bluuebunny/crossref_metadata_2025 huggingface dataset:
Solar Submillimeter and Millimeter Spectroscopy between 7 and 30 cm–1 from the James Clerk Maxwell Telescope
Authors: Naylor D. A. , Tompkins G. J. , Clark T. A. , Davis G. R. , Duncan W. D.
Published: June 2019

A two-beam Martin-Puplett polarizing interferometer has been used in the rapid-scan mode on the 15 meter JCMT in conjunction with the facility detector, UKT14, to survey the solar sub-millimeter and millimeter spectrum in the four wavebands at 7-11, 11-15, 21-24 and 27-30 cm–1 to a spectral resolution of 0.01 cm–1 and at spatial resolutions of 19″, 16″, 7″ and 6″, respectively. Overall atmospheric transmission through these windows has been evaluated by comparison with synthetic spectra generated with FASCOD/HITRAN. A search has been made for contributions to these spectra from high-n transitions of H and heavier elements by several methods, including the comparison of solar with lunar and limb with disk center spectra.
The Structure of Umbral Fluxtubes
Authors: Degenhardt D , Lites B. W.
Published: June 2019

Subsurface filamentation of sunspot magnetic fields has been postulated as a source of the visible small-scale structure of sunspot umbrae. We examine this possibility by investigating the magnetohydrodynamic structure of thin, vertical magnetized gas columns embedded in sunspot umbrae. These umbral fluxtubes are assumed to have weaker field strengths than the surrounding umbral atmosphere. The steady-state magnetohydrodynamic equations are solved numerically in the slender fluxtube approximation, thus allowing for stationary internal mass flows. We include the radiative exchange of heat between the umbral fluxtube and the ambient medium using a simple relaxation time approach.

The geometric shape of the steady flow solution is a gas column converging with height. We discuss the relationship of our results to observed properties of umbral brightenings (umbral dots). We show that, even if there is a large difference in magnetic field strength between the dot and the ambient medium in deeper layers, the field strengths are nearly equal in the observable layers, a result required by the observations. We also show that either high temperatures at the lower boundary of the dots or strong upflows are needed in order to produce bright continuum structures.
The ATMOS Solar Atlas
Authors: Farmer Crofton B.
Published: June 2019

The ATMOS solar atlas covers the infrared spectrum of the Sun observed from space, over the frequency range from 650 to 4800 cm–1 at a resolution of 0.01 cm–1. The spectrum reveals a large number of molecular and atomic features that are not visible in spectra taken from the ground. The acquisition of the spectra, details of their presentation in the atlas, and some highlights of the solar features are described.
Line Shifts and Asymmetries in the IR Solar Spectrum
Authors: Blomme R. , Sauval A. J. , Grevesse N.
Published: June 2019

Line shifts and asymmetries of spectral lines have been found in the ATMOS spectra. These are due to the granulation at the solar surface. A two-component model for the solar photosphere is used to calculate theoretical profiles which are compared to the observations. The ATMOS lines provide additional constraints on models for the solar photosphere.
Solar Abundances of C, N, and O
Authors: Grevesse N , Sauval A. J. , Blomme R
Published: June 2019

We briefly review the many indicators, atoms as well as molecules, of the photospheric abundances of C, N and O and present preliminary updated values of these abundances.
Prospects in Adaptive Optics for Solar Applications
Authors: Roddier François , Graves J. Elon
Published: June 2019

We review the theoretical perspective for problems in adaptive optics, outline recent progress, and consider its application in the infrared. Techniques in adaptive optics are on the threshold of revolutionizing modern astronomy. These techniques are particularly applicable in the infrared, where refractive effects of turbulence are reduced, characteristic cell sizes are greater, and the isoplanatic patch diameter is increased. Adaptive techniques could be especially appropriate for modern large solar telescopes now under consideration that could operate in the infrared.
The Anisotropy in the distribution of Extragalactic Infrared Sources and Background
Authors: de Bernardis P. , Fabbri R. , Masi S. , Melchiorri F. , Olivo B. , Pecorella W.
Published: June 2019

