bluuebunny/crossref_metadata_2025 huggingface dataset:
Hot Gaseous Halo in the Elliptical and Spiral Galaxies
Authors: Awaki H.
Published: July 2016

The Einstein observations revealed that starburst and luminous elliptical galaxies had X-ray halo. These galaxies have quite different stellar population. Starburst galaxies contain young massive stars, while elliptical galaxies generally contain an old-metal rich population dominated by K and M giants. Therefore a question is why these two type of galaxies commonly have hot gas, in spite of quite different stellar populations. In order to address this question, we observed these galaxies with ASCA. In this paper, I would like to present observational results, then compare the physical parameters of the hot gas in these galaxies.
Mass Measurement of Accreting Magnetic White Dwarfs with Hard X-Ray Spectroscopy
Authors: Ishida M. , Fujimoto R.
Published: July 2016

Accreting magnetic white dwarfs are usually found as component stars in Magnetic Cataclysmic Variables (MCVs), in which a white dwarf with B = 105-8 G accepts mass from a late type (secondary) star via Roche Lobe overflow. Matter from the secondary is funneled by the magnetic field and concentrates on the magnetic pole(s) of the white dwarf. Since the accretion flow becomes highly supersonic, a standing shock wave is formed close to the white dwarf. The temperature of the plasma at the shock front reflects the gravitational potential and can be denoted as a function of the mass (M) and the radius (R) of the white dwarf as:

Note here that the height of the shock is expected to be within 10% of the white dwarf radius, and hence neglected here.
Detection of TeV Gamma Rays from SN1006
Authors: Tanimori Toru
Published: July 2016

In spite of the recent progress of high energy gamma-ray astronomy, there still remains quite unclear and important problem about the origin of cosmic rays. Supernova remnants (SNRs) are the favoured site for cosmic rays up to 1016 eV, as they satisfy the requirements such as an energy input rate. But direct supporting evidence is sparse. Recently intense non-thermal X-ray emission from the rims of the Type Ia SNR SN1006 (G327.6+14.6) has been observed by ASCA (Koyama et al. 1995)and ROSAT (Willingale et al. 1996), which is considered, by attributing the emission to synchrotron radiation, to be strong evidence of shock acceleration of high energy electrons up to ~100 TeV. If so, TeV gamma rays would also be expected from inverse Compton scattering (IC) of low energy photons (mostly attributable to the 2.7 K cosmic background photons) by these electrons. By assuming the magnetic field strength (B) in the emission region of the SNR, several theorists (Pohl 1996; Mastichiadis 1996; Mastichiadis & de Jager 1996; Yoshida & Yanagita 1997) calculated the expected spectra of TeV gamma rays using the observed radio/X-ray spectra. Observation of TeV gamma rays would thus provide not only the further direct evidence of the existence of very high energy electrons but also the another important information such as the strength of the magnetic field and diffusion coefficient of the shock acceleration. With this motivation, SN1006 was observed by the CANGAROO imaging air Cerenkov telescope in 1996 March and June, also 1997 March and April.
Impulsive Flare Plasma Energization in the Light of Yohkoh Discoveries
Authors: Voitenko Yurii M.
Published: July 2016

Flare scenario, based on Yohkoh observations and magnetic reconnection (MR) hypotesis, has been elaborated recently (Tsuneta, 1996; Shibata, 1997). Using theoretical prediction that the fast MR results in a high-speed outflows from reconnection site, the reconnection downflow has been supposed to collide with the top of underlying magnetic loop, producing superhot plasma and high-energy particles.
The X-Ray Spectrum of Supernova SN1993J
Authors: Uno Shin'ichiro , Mitsuda Kazuhisa , Takahashi Tadayuki , Inoue Hajime , Makino Fumiyoshi , Makishima Kazuo , Ishisaki Yoshitaka , Kohmura Yoshiki , Itoh Masayuki , Lewin Walter H.G.
Published: July 2016

SN1993J is very unique object which was discovered in the nearby Sb galaxy M81 (NGC 3031) on March 28. The first detection of the radio emission was at 22.5 GHz by the VLA only 5 days after the optical outburst. Subsequently X-ray emission was detected by ROSAT and ASCA at 6 days and 8 days after the explosion respectively. These emissions are expected when the SN shock front sweeps out the circumstellar matter (CSM). The early detection of radio and X-ray emission implies the existence of high-density CSM in the vicinity of the supernova(e.g.).
The Morphologies of SNRs and Their ISM and CSM
Authors: Wang Zhenru
Published: July 2016

Recently, many unusual morphologies of supernova remnants (SNRs) have been discovered: semicircular shell; center-brightened but without center point source; two-lobed; bipolar; irregular, etc. To understand these varieties of morphologies, we have made theoretical models. One of the main reasons of their unusualness is the multiphase structure of the interstellar medium (ISM) and circumstellar medium (CSM) where they evolved, and the CSM is connected with their progenitor.
Observations of Interstellar O VI Absorption at 3 km/s Resolution
Authors: Jenkins E.B. , Sofia U.J. , Sonneborn G.
Published: July 2016

For studies of diffuse gases in the temperature range 105 – 106K, observations of O VI absorption in the spectra of background stars provide an important supplement to information from surveys of soft x-ray emission. We report here the first observations of O VI absorption recorded at a resolution of 3 km s−1 for the stars 15 Mon and HD 64760. Both stars are behind regions that are suspected to be old supernova remnants. The observations were made with the Interstellar Medium Absorption Profile Spectrograph (IMAPS) during its flight on the ORFEUS-SPAS II mission in late 1996.
Hydrodynamical Model of X-Ray Emitting Gas Around Elliptical Galaxies
Authors: Saito Ryo , Shigeyama Toshikazu
Published: July 2016

