bluuebunny/crossref_metadata_2025 huggingface dataset:
Gamma-Ray Bursts and Binary Neutron Star Mergers
Authors: Piran Tsvi
Published: July 2016

Neutron star binaries, such as the one observed in the famous binary pulsar PSR 1913+16, end their life in a catastrophic merger event (denoted here NS2M). The merger releases ∼5 1053 ergs, mostly as neutrinos and gravitational radiation. A small fraction of this energy suffices to power γ-ray bursts (GRBs) at cosmological distances. Cosmological GRBs must pass, however, an optically thick fireball phase and the observed γ rays emerge only at the end of this phase. Hence, it is difficult to determine the nature of the source from present observations (the agreement between the rates of GRBs and NS2Ms providing only indirect evidence for this model). In the future a coinciding detection of a GRB and a gravitational-radiation signal could confirm this model.
Performance and first results from the GOLF instrument on SoHO
Authors: Gabriel A. H. , Charra J. , Grec G. , Robillot J.-M. , Cortés T. Roca , Turck-Chièze S. , Ulrich R. , Baudin F. , Bertello L. , Boumier P. , Decaudin M. , Dzitko H. , Foglizzo T. , Fossat E. , García R. A. , Herreros J. M. , Lazrek M. , Pallé P. L. , Pétrou N. , Renaud C. , Régulo C.
Published: July 2016

GOLF is designed to measure the Global Oscillations of the integrated solar disk, by determining the line-of-sight velocity of the photosphere as a function of time, over the frequency range 10−7 to 10−2 Hz.
Structure inversions with the VIRGO data
Authors: Appourchaux Thierry , Sekii Takashi , Gough Douglas , Lee Umin , Wehrli Christoph ,   The VIRGO Team
Published: July 2016

The p-mode frequencies obtained by the VIRGO instrument have been inverted to derive the solar core structure. Two sets of frequencies have been used in the inversions. The sets are derived from different time series (the second containing the first), using different procedures for fitting the spectra. The influence of the correlations between the p-mode frequencies has been implemented in the inversion procedure. The two data sets are in good agreement with each other, and show no evidence that the sun is significantly different from the latest available standard solar model.
An observational study of the interaction of impulsive and periodic perturbations in the solar atmosphere
Authors: Deubner F.-L. , Kleineisel R.
Published: July 2016

Time series of simultaneous high resolution filtergram observations in white light and in CaK2 have been employed to study the dynamical interdependence of the ‘low’ and the ‘high’ layers of the solar atmosphere, the 3-D propagation of perturbations in the stratification, and the excitation of p-mode and other oscillations. Impulsive and oscillatory perturbations have been isolated in the wavenumber and frequency regime, and their mutual interaction was also studied.

Several of our findings challenge interpretation and deserve further study.

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The occurrence of a granule can be clearly recognized in the upper chromosphere.

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A granule induces low brightness and low oscillation amplitudes at the CaK2 level, whereas the opposite happens at the intergranular border.

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It is not always evident that the ‘source’ of the perturbation is located at the lower, i.e. the photospheric layer.

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It is far from being clear which components of the various perturbations contribute to a net outward mechanical energy flux.
Asteroseismology from Space. COROT and other projects
Authors: Baglin A. , Auvergne M.
Published: July 2016

The scientific objectives and the observational strategy of asteroseismology from space are presented. The projects proposed in different contexts are briefly reviewed, with a particular emphasis on the COROT experiment, now accepted for a launch in 2001 in the framework of the french “Petites Missions” program.
Three Years of ANTENA: what we have done!
Authors: Belmonte J. A. , Hernández M. M. , Pérez Hernández F. , Vidal I. , Cortés T. Roca , Michel E. , Auvergne M. , Chevreton M. , Goupil M. J. , Soufi F. , Baglin A. , Frandsen S. , Viskum M. , Kjeldsen H. , Christensen-Dalsgaard J. , Schmider F.X. , Fossat E. , Delache Ph. , Provost J. , Audard N. , Berthomieu G. , Paparó M. , Kovács G. , Szabados L.
Published: July 2016

The European Union Network ANTENA started to work in October 1993. During these last three years, several collaborative projects have been undertaken. ANTENA has offered a very good opportunity for most of the European people doing asteroseismology to work together. The asteroseismological networks STEPHI and STACC have run within the framework of the project, obtaining fairly good results. New instrumentation has also been developed, such as the Four-Channel Stellar Photometer.
Herbig-Haro Objects as Searchlights for Dense Cloud Chemistry
Authors: Taylor S. D.
Published: July 2016

Stars form from dense pockets of gas that have undergone gravitational collapse, and young stars are still embedded in this molecular material. There is no lack of evidence that the outflows from these stars, manifested in the form of Herbig-Haro objects and jets, interact dynamically with the dense gas either in the form of shock excitation or the imparting of momentum; molecular outflows, H2 emission, and perhaps also CO and SiO bullets and jets, are tracers of this phenomenon. However there are a set of radio observations of molecules showing emission near HH objects that are remarkable for their apparent lack of signatures of such dynamic interaction. A likely cause of this ‘quiescent’ emission is a radiative interaction between the HH shock system emission and ambient gas.
Asymptotic Structure of Rotating MHD Winds and Its Relation to Wind Boundary Conditions
Authors: Heyvaerts J. , Norman C.A.
Published: July 2016

