bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulated X-Ray Emission from Starburst Driven Winds
Authors: Strickland D. K. , Stevens I. R. , Ponman T. J.
Published: July 2016

Winds from massive stars and supernovae in starburst galaxies drive global outflows of hot X-ray emitting plasma, as seen in M82 and NGC 253. These galactic winds are important for understanding galaxy evolution & formation, chemical enrichment of the IGM, and the starburst phenomenon itself.

X-ray observations provide the only direct probe of the hot gas in these winds. However, the limitations of current X-ray observatories and factors such as complex temperature structure, mass loading by ambient material and projection effects all make the link between the observed data and existing 1 & 2-D modeling and theory difficult to make.

We have therefore begun a program of numerical simulations of galactic winds, concentrating on predicting their observable X-ray properties. We present some initial results, comparing them to the archetypal starburst wind system M82.
X-Ray Observations of M32 with ASCA
Authors: Toneri T. , Hayashida K. , Loewenstein M.
Published: July 2016

M32 is the nearest dwarf elliptical galaxy. Its center is known to have a mass concentration of 3 × 106 M⊙, which is usually interpreted as an evidence of a super massive black hole. We observed M32 with ASCA two times in July and August of 1996. An X-ray source was detected at the center of M32 and its first broad-band X-ray spectra were obtained. ASCA observations of M32 limit the activity of the central black hole to be less than 10−6 times of the Eddington limit. We also found two other bright sources within 12 arcmin from the M32 center. One is the newly appeared X-ray source and the other is G144. In this paper, we summarize the results on the new source and G144. For M32, please refer to the publication (Loewenstein et al. 1997).
X-Ray Properties of ASCA Observed 43 Clusters of Galaxies
Authors: Akimoto F. , Watanabe M. , Furuzawa A. , Tawara Y. , Kumai Y. , Satoh S. , Yamashita K.
Published: July 2016

Much attempts of statistical approach have been made to study the origin of heavy elements, distribution of dark matter and evolution of clusters of galaxies. Henry et al.(1991) reported a power-law relation; LX ∝ kTγ, γ ~ 2.7. Edge and Stwert(1991) found significant scatter in the correlation using 45 clusters. David at al.(1993) reported γ ~ 3.4 using 104 clusters.
The Fate of Intra-Group Medium
Authors: Ishimaru Yuhri
Published: July 2016

Combining X-ray data for clusters of galaxies, groups, and elliptical galaxies, we have obtained the evidence for that groups eject parts of the intra-group medium (IGM) via supernovae-driven ‘group winds’ like ellipticals. This scenario is confirmed by 1D hydrodynamical simulations.
Magnetic Field Amplification and Intergalactic Plasma Heating through Magnetic Twist Injection from Rotating Galaxies
Authors: Matsumoto R. , Valinia A. , Tajima T. , Mineshige S. , Shibata K.
Published: July 2016

We propose a mechanism of amplification of magnetic fields and plasma heating in clusters of galaxies. Recent observations indicate the existence of ~ μG magnetic fields in clusters of galaxies (e.g., Kronberg 1994). There should be some mechanism which locally amplify magnetic fields. In clusters of galaxies, individual motions of galaxies may create locally strong field region by stretching and tangling the magnetic fields threading the galaxies. Magnetic reconnection taking place in the tangled magnetic fields may convert the kinetic energy of the galaxy motion into the inter-galactic plasma heating (Makishima 1996).
Multilayer X-Ray Optics for Future Missions
Authors: Yamashita K. , Kunieda H. , Tawara Y. , Tamura K.
Published: July 2016

Multilayers have a great potentiality to improve the image quality, spectral resolution and energy coverage of x-ray optical systems. The angular resolution of a normal incidence telescope aims at approaching the diffraction limit in the soft x-ray region. Multilayer supermirror makes it possible to fabricate a grazing incidence telescope with high sensitivity in hard x-ray region. Multilayer coated gratings are also useful dispersive elements with high efficiency and spectral resolution in the 2-10keV region. The application of multilayers is expected to open up a new field in astronomical imaging and spectroscopic observations which are not accessible by present telescopes.
Energy Spectra of X 1636-536 Observed with ASCA
Authors: Asai K. , Dotani T. , Mitsuda K. , Inoue H. , Tanaka Y. , Lewin W. H. G.
Published: July 2016

Absorption line features were detected at 4.1 keV from X 1636-536 with the Tenma satellite in the spectra of X-ray bursts (Waki et al., 1984). Similar features were also detected from X 1608-52 and EXO 1747-214 during bursts (Nakamura et al., 1988; Magnier et al., 1989). These features at 4.1 keV may be interpreted as the redshifted Kα absorption line of helium-like iron atoms. However, such interpretation requires extremely soft equation of state for the nuclear matter, and confirmation with high resolution detectors is urged (Lewin et al., 1993). To investigate the line features, we observed X 1636-536 with ASCA for ~ 240 ksec.
The Circumstellar Matter of Cygnus X-3
Authors: Kitamoto S. , Kawashima K.
Published: July 2016

X-ray source in Cyg X-3 is embedded in the photo-ionized circumstellar gas. Recombination edges and emission lines were detected by ASCA observation (Kawashima, Kitamoto 1996; Liedahl, Paerels 1996). The strength of the Kα line and the recombination edge are simply determined by the atomic process. Therefore, the comparison of observed these intensities is a good tool to study the Cyg X-3 system.
The ASCA Observation Campaign of SS433
Authors: Kotani T. , Kawai N. , Matsuoka M. , Brinkmann W.
Published: July 2016

