bluuebunny/crossref_metadata_2025 huggingface dataset:
The fate of dwarf satellite galaxies (or: Can we observe soft merging?)
Authors: Richter G. , Vennik J. , Böhm P. , Capaccioli M.
Published: July 2016

Dwarf satellite galaxies and globular clusters bound to luminous (in particular early type) galaxies, can be steered by interactions to orbits penetrating deep into the potential of their parent galaxy, where the outer stars are eroded and the dwarf satellite is completely destroyed in a relatively short time, resulting in very faint disturbances (soft merging) in the form of faint rings in the parent galaxy.

With special image processing methods we have found faint structures in E and SO galaxies, which for many reasons (mass, statistics, etc.) can be interpreted as observational evidence of this type of soft merging. This debris of dwarf satellites can provide a considerable part of the mass of the parent galaxy.
Neutral Hydrogen in HCG 95
Authors: Huchtmeier W. K. , Verdes-Montenegro Lourdes , Yun Min , del Olmo A. , Perea J.
Published: July 2016

We have observed Hɪ emission and radio continuum emission from the compact group of galaxies HCG 95 with the Very Large Array (VLA)1. Two continuum sources coincide in with galaxies in this group: HCG 95 B (3.9 mJy) and HCG95C (6 mJy). Hɪ emission and absorption was detected in galaxy HCG 95 C. In addition we detected two so far unknown dwarf galaxies by their Hɪ emission within 3.5 arcmin of the group center. We did not detect galaxy b (with ç = 8000 kms−1 it is obviously a foreground object) and galaxy d — an edge-on Sc galaxy. This group definitely is Hɪ deficient compared with the average Hɪ content expected for spiral galaxies of the same luminosity and type. The first-ranked elliptical galaxy HCG 95 A might be responsible for the observed Hɪ deficiency in this group.
X-ray Observations of Poor Groups
Authors: Mulchaey John S.
Published: July 2016

X-ray observations of groups have provided considerable new insight into these cosmologically important systems. Recent ROSAT surveys of loose and compact groups suggest that ≃ 50% of all nearby groups contain a hot intragroup medium, including many spiral-rich groups. However, spiral-only groups tend not to be X-ray detected. Spectroscopic studies of X-ray groups indicate that these systems contain a large number of faint galaxies. The existence of a large population of faint galaxies, combined with the extended X-ray halos, is consistent with X-ray detected groups being real, bound systems. The nature of non-X-ray detected groups, which do not contain an extensive faint galaxy population, is still unclear.

ROSAT observations have also revealed the existence of individual elliptical galaxies with X-ray properties and total masses similar to those of X-ray groups. These objects may be the merger remnants of X-ray groups or ‘failed groups’ (i.e. overdensities that formed only a single galaxy). The number density of these objects suggests they make a non-negligible contribution to the mass density of the universe.
The Nature of Compact Groups
Authors: Tovmassian H. M. , Tiersch H. , Martinez O. , Yam O.
Published: July 2016

We show that compact groups (CGs) are real physical entities, that almost all HCGs are dynamically associated with generally elongated loose groups of galaxies, that HCGs are compact cores of loose groups, and that they are longer living formations.
Regular and Chaotic Motion in a Restricted Three–Body Problem of Astrophysical Interest
Authors: Muzzio J. C. , Wachlin F. C. , Carpintero D. D.
Published: July 2016

We have studied the motion of massless particles (stars) bound to a stellar system (a galactic satellite) that moves on a circular orbit in an external field (a galaxy). A large percentage of the stellar orbits turned out to be chaotic, contrary to what happens in the usual restricted three–body problem of celestial mechanics where most of the orbits are regular. The discrepancy is probably due to three facts: 1) Our study is not limited to orbits on the main planes of symmetry, but considers three–dimensional motion; 2) The force exerted by the satellite goes to zero (rather than to infinity) at the center of the satellite; 3) The potential of the satellite is triaxial, rather than spherical.
Triplets of Galaxies: Some Dynamical Aspects
Authors: Aceves Héctor
Published: July 2016

In celestial mechanics the 3-body problem has a long and rich history, yet the particular problem of 3-galaxy systems has been rather less studied (see review by Valtonen & Mikkola 1991). Most of the up-to-date works have addressed the 3-galaxy problem using a point-like approach, although some explicit-physics simulations have been performed to simulate dynamical friction effects and merging processes (Zheng et al. 1993). These studies have provided important understanding on the general behaviour of observed galaxy triplets (Karachentsev 2000), and some accordance with observations has been obtained.

However galaxies are not point-like particles, but rather consist of a large number of stars which can be approximated as point-like particles. Qualitative and quantitative differences result in the dynamics when the 3-galaxy problem is addressed self-consistently; i. e. when galaxies are able to redistribute energy and angular momentum among their stars. Since not using self-consistent galaxies necessarily casts some doubts on earlier results, we address here the 3-galaxy problem self-consistently and compare some results with observations. A full report on this work is in preparation.
Evolution of multiple black hole nuclei in merged galaxies
Authors: Valtonen Mauri , Mikkola Seppo , Heinämäki Pekka
Published: July 2016

The evolution of three and four black hole clusters which arise in mergers of small galaxy groups have been simulated. Typically, the chaotic dynamics of these multiple black hole systems leads to a decay via the slingshot process. Orbits of 100,000 initial configurations have been calculated and the final configurations have been classified in seven different categories. Examples of the orbits in each category are illustrated.
The origin of the multiple stellar arcs
Authors: Efremov Yu. N.
Published: July 2016