Approximate asymptotic solutions for rotating MHD winds are obtained analytically in terms of the first integrals of the motion. It is shown that the paraxial region of such winds is a line-shaped boundary layer which has, even at large distances, the structure of a pressure-supported current pinch. A necessary condition for cylindrically focused asymptotics to be possible is derived. A simplified model by which the asymptotic structure of such winds can be obtained in terms of general boundary conditions at the wind source is introduced. Results of semi numerical solutions of the model are reported. The model is analytically solved in the limit of very fast rotators, giving in this particular case an explicit and complete description of the wind outputs and asymptotic structure in terms of arbitrary boundary conditions at the wind source.
Magnetospherically Mediated Accretion in Classical T Tauri Stars
Authors: Edwards S.
Published: July 2016

Observational evidence suggests that disk accretion in low mass stars is mediated by the stellar magnetosphere in the inner few stellar radii of a star/accretion disk system. A strong stellar field appears to disrupt the inner disk and channel accreting material in a funnel flow toward the stellar surface. It is possible that coupling between the stellar magnetosphere and the inner accretion disk plays a profound role in the evolution of a forming star, regulating its spin, establishing its initial angular momentum, and launching the ubiquitous accretion-driven outflows which are the subject of this symposium. Although the evidence that forming low mass stars undergo magnetospherically mediated accretion is considerable, there are a growing number of challenges to this paradigm which require close observational scrutiny.
Jets, Disk Winds, and Warm Disk Coronae in Classical T Tauri Stars
Authors: Kwan John
Published: July 2016

Arguments, based on analysis of the forbidden line emission, are summarized that point to two components of mass ejection in classical T Tauri stars. A low-speed wind originates from the accretion disk at between ∼ 0.05 AU and ≳3 AU from the star, and a high-speed flow, which becomes collimated into a jet within ≲ 100 AU, originates as a wind from either the star or the very inner part of the accretion disk. The [OI] λ5577 emission in the low-speed component also requires the presence of a warm disk corona, with an electron density of ∼ 107 cm–3 and a temperature of ∼ 8000 K. Additional indication of a warm disk corona comes from analysis of the central absorptions seen in the profiles of the hydrogen Balmer lines. The need to heat the disk corona implies that a substantial fraction of the energy released in the accretion of matter through the disk may be dissipated at the disk surface.
Evidence for Magnetic Fields in the Outflow from T Tau S
Authors: Ray T.P. , Muxlow T.W.B. , Axon D.J. , Brown A. , Corcoran D. , Dyson J. E. , Mundt R.
Published: July 2016

We have observed at 5GHz the T Tau system with high resolution (≲0″.1) using the Multi-Element Radio Linked Interferometer (MERLIN) based at Jodrell Bank. Both the optical star (T Tau N) and its well-known infrared companion (T Tau S) were detected. The radio emission from T Tau S was found to be roughly extended in the direction of what is thought to be its outflow axis. More importantly we discovered that this radio emission split up into two spatially separated lobes of opposite helicity in the left and right-circular polarization channels. The circularly polarized lobes appear to straddle the star so that the “flow” and the “counterflow” were of opposite helicity. Such observations are the first direct evidence for the presence of magnetic fields in extended outflows that we are aware of. The radio flux appears to be due to gyrosynchrotron emission from mildly relativistic electrons (γ≈2–3). These electrons may have been accelerated in shocks close to the source. Using reasonable assumptions, the inferred magnetic fields strengths are surprisingly large (≳ several gauss) at distances of approximately 10-20 AU from their source. This is consistent with the magnetic fields being part of a collimated flow.
Hydrogen-Line Photometry of Close Binaries
Authors: Dorren J. D. , Siah M. J. , Guinan E. F. , McCook G.P.
Published: July 2016

A program of Hα and Hβ narrow- and intermediate-band photometry of close binaries has been carried out at Biruni Observatory since 1977 and at Villanova University Observatory since 1971. The advantages of this type of photometry for close binary work are discussed. Stars which have extensive coverage are listed and results for Cyg X-1, WZ Sge, W Ser and HR 1099 are briefly discussed.
Determination of Absolute Dimensions of Main Sequence Binaries
Authors: Andersen J. , Clausen J. V. , Nordström B.
Published: July 2016

Determinations of absolute dimensions of main sequence binaries are no longer useful unless random and systematic errors are kept appreciably below 10%. Some essential conditions for achieving this are reviewed.
Observed Period Changes in Detached Binary Systems
Authors: Herczeg Tibor J.
Published: July 2016

A comprehensive study of period changes in eclipsing binaries is being carried out at the University of Oklahoma. The survey of available information is supplemented by observations obtained at the University Observatory, at Kitt Peak and Cerro Tololo observatories, and, as part of a cooperative program, at Ankara University. The present review reports the behaviour of 20 systems classified as detached, some of which do show noticeable variations of the period.
The Surface Distribution of Chemical Anomalies of Ap Components in Detached Close Binaries
Authors: Kitamura M.
Published: July 2016

By estimating the orbital inclinations of non-eclipsing detached close binaries with Ap spectra, a marked statistical preference is obtained on the frequency distribution of the inclination which suggests that the abundance anomalies of Ap components tend to concentrate towards the stellar polar region.
Do Blue Stragglers Form by Common Envelope Evolution?
Authors: Meyer F. , Meyer-Hofmeister E.
Published: July 2016