Here we present a very short review of the ASCA observation campaign of the enigmatic galactic jet system SS433. The campaign started in 1994 just after the launch, and ended in 1996. Various phases of the 162.5-day precession and 13-day orbital motion were sampled. With ASCA, the Doppler-shifted pairs from various ion species from Si to Ni were resolved for the first time (Kotani et al. 1994). The Doppler-shift parameters were determined with an accuracy comparable to optical spectroscopy (Kawai 1995). No velocity gradient was found between the X-ray emission region of the jet and the optical. The distance between them was constrained to be less than 1015 cm. Line intensity ratios of Fe XXVI/Fe XXV give the base temperature of the jet to be 20 keV (Kotani et al. 1996). The variation of the apparent base temperature of the jet can be explained in terms of the partial occultation of the jet by a precessing accretion disk (Kotani et al. 1997a). From the variation, the disk radius and the disk height in unit of the X-ray jet length were estimated to be 0.23 ± 0.10 and 0.0232 ± 0.0049, respectively. (These are an improved version of the values in Kotani et al. (1997a).) SS433 is also known as an eclipsing binary. Because the emission from each jet with ASCA, it is possible to know how much of which jet is occulted by the companion star during an eclipse. Relative size of the companion star gives Roche lobe size and thus mass ratio MX/MC = 0.22+0.09-0.16 (Kotani 1997b). With the help of Doppler modulation, compact star mass is constrained. However, the values of Doppler modulation reported from optical observations largely scatters. D'Odorico et al. (1991) reported 112 km s−1 and this gives MX = 0.68+0.43-0.53 M⊙, i.e., a white dwarf, while Fabrika and Bychkova (1990) reported 175 km s−1, which gives 2.6+1.6-2.0 M⊙. (This error includes systematic errors of the X-ray data, and will be reduced in future analysis.) On the other hand, the absolute size of the system were determined with a satisfactory precision. For example, the X-ray jet length was determined to be 2×1013 cm, ten times larger than previous estimations (Kotani et al. 1997c). Other physical parameters of the jet can be derived from the X-ray jet length. Mass outflow rate and the kinetic luminosity of both jet were determined to be 8 × 10−6 M⊙ yr−1 and 1.6 × 1040 erg s−1 (Kotani et al. 1997d), implicating a highly super critical accretion. Most of these values are first precise measurements and/or “radical” revisions of previous estimations. The new picture of SS433 drawn here is far stormy and highly energetic.
Non-Detection of kHz QPOs in GX 9+1 and GX 9+9
Authors: Wijnands Rudy , van der Klis Michiel , van Paradijs Jan
Published: July 2016

In numerous low-mass X-ray binaries quasi-periodic oscillations (QPOs) between 300 and 1200 Hz have been discovered (the kHz QPOs; see van der Klis 1997 for a recent review on kHz QPOs). Here we present the search for kHz QPOs in the atoll sources GX 9+1 and GX 9+9.
Spectral Evolution of the Thermal Component in Cygnus X-1 during Intensity Variations in the Soft State
Authors: Balucinska-Church M. , Church M. J. , Mitsuda K. , Dotani T. , Inoue H. , Nagase F.
Published: July 2016

Cygnus X-1 was in the Soft State between May and September 1996 for the first time in more than 20 years creating an opportunity to study the thermal component, its spectral evolution, time variability and its relation to the hard component during intensity variations. We will show how the luminosity of the thermal component changes in relation to its temperature and attempt to determine whether the emitting area varied during the variations.
Multiwavelength Temporal Behavior of GRS 1915+105
Authors: Hannikainen D. , Durouchoux Ph.
Published: July 2016

The transient X-ray source GRS 1915+105 was discovered in August 1992 with the GRANAT/WATCH all-sky monitor (Castro-Tirado et al. 1994). Subsequent VLA observations from March through April 1994 led to the discovery of apparent superluminal motion in a pair of radio condensations moving away from the compact radio core (Mirabel & Rodriguez 1994). These jet-like features are interpreted as a bipolar outflow with bulk velocity ~ 0.9c. Although no optical counterpart has been observed, due to the heavy extinction in the Galactic plane, and therefore not enabling measurements of the mass of the compact object, the hard X-ray spectrum and high luminosity (~ 1039 erg s−1), extreme variability in the X-ray light curve and the relativistic jets make GRS 1915+105 a strong black hole candidate.
Evidence for a Dramatic Activity Decline in the Nucleus of the Radio Galaxy Fornax A
Authors: Iyomoto N. , Makishima K. , Tashiro M. , Matsushita K. , Fukazawa Y. , Kaneda H. , Osone S.
Published: July 2016

Fornax A (NGC 1316) is a radio galaxy with prototypical double lobes. Feigelson et al. (1995 ApJ 449, L149) and Kaneda et al. (1995 ApJ 454, L13) detected inverse Compton X-rays for the first time from its radio lobes, and unambiguously derived the lobe magnetic field intensity of 2-4 μG. Accordingly, the radio-emitting electrons in the lobes are inferred to have a Lorentz factor of 104, and hence a synchrotron life time of ~108 yr. This means that Fornax A was highly active at least 108 years ago.
Optical Follow-Up Observations of the ASCA Large Sky Survey
Authors: Akiyama M. , Ohta K. , Yamada T. , Ueda Y. , Takahashi T. , Sakano M. , Tsuru T. , Boyle B.
Published: July 2016