We analyze the anisotropies in the extragalactic infrared background and in the source counts in standard cosmology perturbed by large-scale, small-amplitude density fluctuations. The dipole anisotropy of the diffuse background is connected to the dipole of the cosmic background radiation and of the source counts, and a full consistency with a large (≃ 7%) anisotropy in the IRAS source counts is found to imply a low density (Ω0 ≃ 0.2) universe, contrary to a previous claim. We analyze also higher order harmonics. Using the IRAS Low-Resolution All-Sky Maps we obtain an upper limit of 0.17MJy/sr on the dipole of the 100 μm background and show that it is consistent with a source-count anisotropy of 7% only for a low intensity, I ≤ 1.2 M Jy/sr, of the background itself.
Possible Inhomogeneities in the Universe on Scales of 100–300 MPC from Observations with the 6-Meter Telescope
Authors: Kopylov A. I. , Kuznetsov D. Yu. , Fetisova T. S. , Shvartsman V. F.
Published: June 2019

In 1986 the programme “The Northern Cone of Metagalaxy” has been finished with the 6-meter Telescope. In the course of the programme redshifts of all very rich compact clusters of galaxies inside the cone with galactic latitude and indirect estimates of redshifts ZLB < 0.28 have been measured. The total volume of the investigated region is V ≈ 500·106 Mpc3 (we accept Hubble constant H=50 km/s Mpc−1). A number of possible indications of existence of inhomogeneities in the Universe on scales greater than 100 Mpc are obtained: 1) the void of 400 Mpc in size; 2) the flat stratum of 150 Mpc thickness and 1000 Mpc diameter; 3) two-point space correlation function ξ (R = 200–300 Mpc) = 0.5±0.2. We found no indications that topology of the Universe is non-Euclidean on scales of 20–200 Mpc.
A fit of the angular 3–point function and biased galaxy formation
Authors: Bonometto S.A. , Lucchin F. , Matarrese S.
Published: June 2019

A study of the 3-point function, based on the analysis of momenta (as was done, e.g., in Sharp et.al. 1984) deduced from the Zwicky catalog, indicates that an expression containing a cubic term, besides the usual second degree polynomials of 2–point functions, provides a good fit of angular data.
Elliptical Galaxies and Large-Scale Velocity Flows
Authors: Faber S. M. , Burstein David , Davies Roger L. , Dressler Alan , Lynden-Bell Donald , Terlevich Roberto , Wegner Gary
Published: June 2019

Motions of nearby elliptical galaxies reveal a large-scale velocity flow relative to cosmic rest towards the point 1=307±10, b = 9±10. The data are fit best by a two-component flow model. The smaller component is due to Virgo, which induces a velocity at the Local Group of 250 km/s. The main flow is due to a more massive concentration located a distance of 4350±350 km/s towards 1=307, b=9, which induces a local velocity here of 570±60 km/s. This larger component falls off away from the mass concentration roughly as r−1. The Centaurus double cluster and its neighbors are in the direction of the mass concentration but are in the foreground and are falling into it. Galaxy counts, radial velocity surveys, and the motions of nearby spirals are consistent with the above model. The IRAS dipole results are less clear but may also be consistent. There is evidence that the distant mass concentration is non-spherical, with the Centaurus cloud a substantial sub-condensation in the foreground. The formal agreement of the large-scale flow with biased (b=2) cold dark matter is low, but the simple methods used so far to assess this are uncertain. The main weakness of the present data in comparing to theory is the fact that they do not penetrate far enough to show the velocity field on all sides of the mass concentration. Sphericity and total extent of the flow are therefore still unknown.
Galaxies, Clusters and Fluctuations
Authors: Schaeffer Richard
Published: June 2019

The luminosity function of galaxies and clusters as well as their correlations can be calculated assuming the many-body correlation functions are scale invariant. The same hypothesis leads to predictions on the fractal dimension of the galaxy distribution. The latter is found to be bifractal that is characterized by two dimensions D=3−γ in the cluster region, and D = (3−γ)(2+α) in the nearly empty regions, α being the index introduced by Schechter for the galaxy luminosity function. Finally, the same models lead to predictions for the evolution of the cluster and x-ray luminosity functions, as well as for the Sunyaev-Zeldovich effect due to all virialized clusters, which is found to be large and to produce fluctuations of order 10−5 at sub-arc minute scalar in the microwave background.
Observations of Faint Field Galaxies
Authors: Koo David C.
Published: June 2019

Number counts, colors, and angular correlations of field galaxies fainter than 20th mag are summarized. Resulting conclusions regarding the presence and nature of luminosity, spectral, and clustering evolution remain controversial. Preliminary analysis of two major spectroscopic surveys near completion suggests that by z ∼ 0.5, larger numbers of very-blue galaxies of moderate luminosities are found than today. These skewer-like surveys also provide new probes of galaxy clustering on scales previously unexplored (>200 Mpc) and over lookback times of several billion years.
N-body Simulations of Galaxy Formation
Authors: Frenk Carlos S.
Published: June 2019