All proposals to explain the formation of blue stragglers advanced up to now seem to have inherent difficulties. One appealing possibility, the formation by coalescence of close binary stars, appears to be ruled out by the existence of blue stragglers with more than twice the turn-off mass of their cluster. We suggest that this contradiction does not exist, since the binary system on its way to coalescence passes through a phase in which a very extended common envelope with a size of several hundred solar radii forms. In this stage a third companion in the range of this envelope will be captured and finally merge to form a blue straggler that can have more than twice the turn-off mass.
Cataclysmic Variables, Hubble-Sandage Variables and η Carinae
Authors: Bath G. T.
Published: July 2016

The Hubble-Sandage variables are the most luminous stars in external galaxies. They were first investigated by Hubble and Sandage (1953) for use as distance indicators. Their main characteristics are high luminosity, blue colour indices, and irregular variability. Spectroscopically they show hydrogen and helium in emission with occasionally weaker Fell and [Fell], and no Balmer jump (Humphreys 1975, 1978). In this respect they closely resemble cataclysmic variables, particularly dwarf novae. In the quiescent state dwarf novae show broad H and HeI, together with a strong UV continuum. Weak FeII in emission has been observed in U Gem and SS Aur (Warner 1976). The Balmer jump is either not present, or weakly in emission. The principal spectroscopic difference is the increased breadth of the occasionally doubled emission lines.
Observational and Evolutionary Aspects of Wolf-Rayet Stars
Authors: Vanbeveren Dany
Published: July 2016

Some of these results are part of a more extended investigation on WR stars that will appear in four papers, i.e. Vanbeveren and Packet (1979), Vanbeveren and Conti (1979), Vanbeveren and Doom (1979), Vanbeveren and de Loore (1979).
Mass Flow Analysis of the Ultraviolet Spectrum of UW Canis Majoris
Authors: Drechsel H. , Kondo Y. , McCluskey G.E. , Rahe J.
Published: July 2016

The ultraviolet spectrum of the close binary UW CMa (= HD 57060; 07f Ia + 0-B), obtained with the COPERNICUS (OAO-3) and IUE satellites, is analyzed in terms of a comparison between observed P Cygni resonance line profiles and theoretical calculations in an expanding model atmosphere.
Spectroscopic Orbits of Algols–A Progress Report
Authors: Popper Daniel M.
Published: July 2016

Preliminary values of masses and radii are presented for twelve Algol systems with cooler components of class F or later. The results are new for nine of the systems and are based on measures of the D lines for the faint cooler components. For most of the systems with periods longer than six days the orbits of the hotter components are uncertain because of absorption by non-photospheric matter in the systems. The masses of the hotter components are approximately normal for their spectral types, while the masses of the Roche-lobe filling components range from 0.2 to 1.4 solar masses.
Accretion and Chemical Structure of Algols
Authors: Packet Wim
Published: July 2016

Evolutionary calculations show that during the last, slow stage of mass exchange in close binary systems, matter with gradually increasing molecular weight is transferred. If no mixing occurs the accreting star moves towards a position in the HR diagram hotter than the main-sequence band, in clear contradiction with observational evidence in Algols. So some efficient mixing mechanism must be present. Several mechanisms are examined, some of which can be definitely ruled out. A closer examination of some others is necessary.
Rotation of the Primary Component of Algol
Authors: Rucinski S. M.
Published: July 2016

1.8 A° segment of the Algol A spectrum centered at 1075.55 A° line of Ni II was scanned repeatedely with the 0.05 A° resolution from the Copernicus satellite. The numerical model is described in which 37 out of the total 55 scans obtained during two eclipses were combined in a least-squares solution, to determine the period of rotation and degree of non-solid rotation of Algol A. The period of rotation suggests full synchronism of rotational and orbital motions; the equatorial velocity is Ve = 53 ± 3 km/s. The non-solid rotation parameter ‘s’ measuring the distribution of angular velocity versus stellar latitude in ω = ωe (1 - s + s cos2 ϑ) has been found equal s = 0.07 ± 0.25 indicating the rotation law not far from solid body.
IUE Observations of the Two Peculiar Binary Systems Beta Lyrae and Upsilon Sagittarii
Authors: Hack Margherita , Flora Umberto , Santin Paolo
Published: July 2016

The common peculiarities of these two systems are: a) the companion is a massive object (probably m2≥10) whose spectrum is not observable; b) both systems show evidence, though in different degrees, of mass-transfer and mass-loss; c) both present, in different degrees, hydrogen deficiency; d) ultraviolet observations have shown, in both cases, the presence of lines of highly ionized elements like N V, C IV, Si IV, probably formed in an extended envelope because they do not show orbital radial velocity shifts, and cannot be explained by the effective temperature of the star whose spectrum we observe. The latter property seems to be common to several close binaries, as shown by the ultraviolet observations with IUE by Plavec and Koch (1979); e) both systems present infrared excess, suggesting the presence of an extended envelope (Gehrz et al. 1974; Lee and Nariai, 1967; Humphreys and Ney, 1974; Treffers et al. 1976).
Ultraviolet Observations of Close Binary Stars
Authors: Polidan R. S. , Peters G. J.
Published: July 2016

In this paper, we present far ultraviolet observations of three interacting binary stars (HR 2142, HR 7084, and λ Tauri). All stars exhibit evidence of a gas stream and extensive mass outflow from the system. Physical parameters are derived for the gas stream in HR 2142.
On the Location of Gas Streams in Algol Systems
Authors: Walter K.
Published: July 2016