To reveal the origin of the cosmic X-ray background (CXB) in the hard band, we are now conducting a wide (~ 7 deg2) and deep (~ 1 × 10−13 erg sec−1 cm−2 in the 2-10 keV band) survey with the ASCA (the ASCA Large Sky Survey, hereafter LSS). We have detected 83 sources above 4 sigma level in the 0.7-10 keV band with the GIS and resolved ~30% of the CXB in the 2-10 keV band into discrete sources (Ueda 1996). AGNs (type 1 and type 2) and clusters of galaxies are expected to be major contributers to these X-ray sources.
The NEP ROSAT Survey
Authors: Mullis C.R. , Gioia I.M. , Henry J.P.
Published: July 2016

The Rosat All-Sky Survey (Trümper 1991, Adv. Spce Res., 2, 241) has its largest exposure times, approaching 10 ks, at the ecliptic poles where the scan circles overlap. The North Ecliptic Pole (NEP) region covers a 9° X 9° field, and contains a total of 465 X-ray sources detected at > 4σ in the 0.1-2.4 keV. We are identifying all sources in the field. The principal derivative is a statistically complete sample of galaxy clusters appropriate for more fully characterizing X-ray Luminosity Function (XLF) evolution. We report preliminary results for two subregions which are identified to the 95% level. These subregions are observed to approximately the median NEP survey exposure. They enclose 16% of the survey area and contain 96 X-ray sources representing 21% of the total NEP. The typical mix of sources is consistent with the Einstein Extended Medium Sensisitivity Survey (EMSS; Gioia et al., 1990a, ApJS, 72, 567). In particular there are 56% AGN/ELG (59% in the EMSS), 25% stars (27% in the EMSS) and 14% clusters against 13% clusters in the EMSS.
Stellar angular diameter measurements by interferometry
Authors: Davis John
Published: July 2016

Stellar angular diameter measurements have been made with a range of interferometric techniques including speckle, aperture masking and long baseline optical/infrared interferometry. The current status of these measurements are summarised in terms of the range of spectral types and luminosity classes measured, the accuracies achieved, the wavelengths used for observations, and the reliability of the results. A number of major long-baseline interferometers are coming on-line, or are under development, and their potential is assessed in terms of wavelength cover, accuracy, angular resolution, and the range of spectral type and luminosity class cover.
Astrometry Using Interferometry at Optical Wavelengths
Authors: Johnston K. J. , Hutter D. J. , Benson J. A. , Elias N. M. , Armstrong J. T. , Mozurkewich D. , Pauls T. A. , Hummel C. A.
Published: July 2016

Interferometry offers an improvement in the accuracy with which astrometric measurements can be made. Using this technique, radio astronomers together with geodeticists have established a global inertial reference frame that is accurate to 0.1 milliarcseconds. At optical wavelengths, interferometry was first developed by Michelson at the turn of the twentieth century, but due to the complexities of precise beam combination at high speeds, it has lagged in its development. Now, with the availability of lasers, detectors and computers that allow path length compensation on millisecond time scales and distance determination between light collectors with a precision of 0.01 μm, interferometry at optical wavelengths will achieve the results in astrometry comparable to those at radio wavelengths.
Lunar occultation measurements of stellar angular diameters
Authors: Richichi A.
Published: July 2016

Offering an angular resolution which has remained unattained by any other technique for decades, lunar occultations have traditionally been the most productive method for the measurement of stellar angular diameters. Unlike interferometric methods, which are limited in resolution by the size of the aperture or of the baseline between apertures, in a lunar occultation the key to high angular resolution is the phenomenon of diffraction by a straight edge, that occurs at the Moon's limb in a turbulence-free environment. For the reader not familiar with the physics and technical aspects of the lunar occultation (LO) technique, it is sufficient here to show in Fig. 1 some practical examples of occultation lightcurves for sources with different angular diameters. It can be noted that the contrast of the fringes is maximum for a point-like source; it then decreases with the angular diameter, and eventually reaches the regime of a monotonic drop in the signal-as predicted by simple geometrical optics- when the angular extent of the source is large. In practice, the LO method is well suited to measure angular diameters in the range 1 to 50 milliarcseconds (mas). There is no real limitation concerning the wavelength of observation, although at present the near-IR is the region of choice for several different reasons (Richichi 1994).
Tests of effective temperature – colour relations
Authors: Bell R.A.
Published: July 2016

This paper discusses some tests of synthetic spectra used in the calculation of synthetic colours, as well as some of the problems which arise in these calculations. Synthetic colours are tested in two ways. Firstly, observed angular diameters of stars are compared with ones predicted from stellar temperatures derived from synthetic colours and the infrared flux method. The average difference is less than 2%. Secondly, a very metal-poor isochrone is transformed to the Mv, B–V and Mv, V–I colour planes and compared with observations of stars in the globular cluster M92. The agreement is good in both colour–magnitude diagrams.
Non-LTE line blanketed atmospheres for hot stars
Authors: Hillier D. J.
Published: July 2016

The modeling of hot star atmospheres falls into two broad classes: those where the plane parallel approximation can be used, and those where the effects of spherical extension and stellar winds are important. In both cases non-LTE modeling is a necessity for reliable spectroscopic analyses.

