bluuebunny/crossref_metadata_2025 huggingface dataset:
Asteroid Mass Distribution Measurement with Gravity Gradiometers
Authors: Forward Robert L.
Published: July 2016

A determination of the internal structure and composition of the asteroids will give us important information concerning the origin of the solar system and the formation of the planets. We can obtain this information by measuring the total mass and the internal mass distribution through the use of spacecraft missions to flyby or to rendezvous, orbit, and land on the asteroids. The Doppler tracking technique used for mass measurement on planetary probes is suitable only for a flyby mission of the larger asteroids (> 20 km) because the gravity force field of the smaller asteroids is not strong enough to appreciably affect the trajectory of the probe during a flyby. If a rendezvous mission is used and the spacecraft is placed in orbit about an asteroid, the mass can be determined from the orbital period, but the effect on the spacecraft orbit due to the mass anomalies under the surface will not be easily seen unless the anomaly is very large because again the gravity force field decreases rapidly with decrease in anomaly size.
Vacuum Ultraviolet Absorption of Dense Plasmas with Resonance Series of Be, B, C, N, Mg, Al and Si
Authors: Mehlman-Balloffet G. , Esteva J. M.
Published: July 2016

Absorption spectra of light elements were observed in the vacuum ultraviolet with an original technique described in an earlier paper (Mehlman-Balloffet and Esteva, 1969). The method utilizes a two-vacuum spark mounting: one of the sparks is emitting the continuous background, the other one generates the absorbing plasma. Several light element have been successsively introduced in the spark anode. For all of them new autoionizing levels have been observed in Rydberg series of resonances exhibiting the asymmetric ‘Beutler-Fano’ profile.

In the beryllium and magnesium spectra three new series corresponding to two-electron excitation process have been identified while for boron, carbon, nitrogen, aluminium and silicon the resonances observed correspond to single subshell electron excitation such as: 2s22p2P0 → 2s2p(3P0)np2De for the case of boron.

All these series lie in the photoionization continuum of the absorbing atomic species and usually between the first and second ionization limit. This means that they were observed with a normal incidence grating spectrograph in the spectral range 500–1500 Å. In the extreme ultraviolet some other transitions involving inner-shell electron excitation were observed. In the beryllium spectra a series lying between 100 and 110 Å was identified while, the magnesium spectra exhibited only isolated resonances in the 220-265 Å range together with an inner-shell 2p electron photoioniation continuum.

A complete description of experimental results with numerical data is being submitted for publication (Esteva and Mehlman-Balloffet, 1972).
The Classification of Fe IX to XVI Emission Lines and Isoelectronic Lines in Laboratory and Solar Spectra
Authors: Fawcett B. C.
Published: July 2016

The spectra of Feix to xvi which dominate the XUV spectrum include the 3pn–3p-1 3d transitions studied earlier (Fawcett et al., 1966, 1967, 1968) (Gabriel et al., 1966) and the 3s23pn–3s3pn transitions. A comprehensive classification of spectra from both these configurations is now completed at the Astrophysics Research Unit. The experimental method used to extend the classification of the 3s23pn–3s3pn+1 lines in the period between potassium and vanadium was to compare the spectra of laser produced plasmas which possessed lines belonging to different ionization stages and is described by Fawcett (1970). Too many lines due to low stages of ionization obscured the 3s23pn–3s3pn+1 lines in chromium, manganese, iron, cobalt and nickel in these laser produced spectra for successful analysis. Volatile compounds of these elements were therefore added to the filling gas of a specially designed theta-pinch (Fawcett et al., 1971). Separation of lines of different stages of ionization was accomplished through the application of a microsecond shutter and adjusting the theta-pinch parameters. Radiation from the cooler ends of the plasma was avoided through viewing the theta-pinch from the side.
Dielectronic Satellite Spectra in the Soft X-Ray Region
Authors: Gabriel A.H.
Published: July 2016

Satellite lines, situated on the long wavelength side of the helium-like ion resonance line, can be observed in highly-ionized ions both in laboratory sources and from the Sun. Although seen for more than 30 years, these lines have only recently been classified in detail as inner-shell transitions in lithium-like ions. Laboratory experiments have shown that under steady-state conditions these satellites are produced by dielectronic recombination, although in transient ionizing plasmas direct inner-shell excitation can be important. Detailed calculations have been carried out for high Z ions up to copper, and the results can be compared with solar flare spectra in iron. Such comparisons allow both the electron temperature and the transient state of the plasma to be determined. Laboratory spectra from such high-Z ions are different in appearance, and may be dominated by processes resulting from the transient ionizing state of the plasma.
Recent High Resolution X-Ray Spectra of the Sun
Authors: Parkinson J. H. , Evans K. , Pounds K. A.
Published: July 2016

New results are presented from high resolution Bragg crystal spectrometers flown in late 1970 on two Skylark rockets. The first instrument, launched on 24 November 1970 at 22 13 UT from Woomera, South Australia, contained two crystal spectrometers, each with an effective area of 50 cm2 and field collimation to 3’ FWHM. This instrument obtained the X-ray spectrum of the quiet corona in the wavelength range 5–14 Å. The second instrument was launched on 6 December 1970 at 11 13 UT from Sardinia, Italy, and contained four crystals of 6 cm2, each collimated to 4’ FWHM. This instrument was pointed at a non-flaring active region near N20 W40(McMath region 11060), and obtained an X-ray spectrum between 5 and 23 Å. This first use of a collimator to limit the field of view has considerably increased the spectral clarity compared with earlier observations by excluding the contributions of other active regions.
Laboratory-Produced Radiation Related to the Solar Flare Emission
Authors: Elton R. C. , Lie T. N.
Published: July 2016