We have performed spherically symmetric, time-dependent hydrodynamical calculations for the X-ray emitting gas around elliptical galaxies, NGC4472, for the purpose to reproduce profiles of temperature and density. Stellar mass loss rate and type Ia supernova rate are assumed to be constant. Thermal conduction is introduced to stabilize against thermal instability due to radiative cooling.
ASCA Observation of “Failed Cluster” of Galaxies Candidate, 0806+20
Authors: Hashimotodani K. , Hayashida K. , Takeuchi T. T.
Published: July 2016

The hypothetical object called “failed cluster” of galaxies is described by Tucker et al. (1995, ApJ, 444, 532) as a large cloud of X-ray emitting hot gas without any visible galaxies. They made extensive survey of this type of objects using Einstein IPC database and found only one candidate, 0806+20.
Mapping the Virgo Cluster of Galaxies with ASCA
Authors: Ohashi T. , Kikuchi K. , Matsushita K. , Yamasaki N. Y. , Kushino A. ,   ASCA VIRGO PROJECT TEAM
Published: July 2016

In the Virgo cluster, we can perform a close study of the gas injection mechanism from galaxies into the cluster space and the interaction between the injected gas and the sorrouding cluster medium. In 1996 to 1997, we carried out mapping observations of a 2.°5 × 2.°5 area in the north-west region of the cluster. There are 16 pointings in total in this region, and the observed results are briefly reported here.
Sunyaev-Zel'dovich Effect Observation Project with the Nobeyama 45-m Telescope
Authors: Tsuboi M. , Ohno T. , Miyazaki A. , Kasuga T. , Sakamoto A. , Noguchi T.
Published: July 2016

The combination of X-ray and Sunyaev-Zel'dovich (S-Z) effect observations toward cluster of galaxies gives the independent estimation of Hubble constant (Sunyaev and Zel'dovich 1970). The measurement of S-Z effect is one of the most difficult observations in radioastronomy because of the weakness of the effect, ΔT= 0.1 × 1 mK (e.g. Rephaeli 1995). Because the field of view of the exist interferometers is smaller than the extended distribution of S-Z effect of low redshifted clusters, single-dish telescopes gain an advantage over interferometers. In addition, to reduce the contaminations from Galaxy and galaxies in the cluster, the mm-wave observation is preferable. Thus, we have started the project of S-Z effect observation with the Nobeyama 45-m telescope, which is the largest mm-wave telescope in the world. Our scientific goal is reliable measurement of S-Z effect of many clusters. To realize this we have made a multi-feed PCTJ-SIS mixer receiver at 40 GHz as a sophisticated tool for the observation of S-Z effect (Noguchi et al. 1995, Kasuga et al. 1995, Tsuboi et al. 1997).
The Equations of Motion for Binary Systems with Relativistic Quadrupole-Quadrupole Moments Interaction
Authors: Xu C. , Wu X.
Published: July 2016

The study of binary systems is one of the most important problems in astronomy. Especially recently, gravitational wave detection made possible by Laser Interferometer Gravitational wave Observatory - LIGO and VIRGO, LISA opens up a completely new window for the observation of our universe, it becomes one of the most important and forward area in the modern general relativistic astrophysics. Coalescing binary neutron star (NS) systems are believed to be the most important source emitted high-frequency gravitational wave. Therefore the study of NS coalescence is regarded as a major challenge in modern relativistic astrophysics. Indeed, if the two-body problem could be solved with a sufficient accuracy, the wealth of information might be extracted from the waveforms of coalescing binaries. Many early works to derive and investigate the gravitational two-body system with spin and quadrupole moment interaction have been done already. A detail appraisal of their works has been made by Xu, Wu and Schäfer where they derived the first post-Newtonian equations of motion for binary systems with monopole, spin and quadrupole interaction by making use of the scheme developed by Damour, Soffel and Xu (DSX)As we know, in the last stages of coalescence in binary system, the distance between two stars is closer, the tidal force is stronger, so the nonspherical size l is larger, l2/r2 can reach the level of v2/c2, where r is the distance between two bodies. In this case, the relativistic qudrupole-quadrupole term is of 3-PN order, so one can not neglect the 1-PN contribution of the q-q terms when 3-PN equations of motion (for mass-monopole) are considered. In order to fit the requirement of more accurate solution for binary system, the relativistic q-q terms in the post Newtonian equation of motion have been calculated in this paper. Our work is the first to obtain explicit 1-PN equations of motion for binary systems with relativistic quadrupole-quadrupole interaction in terms of only collective coordinates and B-D moments.
Supersoft X-Ray Source RX J0019.8+2156
Authors: Matsumoto Katsura , Okugami Masamitsu , Fukue Jun
Published: July 2016

RX J0019.8+2156 (RX J0019) is one of supersoft X-ray sources (SSXSs) which were rarely found in the Galaxy, and the brightest one upto now (Beuermann et al. 1995). Although the binary systems of SSXSs are still not perfectly revealed, if the model with nuclear burning white dwarf (van den Heuvel et al. 1992) is adopted, it is supposed that most of radiative energy are generated on the surface of the white dwarf. The radiation strongly irradiates the accretion disk and companion, and the reprocessing has an influence upon an observed flux of SSXSs in lower frequencies (Popham, DiStefano 1996).
ASCA Observations of the SgrA Region
Authors: Maeda Y. , Koyama K. , Murakami H. , Sakano M. , Ebisawa K. , Takeshima T. , Yamauchi S.
Published: July 2016