Modern N-body techniques allow the study of galaxy formation in the wider context of the formation of large-scale structure in the Universe. The results of such a study within the cold dark matter cosmogony are described. Dark galactic halos form at relatively recent epochs. Their properties and abundance are similar to those inferred for the halos of real galaxies. Massive halos tend to form preferentially in high density regions and as a result the galaxies that form within them are significantly more clustered than the underlying mass. This natural bias may be strong enough to reconcile the observed clustering of galaxies with the assumption that Ω = 1.
Observational Evidence for Spectral Evolution of Cluster Galaxies
Authors: Dressler Alan , Gunn James E.
Published: June 2019

The study of galaxy evolution with large lookback times is dominated by two difficult issues. The first is a technical matter. Even the most luminous galaxies are faint (mr < 19) at significant lookback times (z ≳ 0.5), and so spectrophotometric observations of average galaxies challenge our present telescope and detector technology. The second issue is the selection of objects in an unbiased way in order to assemble a representative sample of galaxies at the remote epoch. It is far too easy to chase only exotic objects whose very peculiarity has brought them to our attention. Though observations of such objects may be fascinating and revealing, they may tell us little about the evolution of an typical galaxy like our own.
On the Observational Discrimination of Friedmann-Lemaître Models
Authors: Chu Yaoquan , Hoell J , Blome H.-J. , Priester W
Published: June 2019

It is the purpose of this paper to illustrate the interrelation between the problems of the “missing mass”, the galactic age and the cosmological constant Λ (or its equivalent quantum vacuum density ).
Substructure in Rich Clusters
Authors: Webster Rachel , Fitchett Michael , Hewett Paul , Colless Matthew
Published: June 2019

We have developed a new statistical method based on maximum likelihood to test for the existence of two subclumps in data of arbitrary dimensionality (Fitchett 1987). The statistic, which is called the Lee function, can be calibrated using Monte Carlo simulations under various null hypotheses.
The 3-D Distribution of Abell Clusters
Authors: Sutherland Will
Published: June 2019

The Struble & Rood catalogue (Ap. J. Supp, 63, 543) of all measured Abell cluster redshifts is analysed, with corrections for the selection biases. This contains 533 redshifts with |b| ≥ 30°, z ≤ 0.3 compared with 104 in the sample of Bahcall & Soneira (Ap. J.270, 20). Although the catalogue contains biases in angular position (redshifts are preferentially measured in apparent “supercluster” regions) the information on redshift clustering is effectively unbiased since one cannot tell a priori whether pairs of clusters close on the sky are really associated in redshift. Thus the distribution of redshift differences for pairs of given angle & distance classes, f(Δz|θ,D1,D2), is a fair sample of the true distribution. Then by normalising to the “correct” angular correlation function, we obtain the joint distribution f(Δz,θ) and hence ξ(r). In practice, in the estimation of ξ we assign each pair a weight a where

where wA is the correlation or cross correlation for the appropriate subset of the whole Abell catalogue. This gives ξ(r) ≈ (r/20 h−1Mpc)−1.8, just slightly smaller than the result of Bahcall & Soneira, but here ξ(r) ≈ 0 for r ≥ 50−1Mpc.
The Large Scale Structure of the X-Ray Universe
Authors: Barcons X. , Fabian A.C.
Published: June 2019

The clustering of the background-contributing X-ray sources is reflected in the excess (i.e., non-Poisson) fluctuations in the X-ray background (XRB). Observational limits on ΔI/I can therefore be used to constrain either the clumpiness of X-ray sources or their contribution to the XRB if their clustering properties are known (see Barcons & Fabian 1987 for details).
Cluster Correlations for Scale-Free Spectra
Authors: Sanz J.L. , Martinez-González E.
Published: June 2019

