation with the classification from the light curves, a calibration of luminosities inducing properties (age, mass, etc.) along the AGB and a comparison of oxygen to carbon-rich stars.
Atmospheric Structure and Mass Loss of O-rich Long Period Variables. A Confrontation of Models with ISO-SWS Observations
Authors: Aringer B. , Kerschbaum F. , Hron J. , Posch T. , Windsteig W. , Jørgensen U.G. , Höfner S.
Published: July 2016

We present ISO-SWS observations of cool oxygen-rich AGB variables and compare them to synthetic molecular and dust spectra based on hydrostatic and dynamic model atmospheres.
Condensation Chemistry of Circumstellar Grains
Authors: Lodders Katharina , Fegley Bruce
Published: July 2016

Thermochemical equilibrium calculations are successful in predicting the mineralogy as well as the major and trace element chemistry of circumstellar grains found in meteorites. The calculations also explain observations of dust close to AGB stars (within 1–3 stellar radii). The trace element chemistry in circumstellar graphite, SiC, and other refractory carbide grains agrees with equilibrium condensation calculations for circumstellar shells of carbon stars. Observed trace element abundance patterns in N stars are complementary to those found in SiC grains indicating fractional condensation in circumstellar shells. Condensation temperatures depend upon total pressure, C/O ratio, nitrogen abundances, and overall metallicity. Therefore for condensation temperatures to be meaningful, the total pressure and elemental abundances (i.e., C/O ratio, metallicity) must be specified.
Imaging the two wind post-AGB interaction in M 1-92
Authors: Alcolea J. , Bujarrabal V.
Published: July 2016

M 1-92, Minkowski's Footprint, is a well studied protoplanetary nebula (PPN). Here we present high resolution observations of this object in atomic and molecular lines, as well as in the continuum, at optical and radio wavelengths. From these observations we conclude that the present bipolar nebula is the old AGB shell, strongly modified by the interaction with some powerful post-AGB bipolar ejections, which started suddenly about 900 years ago. The nature of these post-AGB ejections as well as its comparison with the present bipolar fast flow are discussed. We conclude that a mechanism different from photon pressure must be invoked in order to explain the morphology and dynamics of M 1-92 and other similar objects.
Mass-losing AGB stars in Galactic Bulge ISOGAL fields
Authors: Blommaert J.A.D.L. , Ganesh S. , Omont A. , Schultheis M. , Ojha D. , Alard C. , Simon G. ,   The ISOGAL Collaboration
Published: July 2016

First results on AGB stars with the ISOGAL mid-infrared survey are presented. We show that M6 and later spectral type giants are detected at 7 and 15 μm up to the distance of the Galactic Centre. Analysis of the observed magnitudes and colours indicates that most of the detected AGB stars in the Galactic Bulge are losing mass. ISOCAM CVF spectra on a field in the Bulge confirm the mass loss and also show a large diversity in the shape of the silicate feature.
Carbon stars in populations of different metallicity
Authors: Groenewegen M.A.T.
Published: July 2016

Our current knowledge of carbon stars in the Local Group and beyond, is discussed. Although many carbon stars and late M-stars have been identified in external galaxies, a coherent understanding in terms of the chemical evolution- and star-formation-rate history of a galaxy is still largely lacking. Issues that need to be addressed are: 1) for some of the larger galaxies only a small fraction in area has been surveyed so far, 2) surveys have been conducted using different techniques, and may be incomplete in bolometric magnitude, 3) only for some galaxies is there information about the late M-star population, 4) not all galaxies in the Local Group have been surveyed, 5) only for a sub-set of stars are bolometric magnitudes available.

From the existing observations one can derive the following: the formation of carbon stars is both a function of metallicity and star formation. In galaxies with a similar star-formation-rate history, there will be relatively more carbon stars formed in the system with the lower metallicity. On the other hand, the scarcity of AGB-type carbon stars in some systems with the lowest metallicity indicates that these galaxies have had a low, if any, star-formation-rate history over the last few Gyrs.
Recent and Future Studies of Circumstellar Matter – A Snapshot
Authors: Jura M.
Published: July 2016

At this meeting, powerful new images and spectroscopy of AGB stars were presented. Theoretical models have advanced, and we are learning more from studies of the pre-solar grains isolated from meteorites.

We suggest that several mass loss mechanisms may be operating in AGB stars: current images imply both spherical winds and highly flattened outflows. There are good arguments that in some cases, a companion may be critical in driving the final outflow. In the near future, a number of extremely powerful new instruments and techniques will be available that will lead to a much deeper understanding of these systems.