While simple ions (e.g., H, He I, and He II) have been treated routinely in non-LTE for many years it is only recently that advances in computing power, computational techniques, and the availability of atomic data have made it feasible to perform non-LTE line blanketing calculations. Present models, with varying degrees of approximation and sophistication, are now capable of treating the effects of tens of thousands of lines. We review the latest efforts in incorporating non-LTE line blanketing, highlighting recent advances in the modeling of 0 stars, hot sub-dwarfs, Wolf-Rayet stars, novae, and supernovae.
Atmospheric motions and granulation in cool stars - observations and theory
Authors: Cottrell P.L.
Published: July 2016

This review presents a number of aspects in our quest for an understanding of the detailed structure of cool star stellar atmospheres through the study of atmospheric motion. It includes the observational tools (e.g. direct imaging, detailed analyses of line profiles) used to determine the type and amount of motion, as well as the modelling techniques (e.g. simulated images, velocity and pressure fields) used to interpret and describe these motions.

Linkages will be made through the solar-stellar connection to provide insight into the structure of stars where detailed imaging is not possible, and to the determination of the fundamental parameters of stars, such as effective temperature, surface gravity and elemental abundances.
Pulsating stellar atmospheres
Authors: Sasselov Dimitar D.
Published: July 2016

We review the basic concepts, present state of theoretical models, and the future prospects for theory and observations of pulsating stellar atmospheres. Our emphasis is on radially pulsating cool stars, which dynamic atmospheres provide a general example for the differences with standard static model atmospheres.
Cool white dwarfs: cooling theory and galactic implications
Authors: Chabrier G.
Published: July 2016

The understanding of the physics of cool white dwarfs (WD) bears important consequences for Galactic evolution and cosmological implications. The observed cutoff in the disk WD luminosity function (WDLF) yields the determination of the age of the Galactic disk, as suggested initially by Winget et aI. (1987). The recent microlensing observations toward the LMC (Alcock et al., 1996) suggest that WDs might provide a substantial fraction of the halo dark matter (Chabrier, Segretain & Méra, 1996; Adams & Laughlin, 1996). The correct analysis of these applications implies a correct WD cooling theory and reliable photometric predictions, which in turn require accurate interior and atmosphere models. Important improvement in this latter domain has been accomplished recently by Bergeron, Saumon & Wesemael (1995) and Bergeron, Wesemael & Beauchamp (1995), which yields the determination of photometric color indices and bolometric corrections down to 4000 K (see Leggett, these proceedings). In this paper, we review the most recent improvement in WD interior and cooling theory.
Stellar chemical evolution
Authors: Norris John E.
Published: July 2016

One of the major achievements of astrophysics has been the demonstration that most of the chemical elements have been synthesized in stars: nucleosynthesis calculations of homogeneous and inhomogeneous big bang cosmologies show that, in comparison with the most metal-poor stars currently known, essentially no elements heavier than B existed at the era of decoupling (see e.g. Wagoner, Fowler, & Hoyle 1967; Kajino, Mathews, & Fuller 1990). Following the pioneering work on stellar nucleosynthesis by Hoyle (1946), the basic precepts and the role of stars was set down in the classic papers of Burbidge et al. (1957) and Cameron (1957), and the ensuing decades have produced a vast body of theoretical and observational effort to more fully understand the details of the process.
Achievements and prospects
Authors: Cram L.E.
Published: July 2016

The scientific study of the topic of this Symposium, “Fundamental Stellar Properties,” was in its infancy at the turn of the Century. As illustrated at this meeting, there has been significant progress in many directions over the past 100 years. Despite this progress, there are however many unsolved problems that will be addressed by theoretical and observational techniques that are emerging only now.
Magellanic Cloud Studies, Past and Future
Authors: Hodge Paul
Published: July 2016

This introduction reviews early observations of the Magellanic Clouds, briefly describes the “Golden Age of Magellanic Discoveries”, and looks ahead at promises for dramatic new results from the powerful telescopes of the 21st century.
New Magellanic Cloud Interstellar Matters
Authors: de Boer K.S.
Published: July 2016

Novel instrumentation has always led to new insights in the nature of the universe. Novel astronomical instrumentation is no exception. In numerous areas new instruments led to the detection of hitherto unknown phenomena. I will review some notable studies of the recent past with some emphasis on those dicoveries not extensively covered by others at this conference. Finally, very recent work based on ORFEUS echelle spectra is presented.
ISO-[CII]-Investigation of Cool HI Clouds in the Large Magellanic Cloud
Authors: Marx-Zimmer M. , Zimmer F. , Herbstmeier U. , Dickey J. M.
Published: July 2016

Despite a strong UV radiation field, the Large Magellanic Cloud (LMC) shows a relatively large abundance of cool HI gas. Neither CO- nor [CII]-lines have been detected in most of these regions in previous surveys. The energy balance of these cool clouds, of which some are located in warm surroundings, is still an open question. The improved resolution and sensitivity of the ISO telescope compared to previous measurements offers a unique opportunity to study the heating and cooling of these clouds in the LMC. Here we present first results of an investigation of the dominant cooling line, [CII] (158 μm), toward cool HI clouds.
Dust and Gas in the Small Magellanic Cloud
Authors: Bontekoe Tj.R. , Kester D.J.M. , Stanimirović S. , Staveley–Smith L. , van der Hulst J.M.
Published: July 2016

Here we present four IRAS high resolution images of the Small Magellanic Cloud, as reconstructed by the HIRAS program using the Pyramid Maximum Entropy method (Bontekoe et al. 1994). (HIRAS is not to be confused with HiRes (Aumann et al. 1990).) The images show much more detail than in Schwering & Israel (1990). Dust temperatures range from 25–41 K (Stanimirović et al. in prep).
The Stellar Population of R136
Authors: Hunter Deidre A.
Published: July 2016