The complex radio source Sgr A is embedded in a region near our Galactic Center. The dynamical center of our Galaxy is considered to be Sgr A*, the compact non-thermal radio source. Dynamical mass within ~0.1 pc from Sgr A* has been estimated to be ~ 3×106 M⊙. This places Sgr A* to be a candidate of a massive blackhole (Eckart and Genzel, 1997 and reference therein).
Spectral Evolution During Dipping of the Low Mass X-Ray Binary XBT 0748-676
Authors: Church M. J. , Bałucińska-Church M. , Mitsuda K. , Dotani T. , Asai K.
Published: July 2016

XBT 0748-676 is a dipping LMXB source, with dips in X-ray intensity occurring at the orbital period of ~ 3.8 hrs. It is a member of the sub-group of dipping sources also including XB 1916-053 and XB 1254-690 in which the spectral evolution in dipping has previously been modelled by the “absorbed plus unabsorbed” approach, in which the dip spectra are modelled by two terms, each having the same form as used for non-dip emission, one of which is strongly absorbed but one which is not absorbed, which has a normalisation decreasing strongly in dipping. This energy-independent decrease has sometimes been taken to imply electron scattering in the absorber.
Optical Flares of Cygnus X-1
Authors: Bochkarev N.G. , Karitskaya E.A. , Lyuty V.M.
Published: July 2016

Photoelectric observations of Cyg X-1 in 1996-97 fulfilled in Tien-Shan, Kazakhstan (WBVR), Mt. Maidanak, Uzbekistan (UBVR) and in Crimea, Ukraine (UBV) have detected unusual optical flare activity. During May-August 1996 Cyg X-1 was in high soft X-ray state and after August 9, 1996 it returned to its ordinary state but with some evidences of X-ray activity.
Cygnus X-1: X-Ray Emission Mechanism and Geometry
Authors: Cui Wei , Zhang S. N. , Swank J. H. , Hua X.-M. , Ebisawa K. , Dotani T.
Published: July 2016

On 1996 May 10, the All-Sky Monitor aboard RXTE revealed that Cyg X-1 started a transition from its hard state to soft state (Cui 1996). Throughout this interesting episode, snapshots were taken with more sensitive detectors on ASCA, RXTE, and CGRO to monitor the temporal and spectral variability of the source over a broad energy range.
X-ray Timing Studies of GRS 1915+105
Authors: Paul B. , Agrawal P. C. , Rao A. R. , Vahia M. N. , Yadav J. S. , Marar T. M. K. , Seetha S. , Kasturirangan K.
Published: July 2016

We have made photometric observations of the galactic superluminal jet source GRS 1915+105 in the energy bands of 2-6 and 6-18 keV during 1997 June 12-29 and August 8-10. During our observations, different types of very intense, quasi-regular X-ray bursts have been observed from this source. We present here the light curves and the power density spectra of our observation of this source in its bright state.
Three-Dimensional Local MHD Simulations of High States and Low States in Magnetic Accretion Disks
Authors: Matsuzaki T. , Matsumoto R. , Tajima T. , Shibata K.
Published: July 2016

Black hole candidates sometimes show a transition between the high (or soft) state and the low (or hard) state. In the low state, low frequency time variations are much larger than the high state. A possible mechanism of the large-amplitude, sporadic time variabilities in the low-state is the magnetic energy release in low-β (β = Pgas/Pmag < 1) disks (Mineshige, Kusunose & Matsumoto 1995). It had been thought that low-β disks cannot exist because buoyant escape of magnetic flux due to the Parker instability may set the lower limit for β inside the disk. Shibata, Tajima & Matsumoto (1990), however, pointed out that in accretion disks, once a low-β disk is formed, it can stay in low-β state partly because the growth rate of the Parker instability decreases when β < 1. They suggested that magnetic accretion disks fall into two types; high-β disks and low-β disks.
Electron-Positron Pair Winds from Central Luminous Accretion Disk with Radiation Drag
Authors: Tajima Y. , Fukue J.
Published: July 2016

The accretion disks are now supposed to be the main driving source of the active astrophysical phenomena. Even the electron-positron pair plasma will be created at the surface of the sufficiently luminous disk. While the effect of radiation drag which causes in the intense radiation fields around the accretion disk is examined recently. Then, we numerically consider the radiative accelerated pair-winds, which blow off from central luminous accretion disk surrounding a black hole, taking into account radiation drag of the order of v/c.
X-Ray Properties of LINERs and Low Luminosity Seyfert Galaxies Observed with ASCA
Authors: Terashima Y. , Kunieda H. , Serlemitsos P.J. , Ptak A.
Published: July 2016

We present ASCA spectra of low luminosity AGNs with X-ray luminosities of 1040-41 ergs s−1. Their X-ray continua are very similar to Seyfert galaxies. Although iron K emissin centered at 6.4 keV or 6.7 keV is detected from a few objects, iron K emission is weak on average. Possible reasons for variety of iron line properties are discussed.
Optical Variability in AGNs; Disk Instability or Starbursts?
Authors: Kawaguchi T. , Mineshige S. , Umemura M. , Turner E. L.
Published: July 2016

Aperiodic optical variability is a common property of Active Galactic Nuclei (AGN), though its physical origin is still open to question. We have compared light curves among the following two models and observation of quasar 0957+561A,B (Kundić et al. 1997) in terms of structure function analysis (§2).
The Hipparcos results
Authors: Turon C.
Published: July 2016

After a brief presentation of the Hipparcos mission, and an overview of the astrometric and photometric results obtained from the main mission and from Tycho, more details are given on the parallaxes. Absolute parallaxes have been obtained for 117 955 entries of the Hipparcos Catalogue, out of a total of 118 218, with a median precision of 0.97 mas for stars brighter than 9. This precision varies with apparent magnitude and ecliptic latitude. The estimated systematic error is smaller than 0.1 mas. The distances of more than 20 000 stars are determined to better than 10 %. Some more statistics are presented.