Seven years ago, at the Parksville Symposium, I reported on first results obtained from light curves of typical Algol systems which were discussed according to principles taking into account the presence of gas streams. According to this modified method the reflection parameter is derived from parts of the light curve outside eclipses which are least influenced by gas stream effects. Light curves rectified in this manner, or expressed more exactly, roughly released from reflection and ellipticity effects, only in parts display a horizontal course, in the surplus in intensity after primary eclipse and by part also before it. This indicates an additional light source visible during about half the orbital period. On the preceding side of the primary eclipse a loss in intensity is frequently also observed, which is caused by absorption effects of the gas stream, and often overlaps the surplus intensity.
Thermonuclear Burning in the Envelope of an Accreting Neutron Star
Authors: Ergma E. , Tutukov T.
Published: July 2016

A simple analytical method has been used to investigate thermonuclear flashes in a degenerate envelope of an accreting neutron star. The heating source is the compression of envelope and the cooling is due to the radiative cooling of the envelope. The role of hydrogen burning is discussed. A possible evolutionary scenario for formation of preburster binaries consisting of a neutron star and a low mass main sequence star is proposed.
Variations in the Profiles of Hβ and He II 4686 A in Vela X-1
Authors: Zuiderwijk Ed. J.
Published: July 2016

The first results are presented of an extensive spectroscopic study of HD 77581 = Vela X-1, based on several averaged Coude spectra. The profile of Hβ is phase-dependent and consists of two absorption components superimposed on one another. The profile of He II 4686 A is of the P-Cygni type around phase 0.7, whereas the line is in absorption with variable strength between phase 0.9 and phase 0.5 (with respect to the X-ray eclipse).
Periodical Variations in the Spectrum of X Persei. Discovery of a 22-Hr Period in the Variations of the Radial Velocities of Hα.
Authors: Galkina T. S.
Published: July 2016

The bright BOe star X Persei has been observed for over 50 years as an emission-line object and as a variable star. Throughout this time, the star displayed typical behavior for such an object. The discovery that it lies very close to the position of a weak X-ray source renewed interest in the star, which is now under close scrutiny. The probable association of X Persei with 3U 0352+30 has been subject to several discussions (Hutchings, Crampton and Redman, 1975; Margon, Bowyer, and Penegor, 1976; Hutchings and Walker 1976; Persi, Viotti and Ferrari-Toniolo 1977, 1978).
Remarks on the Complicated Close Binary Systems RT Lacertae, CG Cygni, and RW Coronae Borealis
Authors: Milone E. F. , Naftilan S. A.
Published: July 2016

The three systems differ in period, scale and degree of contact: RW Com is a contact system, RT Lac is semi-detached and CG Cyg is a detached system. Yet they share the properties of a variable asymmetric light curve in the UBV, Ca II H and K emission, apparent infrared excesses, and period variability. If it may be argued that this ensemble of symptoms has similar origins in the different systems, then our intensive studies of these three binaries may have implications for the nature of all systems showing the RS CVn properties. We feel that the evidence points to the presence of circumstellar matter in the three binaries. We pose the questions: does this material create the photometric pecularities, is it incidental to them or does it arise from some other light-curve perturbing source?
Ultraviolet Observations of AM Herculis
Authors: Raymond J. C. , Branduardi G. , Dupree A. K. , Fabbiano G. , Hartmann L.
Published: July 2016

Spectra of AM Herculis taken with IUE show a continuum which is partially eclipsed in phase with the X-ray eclipse and can be separated into two components; a black-body component (kTBB = 25 − 30 eV) which accounts for the ¼ keV X-rays and the eclipsed UV continuum; and a component roughly described by Fν ∂ ν−1 which is not eclipsed.
Observational Structure of Disk-like Envelope in the System DQ Her
Authors: Cherepashchuk A. M. , Dmitrienko E. S.
Published: July 2016

The analysis of the eclipses in the system DQ Her based on the photometric observations of different authors during 1954, 1956 and 1975 allows us to obtain the photometric elements of the system and the structure of disk-like envelope surrounding the white dwarf. The orbit inclination of the system is i = 80° ± 3°, the major axis of the secondary component is 0.40 ± 0.03, the orbit radius is (10 ± 2)1010cm, the masses of the components are: mwd = (0.65 ± 0.35)M⊙, m2 = (0.50 ± 0.15)M⊙. A decrease in the optical luminosity of ≃20% and a total decrease in size of the disk-like envelope of ≃10% is observed from 1954 to 1975. The brightness of the disk-like envelope increases towards its center. The radiation temperature increases toward the center according to the laws T ≃ r−0.20 and T ≃ r−0.35 for 1954 and 1975, respectively. The average value of the radiation temperature of the disk-like envelope is about 104K. The bolometric luminosity of the envelope is (1 to 2)L⊙. The bolometric luminosity of the central white dwarf is anomalously high: ≃(20 to 200 L⊙) and the effective temperature of its surface is ≃(1.0 to 1.7)105K. All these results indicate that the disk-like envelope in the system DQ Her is an accreting disk.
Current Observational Development in Early-Type Contact Binary Systems
Authors: Leung Kam-Ching
Published: July 2016