A review is given of continuing efforts to generate laboratory spectra at photon energies above 1 keV from highly ionized atoms. Emphasis is placed on the most easily-interpreted highest ion stages such as the hydrogenic, helium-like and lithium-like species. The close similarities to solar flare observations of certain signatures, such as the line and continuum X-ray spectra and microwave emission as well as their sequence of occurrence, are pointed out and scaling factors are given.
Thermal and Non-Thermal Soft X-Ray Bursts
Authors: Landini M. , Monsignori Fossi B. C. , Pallavicini R.
Published: July 2016

Soft X-ray enhancements of solar radiation are on many occasions recorded by Solrad 9 which is instrumented with several photometers sensitive to X-ray emission in the range 2–25 keV. A non-thermal interpretation of X-ray bursts for energy larger than 10–20 keV is usually given in the literature, while for the soft X-ray region below 10 keV the common interpretation is a thermal one.
A Focusing X-Ray Telescope Monochromator
Authors: Filler Aaron S. , Fraenkel Benjamin S.
Published: July 2016

In order to resolve clusters of X-ray lines emitted by flares (Fritz et al, 1967; Neupert and Swartz, 1970) and to determine line shapes, a considerable resolving power is needed. The angular size of flares, typically about 2’ will not allow the necessary resolution to be obtained without a very fine slit system combined with the flat crystal X-ray spectrometer. In stellar X-ray spectroscopy large plane diffracting crystals will be associated with large counters, which in turn would act as a source of considerable noise.
Cosmic X-Ray Spectra
Authors: Pounds K. A.
Published: July 2016

Nine years of rocket and balloon observations, considerably enhanced in the last few months by the survey experiment on the Uhuru satellite, have revealed a large number – now approaching 100 – of cosmic x-ray sources, remarkable in both their luminosities (Lx= 1036–1046 ergs s-1) and apparent variety. Spectral data, expected eventually to be of crucial importance in revealing the emission processes and dynamics of individual sources, have been of generally inadequate quality to date (e.g. Figure 1).
Orbital Solutions for WZ Sagittae During Quiescence
Authors: Gilliland Ronald L.
Published: July 2016

WZ Sagittae was one of the first cataclysmic variables shown to be a binary system (Kraft 1961) from spectroscopic observations. Krzeminski (1962) found that WZ Sge was an eclipsing binary with an 81 min 38 s orbital period. Krzeminski and Kraft (1964, hereafter KK) in the first of many comprehensive analyses of the WZ Sge system to appear in the literature stated “a lower limit to certain detection of orbital velocity changes for the double emission feature is 2K = 75 km s-1 .” Interpreted as an upper limit to K^ of 37.5 km s-1 this fundamental result has remained untested for two decades, although interpretations and observations of WZ Sge have led to a vast literature. Despite the lack of a well determined orbital velocity, WZ Sge is one of the most thoroughly studied cataclysmic variables. The photometric properties during quiescence have been thoroughly studied and discussed (Robinson, et al. 1978; Fabian, et al. 1978; Ritter and Schroder 1979), although a consensus on model parameters has remained elusive.
Spectra of Symbiotic Stars
Authors: Netzer Hagai , Leibowitz Elia M. , Ferland Gary
Published: July 2016

We have observed Z And and other symbiotic stars at the Wise Observatory and have obtained absolute flux measurements of many emission lines. Preliminary analysis of the data shows that the line emitting gas is probably photoionized by a hot, T* ≳ 200,000 OK continuum, which can explain the extremely strong Hell lines. The hydrogen Balmer line intensities are different from what is predicted by recombination theory and the optical depths in Hα and Hβ must be significant. Our photoionization model can be used to deduce the geometry, density and temperature of the line emitting gas, and the nature of the hot companion.
Alpha Beta Discs
Authors: Bath G.T. , Edwards A.C. , Mantle V.J.
Published: July 2016

Following earlier work of Lynden-Bell & Pringle (1974) and Lightman (1974a, 1974b), Bath & Pringle (1981) have presented a simple method for studying the time-dependent evolution of viscous accretion discs. These models are axisymmetrlc, with the vertical structure reduced to integrated averages of local physical conditions. Published work examines models of dwarf nova eruptions driven by mass transfer bursts (Bath & Pringle 1981 – Paper I), eruptions produced by global viscous changes within the disc (Bath & Pringle 1982a Paper II), and the time-dependent properties of giant discs in symbiotic binaries (Bath & Pringle 1982b – Paper III).
Did Nova Aquilae 1982 Possess a Supercritical Wind?
Authors: Friedjung M.
Published: July 2016

The extremely high velocity absorption components observed in the ultraviolet with IUE, could have been produced by a supercritical wind. In this case most radiation would have been emitted shortwards of Lyman a, even at the time of the first IUE observations.