A few applications of this fantastic amount of new and accurate data are presented, in the fields of absolute magnitude calibrations, stellar physics, distance scale determination.
Stellar distances by the Baade-Wesselink method
Authors: Benedetto G. P. Di
Published: July 2016

Galactic and extragalactic distances to Cepheid variable stars according to a modern realization of the geometric Baade-Wesselink method are presented. Reliable results as accurate as few percent are currently achievable, allowing the cosmic distance scale calibration to be significantly improved with respect to previous calibrations.
The bolometric luminosities of stars
Authors: Bless R. C. , Percival J. W.
Published: July 2016

The total energy emitted by a star is one of its basic parameters. It is also one of the most difficult to determine, requiring space-based as well as ground-based measurements of the absolute flux from stars. We review the current status of these observations in the ultraviolet, visible, and near infrared, and estimate the uncertainties of the absolute flux measurements in these spectral regions. We compare recent determinations of the bolometric luminosity of early-type stars with the first (mostly) empirical results of 20 years ago. We close with a few comments on possible improvements of these measurements in the future.
Abundance anomalies in globular clusters
Authors: Costa G. S. Da
Published: July 2016

The galactic globular clusters presumably formed rapidly as high density concentrations at the centres of extensive star forming regions and the natural expectation is that they will be chemically homogeneous. In general, this is confirmed by observation — most globular clusters are extremely homogeneous with regard to most elements. (There are two exceptions: ω Cen and M22 both have intrinsic internal abundance ranges. While of considerable interest, e.g. Norris et al. 1996, this type of “abundance anomaly” will not be discussed here). But we have known for more than twenty years that the surface abundances, which are what we observe, of elements such as C, N and O can vary substantially from red giant to red giant within an individual globular cluster. Indeed it has become clear that “abundance anomalies” of this type are common in the galactic globular cluster population. Briefly, the observed anomalies can be summarized as: (i) the “anomalous” stars are depleted in C and enhanced in N. Depletions of O also often accompany the depletions in C. (ii) The C, N and O variations are usually accompanied by enhancements of Na and Al and when the O depletion and the Al enhancement are both large, Mg is depleted. No other elements, including r- and s-process indicators, vary.
Progress on model atmospheres and line data
Authors: Kurucz Robert L.
Published: July 2016

I discuss errors in theory and in interpreting observations that are produced by the failure to consider resolution in space, time, and energy. I discuss convection in stellar model atmospheres and in stars. One dimensional convective models can never work well, but the errors in predicted diagnostics for temperature, gravity, and abundances can be calibrated. I discuss the variation of microturbulent velocity with depth, effective temperature, and gravity. These variations must be dealt with in computing models and grids and in any type of photometric calibration. I describe the state of the art in computing a model atmosphere and complete spectrum for stars with arbitrary abundances. I have made no significant progress on atomic or molecular line data for the last two years, but I will soon begin large scale production. I will continue to distribute the results on CD-ROMs, and I will make them available on the World Wide Web.
Summary and review: Interaction of observations and theory of stellar interiors
Authors: Kawaler Steven D.
Published: July 2016

As we move into the next century of stellar astronomy, it is helpful to consider the modes by which stellar astronomy has advanced in the modern era. At this conference, our attention has been focussed on precision measurement of stellar fundamental properties such as mass, luminosity, and radius. This mode of inquiry is one of several that have borne fruit. In this review, I will discuss some of the topics that have arisen here with respect to how our understanding of stellar interiors progresses through interaction between theory and observation.
The Cool Atomic Gas in the Large Magellanic Cloud
Authors: Marx-Zimmer M. , Zimmer F. , Herbstmeier U. , Dickey J. M. , Staveley-Smith L.
Published: July 2016

Studying the cool atomic phase of the interstellar medium is of special significance as cool atomic clouds can become the raw material for star formation and so determine the evolution of the whole galaxy. The cool atomic interstellar medium of the Large Magellanic Cloud (LMC) seems to be quite different from that in the Milky Way. In three 21 cm absorption line surveys using the Australia Telescope Compact Array (ATCA) the physical properties of the cool atomic hydrogen in the LMC and the halo of the Magellanic Clouds have been studied. Here we present the results of the third HI absorption line survey. A detailed investigation of the cool HI has been done toward the supergiant shell LMC4, the surroundings of 30 Doradus and in the direction of the eastern steep HI boundary. The data have been compared with survey 2 (Dickey et al. 1994) to probe the cool gas fraction for these different regions of the LMC and to study the differences of the cool atomic phase of the LMC and that of the Milky Way.
The Absorption Line Systems of the Supershell LMC2 in the Large Magellanic Cloud
Authors: Caulet Adeline
Published: July 2016

The interstellar medium of LMC2, a well studied supershell in the Large Magellanic Cloud, has been probed in UV and optical absorption lines. The data allow to derive the kinematics, abundances and depletions of gas clouds in this supershell. The relative gas-phase abundances of observed elements with respect to sulphur are useful to determine the origins of the supershell absorption-line clouds.
The Kinematic Structure of the Supergiant Shell LMC 2
Authors: Points Sean , Chu You-Hua , Kim Sungeun , Gruendl Robert , Smith R. Chris , Snowden Steve , Brandner Wolfgang
Published: July 2016