This is a summary of current observational results of early-type contact binary systems. The classical approaches to derive a photometric solution of a very close binary are found to be incapable of distinguishing whether a system is detached, semidetached, or in contact. A survey of contact systems based on the more modern approach of Wilson and Devinney (1971) and others are summarized in the following. Contact systems with spectral type 0 are: V382 Cyg (Devinney 1976 private communication, Bloomer et al. 1979), V729 Cyg (Leung and Schneider 1978c), UW CMa (Leung and Schneider 1978b), AO Cas (Schneider and Leung 1978); with spectral type B are: SV Cen (Wilson and Starr 1976, Rucinski 1976), V701 Sco (Wilson and Leung 1977, Anderson et al. 1979), BH Cen (Leung and Schneider 1977), RZ Pyx (Devinney 1976 private communication); with spectral type A are: AU Pup (Leung and Schneider 1978a), V1073 Cyg (Leung and Schneider 1978a), V535 Ara (Leung and Schneider 1978a), BV 845 (Leung and Darland 1978), V1010 Oph (Leung and Wilson 1977).
IUE Observations of Z Andromedae
Authors: Friedjung M.
Published: July 2016

The preliminary results of a joint study of this symbiotic star with 6 Italian astronomers are reported. The relative intensities of the intercombination emission lines indicate electron densities of 1010 and an upper limit to the dilution factor between 10−4 and 10−6. The resonance emission lines give a maximum thickness in the line of sight. A hot (T between 19000° and 26000°) continuum is interpreted as coming from a hot subdwarf, but the high excitation emission lines appear to be formed near the cool giant component of what is probably a close binary.
The UV Spectrum of W Cep.
Authors: Faraggiana R.
Published: July 2016

IUE spectra of VV Cep have been obtained in 1978 and 1979 during the chromospheric phase of the eclipse. The profiles of the Mg II resonance lines differ from one another and this peculiarity, common to other M type supergiants, is examined. The value of Mv derived from the extension of the Wilson and Bappu relation to Mg II lines is compared with other determinations. The variation of the absolute flux in the 1200-2000 Å range is presented.
Refraction in radioastronomy
Authors: Altenhoff Wilhelm J.
Published: July 2016

In the last few years there was no paper in the astronomical literature reporting on new measurements of radioastronomical refraction. But there are some important review papers on different aspects of this topic, e.g. on the ionosphere by M.M. Komesaroff (1960) and T. Hagfors (1976), on the prediction of tropospheric refraction with ground based meteorological data by B.R. Bean (1962), B.R. Bean and G. Teleki (1974), and R.K. Crane (1976), on range measurements, predicted again by surface weather data, by H.S. Hopfield (1971).

For astrometry only interferometric observations give the necessary positional accuracy. The result of the interferometer is not affected, if the delay by the atmosphere is the same for each antenna, therefore this technique is not sensitive to normal refraction.

Differential delays can originate in the uneven distribution of water vapor in the atmosphere. Wesseling et al (1974) measured these differential delays with an infrared hygrometer; their attempts to correlate the water vapor with the observed interferometer phase were only partially successful.

Hinder (1970) has investigated the differential delays as function of baseline and of season. One can conclude that improvements of positional accuracy either by going to longer baselines or to shorter wavelengths depend on the success to predict the differential delays either by infrared hygrometers or similar means.
Environmental systematics and astronomical refraction II
Authors: Hughes James A.
Published: July 2016

The role of urban heat islands in producing systematic isopycnic tilts is explored in more detail, and with greater rigor, than in Part I of this series. (Perth, 1974).

Specifically, a three dimensional integration is carried out, and light rays are, in effect, “traced” through the resulting perturbation field by evaluating the integral of anomalous refraction. This is done for various values of the parameters, viz., wind direction and observatory location relative to the heat island, strength of the central perturbation, zenith distance of the observed object, etc.

It is stressed that heat islands are not the only source of such systematic effects.

Finally, a brief discussion of some possible methods of determining observationally the effects here treated theoretically, as well as other site dependent effects, is appended.
An origin of the variations of astronomical refraction
Authors: Yasuda Haruo , Fukaya Rikinosuke
Published: July 2016

There exists an empirical relation between the anomalous refraction and the atmospheric density in the surface layer. From the relations the variations of scale height for each night can be determined by the temperature and pressure in the surface layer. A correction term to the refraction table is derived in an analytical expression.
On astronomical refraction for a three-dimensional model atmosphere.
Authors: Sergienko V.I.
Published: July 2016

The existing refraction theories for a one-dimensional model atmosphere do not account for anomalous refraction. The latter can be calculated using a three-dimensional model atmosphere.
On the calculation of refraction in model atmospheres
Authors: Saastamoinen J.
Published: July 2016

Approximations have been removed from the derivation of the coefficients in the binomial expansion for astronomical refraction, , allowing the calculation of any number of terms to any precision desired. The range of the refraction formula has been extended to greater zenith distances (<90°) by inserting a damping factor into the binomial formula, truncating the expansion at a proper point, and rearranging the terms. Another, computer-manipulated series has been developed for zenith distances at or near the horizon. Further applications include the calculation of photogrammetric and parallactic refractions, as well as range corrections in satellite geodesy.
Path length variations due to changes in tropospheric refraction
Authors: Anderson Allen Joel
Published: July 2016

An experiment is described in which microwave Doppler is used to determine very small changes in path length to spacecraft tracked by the Deep Space Tracking Network (DSN). The experiment was carried out to test the detection capabilities of the DSN system to gravitational radiation of very low frequency (10−2–10−4 Hz). In this work spectral analysis of Doppler variations were performed for periods over 4 hours and more.