We argue that multiple stellar arcs are formed by single beamed super-explosions or long-standing jets produced by objects connected with Gamma-ray bursts.
On the Stability of Homographic N-body Configurations
Authors: Mylläri A. A.
Published: July 2016

Stability of expanding homographic configurations formed by an even number of bodies of equal mass and placed at the vertices of regular polygons and polyhedrons is studied. It is shown that for every configuration considered, there is always an unstable perturbation that divides the system into pairs of bodies.
The Be Phenomenon: Connections to B-supergiants
Authors: Kaufer Andreas
Published: July 2016

In this contribution the spectral characteristics, physical properties, and the evolutionary status of B-type supergiants is reviewed with respect to the Be phenomenon. Long-term monitoring campaigns in the UV and the optical have recently revealed the distinct variability patterns of the photospheric and the emission-line spectra of this class. The various proposed scenarios for the spatially structured circumstellar envelopes and their rotational modulation are presented. The possibility of generating and maintaining large-scale wind structures by photospheric processes which structure the underlying stellar surfaces is discussed. Some open questions in connection with these hypotheses will be identified.
Hipparcos Positions of B/Be Stars on the HR Diagram
Authors: Briot Danielle , Robichon Noel
Published: July 2016

Absolute magnitudes of Be and B stars are computed for each spectral type and luminosity class V and IV, using the Hipparcos parallax measurements. Some simulations have been carried out in order to estimate the effects which could bias the mean absolute magnitude calculations. As a result, only stars with σπ/π < 15% have been used. A first result is that B stars are fainter than previous estimations by about 0.5 magnitude on average. We then observe that on average Be stars are brighter than B stars of the same spectral type and this over-luminosity increases with the spectral type. A possible interpretation is proposed based on the fact that the rotational velocity of the late Be stars is near the critical rotational velocity.
NRP Modeling of the Line Profile Variations ofλEri in the 1994 Campaign
Authors: Kambe Eiji , Hirata Ryuko , Fabregat Juan ,   1994 Campaign Team
Published: July 2016

We report attempts to model the observed line-profile variations (lpv) of λ Eri during a productive spectroscopic and photometric campaign in 1994 November. We find that none of the nonradial pulsation spheroidal modes withm= −1 — −3 could explain thelpvassociated with the dominant 16.9 hr period since the horizontal velocity components and the temperature variations dominate thelpvfor such modes. In contrast, certain tesseral toroidal modes can reproduce the observedlpvwell both for the main 16.9 hr period and the 6.45 hr period.
Theory of Global Disk Oscillations
Authors: Okazaki Atsuo T.
Published: July 2016

We discuss the characteristics of global oscillation modes in Be disks and review recent studies related to the disk oscillation model. Since the m = 1 modes are present only in near Keplerian disks and the mode confinement occurs only in the region in which the radial flow is subsonic, the model of global disk oscillation strongly prefers the viscous decretion disk scenario proposed by Lee et al. (1991), whereas it is incompatible with the wind-compressed disk scenario of Bjorkman & Cassinelli (1993), which predicts angular-momentum conserving disks with supersonic radial flow. Based on the viscous decretion disk scenario, we discuss transonic solutions of decretion and examine the effect of viscosity on the global one-armed modes.
Paschen and Brackett Lines in Be stars
Authors: Cidale L. , Zorec J. , Maillard J.P. , Morrell N.
Published: July 2016

The activities detected in Be stars indicate that the formation of the circumstellar envelope and its structure cannot be studied independently of the phenomena taking place in the outermost layers of the central stars. Assuming that related to the stellar activity there is an expanding atmospheric region with temperatures Te > Teff followed by an envelope with a decreasing temperature, we calculated hydrogen line profiles for different velocity fields and different positions of temperature maxima relative to the underlying photosphere. Results show that the Hα line is not very sensitive to changes introduced to the stellar atmosphere and to the nearby circumstellar layers. Moreover, the Hα emission line profiles look like those produced by disc-like circumstellar envelopes seen pole-on, although the model for the circumstellar envelope is spherical. However, the first members of the Paschen and Brackett series are strongly sensitive to any changes introduced in the photospheric and exophotospheric layers. We conclude that the study of these lines may then be valuable to obtain new insight on the activity of central stars and on the phenomena involved in circumstellar envelope formation in Be stars.
Interpretation of the Cyclic Balmer Progression Phenomenon
Authors: Hirata Ryuko , Okazaki Atsuo T.
Published: July 2016

We have computed the Balmer-line profiles for the one-armed oscillation model and found that the model can naturally account for the cyclic Balmer progression phenomenon observed in the V/R variable shell stars.
Long–term Variability of π Aqr
Authors: Bjorkman K.S. , Miroshnichenko A.S. , McDavid D.A. , Pogrosheva T.M.
Published: July 2016

We present our recent photometric and spectroscopic observations of the bright classical Be star π Aquarii and analyse those available in literature. This star currently shows only weak signs of circumstellar emission and a low optical brightness. Physical parameters of the underlying star are determined from data obtained during quiescence, while those of its circumstellar disk are estimated during the active period.
Effect of Instability-Generated Clumping on Wind Compressed Disk Inhibition
Authors: Owocki S. P. , Cohen D. H.
Published: July 2016