LMC2 was one of the first supergiant shells in the Large Magellanic Cloud (LMC) to be identified, based on the detection of long, curved Hα filaments extending over 900 pc (Goudis & Meaburn 1978). LMC 2 is located to the east of the active star formation region south of 30 Doradus. LMC 2 is a spectacular supergiant shell in the LMC, having the most coherent filamentary structure and the highest X-ray surface brightness. As shown in Fig. 1, the diffuse X-ray emission from LMC 2 is bounded by the Hα filaments in the north and east. A bright X-ray arc is seen in the southwest quadrant, extending from N 158 and N 159.
ROSAT Survey of X-ray Sources in the Magellanic Clouds
Authors: Haberl F. , Pietsch W. , Filipovic M.
Published: July 2016

More than 250 pointed observations of the Magellanic Clouds were performed with the ROSAT PSPC during its nominal operation phase. From an analysis of the images we obtained a list of about 750 point-like sources in the LMC and more than 500 sources in the SMC region. In combination with the ROSAT all-sky survey this large amount of data offers the unique opportunity to study the detailed physical properties of individual X-ray sources as well as the global statistical properties of different types of X-ray sources of a small galaxy as a whole. We report on the first results obtained from cross-correlations of our PSPC source catalogues with catalogues from other wavelength bands. Proper selection criteria, based on comparisons with known sources, permits the identification of new candidates for various source classes in the Magellanic Clouds such as supersoft sources, X-ray binaries and supernova remnants, and makes it possible to discriminate them from foreground stars and background objects.
HST/NICMOS Survey in the 30 Doradus Nebular Filaments
Authors: Barbá Rodolfo H. , Walborn Nolan R. , Brandner Wolfgang , Probst Ronald G. , Rubio Mónica , Grebel Eva K.
Published: July 2016

On the basis of ample evidence accumulated during recent years for current star formation within the 30 Doradus Nebula, which appears to have been triggered by the massive central cluster (R136) in and just beyond the curved nebular filaments surrounding it, an HST/NICMOS survey of these regions was undertaken.
Element Abundances in Magellanic Cloud H II Regions from Carbon to Argon
Authors: Garnett Donald R.
Published: July 2016

I review measurements of heavy element abundances within H II regions in the Magellanic Clouds, highlighting in particular improved determinations of carbon abundances based on UV spectroscopy with Hubble Space Telescope. In general, the Magellanic Cloud H II regions show average underabundances in O, Ne, and S (relative to their Galactic counterparts) that are similar to those measured in Magellanic Cloud stars. However, comparison of stars and ionized gas shows discrepancies in C and N abundances that may be related to recently recognized mixing processes that may be operating in massive stars.
On the Star-formation History in the LMC: Observations of the Interstellar C18O/C17O Ratio
Authors: Heikkilä Arto , Johansson Lars E.B. , Olofsson Hans
Published: July 2016

The re-cycling of gas between stars and the interstellar medium (ISM) leads to a gradual metal-enrichment of a galaxy. Accordingly, information on the chemical evolution of a galaxy, e.g., its star-formation history (SFH), is contained in the chemical composition of the ISM. In this context, the abundance ratio of the rare oxygen isotopes, 18O/17O (usually taken as the C18O/C17O column density ratio), appears to be a particularly promising probe of the SFH. According to present understanding of stellar nucleosynthesis, 17O is mainly produced in intermediate-mass stars (say a few to ten M⊙) while 18O is synthesised in massive stars (say >10M⊙) (e.g., Prantzos et al. 1996). Thus, the 18O/17O abundance ratio possibly reflects the relative number of massive stars compared to intermediate-mass stars, and thereby (qualitatively) constrains the SFH in terms of the average star-formation rate (SFR) and the initial mass-function (IMF). However, it should be remembered that the stellar nucleosynthesis of 17,18O is not yet fully understood, leaving room for other interpretations of the 18O/17O ratio.
A Photometric Survey of the LMC Field near NGC 2257
Authors: Walker A. R. , Schommer R. A. , Suntzeff N. B. , Hodge P. W. , Mateo M. , Olszewski E. W.
Published: July 2016

Star formation in the outermost regions of the LMC, several kpc from the center, has been dormant for some Gyr. With deep HST and wide-field ground-based imaging surveys, sufficient stars can be measured to accurately delineate the critical turn-off and subgiant branch regions of the CMD, and thus provide a picture of the first 10 Gyr of star formation in the LMC.
2MASS Observations of the Large Magellanic Cloud
Authors: Van Dyk S.D. , Cutri R. , Weinberg M. D. , Nikolaev S. , Skrutskie M. F.
Published: July 2016

The Two Micron All Sky Survey (2MASS) has observed a portion of the Large Magellanic Cloud (LMC) at J (1.25 μm), H (1.65 μm), and Ks (2.17 μm), as part of its routine nightly operations with an automated 1.3-m telescope at CTIO, Chile. The camera observes the sky in the three channels simultaneously, using 256 × 256 HgCdTe detector arrays. The survey samples the sky in 6° x 8.′3 scans. The 2MASS Production Processing System provides final atlas images and source extractions with precise photometric calibration and astrometric positions. The survey's 10σ sensitivity is 15.8 mag at J, 15.1 at H, and 14.3 at Ks. 2MASS will ultimately detect ~107 point sources in the LMC and will support analyses of the ages, luminosity and mass functions, and metallicities of the red stellar populations and a census of AGB and carbon stars, as well as extinction maps, across the LMC. This work presents an initial analysis of ~20 square degrees.
AGB Stars in the Large Magellanic Cloud as Seen with DeNIS
Authors: Cioni M. R. , Habing H. J. , Loup C. , Epchtein N. , Consortium the DeNIS
Published: July 2016