These results indicated that one of major sources of noise was due to rapid variations in tropospheric refraction. The results obtained a differential path length variation, ΔL/L, of 1 part in 1014 for periods between 100 and 1 000 seconds.

Doppler spectra are shown and a general discussion of the experiment is given.
Statistics applied to the estimation of the influence of the environment on results of observations
Authors: Szacherska M. K. , Wiśniewski Z.
Published: July 2016

The assumption of a generalized model of the composition of random and systematic errors of measurements can constitute a basis for the estimation of the influence of the environment on the results of geodetic observations in the course of their numerical elaboration. The method of the estimation of systematic errors on the basis of the analysis of an empiric distribution of the results of observations has been established on the assumption of such a model, which permits also to estimate systematic errors in the course of the adjustment of observations, these errors being treated as additional unknowns in the system.
Evaluation of refraction by geodetic measurements
Authors: Hradilek Ludvík
Published: July 2016

The merits of two refraction methods are discussed with the result that the line refraction method is appropriate for elaboration of trigonometric leveling traverses whereas the station refraction method is comparatively more convenient for trigonometric and three-dimensional networks of a larger extent especially those designed in high mountain regions.
Notes on some abnormal refraction phenomena in the atmosphere
Authors: Liljequist G. H.
Published: July 2016

To geodesists and astronomers atmospheric refraction is a phenomenon, which makes it necessary to introduce corrections to the observations of carefully performed measuring series. Such corrections are generally obtained from tables giving values, which are applicable under “normal” or standard conditions. These conditions may be taken as more or less obtaining with a mean variation of temperature with height in the atmosphere - in the troposphere mainly a decrease of 0,6 – 0,7° per 100 m.
The role of refraction in the measurement of three-dimensional movements by geodetic methods
Authors: Dodson A. H.
Published: July 2016

The measurement of three-dimensional movements by geodetic techniques involves the determination of spatial co-ordinates by the observation of horizontal theodolite angles and EDM distances, with either vertical angles or spirit levelling providing the height control. For correct interpretation of the results it is essential that estimates of the accuracy of the position determinations are also provided.
Far-ultraviolet Studies. VIII. Apollo 17 Search for Zodiacal Light
Authors: Henry R. C. , Anderson R. C. , Fastie W. G.
Published: July 2016

Solar System dust particles reflect sunlight, producing the so-called zodiacal light (Leinert 1975). The spectrum of the zodiacal light in the far ultraviolet has been a matter of controversy in the past, and remains a subject of great interest.
Photometric Axis Measurements of the Zodiacal Light at Large Elongations
Authors: Tanabe H. , Takechi A. , Miyashita A.
Published: July 2016

Measurement of the position of the photometric axis of the zodiacal light at large elongations (90 ° < λ − λ⊙ < 270°; λ:ecliptic longitude, λ⊙: ecliptic longitude of the sun) provides information about the spatial distribution of the interplanetary dust outside the orbit of the Earth. However, modern photoelectric measurements in this part are scarce, except for the Gegenschein region, because of the observational difficulty due to faintness of this part of the zodiacal light.
The Symmetry Plane of the Zodiacal Cloud Near 1 AU
Authors: Misconi Nebil Y.
Published: July 2016

Analysis of zodiacal light observations from Mt. Haleakala, Hawaii show that the symmetry plane of the zodiacal cloud near 1 A.U. is close to the invariable plane of the solar system. Since the symmetry plane of the inner zodiacal cloud is close to the orbital plane of Venus (Misconi and Weinberg, 1978; Leinert et al., 1979), we suggest that the symmetry plane changes inclination with heliocentric distance.
Method of Scattering Plane Scanning
Authors: Buitrago J. , Alvarez P. , Lôpez G. , Mujica A. , Sánchez F.
Published: July 2016

The number density of interplanetary dust particles as a function of altitude above the symmetry plane can be determined from ground-based measurements by a new method.
Wavelength Dependent Models of the Zodiacal Light
Authors: Staude H. J. , Röser S.
Published: July 2016

We discuss the significance of our zodiacal light models, which are based on Mie theory and refractive indices measured in the range 0.15 μm ≤ λ ≤ 100 μm. The models include scattering and thermal emission. They are absolute, since particle number density at 1 AU, size distribution and radial density gradient in the Ecliptic are fixed by lunar microcrater counts and by Helios and Pioneer results. The only free parameter is the chemical composition of the dust.
Serial Correlation of Meteor Radar Rates
Authors: Lindblad B. A.
Published: July 2016

Fluctuations in meteor rates. A fundamental concept in meteor astronomy is the rate of occurrence of meteors (hourly rate). The diurnal and seasonal behaviour of meteor radar rates has been the subject of many studies in the past. In these studies the tacit assumption is made that the observed rate variations are of an astronomical nature. Radar rate changes of an instrumental nature, or rate variations induced by changes in the atmospheric conditions, are generally neglected.
Ground Radar Detection of Meteoroids in Space
Authors: Kessler Donald J. , Landry Preston M. , Gabbard John R. , Moran John L.T.
Published: July 2016