In rapidly rotating stars with a purely radially driven stellar wind, conservation of wind angular momentum can lead to formation of an equatorial Wind Compressed Disk (WCD). However, for a line-driven stellar wind, recent 2D hydrodynamical simulations based on a localized, Sobolev treatment of the line-force indicate that nonradial components of the line-force can effectively inhibit formation of such a WCD. This presentation will describe current efforts to extend such 2D simulations to a nonlocal, smooth-source-function treatment of the line-force that can incorporate the intrinsically strong instability of line-driving to formation of small-scale, clumped structure. Key questions are how such small-scale clumped structure affects the nonradial line-force components that arise from large-scale velocity-gradient asymmetries, and in particular whether such nonradial forces can still inhibit WCD formation in a clumped flow. The results have important implications for the viability of the WCD mechanism as a paradigm for disk formation in Be stars.
The Steep Spectrum Pulsar Population
Authors: Kaplan D. L. , Cordes .J. M. , Condon J. J.
Published: July 2016

We have sampled the population of compact (θ≤ 25") radio sources with spectral indices 1.5 ≤ α ≤ 3.2 (whereSv∝v—α) using two large scale radio surveys. This yields a statistically useful sample of 74 radio sources withS1.4GHz≥ 2.5 mJy andS365MHZ≥ 200 mJy. The majority of the sources appear to be extragalactic, resembling either high redshift radio galaxies or relic radio galaxies. However, six known pulsars were detected, as well as 16 sources of unknown nature that appear too small and have spectra too steep to be extragalactic. We are using VLBA, pulsar searching, optical/IR spectroscopy, and other techniques to definitively classify these sources. If any are new pulsars, they are potentially very interesting as they were missed by previous surveys.
Millisecond Pulsars and a WSRT Search for Candidates
Authors: Tian W. W. , Strom R. G. , Stappers B. , Zhang X. Z. , Wu X. J. , Ramachandran R.
Published: July 2016

Seven millisecond pulsars (MSPs) have been identified from the NVSS by positional coincidence. Our examination of the characteristics of about, 280 known pulsars and 40 MSPs has shown that they have high polarization and a steep spectrum. We identify likely MSP candidates from both the NVSS at 1.4 GHz and the WENSS at 325 MHz. The first sample of 14 candidates has been observed by the WSRT using PuMa at both 92 and 21 cm in May 1999. From our preliminary analysis of the 382 MHz data, we find no evidence for MSPs in the first sample.
Glitch Behavior of the Pulsar B1822–09 in the Range 0.1–2.3 GHz
Authors: Shabanova T.V. , Urama J.O.
Published: July 2016

Results of timing observations of the glitching pulsar B1822–09 made practically simultaneously at widely separated frequencies of 0.1 and 1.6/2.3 GHz during seven years since 1991 to 1998 are discussed.
Pulse Fluctuation Properties at 35 MHz
Authors: Asgekar Ashish , Deshpande A. A.
Published: July 2016

A few bright pulsars were observed at 35 MHz for ≳ 1000s using the Gauribidanur Radio Telescope, and the data were analysed to study their single-pulse fluctuation properties (Asgekar & Deshpande, 1999a; & ref.s therein).

The well-known drifterB0943+10shows a well resolved two-component profile at 35 MHz. The longitude-resolved fluctuation spectrum (Fig 1) shows a stable phase modulation feature (aliased) at 0.459c/P1, consistent with its drifting pattern seen at higher radio-frequencies. Using the “Cartographic Transform” technique (Deshpande & Rankin, 1999; hereafter DR), we have mapped the pattern of its polar emission at 35 MHz (Asgekar & Deshpande, 1999b) as shown in fig 1. Helped by the larger cone radius at lower frequencies, the subbeams can be sampled in their full radial extent at 35 MHz. These results combined with those at higher frequencies (DR) suggest a steadily rotating system consisting of 20 emission-columns in the polar region as that responsible for the observed fluctuations over the entire range of observed frequencies.
Pulsar Studies at High Radio Frequencies
Authors: Wielebinski Richard
Published: July 2016

Pulsars were discovered at 81.5 MHz and a lot of the studies of these exciting objects have been made up to the present time at radio frequencies below 1.6 GHz. The reasons for this concentration on the low radio frequency characteristics of pulsars is the fact that the spectra are very steep and that very few radio telescopes exist that are capable of efficient operations at high radio frequencies. The Effelsberg 100-m radio telescope of the Max-Planck-Institut fur Radioastronomie operates regularly up to the frequency of 50 GHz and was used to study pulsars at cm/mm-wavelengths. In the southern skies the Parkes 64-m telescope has been used to study pulsars up to 8.4 GHz. One pulsar has been detected at 87 GHz with the 30-m Pico Veleta telescope of IRAM.

The studies of pulsars over the whole frequency range are of great importance because this is necessary for the elucidation of the mechanism that is responsible for the pulsar emission. The high polarization of pulsar radio emission at lower radio frequencies has supported the hypothesis of a coherent emission mechanism, which is required to generate the high luminosity. It has been known for some time that pulsars, unlike other radio sources, have a lower polarization at high radio frequencies. Recently a change of pulsar spectrum, a flattening or possibly an inversion has been observed at the highest radio frequencies. The inversion of the pulsar spectrum seems to coincide with a complete depolarization of some pulsars.