We present infrared photometry of LMC stars taken from a region of 2.5° in right ascension from the DeNIS (Deep Near Infrared Southern Sky Survey) survey.
Stellar Associations in the LMC
Authors: Kontizas E. , Kontizas M. , Gouliermis D. , Dapergolas A. , Korakitis R. , Morgan D. H.
Published: July 2016

The stellar associations are defined as loose unbound concentrations of young stars with a bright OB stellar component, mainly located at the most recent star forming regions, representing the smallest units in the hierarchy of stellar systems in galaxies. The definition of the associations is discussed and the main properties of their stellar content are summarized. Using plates taken with the 1.2m UK Schmidt Telescope a method is developed to detect all stellar associations in the LMC and to find their spatial distribution relative to the LMC's recent star formation history. In 40% of the LMC region, the number of “single peak” associations has increased considerably (~ 3x). A very interesting result is that the faint limit, where the identified associations are revealed, varies by about 3 mag. This indicates not only extinction differences but also the presence of pre-main sequence stars at a wide range of masses.
Young Populous Clusters in the Magellanic Clouds – Implications for Stellar Evolutionary Models
Authors: Keller Stefan C. , Bessell Michael S. , Costa Gary Da
Published: July 2016

We present new UV, visual and Hα photometry obtained with the WFPC2 of NGC 330, NGC 1818, NGC 2004 and NGC 2100, four young populous clusters in the MCs. We present observational evidence for a degree of convective core overshoot in excess of that currently applied in standard models.
Three Old LMC Globular Clusters
Authors: Johnson Jennifer A. , Bolte Michael , Bond Howard E. , Hesser James E. , de Oliveira Claudia M. , Richer Harvey B. , Stetson Peter B. , Vandenberg Don A.
Published: July 2016

We used deep HST imaging of three LMC clusters, NGC 2257, NGC 1466 and Hodge 11, to determine their ages relative to Milky Way clusters. They all have similar ages to within ± 1 Gyr. For NGC 2257 and NGC 1466, we measured the blue straggler specific frequencies and find them to be similar to those of Galactic clusters.
HST Study of the Stellar Populations Within 30 pc of SN1987A
Authors: Romaniello Martino , Panagia Nino , Scuderi Salvatore
Published: July 2016

We present the results of a study of the stellar population around SN1987A in the Large Magellanic Cloud based on an analysis of multi-band HST-WFPC2 images.
A Search for Tidal Stellar Debris from the Magellanic Clouds: Survey Results from the First Two Years
Authors: Majewski S. R. , Ostheimer J. C. , Kunkel W. E. , Johnston K. V. , Patterson R. J. , Palma C.
Published: July 2016

An important discriminant between leading models for the origin of the Magellanic Stream is the presence of a stellar counterpart to the HI gas stream: ram pressure stripping of gas by a putative hot Galactic halo would act only on Magellanic gas while gravitational tidal stripping would act on both gas and stars. Several previous attempts to find tidal stellar debris have failed to find carbon stars, A stars, or other main sequence stars in the Magellanic Stream (Mathewson et al. 1979; Recillas-Cruz 1982; Brück & Hawkins 1983; Guhathakurta & Lin 1999). However, there has long been a suggestion (Kunkel 1979; Lynden-Bell 1982) of a possible Magellanic association of satellite galaxies and globular clusters that have similar orbits and may derive from the break up of a greater Magellanic galaxy (Lynden-Bell & Lynden-Bell 1995; Majewski et al. 1997). Recent models (Moore & Davis 1994; Johnston 1998) of the tidal disruption of Large Magellanic Cloud (LMC)-like systems indicate a wide dispersal of debris, much wider than the rather confined HI stream, so that the contrast of tidal debris against the Galactic fore/background would be low. If true, this could explain some of the previous negative results for tidal debris searches.
Distance to SN 1987A and the LMC
Authors: Panagia Nino
Published: July 2016

Using the new reductions of the IUE light curves by Sonneborn et al. (1997) and an extensive set of HST images of SN 1987A we have repeated and improved Panagia et al. (1991) analysis to obtain a better determination of the distance to the supernova. In this way we have derived an absolute size of the ring Rabs = (6.23 ± 0.08) x 1017 cm and an angular size R″ = 808 ± 17 mas, which give a distance to the supernova d(SN1987A) = 51.4 ± 1.2 kpc and a distance modulus m–M(SN1987A) = 18.55 ± 0.05. Allowing for a displacement of SN 1987A position relative to the LMC center, the distance to the barycenter of the Large Magellanic Cloud is also estimated to be d(LMC) = 52.0±1.3 kpc, which corresponds to a distance modulus of m–M(LMC) = 18.58±0.05.
Observations of Cepheid Variables in Two LMC Clusters Using EROS 2 Data
Authors: Ripepi V. , Bauer F. , Beaulieu J. P.
Published: July 2016

It is well known that Cepheid variables are very important distance indicators because of their PL and PLC relations. The distances derived through the quoted relations are affected by well known systematic effects, since, in general, we have a poor knowledge of both reddening and metallicity of the Cepheid sample. Good estimates of the quoted parameters can be achieved if the observed Cepheids are cluster members since, by comparison between cluster CMD and theoretical isochrones we can estimate the cluster reddening, metallicity and age, i.e., the evolving masses for each evolutionary phase. The ideal objects to be searched for Cepheid membership are Magellanic Cloud clusters since they are well populated in the relevant evolutionary phases.
Planetary and lunar ephemerides, lunar laser ranging, and lunar physical librations
Authors: Newhall X X , Williams J. G. , Standish E. M.
Published: July 2016