Nova Aquilae 1982 was discovered on January 27, but was difficult to observe at first because of closeness to the sun. A number of IUE spectra were obtained by Blades and Snijders from February 24, and the results were communicated to members of the ESA + SERC nova target of opportunity team. A preliminary report concerning these spectra has been made by Snijders, Seaton and Blades (1982).
Energy Distribution of Hard X-Ray Emitting Cataclysmic Variables
Authors: Mouchet Martine
Published: July 2016

We present the energy distribution of three hard X-ray sources H2252-035, 4U1849-31 and 2A0526-328 identified with intermediate polars. The ultraviolet and optical continuum can be well described by the standard disc model but this requires rather large discs and high accretion rates. Other possible contributions to the energy distribution are estimated. The predicted high accretion rates as well as the amplitude of the optical pulsations are in disagreement with the observed X-ray luminosity suggesting the existence of an unseen soft X-ray or extreme UV component.
Circular Polarimetry of AM Herculis
Authors: Piirola V. , Vilhu O. , Tuominen I.
Published: July 2016

Circular polarimetry in the red and simultaneous photometric observations in the UBVRI bands during the period June 1-3, 1981, are discussed. The peak value of negative circular polarization PV ~ -15 % is stronger than observed in 1976-79. Variations in the shape of the polarization and light curves occur from night to night. The positive crossover and reversal of the sign of the circular polarization are only marginal. A probable explanation of the short term variations seems to be the changing shape and position of the accretion columns with respect to the magnetic axis
Concluding Remarks
Authors: Warner Brian
Published: July 2016

The great success of this Colloquium has been in a large part due to the high quality of the results presented. Not all of the results have been understandable; neither have all topics been covered. In picking out a few on which to comment I run the risk of offending those whom I omit and possibly offending those whom I include. Nevertheless, these are my thoughts.
High Resolution Spectroscopy of Six New Extreme Helium Stars
Authors: Heber U. , Jonas G. , Drilling J.S.
Published: July 2016

High resolution spectra of six newly discovered extreme helium stars are presented. LSS 5121 is shown to be a spectroscopical twin of the hot extreme helium star HD 160641. A preliminary LTE analysis of LSS 3184 yielded an effective temperature of 22000 K and a surface gravity of log g = 3.2. Four stars form a new subgroup, classified by sharp-lined He I spectra and pronounced 0 II spectra, and it is conjectured that these lie close to the Eddington limit. The whole group of extreme helium stars apparently is inhomogenous with respect to luminosity to mass ratio and chemical composition.
The Period of the Extreme Helium Star BD+1°4381
Authors: Jeffery C.S. , Hill P.W. , Morrison K.
Published: July 2016

Photometry of the variable extreme helium star BD+1°4381 is used to improve the 21.2 day period found by Jeffery & Malaney (1985). The amplitude of the light-curve appears to be variable, resembling that of RY Sgr. Variability in the extreme helium star BD−1°3438 is also reported.
SB 939 - A New Intermediate Helium Star at High Galactic Latitudes
Authors: Langhans G. , Heber U.
Published: July 2016

SB 939 was analyzed spectroscopically for the basic atmospheric parameters Teff, log g and helium content. It was shown to be an intermediate helium star (helium abundance = 22% by number) situated unusually far away from star-forming regions.
Temperatures for Hot and Pulsating Helium-Rich (DB) White Dwarfs Obtained with the IUE Observatory
Authors: Liebert J. , Wesemael F. , Hansen C.J. , Fontaine G. , Shipman H.L. , Sion E.M. , Winget D.E. , Green R.F.
Published: July 2016

Ultraviolet energy distributions are analyzed for several hot, helium atmosphere DB white dwarfs, including the four known pulsating stars which define an empirical DB instability strip. Temperatures are derived exclusively from fits to the ultraviolet energy distributions. The blue edge of the empirical DB instability strip lies at 30,000 ± 4,000 K, and the red edge lies near 24,000 ± 2,000 K. The hottest DB star — and the only known one hotter than the instability strip — is PG0112+104 at or above 30,000 K. This leaves no known helium-atmosphere degenerate stars in the interval 30,000 ≤ Te ≤ 45.000K.
Detection of an Extremely Active State of AM Canum Venaticorum
Authors: Kutty K.R. Narayanan , Marar T.M.K. , Padmini V.N. , Seetha S. , Kasturirangan K. , Rao U.R. , Bhattacharyya J.C. , Mohin S. , Jayakumar K.
Published: July 2016

We report fast photometric observations on AM CANUM VENATICORUM (AM CVn) the ultra short period, hydrogen deficient variable. We have detected on 24th February, 1985 an intense flare of (Δm)peak≈0.34 in white light lasting over 200s. Following this flare we observe an enhanced double humped structure lasting for 1051s which is the dominant periodicity exhibited by AM CVn. We have also detected the 525s and 1051s periods. In addition, we report flickerings, lasting typically 1-2 minutes, that are characteristic of cataclysmic variables.
Pulsations of Hydrogen Deficient Stars
Authors: Saio Hideyuki
Published: July 2016

A review is given on the properties of the pulsating hydrogen-deficient stars. Since they lie in a large area of the HR diagram, the properties of pulsations are greatly different among them. Pulsations tend to change from radial pulsations to non-radial pulsations as the surface gravity increases. Strong nonadiabaticity affects the dynamical properties of pulsations in high luminosity helium stars. The kappa and gamma mechanisms for helium ionization excite radial pulsations in relatively cool helium stars and nonradial pulsations in DB (helium atmosphere) white dwarfs, while the cyclical ionization of the K-shell electrons of carbon and oxygen seems to be responsible for the excitation of the nonradial pulsations in the GW Vir (PG1159-035) stars (very hot hydrogen-deficient pre-white dwarf stars). The excitation mechanism of the radial pulsations in a unique extreme helium star V652 Her (BD+13°3224) is not known. Period changes have been detected for many pulsating helium stars except the pulsating DB white dwarfs.
Does 𝓿 Cep indicate a non-axisymmetric dynamo?
Authors: Krause F. , Scholz G.
Published: July 2016