The luminous, compact star cluster R136 in the Large Magellanic Cloud is 300 times more spatially concentrated than a typical OB association and contains at least 39 O3 stars, the most massive of which is ~150 M⊙. Yet, the stellar IMF for 2.8–120 M⊙ is normal. The massive stars are 1–2 Myrs old, and Wolf-Rayet stars are not evolved.
NLTE Abundances from Magellanic Cloud B Stars
Authors: Korn Andreas J. , Wolf Bernhard
Published: July 2016

Nine MC young globular cluster and field stars are analysed using fully line-blanketed LTE ATLAS 9 atmospheres and the DETAIL/SURFACE non-LTE line formation code. CNO mixing seems to occur much earlier than predicted by standard theory.
A Laboratory of Stellar Nuleosynthesis: Isotope Ratios in the Magellanic Clouds
Authors: Chin Yi-nan
Published: July 2016

In radio astronomy, interstellar isotope ratios have been measured for more than two decades towards different parts of the Milky Way and central regions of some star-burst galaxies. While signals are often too weak to detect rare isotopic species in relatively distant extragalactic sources, our Galaxy only provides an environment with limited metallicity range. Obviously, this constraint can be removed by observing isotopic species in the Magellanic Clouds, located only 50–60 kpc away from us. We thus observed isotope ratios of hydrogen, carbon, nitrogen, oxygen, and sulfur and the results are given in Table 1.
Carbon Stars in the Magellanic Clouds
Authors: Azzopardi M.
Published: July 2016

Thanks to their pronounced and well recognizable spectral features, carbon stars can be identified easily in Galactic halo and galaxies. In this paper we will review the extensive searches for carbon stars in the Magellanic Clouds with emphasis on the recent work devoted to the carbon stars of low luminosity and the more classical carbon stars populating the outer regions of these systems.
AGB Stars in the Large Magellanic Cloud
Authors: Loup C.
Published: July 2016

This paper reviews the luminosity distribution of AGB stars in the Large Magellanic Cloud. I briefly summarize the history and results of the previous surveys, and then present a first analysis of the DENIS survey in the IJKS bands, and ISOCAM observations at 4.5 and 12 μm.
Planetary Nebulae in the Magellanic Clouds
Authors: Dopita Michael A.
Published: July 2016

The proximity, accurately known distance and low line-of-sight reddening give the ideal circumstances to pursue studies of individual stellar populations in the Magellanic Clouds. Here we show how our understanding of the evolution and chemical composition of the planetary nebulae in the Magellanic Clouds has been impacted by imaging and UV spectroscopic studies using the Hubble Space Telescope. Images provide sizes, internal morphological structure, absolute fluxes, and dynamical ages, while spectra allow us to place the central stars accurately on the H-R Diagram, and we can also examine the details of the evolution, of mass- and age- dependent chemical dredge-up processes, and infer the star-formation history of the Magellanic Clouds.
The LMC Centre Unfolding
Authors: Ardeberg A. , Linde P. , Gustafsson B.
Published: July 2016

We study star formation history and chemical evolution in the LMC Bar centre. With the HST PC and WFC plus uvby photometry, we find 30% of the stars younger than 200 My and evidence for reduced star formation 3 to 0.2 Gy ago. The overall [Fe/H] is −0.5. Many stars older than 4 Gy contradict a very young Bar.
New R Coronae Borealis Stars in the LMC, Discovered in the MACHO Photometry Database
Authors: Clayton Geoffrey C. , Kilkenny D. , Welch D. L. ,   The MACHO Collaboration
Published: July 2016

An extensive search has been made in the MACHO Photometry Database for new R Coronae Borealis (RCB) stars in the LMC. Only three such stars were known previously. Eleven new LMC RCB stars have been spectroscopically confirmed so far.
The Formation of Carbon Stars in the Magellanic Clouds from Mass Transfer in Close Binaries
Authors: Frantsman Ju.
Published: July 2016

The presence of the carbon stars in the MC with luminosities higher or lower than predicted for thermally-pulsing (TP) AGB stars, can be explained by processes that happen during the early AGB (E–AGB) stage. I examine this assumption by means of a population simulation technique. I find that there must be TP–AGB C and S stars in the MC that formed as a result of mass transfer in binary systems. Their presence may influence the age determinations of MC clusters.
Obscured Asymptotic Giant Branch Stars in the Magellanic Clouds
Authors: van Loon Jacco Th.
Published: July 2016

I present results from an ongoing study of the evolution and mass loss of AGB stars with optically thick circumstellar envelopes in the Magellanic Clouds.
Properties of a Proper-Motion Selected Sample of Giants in the Small Magellanic Cloud Near NGC 121
Authors: Suntzeff Nicholas B. , Walker Alistair R. , Smith Verne V. , Kraft Robert P. , Klemola Arnold , Stetson Peter B.
Published: July 2016

We observed a sample of zero proper-motion stars (μ < 0.″50 cent−1) from a field previously studied by Suntzeff et al. (1986). This field is 2°.5 NW (2.6 kpc) of the center of the SMC. We obtained spectra for ~ 40 stars in the region of the Ca II infrared triplet using the CTIO Argus fiber-fed spectrograph. We also obtained Argus echelle spectra of a single order at 6300Å with R = 18000 in one run. The low-dispersion spectra were reduced to metallicities based on the Ca II equivalent widths using the Da Costa & Armandroff (1995) technique and the metallicity scale from Zinn & West (1984). The typical abundance error is 0.12 dex. For half the sample, we have echelle velocities which are accurate to 1.5 km s−1. For the rest of the sample, the low-dispersion data yield single-observation velocities accurate to about 5 km s−1 based on repeat observations.
Young Magellanic Cloud Clusters (< 1 Gyr): Census, Properties, Star Formation History
Authors: Grebel Eva K. , Zaritsky Dennis , Harris Jason , Thompson Ian
Published: July 2016