Millisecond pulsars are less luminous than normal pulsars. This makes them even more difficult to detect at higher radio frequencies. Recent observations have extended the spectra of ten millisecond pulsars up to 4.85 GHz. The results imply that millisecond pulsars have properties very similar to normal (slow) pulsars, which suggests similar emission mechanisms.
Pulsar radio spectra and the interstellar scintillation
Authors: Malofeev Valerij M.
Published: July 2016

A review of the pulsar radio spectra is continued. Two approches of the spectrum construction are considered. The influence of the interstellar stcintillations on the pulsar flux density measurements and spectra is examined. The description of new pulsar spectra catalog is made. Examples of different types of spectra including one for Geminga are presented.
Observations of millisecond pulsars at 102 MHz
Authors: Kuzmin Arkady , Losovsky Boris
Published: July 2016

Millisecond pulsars are differ to ”normal” ones in much weaker frequency dependence of the width of integrated profiles and the absence of the low-frequency turn-over in pulsar spectra.
PSR B0656+14: Combined Optical, X-ray & EUV Studies
Authors: Golden Aaron , Shearer Andy , Edelstein Jerry
Published: July 2016

PSR B0656+14’s high energy emission is consistent with that of combined magnetospheric and thermal (surface & polar cap) emission. Uncertainties with the radio-derived distance and X-ray instrumentation sensitivities complicate a definitive thermal characterisation however. A re-analysis of combined ROSAT/EUVE archival data in conjunction with integrated & phase-resolved optical photometry is shown to constrain this characterisation.
ASCA Observations of the Crab-Like Pulsar PSR B0540 – 69
Authors: Nagase F. , Endo T. , Hirayama M. , Kawai N. , Itoh M.
Published: July 2016

We report on the spectral and temporal properties of the 50 ms pulsar PSR B0540–69 using ASCA archival data obtained during 1993 to 1995. From the spectral analysis it was found that the spectra of the whole (nebular and pulsed) emission and pulsed emission in the range 1-10 keV can be represented by a single power law of photon index, Γ = 2.00 ± 0.02 and Γpulsed= 1.7 ± 0.3 respectively. The parameters for pulse frequency change during 1993-1995 were obtained using the 9 pulse frequency measurements with ASCA. The parameters derived from the ASCA observations are consistent with the previous measurements, suggesting high stability of this pulsar, ΔΩ/Ω ≲ 0.5 × 10−7over the past 10 years. These results confirm similarity of this pulsar with the Crab pulsar.
Scattering and Diffraction in Magnetospheres of Fast Pulsars
Authors: Lyutikov Maxim , Parikh Anuj
Published: July 2016

We show that under conditions of strong density modulation the effects of magnetospheric scintillations in diffractive and refractive regimes may be observable. The most distinctive feature of the magnetospheric scintillations is their independence on frequency. Results based on diffractive scattering due to small scale in homogeneities give a scattering angle that may be as large as 0.1 radians, and a typical decorrelation time of 10−8seconds. Refractive scattering due to large scale inhomogeneities is also possible, with a typical angle of 10−3radians and a correlation time of the order of 10−4seconds. Temporal variation in the plasma density may also result in a delay time of the order of 10−4seconds. The different scaling of the above quantities with frequency may allow one to distinguish the effects of propagation through a pulsar magnetosphere from the interstellar medium. In particular, we expect that the magnetospheric scintillations are relatively more important for nearby pulsars when observed at high frequencies.
A possible mechanism for flattening of pulsar spectra at high frequencies
Authors: Malov I.F.
Published: July 2016

Pulsar spectra have three characteristic parts: a low frequency turnover (the region of the maximum), a linear part with a constant spectral index, and a high frequency cut-off (after it the spectrum becomes considerably steeper) (Malofeev et al. 1994). These three parts can be described in the frame of the usual model of curvature radiation (Malov 1979; Ochelkov & Usov 1984; Kuz’min & Solov’ev 1986; Malov & Malofeev 1991). Kramer et al. (1997) have found a flattening in the spectra of 4 pulsars at frequencies above 30 GHz. It cannot be understood in such model. We propose the possible explanation for the unusual behaviour of these spectra.
A Model for the Pulsar Radio Emission
Authors: Melikidze G. , Gil J. , Pataraya A.
Published: July 2016

New, self-consistent theory of coherent pulsar radio emission based on the sparking model of the polar gap first suggested by Ruderman & Sutherland (1975) and modified by Gil & Sendyk (1999), is proposed.
Pulsar Scintillation Measurements: Is there any evidence for a Local Bubble Shell or effects from pulsar bow shocks?
Authors: Minter Anthony
Published: July 2016

Bhat et al. (1998) presented a model in which they explain the increase in scintillation bandwidth with decreasing pulsar distance as being due to a shell of scattering material associated with the Local Bubble. However, Britton et al. (1998) concluded that the scattering material for local pulsars is nearer to the pulsar (i.e. possibly in a bow shock or shell near the pulsar). We have investigated the effects of the local bubble shell and pulsar bow shocks on the scintillation bandwidth, the scintillation timescales and the angular broadening of pulsars. We find that a) there is no evidence for a shell of scattering material associated with the Local Bubble because the scintillation timescale data do not fit the Bhat et al. model and the angular broadening measurements do not suggest a scattering screen near the Sun, and b) that pulsar bow shocks cannot produce any enhanced scintillations.
Interstellar scintillation of the radio source associated with the gamma ray burst of 8 May 1997
Authors: Smirnova T.V. , Shishov V.I.
Published: July 2016