According to observations of Scholz and Gerth the super-giant 𝓿 Cep has a magnetic field with a maximum field strength up to 2500 Gauss. This field shows a period of about 5 years. It is unplausible that this magnetic field is a relic since 𝓿 Cep was formed by expansion of a B-star. We claim here that 𝓿 Cep represents a dynamo exciting a magnetic field which in the average strongly deviates from symmetry about the rotation axis.
Characteristic Absorption Features in the Spectra of Ap-Si Stars between 1250 and 1850 Å.
Authors: Artru Marie-Christine , Lanz Thierry
Published: July 2016

On the basis of lUE data, the specific absorption features in the spectra of Ap-Si Stars are displayed in the 1250–1850 Å range and identified when possible. The contribution of the Si II multiplets is calculated in LTE for a typical overabundance × 102 of silicon. It accounts for only a small part of the observed absorption. Common unidentified structures, smaller than the 1400 Å depression are pointed out.
Systematics of CP Stars
Authors: Hensberge H. , Van Rensbergen W.
Published: July 2016

This review is concerned with the following topics: 1. The occurrence of chemical peculiar stars in binaries; 2. Determination of masses of CP stars; 3. Determination of radii of CP stars; 4. CP stars in clusters. The paper emphasizes the literature from the 23rd Liege Colloquium in 1981 on, and does not refer systematically to earlier papers.
Light Curve Analysis of Rotating Variable Stars
Authors: Hempelmann A. , Schöneich W.
Published: July 2016

A short description of a method for analysing light curves of rotating variable stars is given. This method is applied to light curves of HD 24712.
Rapid Oscillations of CP2-Stars
Authors: Weiss Werner W.
Published: July 2016

With the announcement in 1978 (Kurtz, 1978) of short periodic photometric variations of HD 101065, the first member of a subgroup of CP2 stars was found. This gained attention due to the possibility of applying the methods of stellar seismology to late A to early F type stars. However, the extremely low photometric amplitude of these stars, which is typically few millimagnitudes in B, and the short periods, ranging from few minutes to about 15 minutes, make these stars difficult to discover and a considerable amount of telescope time is required to accumulate sufficient data for a reliable analysis of the frequency spectrum. As a consequence aliasing imposes serious problems. Synchronous observations from observatories well separated in longitude could overcome this dilemma, and have indeed proven to be sucessful (Kurtz and Seeman, 1983; Kurtz and Balona, 1984; Kurtz, Schneider and Weiss, 1985; Kurtz and Kreidl, 1985).
Cool Magnetic CP Stars
Authors: Adelman Saul J. , Cowley Charles R.
Published: July 2016

We review progress in research on the cool magnetic CP stars especially during the past four years. Studies of energy distributions and abundances are analyzed to reveal their systematics. Model atmospheres do not yet accurately describe the average energy distributions much less the variability with the rotational periods of these stars.
Abundance Analysis of Three Ap Stars: Hd2453, Hd8441, and Hd192913
Authors: Ryabchikova T.A. , Ptitsyn D.A.
Published: July 2016

Using 9 Å/mm-dispersion spectra of two Ap stars (HD2453 and HD8441) from the list by Adelman (1973) and the SiCr star HD192913 the abundances of 19 elements are obtained by the model atmosphere technique. The curve-of-growth method is used to estimate the surface magnetic field from Fe, Cr, and Ti lines.
The Age of ε Uma
Authors: Hubrig S.
Published: July 2016

A critical rediscussion of the luminosity confirms that ε UMa is brighter than expected for a star on the main sequence, in our determination by 0m.6.
Spectroscopic Analyses of Hot Main Sequence Stars
Authors: Sadakane Kozo
Published: July 2016

Spectroscopic studies of normal O and early B type stars in the visual region are discussed. Present status of UV spectroscopic analyses of hot normal stars is reviewed. Discussions on a few practical problems in analyses of UV spectra are presented.
Twentieth-Century Amateur Astronomy
Authors: Meadows A.J.
Published: July 2016

Little distinction was drawn between amateur and professional astronomers for much of the nineteenth century. They mixed in the same scientific societies and often carried out overlapping studies. Towards the end of the century, however, new factors arose - increasing expense of instrumentation, increasing sophistication of theoretical knowledge, etc., which led to a greater degree of differentiation. It was then that societies specifically aimed at amateurs were established. The split has never been complete – professionals have always been members of amateur societies and vice versa - but a gap between amateur and professional opened up and has continued since. Amateurs of the standing of Percival Lowell, who could compete with professionals both in terms of equipment and theoretical knowledge, effectively died out before the mid-twentieth century.
Some French Amateurs of the 2nd Half of the 19th Century
Authors: Hourmat Françoise
Published: July 2016

At that period there was keen popular interest in astronomy, and in many Paris squares, astronomers with terrestrial refractors gave talks on astronomy for a small sum. Léon Joubert created a observatory for scientific research and popularisation, allowing anyone to learn about the universe and use good instruments. He made 120 instruments: refractors, reflectors, projectors, and photographic instruments.