The Jet Propulsion Laboratory (JPL) has recently produced a new integrated planetary and lunar ephemeris DE403/LE403. This ephemeris spans the interval JED 624912.5 (December 2, −3002, Julian) – JED 2817104.5 (November 14, 3000, Gregorian) and is an improvement on DE102 (Newhall et al., 1983) and DE200 (Standish, 1990). This integration carries the Cartesian states of the Sun, Moon, and planets, along with the three Euler angles describing the lunar physical librations.
Marginal stability and chaos in the solar system
Authors: Laskar Jacques
Published: July 2016

The motion of the planets is one of the best modelized problems in physics, and its study can be practically reduced to the study of the behavior of the solutions of the well known gravitational equations, neglecting all dissipation, and treating the planets as mass points. In fact, the mathematical complexity of this problem, despites its apparent simplicity is daunting and has been a challenge for mathematicians and astronomers since its formulation three centuries ago.
The need for more accurate 4000-year ephemerides, based on lunar and spacecraft ranging, ancient eclipse and planetary data
Authors: Pang Kevin D. , Yau Kevin K.
Published: July 2016

Long planetary and lunar ephemerides like the JPL DE102 and LE51 (Newhall et al., 1983) and the Bureau des Longitudes VSOP (Bretagnon, 1982) and ELP (Chapront-Touze and Chapront, 1983) have enabled more positive ancient eclipse, planetary and cometary identifications, which have in turn refined ephemerides, e.g., the reconstruction of the orbit of comets Halley and Swift-Tuttle (Yeomans and Kiang, 1981; and Yau et al., 1994). The data used to initialize DE102 are pre-1977. Much more observational data have been collected since. The lunar ephemeris has also been improved. The secular lunar acceleration, , from laser ranging, is −25.9±0.5″/cen2 (Williams et al., 1992). We can now uniquely solve for ΔT, the clock error, from ancient eclipse records. The lack of ΔT values before 700 B.C. has left the early timescale of the ephemerides unconstrained (Morrison, 1992). Our solution of this problem is outlined here.
Foundations of a theory of the motion of the orbit plane of Hyperion
Authors: Message P.J.
Published: July 2016

The principles are set out for the construction of a theory of the motion of the orbit plane of Hyperion, using the mixed set of angle parameters, using different reference planes for different angles, which it has proved convenient to use. It is found that this leads to additional terms, which have not been shown in previous published theories. The theory is developed in general principles exactly, and in detail as far as is needed to enable comparison to be made with the observational data at present available, and, from parameters which have been derived from opposition means from the period 1875 to 1922, the co-efficients of some of the larger long-period terms are computed.
On the dynamics of Trojan asteroids
Authors: Érdi B.
Published: July 2016

The author's theory of Trojan asteroids (Érdi, 1988) is developed further. The motion of the Trojans is considered in the framework of the three-dimensional elliptic restricted three-body problem of the Sun-Jupiter-asteroid system including also the secular changes of Jupiter's orbital eccentricity and the apsidal motion of Jupiter's elliptic orbit. An asymptotic solution is derived, by applying the multiple-timescale method, for the cylindrical coordinates of the asteriods and for the perturbations of the orbital elements. This solution is used for the analysis of the long-time dynamical behaviour of the perihelion and the eccentricity of the Trojans.
Asteroid mass determination: (1) Ceres
Authors: Carpino M. , Knežević Z.
Published: July 2016

Recent improvements of observational accuracy, stellar catalogues and efficiency of the procedures for searching for asteroid close encounters (Kuzmanoski and Knežević, 1993) gave rise to an increased interest in the problem of determination of asteroid masses (Bowell et al., 1995).
Ejecta transfer between terrestrial planets
Authors: Gladman B.J. , Burns J.A. , Levison H. , Duncan M.J.
Published: July 2016

As meteorites from the Moon and Mars continue to be discovered, it is increasingly clear that impact fragments can escape from large bodies more easily than previously believed. These escaping fragments are then subject to the gravitational perturbations of the planets, allowing them to be transferred to a body other than their parent. The lunar meteorites and SNC meteorites prove the plausibility of this process. Warren (1994) summarizes cosmic ray exposure ages and other properties of the lunar and martian meteorites. Their existence confirms that lightly shocked material can be launched at greater than the escape speed of the Moon and Mars.
Analytical integration of a generalized Euler-Poinsot problem: Applications
Authors: Molina R. , Vigueras A.
Published: July 2016

We consider a generalized Euler-Poinsot problem for a stationary gyrostat whose first two components of the gyrostatic momentum are null. The problem is formulated in the Serret-Andoyer canonical variables and analytically integrated by means of the Hamilton-Jacobi equation in terms of elliptic functions and integrals. The obtained solutions are just the same as those for rigid bodies if a specific constant is annulled. Finally, two applications are proposed: 1) to obtain the action-angle variables of this problem, and 2) to the problem of the rotation of the Earth, using a triaxial gyrostat as a model.
Fast evaluation of ephemerides by polynomial approximation in the Chebyshev norm
Authors: Coma J. C. , Lara M. , Moratalla T. J. López
Published: July 2016

Normally the planetary and satellite ephemerides are provided in tabular form, where the user interpolates between points in order to obtain the ephemerides. There are other methods of providing ephemerides by means of polynomial representations. The user is supplied with the coefficients of a set of polynomials which allow him a fast ephemerides evaluation.
Ephemerides software of natural satellites
Authors: Emelianov N.V.
Published: July 2016