We show that variability of the radio source associated with the gamma ray burst of May 8, 1997 can be explained by scintillations on interstellar plasma inhomogeneities in the weak regime at 4.86 and 8.46 GHz, and by the refractive component of saturated scintillations at 1.43 GHz. Cosmological distance of this source R ≊ 1028cm is more preferable. The source has the size about 2μarcsec at frequency 4.86 GHz and the velocity of spreading is about 25μarcsec/year.
Braking Indices for Twenty Pulsars
Authors: Johnston Simon , Galloway David
Published: July 2016

We have derived a formula for the braking index of pulsars via integration rather than the conventional differentiation method. We applied the method to 20 pulsars and find that virtually all the derived braking indices are dominated by the effects of (unseen) glitches, the recovery from which corrupts the value of. However, any real, large, positive braking index has implications for magnetic field decay and offers support to recent models of pulsar evolution.
On the origin and parameters of the pulsar-like white dwarf in AE Aquarii
Authors: Ikhsanov Nazar R.
Published: July 2016

The rapid braking on the white dwarf in the close binary AE Aqr can be explained in terms of the canonical pulsar mechanism provided the magnetic moment of the starμ∼ 1.5 × 1034G cm3. The scenario for the origin of the fast rotating (Ps= 33 s), magnetized white dwarf, which is based on the magnetic field amplification in differentially rotating stars, is presented.
Gravitational Waves and Neutron Stars
Authors: Schutz Bernard F.
Published: July 2016

The first generation of laser-interferomteric gravitational wave observatories will make intensive searches for gravitational radiation from spinning neutron stars. Sensitivity to a number of possible sources, including the Crab pulsar, will be better than any existing observational limits, and will improve dramatically over the next decade. This paper reviews these developments and expectations, and discusses ways in which pulsar radio astronomers and gravitational wave astronomers can benefit from one another’s work.
Polar Motion: A Historical Overview on the Occasion of the Centennial of the International Latitude Service
Authors: Dick Steven J.
Published: July 2016

The study of polar motion, termed “variation of latitude” at the time of its discovery in the late 19th century by F. Küstner and S. Chandler, is of historical interest for many reasons. From a scientific viewpoint, its discovery must be seen in the context of positional astronomy, geodesy and Earth rotation studies. From an institutional viewpoint, the founding of the International Latitude Service (ILS) in 1899 represents an early case of international cooperation in astronomy, preceding the International Astronomical Union by two decades. In addition to discussing these themes in this review, we analyze in some detail the Gaithersburg (USA) station of the ILS as a case study of the early problems and promise of polar motion studies. With milliarcsecond accuracies, polar motion studies are important today not only for astronomy and geophysics, but also for practical problems like spacecraft navigation and positioning.
On the Contribution of the Geodetic Institute Potsdam to the International Latitude Service
Authors: Höpfner Joachim
Published: July 2016

The paper reviews in what ways the Geodetic Institute Potsdam contributed to the foundation of the International Latitude Service (ILS) and took part in its activities through the work of Helmert, Albrecht, Wanach and Mahnkopf. Based on international scientific cooperation, the results were the rectangular coordinates of the polar motion from 1890.0 to 1922.7 at 0.1 year intervals, in particular those derived from the latitude observations at independent stations from 1890.0 to 1899.8, and those derived from the latitude observations at the ILS stations from 1899.9 to 1922.7.
Project MERIT and the Formation of the International Earth Rotation Service
Authors: Wilkins G.A.
Published: July 2016

Project MERIT was an international programme to Monitor Earth Rotation and Intercompare the Techniques of observation and analysis. It was conceived by a working group that was set up by the International Astronomical Union in 1978 and was carried through with additional support from the International Union of Geodesy and Geophysics. The first objective was to encourage the development of the use of new techniques, such as laser ranging and radio interferometry, for the regular determination of universal time and polar motion. A successful ‘short campaign’ of observations by six techniques was carried out during the period 1980 August to October. Operational and analysis centres were set up for each technique and a coordinating centre was established at the Bureau International de l’Heure (BIH). The results were reported and discussed at the first MERIT Workshop in 1981.

The preparations for the ‘main campaign’, which was held from 1983 September 1 to 1984 October 31, and the plans for the activities that were to follow it were reviewed at the second MERIT Workshop in 1983. Important additional features of the campaign included the use of ‘MERIT Standards’ for the reduction and analysis of the data, the use of electronic techniques for the distribution of data, the comparison of the results with the changes in the angular momentum of the atmosphere and special emphasis on the improvement of the terrestrial reference frame. Proposals for a new International Earth Rotation Service were prepared at the third MERIT Workshop in 1986. The MERIT programme was continued from 1984 until the new service formally started on 1988 January 1. Over the decade the accuracy of the Earth-rotation parameters improved considerably.
Analysis of Long Time Series of Polar Motion
Authors: Schuh H. , Richter B. , Nagel S.
Published: July 2016

Two long time series of polar motion were analysed with respect to a linear drift, decadal variations, Chandler wobble and annual wobble: the C01 series published by the International Earth Rotation Service (IERS) and the pole series which J. Vondrák, obtained by re-analysis of the classical astronomical observations using the HIPPARCOS reference frame (1899.7–1992.0). By a least-squares fit the linear drift of the pole, usually called ‘secular polar motion,’ was determined to 3.31 milliarcseconds/year (mas/yr) toward 76.1° West longitude. For this fit the a priori correlations within each pair of pole coordinates were taken into account, and the weighting function was calculated by estimation of empirical variance components. The decadal variations of the pole path were determined by Fourier analysis. Using a sliding window analysis, the variability of the periods, the amplitudes and the phases of the Chandler wobble and annual wobble was investigated. The variances of the results and the number of iterations needed to get a convergence in the nonlinear approach show that the new time series by Vondrák is more homogeneous and consistent than the IERS C01 series.
On the Chandler periodicity (Polar Motion, LOD and Climate)
Authors: Buffa F. , Poma A.
Published: July 2016