Hermann Goldschmidt (1802–1866), born at Frankfurt am Main 17 June 1802, had poor health, became a painter and sought his fortune in Paris. He became an astronomer by accident after following a course of lectures at the Sorbonne given by Le Verrier. From a modest studio on the 6th floor of an old house in the heart of Paris, he discovered 14 minor planets between 1852 and 1861, the first being called Lutetia by Arago.
Observations of Comets, Minor Planets and Meteors in Japan
Authors: Hasegawa Ichiro
Published: July 2016

In the early period of this century, some comets were discovered by Japanese amateur astronomers. Just fifty years ago, in 1937, Minoru Honda began to search for systematically comets with his 15-cm reflector. He observed Comet Encke without an ephemeris in November, 1937, and made his firts discovery of a comet in 1940. This comet was also discovered independently by Shigeki Okabayashi (Comet Okabayashi-Honda, 1940e). Subsequently, Honda discovered Comet Friend-Reese-Honda (1941a) in 1941. Unfortunately, Okabayashi was killed at the Second World War in 1945.

After the end of the war, Honda discovered ten comets during 1947 and 1968. In 1968, he discovered three comets in a year. He has been an active observer of comets and novae. Stimulated by Honda’s success, Tsutomu Seki began his comet hunting in 1950, and his long and patient efforts were rewarded with the discovery of Comet Seki, 1961f. Seki later discovered six comets, and rediscovered six short-period comets before 1981. In that year, Seizo Goto, a well-known telescope maker in Japan, donated a 60-cm reflector. Since then, with the Goto telescope, Seki has made many astronomic observations of comets and minor planets. He has rediscovered some periodic comets and has discovered many minor planets every year.
Making a Telescope Mirror
Authors: Becker J.M.
Published: July 2016

A video presentation of all stages in the manufacture and testing of a 200-mm mirror. [The video cassette may be obtained from ASTAM, Viry, 39360 Vaux-les-Sainte Claude, France].
Image Digitizer
Authors: Magnien Pierre A.
Published: July 2016

Equipment for digitizing 24 × 36 mm negatives was described. The sensing unit is a 1024-element CCD. Apart from the optical train, the transparency is held in a rigid carrier that is moved by a stepper motor to scan one row at a time. The whole operation is controlled by computer, and results in a 170.5 kb file for each image.
“Comet” Software
Authors: Butzbach P. , Parisot J.P.
Published: July 2016

A suite of programs written in BASIC for use on Apple (II, IIe, etc.) computers was described. A data file, extracted from the general catalogue by Marsden is incorporated. The programs are applicable to any geographical location and allow the determination of positions (in both celestial and horizontal coordinates), times of rising, transit and setting, and the calculation of ephemerides from orbital elements.
Refining the Orbit of Visual Double Stars
Authors: Soulie Edgar
Published: July 2016

An iterative method of refining the orbital parameters of visual double stars was described. The sum of the least-square differences is minimized by the Levenberg-Marquardt method. The application to two examples was described, including one highly inclined orbit, ADS 8862 = Hussey 664 (i = 94.3 degrees).
Photographic Observation of Stellar Occultations
Authors: Tomić A. , Čabrić N. , Čelebonović V.
Published: July 2016

Stellar occultations are usually observed visually, but this can also be done photographically. Our method has some advantages:

–

the obtained moments of contacts refer to the smoothed lunar limb,

–

the error in the determination of contacts is calculable,

–

the error may be less than in visual work,

–

the reduction of photographs is fast, due to the application of an “on-line” computer [1].

In order to achieve all this, it is necessary to make a series of photographs of the Moon and the object being occulted before the first and after the last contact. This is a crucial step in our method, because the photographs must be of high quality. This demands two things:

–

the images of the occulted object and the Moon must be reliably recorded and

–

the illuminated limb of the Moon must give optimal darkening on the film.
Analysis of the Light-Curve of Comet P/Halley in 1985–1986
Authors: Valls-Gabaud David , Gómez Angel
Published: July 2016

We analize the light curve of comet P/Halley resulting from 187 observations made by amateurs. We try to derive some constraints on the physical properties of the comet through the application of the semi-empirical photometric model (SEPM) developped by R.L. Newburn.

The m1 (Fig. 2) and V(1,0) light curves show a clear transition phase in the pre-perihelion apparition, between ~ 1.9 and ~ 1.2 A.U. which supports the division into 3 parts made by Hasegawa. It is remarkable to find that the light curve obtained by amateurs is so close to those obtained by experienced observers.

We derive an effective equivalent radius of β = 4.9 ± 0.8 (1σ) km, and a geometrical albedo of pυ = 0.06 ± 0.02 (1σ) using the method suggested by Delsemme and Rud.
The IOTA Expedition Results from the Total-Annular Eclipse in Gabon, 1987
Authors: Maley Paul D.
Published: July 2016

The results of the IOTA expedition to Gabon to observe the rare total-annular eclipse of 1987 March 29 were described. Multiple stations were used to determine data from Baily’s Beads about the contact times. The techniques used and their application to future eclipses were evaluated. An additional aim was to develop a database to resolve corrections to the solar radius at specific epochs in order to determine the amplitude of time-dependent oscillations of the Sun’s surface.
Two Solar Observation Programmes
Authors: Marthes Marie J. , Malherbe Jean M. , Vial J.
Published: July 2016

The Solar Section of the Societé Astronomique de France has organized various programmes designed to enable amateurs to carry out high-quality and scientifically useful observations. Two particular programmed will be described.
The Moonwatch Program: A Model for Amateur Contributions to the ISY
Authors: Cornell James
Published: July 2016

Largely forgotten today is the role that amateur astronomy played in the early days of space exploration. For example, 1987 is not only the 30th anniversary of the first artificial satellite but also of history’s most successful global organization of amateur astronomers: Moonwatch.