The North American Air Defense Command (NORAD) has the responsibility of detecting and tracking artificial satellites in Earth orbit. Objects detected with a velocity in excess of the escape velocity of Earth are normally disregarded by the ground radar since they are obviously not orbiting satellites. During a special test conducted by NORAD for NASA to lower the detection threshold for small satellites, part of the radar software was modified, resulting in acquisition of what appears to be important new meteoroid data. The purpose of this paper is to describe the special test and give a preliminary analysis of the meteoroid data.
Physical Characteristics of Cometary Dust from Optical Studies
Authors: Hanner Martha S.
Published: July 2016

Observations of the scattered sunlight and thermal emission from cometary dust provide information on the composition and dominant size of the dust. The observations will be summarized here and compared to theoretical models for dielectric and absorbing materials, with emphasis on the thermal emission. The compatibility of the optical data with the size distribution derived from dynamical studies is discussed.
On the Particle-Size Distribution Function of Cometary Dust
Authors: Sekanina Z.
Published: July 2016

The Finson-Probstein (1968a) method of analysis of the distribution of light intensity in dust tails has so far been applied to only a handful of comets. Yet, the results already suggest a striking diversity in the properties of the particle-size related distribution function f(β), one of three parametric functions determined. Here β is the acceleration exerted on the particle by solar radiation pressure, measured in units of solar attraction. For a spherical particle β is a function of its radius a, density ρ, and the integrated efficiency factor for radiation pressure Qpr (i.e., the ratio of the particle's effective cross-section for radiation pressure to its geometric cross-section):

where c0 = 0.585 × 10−4 g/cm2.
Dust Experiment for a Rendezvous Cometary Mission
Authors: Dalmann B.-K. , Bahr D. , Fechtig H. , Kissel J.
Published: July 2016

During a Rendezvous-type cometary mission it will be possible to collect dust particles on exposed surfaces. A secondary-ion-mass-spectrometer is proposed for the subsequent chemical investigation of such dust collections. An ion gun shoots inert gas or oxygen-ions onto the sample. The energy of these primary ions can be chosen between 1 and 5 keV. The positive and negative secondary ions emitted from the dust surfaces are then analysed with a quadrupole mass filter. The mass range of the instrument will be 1-150 amu. The sensor is able to measure (a) nearly all elements in this mass region, (b) molecules and organic components present in the dust, (c) isotopic ratios of interesting elements. Results of a first series of simulation studies are reported.
An Impact Mass-Spectrometer for the Halley-Probe
Authors: Braun G. , Grün E. , Kissel J. , Pailer N.
Published: July 2016

The relative speed between Comet Halley and the presently planned Halley Probe will be approx. 55 km/s. At such a speed the method of impact ionization mass-spectrometry is perfectly suited to analysing cometary dust particles with masses from 10−16g to 10−10g. First results are reported by Dalmann et al. If a micrometeoroid hits the sensitive target, ions from both particle and target material are produced. The total number of ions is registered with a charge-sensitive amplifier and this signal Q allows the determination of the particle mass m (Q ∼ m). By an electric potential difference of 3 kV, ions are drawn into a field-free drift-tube. The ions are separated in time in the TOF-Spectrometer due to their different masses. The mass spectrum is registered as output current of the particle multiplier at the end of the TOF-tube. It gives information about the chemical composition of the detected particle. Characteristics of such spectra recorded with the Impact-Spectrometer currently used in the laboratory are the following: a) mass resolution m/Δm > 100 at 23 amu, b) flight-time (t ∼ 14 μs at 100 amu; the corresponding Δt ∼ 70 ns between 99 and 100 amu).
A Simple Derivation of the Radiation Forces Felt by Scattering Particles
Authors: Burns Joseph A. , Soter Steven
Published: July 2016

The radiation pressure (RP) felt by a perfectly absorbing particle is due to the momentum withdrawn each second from the beam. The Poynting-Robertson (PR) drag is produced since the particle continually absorbs mass in the form of radiation, which, upon re-emission, has the same mean momentum density as the particle itself. We find that, relative to the force felt by a perfectly absorbing particle, the RP+PR forces felt by a scattering particle must be multiplied by Qpr, the radiation pressure coefficient, which can be evaluated from Mie theory.
The Motion of Charged Dust Particles in Interplanetary Space
Authors: Morfill G. E. , Grün E.
Published: July 2016

The problem of electromagnetic perturbations of charged dust particle orbits in interplanetary space has been re-examined in the light of our better understanding of the large scale spatial and temporal interplanetary plasma and field topology. In the equatorial plane, the magnetic sectors, caused by the warped current sheet, produce stochastic orbit perturbations. From this a diffusive description of particle motion can be derived, provided the dust particles are sufficiently small. The effects of large unipolar magnetic field regions at high heliographic latitudes will be briefly discussed.
Laboratory Measurements on the Infrared Features of Interstellar Silicate Grains
Authors: Krätschmer W.
Published: July 2016

Thin layers of an amorphous silicate coating were obtained by ion sputtering of crystalline olivine on KBr substrates. The dielectric functions of the coating were determined from reflection and transmission measurements in the wavelength range between 5 and 25 μ. The small particle extinction of the amorphous silicate shows a strong feature at 9.7 μ and a weaker one at 17.5 μ. In wavelength position both absorption bands agree with astronomically observed features.
Cosmic Dust Synthesized in Reducing Environments
Authors: Khare B. N. , Sagan Carl
Published: July 2016