The 14-month Chandler period is associated with the free nutation of the Earth about its spin axis. The observed value of the Chandler period comes usually from the analysis of astronomical series of polar motion data as well as from superconducting gravimeter measurements. At the observation level a periodicity of about 420–440 days also was noticed in microseismic activities. Recently we found evidence of a signal with period similar to the Chandler one in the Sardinia rainfall time series.
Overview and Proposition for a Modern Definition of the CEP
Authors: Capitaine Nicole
Published: July 2016

The current IAU conventional models for precession and nutation are referred to the Celestial Ephemeris Pole (CEP). However, the concept corresponding to the CEP is not clear and cannot easily be extended to the most recent models and observations. Its realization is actually dependent both on the model used for precession, nutation and polar motion and on the observational procedure for estimating the Earth orientation parameters. A new definition of the CEP should therefore be given in order to be in agreement with modern models and observations at a microarsecond level. This paper reviews the various realizations of the pole according to the models and observations and discusses the proposals for a modern definition of the CEP that are under consideration within the work of the subgroup T5 entitled “Computational Consequences” of the “ICRS” IAU Working Group.
The RS CVn Binaries and Binaries with Similar Properties
Authors: Hall Douglas S.
Published: July 2016

This paper will review reasonably thoroughly and comprehensively the many observational properties of the remarkable RS CVn-type binaries. In addition this paper will show that many of these same properties are observed in other types of binary systems.
Construction of Planetary Theory by Iterative Procedure
Authors: Ivanova T.V.
Published: July 2016

In this paper the method of determination of the planetary perturbations is proposed which is a modification of Dziobek-Brouwer’s method [1,2]. For the simplicity the case of two mutually disturbing planets is considered. In the original version of the method the perturbations of rectangular planetary coordinates are presented by means of the formal integrals

where index i corresponds to the number of the planet; δXik are perbations of Xik coordinates; Gik – components of the perturbating accelerations. The coefficients of aik, cik bij are the well-known functions of the coordinates of the elliptic motion which can be developed as double Fourier series in mean longitudes. The denominators in Davis’ formulas [3] for these coefficients contain the eccentricities. For this reason Musen [4] expressed an opinion that Brouwer’s method would lose its effectiveness when small eccentricities are involved. These fictitious peculiarities are eliminated in the present paper by means of trivial transformations and the expressions for the coefficients are given in a simple symmetric form.
Construction D’Une Theorie Planetaire Au Troisieme Ordre Des Masses
Authors: Simon J. L.
Published: July 2016

Les théories planétaires avec termes séculaires ne sont valables, par suite de la présence de termes augmentant avec le temps dans les éléments métriques, que dans un intervalle de temps limité (de l’ordre de mille ans) mais on peut les construire avec une bonne précision sur cet intervalle. Les recherches récentes sur la construction de formulaires pour le développement de la fonction perturbatrice bien adaptés au calcul sur ordinateur (Iszak 1964, Brumberg 1967, Chapront 1970) et les progrès réalisés dans les méthodes de calcul utilisées (Chapront et al. 1974) nous permettent d’espérer une amélioration sensible des théories existantes et des éphémérides qui en résultent.
Third-Order Solution of An Artificial-Satellite Theory
Authors: Kinoshita Hiroshi
Published: July 2016

A third-order solution is developed for the motions of artificial satellites moving in the gravitational field of the Earth, whose potential includes the second-, third-, and fourth-order zonal harmonics. Third-order periodic perturbations with fourth-order secular perturbations are derived by Hori’s perturbations method. All quantities are expanded into power series of the eccentricity, but the solution is obtained so as to be closed with respect to the inclination. A comparison with the results of numerical integration of the equations of motion indicates that the solution can predict the position of a close-earth satellite with a small eccentricity with an accuracy of better than 1 cm over 1 month.
Construction De Solutions Periodiques Du Probleme Restreint Elliptique Par La Methode De Hale
Authors: Sergysels-Lamy Anne , Sergysels Roland
Published: July 2016

Les équations du mouvement du troisième corps, dans les variables sans dimensions définies par Szebehely (1967, page 591) ont été données dans un article précédent (Sergysels-Lamy, 1975).
Classification of C-Rich Stars According to Their Mid-IR Signatures
Authors: Papoular R.
Published: July 2016

The spectra of the IRAS low-resolution-spectrometer in tape form have been submitted to a systematic morphological analysis, using classical quantitative discriminants (O.Gal et al. 1987, A & A 183, 29; Y. Baron et al. 1987, A & A 186, 271; R. Papoular 1988, A & A , in press). Spectra which display the 11.5μ feature of SiC fall into 4 classes of average spectral excesses. They differ by the width of the SiC feature and by the presence or absence of secondary features at ~8.6, ~11.7 and ~12.8μm.