As a worldwide network of volunteer visual observers, Moonwatch was a vital adjunct to Western satellite tracking efforts. In nearly two decades of operation, more than 500 individuals made some 400,000 observations of approximately 6000 objects. Although now only a footnote to space history, Moonwatch suggests that some comparable organization of dedicated and talented amateurs might contribute to the International Space Year of 1992.
GEOS – Groupe Europeen d’Observations Stellaires
Authors: Dumont Michel
Published: July 2016

GEOS was formed in 1973 from several European groups (French, Italian, Spanish and Belgian). All the members of GEOS have the same aims: to observe variable stars and to analyse their observations themselves.

Other objects are also observed by GEOS: artifical satellites and minor planets, in particular minor-planet occultations. Observations are treated statistically and the procedures allow accidental, and – if there are several observers of the same star – systematic, errors to be corrected, thus improving the accuracy of the results and the light-curves.
A Planetarium for Astronomy
Authors: Acker Agnès
Published: July 2016

Planetariums are continuing to open in Europe and recent years have seen several organizations and meetings devoted to their use. How should a planetarium show be constructed? What are the principles to be followed and the pit-falls to be avoided? This is a problem, because people running planetariums are only rarely astronomers. One great debate centres around the question of whether to use a pre-recorded show or a “live” one.

An automatic show allows a constant level of presentation, however tired or incompetent the lecturer. The Sun rises at the right moment, just as the chosen music starts and either a piece of text or a picture appears. Simultaneous effects can be incorporated, even complicated ones, which often explains a difficult point better.
Preparing Astronomical Videotapes
Authors: Suagher Françoise , Chopard Pierre , Magnien Pierre , Marchand Jean-Pierre , Parisot Jean Paul
Published: July 2016

In 1982, the Association Astronomique de Franche Comté prepared a slide show entitled “Meet History’s Comet”. This had been so successful, being presented in more than 100 towns, that a second show entitled “Worlds in the Sky” about the Solar System had been prepared and made by an audio-visual workshop. The high cost (20 000 Fr) had been largely covered by a grant.
The Starlab Mobile Planetarium in the Mid-Pyrenees
Authors: Chrétien Jean-Pierre , Brunet Jean-Pierre
Published: July 2016

This planetarium with inflatable dome is available to schools, colleges and youth centres in the region. Each institution using the equipment provides its own lecturer, supported by various levels of documentation, discussion sessions and alternative displays. In the first year about 50 organisations used it, each for about a week, with some 15 000 child, and 6000 adult visitors. No serious problems were encountered despite this intensive use.
Twenty Years of the Japan Amateur Astronomers’ Convention
Authors: Kimura Seiji
Published: July 2016

In 1967, the Kawasaki Astronomy Club organized the first national assembly for amateur astronomers. This was such a success that a second was held in 1969 and yearly thereafter. Since the establishment in 1982 of the Kaho Prize commemorating Kaho, who was the first Japanese to discover a new comet (in 1936), this award has been presented at the Convention.
The Bochum Observatory
Authors: Feitzinger J.V. , Hünerbein M. , Kordecki R. , Monstadt G. , Prölss J.
Published: July 2016

The various units of this observatory consist of a planetarium – which has a complex computer-controlled system – the programmes for which are varied with different degrees of astronomical information and entertainment value; observing stations with 12.5, 40, and 60–cm instruments, used for regular public observing nights, special events, and special programmes for young children and their parents as well as specific older groups; a mobile observatory with a 32–cm telescope; and a series of astronomical courses.
The Strasbourg Observatory
Authors: Hellot Roger
Published: July 2016

The Alsace Group of the S.A.F. is closely associated with the Strasbourg Observatory and is responsible for supervising visits by the public after planetarium shows. The 6-inch refractor was restored by three of the amateurs and the Group has the use of the 21-cm refractor for planetary photography and other projects.
Main Sequence Abundances, Mass Loss and Meridional Circulation
Authors: Michaud Georges
Published: July 2016

Constraints that abundance anomalies observed on main sequence stars put on turbulence, meridional circulation and mass loss are reviewed. The emphasis is on recent observations of Li abundances.

Upper limits to turbulence are obtained from the Be abundance in the Sun and from underabundances of Ca and Sc in FmAm stars. The Li abundance in G type stars suggests the presence of turbulence below convection zones.

The abundance anomalies, both over and underabundances, observed in FmAm and λ Booti stars can be explained by diffusion in the presence of mass loss. A mass loss rate of 10−15 Mo yr−1 is required to explain the FmAm stars while a mass loss rate of 10−13 Mo yr−1 is required by the λ Booti stars.

The position and width of the Li abundance gap observed in Hyades and other open clusters is explained by diffusion. A detailed reproduction of the Li(Teff) curve seems to require a mass loss rate of slightly more than 10−15 Mo yr−1, of the same order as the mass loss rate required by the FmAm stars. In the presence of such a mass loss only small overabundances of heavy elements are expected. The observed variations in the Li abundance as a function of the age of clusters suggests that the Li abundance observed in old halo stars does not represent the cosmological abundance.