We report preliminary results from an automated cluster survey of the Magellanic Clouds aimed at improving the cluster census and at deriving cluster properties from their resolved stellar content. The survey is tripling the number of known clusters. The cluster age distribution shows similar peaks at 100–200 Myr in LMC and SMC, coincident with the closest encounter of the Clouds and perigalacticon.
Nonuniform Star Population of the LMC Cluster NGC 1978?
Authors: Kravtsov V.
Published: July 2016

The LMC cluster NGC 1978 shows different properties in the two parts divided by its minor axis. These two parts have different color distributions of the core He-burning (CHB) stars and giant branch (GB) positions on the CMDs at and below the level of the CHB stars. These differences may be caused by spread in metallicity.
Binary Clusters in the Magellanic Clouds
Authors: Dieball A. , Grebel E. K.
Published: July 2016

Binary clusters account for more than 10% of the cluster population in the Magellanic Clouds. Statistically fewer than 50% of the found pairs are expected to be chance superpositions. We are studying binary cluster candidates in the Magellanic Clouds to investigate whether the cluster pairs are of common origin and if they show evidence for interaction. We determine ages for the cluster components through isochrone fitting (isochrone models based on Schaerer et al. 1993, and Bertelli et al. 1994) to the colour magnitude diagrams (CMDs). We investigate the stellar spatial density in the surroundings of the clusters to look for signs of possible interactions between the components.
AM-3: An Intermediate-Age Star Cluster in the Extreme Outskirts of the SMC
Authors: Da Costa G. S.
Published: July 2016

The faint star cluster AM-3 is one of three such objects discovered by Madore & Arp (1979). AM-1 has since been shown to be one of the most distant of the Galaxy's halo globular clusters, while AM-2 is now recognized as a distant, reddened Galactic open cluster. AM-3, however, has been largely ignored despite the fact that it lies only ~4.5 degrees from the center of the SMC making association with the SMC a possibility. This possibility was strengthened by the results of Irwin (1990) who showed that AM-3 lies (in projection) just within the outermost density contours of the SMC field population.
Results from HST Observations of Six LMC Globular Cluster Fields
Authors: Olsen K. A. G. , Hodge P. W. , Mateo M. , Olszewski E. W. , Schommer R. A. , Suntzeff N. B. , Walker A. R.
Published: July 2016

We present deep HST color-magnitude diagrams of fields centered on the six old LMC globular clusters NGC 1754, NGC 1835, NGC 1898, NGC 1916, NGC 2005, and NGC 2019. Separate cluster and field star CMDs are shown. The time of formation of the LMC is studied from an analysis of the cluster CMDs. Based on a comparison of the CMDs with sequences of the Milky Way clusters M3, M5, and M55, we suggest that the LMC formed its first stars at the same time as the Milky Way to within 1 Gyr. We find additional evidence that these LMC globular clusters are as old as the oldest Milky Way clusters through a comparison of our data with the horizontal branch evolutionary models of Lee, Demarque, & Zinn (1994).

The evolution of the LMC following its formation is studied through an analysis of the field star CMDs. Through an automated comparison with stellar evolution models, we extract the star formation histories implied by the CMDs. Our best-fit star formation histories imply that the LMC has been actively forming stars over the last 4 Gyr, in agreement with previous field star studies. The four fields that lie in the Bar also contain significant numbers of stars with ages of 4–8 Gyr in the best-fit cases. The most notable disagreement between the best-fit models and observed CMDs is in the color of the red giant branch.
Proper Motions of the Clouds
Authors: Anguita Claudio
Published: July 2016

The proper motion of the LMC relative to three background QSOs has been determined. 125 CCD frames taken from 1989.0 to 1997.2 at the Cassegrain focus of the CTIO 1.5 m telescope were used. The method of observation and reduction is breafly presented. The results are compared with those obtained by other authors who use different methods and proper motion reference systems. We find a good agreement in μαcosδ, but a rather large discrepancy in μδ. Our LMC proper motion seems to indicate that the LMC is not leading the Magellanic Stream.
Review of N-Body Models of Tidal Interactions
Authors: Gardiner L. T.
Published: July 2016

Considerable progress has been made in the current decade with the help of N-body simulations towards a deeper understanding of the nature of the dynamical relationship between the Large and Small Magellanic Clouds and the Galaxy. The origin of such features as the Magellanic Stream, the inter-Cloud Bridge, the Wing and large extension in depth of the SMC has come to be interpreted in the context of the tidal interactions among the members of the LMC-SMC-Galaxy triple system. The inclusion of gas-dynamical effects and star formation in the latest models has added further refinements to this picture and confirmed the enhancement of the star formation rate in the SMC as a result of the recent LMC-SMC encounter.
Cepheid Variables in the LMC and SMC
Authors: Welch D.L. ,   the Macho Collaboration
Published: July 2016

In this paper, we will review major new results regarding classical Cepheids, in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC). Specifically, we discuss recent work regarding multimode Cepheids and describe new observations of a W Vir star (HV 5756) and a Cepheid which are each in eclipsing binary systems. An additional interesting pulsating supergiant in an eclipsing system is also identified. Ephemerides for eclipses for the three systems are provided.
The Distance to the Large Magellanic Cloud; A Critical Review
Authors: Feast Michael
Published: July 2016