A majority of these spectra have a lower 12-25μm colour temperature than do most optically selected C-stars, presumably because of thicker dust envelopes. While most spectra belong to LRS class 4n, 20% of the total were found among the brightest 20% of the much larger class In, suggesting that the relative abundance of C-stars is much higher than previously assumed.
Are the Barium and Am Stars Related?
Authors: Hakkila J.
Published: July 2016

A study of barium star kinematics from 112 stars with known radial velocities indicates a solar motion of
All values have errors of roughly ±2.6 km/s.

Parameters of the velocity ellipsoid from 32 barium stars with independently-determined absolute magnitudes are.
HD 39853: A High Velocity K5III Star With an Exceptionally Large Li Content
Authors: Gratton Raffaele G. , D'Antona Franca
Published: July 2016

High dispersion spectra of the high velocity star HD 39853 show that it is a slightly metal-poor ([Fe/H]=−0.5±0.1) giant of the old disk population, with exceptionally strong lithium lines. The abundance of Li, derived by synthetic spectra of the 6103.6 and 8126.4 Å lines, is log N(Li)=2.8±0.2. Abundances for the other observed elements are typical for mildly metal-poor giants: oxygen is slightly overabundant ([O/Fe]=+0.25±0.15); the C/N ratio is large (10±2); the 12C/13C ratio is small (6.6±1.2); and light elements (Na, Mg, Al, Si, Ca and Ti) are enhanced with respect to Fe by about a factor of 2.5. Observed s-elements (Zr and La) are not overabundant. Finally, no variation in the radial velocity of the star were detected at a level of 1 Km s-1.
Theoretical and Observational Tests for the Mass Transfer Scenario of Ba II stars
Authors: Boffin H.M.J.
Published: July 2016

Ba II stars are red giants showing an enhancement of carbon and s-process elements. The elucidation of their nature seems to require a mass transfer, either by wind or Roche lobe overflow, during their past evolution. Were it really the case, all Ba II stars would be binaries with a white dwarf as companion. To better understand the exact role of their binarity, more orbits are definitely needed. They can be obtained by monitoring the radial velocity variations of those stars. However, a quicker way to find new Ba II stars with orbital elements would be to search for their existence among known spectroscopic binaries. This would also crucially test whether mass transfer is a necessary and sufficient condition to explain Ba II stars. If it is indeed the case, then all spectroscopic binaries, made of a giant and a white dwarf, in a reasonable range of periods, would exhibit the Ba II pecularity. However, the discovery of a peculiar giant+main sequence binary system would imply a revision of our ideas about Ba II stars. To this end have we begun a systematic spectral survey of spectroscopic binaries with orbital periods in the range characteristic of known Ba II stars and containing a red giant. The realization that some stars of the catalogue we compiled were already identified as semibariium stars encourages us to pursue our investigation. Coude spectra were taken with the 152 cm telescope, at a dispersion of 12 Å mm−1 . Until now, 2 stars out of a sample of 31 present a slight enhancement of s-process elements (their anomaly being in the range Ba 0.3 to 0.5), and 2 more appear to be good candidates. The study of a larger sample is currently in progress. A discussion of the nature of the companion to the 2 newly discovered semibarium stars is presented on grounds of their mass function and photometric indices.
The Evolution of Stars on the AGB: The Mass Loss Intensity and the Formation of Carbon Stars
Authors: Frantsman Yu. L.
Published: July 2016

Simulated populations of white dwarfs and N type carbon stars were generated for a Salpeter initial mass function and constant stellar birth rate history. The effect of very strong mass loss on the mass distribution of white dwarfs and the luminosity distribution of carbon stars is discussed and the results are compared with observations. A significant mass loss by stars on the TP-AGB occurs besides regular stellar wind and planetary nebulae ejection. Thus it is possible to explain the luminosity functions of carbon and M stars in the Magellanic Clouds (with very few stars brighter than Mbol = -6.0), the very narrow mass distribution of white dwarfs, and the very small number of white dwarfs with M > 1.0 MΘ. The luminosity of some AGB stars in the SMC is so high that they may be supernova of type 1 1/2 precursors. There are no such stars in the LMC. Comparison of the theoretical and observed luminosity distributions of high-luminosity AGB stars in the Magellanic Clouds shows that the mass-loss rate of these stars in the LMC is about an order of magnitude larger than in the SMC. In the Galaxy carbon stars may form only from stars with initial mass less than 1.5 MΘ due to the relatively small initial heavy element abundance in these stars; this is perhaps the main reason for the absence of carbon stars in open clusters in the Galaxy.
Comparison of s-Processing Occurring in a Low Mass AGB Star of Low Metallicity and the Results of s-Classical Analysis
Authors: Busso M. , Picchio G. , Gallino R. , Kappeler F. , Raiteri C.M.
Published: July 2016

We examine the results of s-Processlng occurring in a low mass star of low metallicity during the pulsed He-instability in AGB phases by comparing them with the s-Classical analysis. Neutron exposures are provided by the C13(Alpha, N)016 reaction, according to the mechanism suggested by Iben and Renzini (1983) for the formation in the interpulse phase of a small zone rich of C13 and its subsequent ingestion in the next pulse.
Mass-Losing Peculiar Red Giants: The Comparison Between Theory and Observations
Authors: Jura M.
Published: July 2016