Detailed two dimensional calculations of diffusion in presence of meridional circulation for HgMn and FmAm stars lead to a cut-off of about 100 km s−1 for the maximum equatorial rotational velocity at which abundance anomalies are expected in these objects. This agrees with observations. A similar calculation for the F stars of the Hyades where Li underabundances are observed leads to a contradiction, unless meridional circulation patterns are modified by the presence of convection zones once they become as large as in late F stars. There remains a possibility that meridional circulation would be responsible for some of the reduction of the Li abundance as observed in the Hyades and UMa. Further observations are suggested to distinguish the effects of settling and nuclear destruction.
On the Distribution of the Lithium Abundance in Normal Late-Type Giants
Authors: Hänni Liia
Published: July 2016

The abundance of lithium in stellar atmospheres presents an important observational constraint to the hydrodynamical models of the outer layers of stars. It can be considered as a cumulative measure of the extent of matter exchange between surface and deeper layers during the stellar evolution.

From the observed large scatter of lithium abundances in evolved stars it follows that the efficiency of mixing has been highly variable from one object to another. At present, it seems to be difficult to find any satisfactory explanation to the lithium abundances of individual stars. We suppose that at this stage the statistics of lithium abundances in different types of stars can give some insight into the character of mixing processes operating in stars. In this report some observational results about the distribution of the lithium abundances in normal late-type giants are presented.
SiO Isotope Emissions from Late-Type Stars
Authors: Ukita N. , Kaifu N.
Published: July 2016

The J=2-1, v=0 emissions of 28SiO, 29SiO, and 30SiO from three late-type stars were simultaneously observed with the Nobeyama 45-m telescope in Jaunuary 1987. The relative intensities of [29SiO] / [30SiO] were measured to be 2.4 for χ Cyg, 1.5 for NML Tau, and 2.9 for V1111 0ph. These values are lower limits for the relative isotope abundance of [29Si] / [30Si], and are larger than the terrestrial value of 1.51. Recext theoretical studies suggest that hydrostatic nucleosysnthesis and supernova explosions result in smaller values of [29Si / [30 Si] than solar. These models cannot explain the observed excess of 29Si.
Chemical and Expansion Properties of Compact Planetary Nebulae in the Galactic Anti-Center Region
Authors: Tamura Shin’ichi
Published: July 2016

A spectroscopic diagnosis on M1-5, M1-9, K3-66, and K3-67 is presented. Our sample were chosen from the catalogue of radial velocities (Schneider et al 1983) by the reason of not only their kinetic peculiarity, but also apparently compact images. Main purpose is to analyze the chemical properties which should give us an information about galactic chemical abundance distribution in the direction of galactic anti-center region based upon kinetic peculiarity. Another one is to study on an expansion characteristics by which we can recognize intrinsically compact planetary nebulae in young phase.

Spectroscopic observations were made at the Okayama Astrophysical Observatory (Shibata and Tamura 1985), the Steward Observatory, and Lick Observatory (Tamura and Shaw 1987).
A systematic study of stellar models for C/O-rich Wolf-Rayet Stars
Authors: Langer N. , Kiriakidis M.
Published: July 2016

A grid of homogeneous stellar models for Wolf-Rayet stars in the mass range from 1 to 60 M⊙ has been computed. For each stellar mass, stars with eight different sets of chemical compositions — from pure helium stars with (Y,C,O)=(1,0,0) to extreme helium poor stars with (Y,C,O)=(0.02,0.11,0.87) — have been calculated in order to investigate the dependence of the stellar structure on the stellar mass and chemical composition. Modern input physics adapted to the exotic chemical composition of the Wolf-Rayet stars has been incorporated in the models, including effects of partial recombination of helium, carbon, and oxygen, and detailed opacity tables for 20 different combinations of the (Y,C,O)-abundances. Furthermore, we estimated the effect of the intense, partly optically thick Wolf-Rayet winds on their apparent effective temperature, using the formalism of de Loore et al. (1982, IAU-Symp. 99, 53) with the parameters: = 3 . 10−5M⊙yr−1, β = 2, and v∞ = 2000 km s−1.
Atmospheric Diagnostics of Wolf-Rayet Stars
Authors: Doom C.
Published: July 2016

Wolf-Rayet (WR) stars are the descendants of massive stars that have lost their hydrogen rich envelope. Recently more accurate data on WR stars have become available: mass-loss rates (van der Hucht et al. 1986), radii and luminosities (Underhill 1983, Nussbaumer et al. 1982).

It may therefore be worthwhile to investigate if combinations of observed parameters shed some light on the structure of the extended stellar wind of WR stars.

In many WR stars the photosphere is situated in the stellar wind. We assume that the wind is stationary and isotropic. Further we assume a velocity law v(r)=v∞(1−Rs/r)β where v∞ is the terminal velocity of the wind in km/s, Rs is the radius where the wind acceleration starts and β > 0 is a free parameter. We can then easily compute the level R in the wind where the photosphere is located (de Loore et al. 1982): R is the solution of the equation 6.27 10−9 τat R v∞/ = fβ(Rs/R) where τat is the optical depth at the photosphere (2/3 or 1), (>0) is the mass loss rate in M⊙/yr and fβ > 1 is a slowly varying function (Doom 1987).
The Galactic Distribution and Subtype Evolution of Wolf-Rayet Stars
Authors: Hidaya B. , Admiranto A. G. , Supeill K. R. , van der Hucht K. A.
Published: July 2016