Five independent methods of deriving the distance modulus of the Large Magellanic Cloud are reviewed and compared. A value in the range 18.60 to 18.80 is presently preferred.
Magellanic Cloud Eclipsing Binaries: Primary Distance Indicators
Authors: Pritchard J. D. , Tobin W. , Clausen J. V. , Guinan E. F. , Fitzpatrick E. L. , Giménez A. , Ribas I.
Published: July 2016

Our collaboration involves groups in Denmark, the U.S.A. Spain and of course New Zealand. Combining ground-based and satellite (IUE and HST) observations we aim to determine accurate and precise stellar fundamental parameters for the components of Magellanic Cloud Eclipsing Binaries as well as the distances to these systems and hence the parent galaxies themselves. This poster presents our latest progress.
Redetermination of the orbit of Iapetus
Authors: Kaixian Shen , Rongchuan Qiao
Published: July 2016

This paper gives a test of the reliability of TASS from Vienne & Duriez via the comparison of the theory of Iapetus given by Harper & Taylor. From fitting it to photographic observations, we derived a redetermination of the orbit of Iapetus.
Numerical mean elements for asteroid orbits
Authors: Lemaitre Anne
Published: July 2016

In the context of the search of asteroid families (i.e. identification of minor planets as potential fragments of an old bigger body), the calculation of proper elements plays an important role. They are quasi-invariants of the motion, obtained by a double averaging process of the restricted N-body problem; firstly the osculating elements are averaged over the short periodic terms (namely the longitudes of the asteroid and of the perturbing planets) so to get the mean elements, and secondly, the mean elements are averaged over the long periodic terms (longitudes of the pericenters and of the nodes of the asteroid and of the perturbing planets) to obtain the proper elements.
Nonlinear optimisation and the asteroid identification problem
Authors: Sansaturio M. Eugenia , Milani Andrea , Cattaneo Luisa
Published: July 2016

Differential correction procedure allows us to improve orbits for which new observations are available; however, it only works provided the original orbit is within the convergence domain of the pseudo-Newton method. Given the strong nonlinearity of the problem, this only occurs when the residuals of the new observations with respect to the old orbit are quite small.
A time-dependent extension to Brouwer's method for orbital elements correction
Authors: Marco F. J. , Lopez J. A. , Martinez M. J.
Published: July 2016

One of the most popular methods for orbital elements correction, by means of O-C calculus, is based on Brouwer's method [2], which is very well adapted for integrating short periods of time. We propose a general method to integrate over long intervals of time, when we have good observations, based upon a time-dependent functional relation between the derivatives of all elements with respect to all variations in the initial elements. First, we verify the truth of the unrestricted hypothesis by means of the proposed analytical method and a numerical derivation. In [6], we have incorporated a correction frame model jointly with this general method and, then, we have constructed the residual function which is minimized by the least squares method. But, as we are going to see later, there are correlations between the parameters frame correction model and the initial elements involved in the adjustment. They are obtained here, as well as an expression for the equinox correction from these frame parameters. Finally, by means of a simply weighted method, with the observations from MPC's magnetic tape, in FK4 system, we obtain an estimation for these frame parameters and an equinox correction which is in great accord with the adopted value (see [3]).
A method for asteroid mass determination
Authors: Kuzmanoski M.
Published: July 2016

It is well known that the perturbing effects of any asteroid are negligible at all times, except during a close encounter. The influence of a perturbing asteroid on the motion of a perturbed one can be investigated by means of the differences of the right ascensions and declinations of the perturbed asteroid, as inferred from two numerical integrations, the one with and the other without taking into account the effects of the perturbing asteroid (Kuzmanoski and Knežević, 1994). These effects before reaching the epoch of the close encounter are very small, as expected. Beyond this epoch, the differences increase with time, due to the fact that the orbit is changed on account of the influence of the perturbing body during the close approach, so that perturbations by major planets act on it in a different way.
Taurid meteoroids and asteroid complex
Authors: Pittich E. M. , Klačka J.
Published: July 2016

The orbital evolution of model meteoroids ejected from the comet Encke and from the asteroid Hephaistos was investigated. The particles abandoned the mother body with velocities 40, 150 and 600 ms−1 at their perihelia within the interval of 10,000 to 20,000 years, respectively. Their 10,000 to 20,000 years old osculating orbits were numerically integrated forward, using a dynamical model of the solar system consisting of all planets. Forces from solar electromagnetic and corpuscular radiation effecting the particles were considered, too. Orbital dispersions of the model meteoroids, ejected in different epochs, compared with those obtained from observations. It seems probable that the comet Encke and the asteroid Hephaistos are sufficient to produce the observed Taurid meteor complex.
Canonical treatment of dissipative forces between Earth mantle and core
Authors: Getino Juan , Ferrandiz Jose M.
Published: July 2016

Dissipative effects arising from the core–mantle interaction are treated in a Hamiltonian framework, using a simple model. Analytical solutions are obtained for free and forced motions. The first show the persistence or damping of the different components. The latter, frequency dependent changes of amplitude and phase. Preliminary numerical values are in acceptable agreement with observational data.
On the tidal function between two real bodies
Authors: Shkodrov V. , Ivanova V.
Published: July 2016

The general expression of the tidal function between two real bodies of arbitrary mass distribution has been derived. The case has been regarded when the distances between the bodies are comparable to their sizes. In this case, the effect of the body figure is substantial.