The mass loss from evolved red giants is considered. It seems that red giants on the Asymptotic Giant Branch (AGB) are losing between 3 and 6 10-4 MΘ kpc-2 yr-1 in the solar neighborhood. If all the main sequence stars between 1 and 5 MΘ ultimately evolve into white dwarfs with masses of 0.7 MΘ the predicted mass loss rate in the solar neighborhood from these stars is 8 10-4 MΘ kpc-2 yr-1. Although there are still uncertainties, it appears that there is no strong disagreement between theory and observation. However, it could also be that we have not yet identified much of the source of the mass-loss from pre-white dwarf stars.
Observations and Models for Red Giants with Unusual Dust
Authors: Griffin Ian , Skinner C.J. , Whitmore B.R.
Published: July 2016

We present near IR (H, K and L band) medium resolution (ƛ/Δƛ ∼ 600) spectra for a selection of 9 red giants which have previously been shown to exhibit anomalous dust emission as characterised by their IRAS LRS spectra. The objects observed (during UKIRT and AAT service time) include Carbon stars whose LRS spectra show the 9.7μm silicate feature and also M stars whose LRS spectra display an 11.3μm feature similar to that usually associated with emission from SiC dust grains.
OH maser survey of very cool IRAS sources
Authors: Hekkert P. te Lintel , Heske A. , Le Squeren A.M.
Published: July 2016

During our 1612 MHz survey of IRAS sources in Parkes, Australia, we found two objects with very large expansion velocities : IRAS15405-4945 and IRAS16342-3814 (P. te Lintel Hekkert et al. 1988, Astron. Astrophys. (Letters), in press.). These two sources and the well known source, OH231.8 + 4.2 , were discovered to have almost identical IRAS colours. The spectra of the three sources could be fitted with a 100 (±15) K black body curve. We than selected, using the IRAS colour-colour plot, a number of bright sources ( F (60 μm) > 25. Jy ) with similar colours to OH231.8 + 4.2 and IRAS16342-3814 . A small survey of about 150 sources was started in the last week of June and will be finished at the end of July 1988. Using the radio telescope in Nançay , we observed all four OH maser transitions, with the hunderd meter radio telescope at Effelsberg only 1612 MHz was observed, the sources found at Nançay were confirmed in Bonn and vice versa. From the preliminary analyses of the first 40 observations six sources were found of which three were not known before.
Molecular Cooling in the Outer Atmospheres of Red Giants
Authors: Muchmore David
Published: July 2016

In the outer atmospheres of cool giants and supergiants there is a competition between heating by shock waves which develop from noise lower down in the convection zone and radiative cooling. The post-shock cooling is most effective in keeping temperatures low and in damping shocks if molecules (especially CO) form. CO is important both because of its high dissociation energy (11 eV) and its large IR opacity.
On the Nature of Radio Emission of Late-Type Giants
Authors: Rudnitskij G.M.
Published: July 2016

Long-period variable stars (LPV's) are considered. Pulsations of the surface of such a star result in formation in the stellar atmosphere of a shock wave in each cycle of the star's variability, ionizing the circumstellar gas which, recombining, gives rise to emissions in optical lines hydrogen and metals. I show the recombining layer behind the shock front to be optically thick in the free-free continuum at the radio wavelengths as short as 1 cm. At the gas temperatures behind the front T = 20000 K, the radio flux density at 1 cm from the front surface at a distance of a few hundred parsees will be several or several tens of mjy. So far, the only positive result of searches for LPVS’ radio continuum is the detection of radio flux from R Aql, obtained at different epochs by several authors. In October 1978 R Aql showed radio emission of 5.3 mjy at 14.9 GHz (Bowers and Kundu, 1979), and in August 1985 - 0.54 mjy at the same frequency (Drake et al.. 1987); these figures are consistent with our model. Besides that, R Aql experienced stronger radio flares at longer wavelengths, up to a few hundred mjy (Woodsworth and Hughes, 1973; Estalella et al.. 1983); these cannot be explained by thermal radio emission and require a nonthermal mechanism (synchrotron or cyclotron maser).
Absorption Spectrum of RCrB During the Light Minimum
Authors: Rao N. Kameswara , Giridhar S. , Ashoka B.N.
Published: July 2016

Observations of RCrB obtained during the 1986 and early part of 1963 light minima show the following changes relative to the spectrum obtained at maximum light.

The molecular band of C2 (Swan System), CN bands at λ4215 and low excitation metal lines are enhanced in absorption.
Report of the Sub-Group on Time
Authors: Guinot B.
Published: July 2016

The report of the Sub-Group on Time (SGT) of the IAU Working Group on Reference Systems (WGRS) is divided as follows.

Sections 2 to 4 recall the scope of the work of the SGT and briefly describe its activity.

Section 5 summarizes the discussions on several topics which form the background of the draft recommendations and notes of Section 6.
Preliminary Report of the Work of the Subgroup on Coordinate Frames and Origins
Authors: Kovalevsky J.
Published: July 2016

The membership of the subgroup on coordinate frames and origins included the following: V.K. Abalakin, S. Aoki, F. Arias, С Boucher, N. Capitaine, K. Johnston, J. Kovalevsky (chairman), C. Ma, I.I. Mueller, C.A. Murray, H. Schwan, C.A. Smith, C. de Vegt and R. Wielen.

In addition, the following colleagues have contributed to the work: V.A. Brumberg, T. Damour, J. Dickey, M. Feissel, T. Fukushima, B. Guinot, T. Huang, M. Standish, J.G. Williams and B.X. Xu.
Hipparcos: Its Link to an Extragalactic Reference Frame
Authors: Argue A.N.
Published: July 2016

This paper reviews the links currently envisaged for a mission of duration 3½ years, with estimates of the precision of each link.