A variety of complex dark brown organic solids called tholins have been produced from a mixture of cosmically abundant gases upon irradiation with ultraviolet light or electrical discharges (Sagan and Khare 1979). Such tholins were probably produced in the primitive solar nebula that contributed to the present composition of carbonaceous chondrites, comets, interstellar grains and gas. Spark tholins produced from approximately equimolar mixtures of CH4 and NH3, with 2.6% H20 exhibit 50% thermal dissociation temperature of about 900°C. Sequential and non-sequential pyrolysis followed by gas chromatography/mass spectrometry are employed to study both UV (Khare et al. 1978) and spark tholins. Typical pyrolyzates of spark tholins include alkanes, alkenes, aromatic hydrocarbon, abundant nitriles, pyrroles, pyrazines and alkylbenzenes. Organic molecules uncovered by microwave line spectroscopy of the interstellar gas are plausibly derived as spallation products of interstellar tholins comparable to the origin we propose for cometary nitriles and aldehydes as the spallation products of the cometary tholins. Spark tholins are highly insulating. Their measured resistivity is 71.4 × 108 ohms-cm and does not change up to a pressure of 105 bars.
Solar Polar Field Reversals and Secular Variation of Cosmic Ray Intensity
Authors: Ahluwalia H. S.
Published: July 2016

The profile of the well-known 11-year variation of the cosmic ray intensity appears to depend upon the emerging solar polar magnetic field regime in a very characteristic manner. During the solar activity cycle 19, the cosmic ray intensity takes about seven years to recover to its solar activity minimum level. But during the solar activity cycle 20, the recovery takes place in only about two years. It appears that these characteristic recovery modes are obtainable every other solar activity cycle. We are led to suggest two model configurations for the heliosphere. We believe that an “open” heliosphere model applies to solar activity cycles 18 and 20. A “closed” heliosphere model is obtainable during solar activity cycles 17 and 19. Our results are discussed.
Interplanetary Response to Solar Long Time-Scale Phenomena
Authors: D'Uston C. , Bosqued J. M.
Published: July 2016

In this paper, we briefly review the experimental knowledge gained in the recent years on the interplanetary response to solar long-time scale phenomena such as the coronal magnetic structure and its evolution. Observational evidence that solar wind flow in the outer corona comes from the unipolar diverging magnetic regions of the photosphere is discussed along with relations to coronal holes. High-speed solar wind streams observed within the boundary of interplanetary magnetic sectors are associated with these structures. Their boundaries appear as very narrow velocity shears.
Reflexion and Transmission of Alfven Waves in an Atmosphere.
Authors: Bel N. , Leroy B.
Published: July 2016

If we want to study the transfer of energy by waves through a stellar atmosphere, we first need to know its reflectivity with respect to each of the three MHD modes. Here, we will consider linear Alfvén waves only. The problem is set as follows. An energy flux being given at the bottom (z=0) of the atmosphere, we ask for how much of it is recorded at an altitude z.
Observation of Dust Generated Hydrogen in the Solar Vicinity
Authors: Fahr H. J. , Ripken H. W. , Lay G.
Published: July 2016

Solar wind protons impinging on interplanetary dust grains are trapped, deionized, and subsequently desorbed. The steady state distribution of desorbed neutral hydrogen inside of 0.4 AU can be deduced by observation of resonantly scattered solar 121.6 nm radiation. Calculated integral intensities and spectral profiles are given, showing the clear spectral separation of the different radiation components. Given a specific solar wind proton flux, the interplanetary dust distribution can be determined. Conversely, dust density profiles from zodiacal light measurements can be used to deduce solar wind proton fluxes at heliocentric distances of 0.4 to 0.15 AU. Observations of latitudinal and short-term temporal proton flux variations seem feasible.
Model Calculations of Solar Wind Expansion Including an Enhanced Fraction of Ionizing Electrons
Authors: Petelski E. F. , Fahr H. J. , Ripken H. W.
Published: July 2016

Collective interactions of the solar wind and newly ionized interstellar gas cause turbulent electron heating to ionizing energies analogous to laboratory experiments on the critical ionization velocity effect. Implications for solar wind and interstellar gas dynamics are calculated by simultaneously solving continuity equations for solar wind protons, interstellar hydrogen atoms, and energetic electrons. Electron impact ionization is shown to be practically as important as photoionization, giving rise to a stronger deceleration and heating of the distant solar wind, a weaker terminating shock, a smaller stand-off distance of the helio pause, and implying higher densities of the outer solar wind and the interstellar neutral gas.
X-Ray Evidence of Coronal Preflare Emission
Authors: Webb D. F.
Published: July 2016

Flares are believed to derive their energy from localized nonpotential magnetic fields; this energy is somehow stored and initially released in the low corona. Therefore, knowledge of coronal conditions prior to flares is essential to our understanding of the flare process. The coronal plasma is constrained by the magnetic field and its characteristic emission is easily observed at soft X-ray wavelengths. Therefore, X-ray imagery is well suited for observing changes in emission influenced by nonpotential magnetic fields in the low corona. This study used soft X-ray images from the Skylab AS&E telescope to search for evidence of coronal preflare emission.
UV Emitting Spicules
Authors: Poletto Giannina
Published: July 2016

Extreme ultraviolet observations of the chromospheric network in a coronal hole obtained in 1973 by the Harvard College Observatory experiment aboard Skylab are analyzed. Upper and lower limits to the actual emission measure in UV spicules have been obtained, and the consistency of the derived values with the hypothesis that UV spicules are Hα spicules falling back after being heated is discussed.