The relations obtained are utilized for the tidal influence of Jupiter on the surface of Io. It has been shown that Jupiter's shape (with J2 = 0.015) causes a deformation in the sub-Jupiter point of about 15m. This is approximately 10% of the total tidal deformation of Io caused by Jupiter's gravitation.
On generators of new methods of the perturbation theory
Authors: Grebenikov E.A.
Published: July 2016

In this article are discussed classical and modern interpretations of the perturbation theory methods.
On two-parameter linearizing transformations for uniform treatment of two-body motion
Authors: Floría Luis
Published: July 2016

Differential changes of time involving two parameters are considered. Universal expressions for dynamical variables of interest in Keplerian motion allow us to reduce the integration of the time transformations to that of integrands depending on an eccentric-like universal anomaly. Elliptic integrals and functions are required to complete the integration.
Relativistic equations of motion of celestial bodies
Authors: Soffel Michael H.
Published: July 2016

The problem of relativistic equations of motion for extended celestial bodies in the first post-Newtonian approximation is reviewed. It is argued that the problems dealing with kinematical aspects have been solved in a satisfactory way, but more work has to be done on the dynamical side. Concepts like angular velocity, moments of inertia, Tisserand axes etc. still have to be introduced in a rigorous manner at the 1PN level.
Des éphémérides astronomiques annuelles en préliminaire à l'Annuaire du Bureau des Longitudes
Authors: Débarbat Suzanne
Published: July 2016

Le Bureau des longitudes est chargé de rédiger la connoissance des temps, qui sera imprimée aux frais de la République, de manière que l'on puisse toujours avoir les éditions de plusieurs années à l'avance; il perfectionnera les tables astronomiques, et les méthodes des longitudes, et s'occupera de la publication des observations astronomiques et météorologiques. (Extrait du Rapport sur l'établissement du Bureau des longitudes par Grégoire, Séance du 7 Messidor, l'an 3 de la République une et indivisible; Suivi du décret de la Convention nationale, et Imprimé par son ordre. Le document, de seize pages se termine par la mention: Adopté; il est dit: A Paris, De l'Imprimerie nationale, Messidor l'An III)
Observation of small solar system objects with spacewatch
Authors: Scotti James V. , Jedicke Robert
Published: July 2016

Since beginning an automated full-time survey for Near-Earth objects in September 1990, the Spacewatch project has discovered 95 new Near-Earth asteroids (NEAs), 3 new comets, and 3 new Centaur asteroids. Spacewatch typically identifies about 2000 main-belt asteroids each lunation while covering about 150 square degrees to a limiting magnitude of Vlim ∼ 20.9. We report automatically measured astrometric asteroid detections to the Minor Planet Center where known and multiply detected objects are identified. NEAs and other interesting objects are identified by their angular rates of motion near opposition at the time of discovery and are scheduled for astrometric follow-up on subsequent nights. Objects with exceptionally high rates of motion, called very fast moving objects, have been detected in near real-time by the observer and followed for several hours to several days. These objects are the smallest yet detected outside the Earth's atmosphere. Careful analysis of their discovery rates and orbits have indicated an enhancement of their magnitude-frequency distribution over that anticipated before the Spacewatch survey began – of about a factor of 40 for objects near absolute magnitude H ∼ 29 (Rabinowitz, 1993; 1994). A subset of these small objects which have almost circular orbits and perihelia near the orbit of Earth have been recognized as having significantly different orbits from those of the previously known NEAs (Rabinowitz et al., 1993). Their origin is still under debate, with possible sources including Earth or Lunar impact ejecta, Earth-Sun Trojans, or more complicated secular resonance interactions of NEA orbits with the giant planets combined with stochastic perturbational encounters with the inner planets (Bottke, 1994; N.W. Harris, 1995, personal communication). The large volume of asteroid detections allows magnitude–frequency studies of the detected main-belt asteroids and Jupiter Trojans. New discoveries of Comets and Centaur asteroids (whose orbits cross those of the outer planets) may allow studies of their magnitude–frequency distributions as well.
Limitations on the accuracy possible in astrometric observations of the satellites of the major plane
Authors: Jones D.H.P.
Published: July 2016

Astrometric accuracy has two components; the accuracy with which an image can be centred on a CCD or photographic plate and the accuracy with which two image centres can be mapped on to standard co-ordinates. Photographic plates cover a sufficient area of sky that several standard stars can be measured with the satellite images and the mapping to standard coordinates can be done in one operation. CCDs have much smaller areas and the number of stars with sufficiently accurate positions may not be sufficient. The surface densities of the best available catalogues are shown in Table I.
Astrometry VLBI in space (AVS)
Authors: Altunin V.I. , Alekseev V.A. , Akim E.L. , Eubanks T.M. , Kingham K.A. , Treuhaft R.N. , Sukhanov K.G.
Published: July 2016

This paper describes a proposal for a new space radio astronomy mission for astrometry which uses very-long-baseline interferometry (VLBI) called Astrometry VLBI in Space (AVS). The ultimate goals of AVS are to improve the accuracy of radio astrometry measurements to the microarcsecond level in one epoch of measurements and to improve the accuracy of the transformation between the inertial radio and optical coordinate reference frames. The scientific objectives of the mission cover a few categories of astrometry tasks such as astrometry of the solar system, reference frames ties, tests of general relativity and cosmology (for references see Lowe and Treuhaft, 1994, Russell et al., 1992, Eubanks et al., 1994).