To make a photograph of a satellite, we have to know how it is located relative to the planet. After processing the plates, the identification of satellites is to be made. Precise coordinates of natural satellites need to be known for this purpose.
Les diamètres du Soleil dans la Connaissance des temps depuis 1795
Authors: Toulmonde Michel
Published: July 2016

Pour calculer les éphémérides nécessaires à l'observation du Soleil, publiées dans la Connaissance des Temps (CdT), les astronomes du Bureau des longitudes ont utilisé depuis 200 ans différentes valeurs de son diamètre: à l'apogée ou à la distance moyenne de la Terre. Ces données, provenant des meilleures mesures les plus récentes, ont évolué avec la précision des techniques instrumentales.
The results of photographic observations of Galilean satellites with 26-inch refractor at Pulkovo
Authors: Kisseleva T.P.
Published: July 2016

Photographic observations of the Galilean satellites of Jupiter have been made in Pulkovo with 26-inch refractor during two periods 1976–1981 and 1986–1993. The internal mean square errors of jovicentric coordinates and mutual distances is equal to 0.10 arcsec. The external errors are equal to 0.08 and 0.17 arcsec in AR and Decl. The systematic errors were analysed. The errors of the theory G-5 of J.E. Arlot do not exceed 0.1 arcsec.
CCD-observations of asteroids: Accuracy and the nearest perspectives for application of the Laplacian orbit determination method
Authors: Bykov O.P.
Published: July 2016

The modern crowded CCD-observations of the Solar system small bodies are very effective and accurate. They easily provide close positions on a short topocentric arc for any celestial body – from several hours during one night to several successive nights at a single observatory. It is obvious, now, that the informational value of such short arc observations is very high. Statistical treatment of these accurate near positions gives an opportunity to calculate the first and second derivatives of spherical asteroid coordinates or an angular topocentric velocity and its positional angle, a topocentric angular acceleration and a curvature of visible trajectory of observed celestial body.
Residual rotation of the FK5 from optical observations of the planets 1960–1994
Authors: Kolesnik Yu. B.
Published: July 2016

In the interval covering last three decades optical observations of the Sun and major planets have been produced with an unprecedented intensity. Most of the published world-wide observations of the Sun, Mercury, Venus and Mars made from 1960 to 1994 with transit circles, astrographs and astrolabes are incorporated here for investigation of the residual rotation of the stellar system with respect to the dynamical reference frame.
The Hipparcos mission and the re-reduction of Belgrade zenith-telescope observations
Authors: Damljanović G.
Published: July 2016

We prepared the results (in a computer-readable form) of the Belgrade ZT observations made in the period 1949–1985 and finished their new reduction in the FK5 reference frame.
The Mpifr Radio Continuum Surveys and Their WWW Distribution
Authors: Fürst E. , Reich W. , Reich P. , Uyaniker B. , Wielebinski R.
Published: July 2016

The observation of an area of 120° × 56° centered on RA=8h DEC=20° at 408 MHz was the first astronomical use of the MPIfR 100-m telescope (1970) and was designed to compile a complete sky survey using also data from Jodrell Bank and Parkes (Haslam et al., 1982). The observation of the northern sky at 1420 MHz started in 1972 using the Stockert 25-m telescope and was finished in 1976 (Reich and Reich 1986). This survey has been completed to an all sky survey using data from Villa Elisa (Argentina). The two surveys are absolutely calibrated. The angular resolutions are 0.8° and 0.59°, respectively. A number of surveys of the Galactic plane have been made with the 100-m telescope at arc minute angular resolution. Surveys at 2695 MHz (|b| ≤ 5°) (Reich et al. 1990, Fürst et al. 1990) and at 1410 MHz (|b| < 4°) (Reich et al. 1990) are public.

At medium Galactic latitudes (up to |b| = 20°) the emission consists mainly of faint extended ridges or arcs superimposed on the still dominating, about 10 times stronger, diffuse Galactic emission. They have never been investigated in a systematic way although they provide important clues for the understanding of the “disk-halo connection”. This region is covered by new observations at 1400 MHz with the 100-m telescope.
Physical Processes in the Large Scale ISM from Dust Observations
Authors: Boulanger F.
Published: July 2016

Over the last two decades observations of dust emission in the infrared have played an important role in the development of research on the interstellar medium. The study of the spectral energy distribution has led to the discovery of small dust particles including the large aromatic molecules (PAHs). Infrared sky images have been used to study the structure of interstellar matter, the evolution of dust within the interstellar medium and the star formation efficiency of interstellar clouds.
Relations Between Star Formation and the Interstellar Medium
Authors: Fukui Y. , Yonekura Y.
Published: July 2016

We review observational results concerning star formation and dense molecular clouds, the interstellar medium most relevant to star-formation process, as well as future prospects.
A New CO Survey of the Monoceros OB1 Region
Authors: Oliver R.J. , Masheder M.R.W. , Thadddeus P.
Published: July 2016

This survey in the (J = 1 → 0) line of CO at 115 GHz was conducted in 1993 and 1994 using the 1.2m millimeter-wave telescope at the CfA (see Oliver et al. 1996 for more complete description). The survey area, l = 196.0° to l = 206.5°, b = −1.5° to b = +3.5° was covered on a square grid in l and b with spacings of 3′.75 (0.4 FWHM) to give uniform sensitivity. All the spectra were position switched against positions measured be free of CO to 0.05 K. Each spectrum has 256 channels 0.25 MHz wide, giving a resolution of 0.65 km s−1 over 166 km s−1. The channel to channel noise temperature in the original spectra was 0.24 K (RMS) which was reduced to 0.115 K per beam by smoothing to 10′.