The galactic distribution of Wolf-Rayet stars is redetermined. In the solar neighbourhood within d < 2. 5 kpc the WN/WC number ratio is 0.54, indicating a larger influence of mass loss and convectlve overshooting than most present evolutionary models account for. The WR density gradient In the solar neighbourhood is constant. From a comparison of WR galactocentric distances and WR cluster and association membership, we find indications that WCE stars descend from WNL stars at R > 6.5 kpc, and that WCL stars descend from WNL stars at R < 8.5 kpc.
Intermittent Transition to Irregular Pulsation with Mass Loss in Hydrodynamic Models
Authors: Aikawa Toshiki
Published: July 2016

Hydrodynamic simulations of non-linear pulsation for less-massive cooler supergiants have been perfoemed by several authors (Tuchman, Sack and Barkat, 1979; Fadeyev and Tutukov, 1981; Fadeyev, 1982, 1984; Nakata, 1987; Buchler et al., 1987). The outburst of large amplitude pulsation at times is one of common features of these models, and renders mass-loss from the atmosphere of pulsating stars by generating strong shock waves.

To find out routes of the transition from limit cycles to this type of irregular pulsation, we performed hydrodynamic simulations for a series of models the luminosity log(L/L⊙ ) = 3.505, and Te = 5300 K with a narrow range of the mass, 1.4 M⊙<M<1.5 M⊙ by using the hydrodynamic code, TGRID (Simon and Aikawa, 1986).
Classical Novae – Before and After Outburst
Authors: Livio Mario
Published: July 2016

Classical nova (CN) and dwarf nova (DN) systems have the same binary components (a low-mass main sequence star and a white dwarf) and the same orbital periods. An important question that therefore arises is: are these systems really different ? (and if so, what is the fundamental difference ?) or, are these the same systems, metamorphosing from one class to the other ?

The first thing to note in this respect is that the white dwarfs in DN systems are believed to accrete continuously (both at quiescence and during eruptions). At the same time, both analytic (e.g. Fujimoto 1982) and numerical calculations show, that when sufficient mass accumulates on the white dwarf, a thermonuclear runaway (TNR) is obtained and a nova outburst ensues (see e.g. reviews by Gallagher and Starrfield 1978, Truran 1982). It is thus only natural, to ask the question, is the fact that we have not seen a DN undergo a CN outburst (in about 50 years of almost complete coverage) consistent with observations of DN systems ? In an attempt to answer this question, we have calculated the probability for a nova outburst not to occur (in 50 years) in 86 DN systems (for which at least some of the orbital parameters are known).
The Chemical Composition of the White Dwarfs in Cataclysmic Variable Systems which Produce Novae
Authors: Sparks Warren M. , Starrfield Sumner G. , Truran James W. , Kutter G. Siegfried
Published: July 2016

Recently a number of studies have been published on the nuclear abundance of nova ejecta, as summarized by Truran and Livio (1986). H is always underabundant (compared to solar) and He is overabundant except for the cases where the heavier elements are far overabundant. The abundances of C, N, and O range from nearly solar to highly overabundant. A few novae are very rich in Ne and Mg as well as O, which has led to the discovery that these novae occur on O/Ne/Mg white dwarfs (Williams, et al., 1985). We will assume that the abundances are an accurate and consistently determined set of data for our purposes. The nova ejecta is a combination of original white dwarf material, remnant material, remaining on the white dwarf from the previous outburst, and accreted material, all of which has undergone thermonuclear processing during the outburst. The question we address here is “Can we untangle the observational abundances to determine the contributions of each source?” A positive answer would allow us to tell whether the white dwarf’s mass is increasing or decreasing and thus have implications on the accreting white dwarf model for a SNI.
The Evolution of the Progenitor of SN 1987A
Authors: de Loore C. , Doom C.
Published: July 2016

It is now almost certain that the progenitor of SN 1987 is the B3 supergiant Sk −69°202 (e.g. Walborn et al. 1988). This provides us with valuable constraints on the SN precursor: According to West et al.(1987) the star has Mv=−6.8. Using the calibrations of Humphreys and McElroy (1984) we find that the precursor had Teff = 13000 − 16000K, −Mbol= 7.7 - 8.1 (log L/L⊙ = 5.04) and a radius of 48 - 60 R⊙.

The SN precursor was not a red supergiant, but a rather blue supergiant, which also explains the peculiar form of the light curve (Woosley, 1988; Schaeffer et al. 1987). However, standard evolutionary calculations would expect such stars to explode as red supergiants.
Model Calculations and Spectroscopic Constrains for SN1987A
Authors: Höflich P.
Published: July 2016

We present synthetic spectra for atmospheres in order to interpret the observed spectra of the supernova 1987A during the first few months after the initial event. Spherical symmetry and density profiles are assumed which are given by the homologous expansion of the stellar structure of a B3 supergiant. For hydrogen, up to eight levels and, for helium, 16 levels are allowed to deviate from LTE. The radiation transport is calculated consistently with the rate equations both for the continua and for the lines. Radiative equilibrium is assumed. The observed spectra and colours in the optical wavelength range can be well reproduced by pure hydrogen models during the first few weeks. The behaviour of the UV flux is due to changes in the effective temperature and the photospheric radius. For later stages, the influence of elements other than hydrogen and helium must be taken into account in order to compare the calculated and observed spectra in the optical wavelength range. Reasonable agreement between calculations and observations can be obtained with the assumption of half solar abundances for all elements but for the s-process elements Sc, Ti and Ba which are overabundant. To explain the small changes in the spectra after about 3 weeks up to 4 months, we need a total hydrogen mass of about 8 to 10 M⊙.