The cluster autocorrelation function ξc and the galaxy-cluster cross correlation ξgc are used to test the biased structure formation for scale-free spectra P(k)∝kn. Following Kaiser (1984), we assume that rich clusters form only at higfr density regions with the matter distribution represented by a Gaussian random field. Then, the correlation ξ of two regions with characteristic scales R1 and R2 lying above the thresholds v1 and v2 (δ ≡ νσ), is given by the expression for the bivariate Gaussian

where z(r) is the coviance function, i.e. and is the correlation of the matter distribution Gaussian filtered on the comoving scales R1 and R2. From the previous equations, one can obtain for P(k)∝ kn, τ≪1 and large r a powers-law form either for ξc or ξgc. Moreover, the amplification factor Ac - gc ≡ ξc/ξgc is
Implementation of a Tree Code for Cosmology
Authors: Bouchet François R. , Hernquist Lars
Published: June 2019

We have adapted the Barnes-Hut hierarchical N-body method for cosmological applications. A detailed study of the resulting code yielded the following conclusions: it is SIMPLE, FLEXIBLE, ACCURATE, ROBUST, and EFFICIENT.
Properties of Galaxies and Galaxy Clusters Associated with Quasars
Authors: Yee H. K. C.
Published: June 2019

Quasars at redshifts < 1.0 provide good markers for discovering galaxies and galaxy clusters at moderately high redshifts. Recent results from a comprehensive program of imaging surveys of galaxies in quasar fields are summarized.
Do Pregalactic Shocks Trigger or Prevent Galaxy Formation?
Authors: Madsen Jes
Published: June 2019

Shock waves from supernova explosions in early stellar generations are likely to play an important role as a feedback mechanism in all models of galaxy formation. In particular in the explosive scenario, where the large scale distribution of galaxies is attributed to fragmentation of cooling gas in huge shocks expanding in a homogeneous medium.
Giant Arcs – Spherical Shells?
Authors: Dekel Avishai , Braun Erez
Published: June 2019

A noticeable fact about the giant luminous arcs, which have been detected in a few high-redshift clusters of galaxies (see contributions by Petrosian and by Mellier in this volume), is that they seem to be segments of almost perfectly circular rings – in one case spanning about one third of a circle. If this is a characteristic property of these arcs, they cannot be segments of randomly-oriented three-dimensional rings, which, when viewed from a random direction, should look acircular in most cases. Perhaps the most generic source for a circular ring is a limb-brightened luminous shell – as in planetary nebulae and supernova remnants. Such shells can naturally arise, for example, from explosion-generated shocks which cooled and fragmented into stars. If the sources are shells, and the arcs are either resolved or their thickness is determined by the seeing conditions (and by the CCD pixle size), there is a very general upper-limit on the possible surface-brightness contrast between the arcs and the regions encompassed by them. For the detected arcs, without any special finetuning, this limit is ≃ 3. It might become twice as big if the shell is transparent and the interior is opaque. This limit could exclude the shell model if the preliminary claims for a detected contrast greater than 10 are confirmed. It is interesting to note that the famous ring nebula presents a similar problem. We checked several mechanisms, such as stimulated radiation, which could, in principle, enhance the observed contrast while retaining the spherical symmetry; if such a mechanism is responsible for the enhanced contrast, it should show clear imprints on the spectrum. The figure shows the surface-brightess profile for a shell of thickness d.
Astrometry With The Yale Heliometer, 1882–1910
Authors: Hoffleit Dorrit , van Altena William
Published: June 2019

In 1880 Yale ordered a 6-inch heliometer from Repsold of Hamburg which was delivered on time for observations of the transit of Venus in 1882. Stellar astrometry, however, was not begun until W. L. Elkin came to Yale in 1884. Trained at Strassburg his Ph.D. dissertation dealt with the parallax of α Centauri (Elkin 1880). He then gained practical experience with Sir David Gill at the Cape. Elkin was the ideal man for the Yale heliometer and to secure his appointment H. A. Newton (1884) solicited subscriptions of $100 per year for three years from ten officers and friends of the observatory.
The Grubb Astrographic Telescopes, 1887–1896
Authors: Wayman P. A.
Published: June 2019

Thomas and Howard Grubb, father and son, made telescopes in Dublin from c.1830 to 1925. The elder Grubb's first telescopes of some size were the 1835 equatorial mounting of a 34-cm Cauchoix objective for E. J. Cooper of Markree Castle, Co. Sligo, Ireland, and a 15-inch reflector for Armagh Observatory (1840), which employed a centrifugal governor and the first mirror-cell with rocking support pads. The firm continued in Newcastle-upon-Tyne in England as Sir Howard Grubb, Parsons and Co.
Status Of Photographic Catalogs: Available Material And Future Developments
Authors: de Vegt Chr.
Published: June 2019

Starting with the Astrographic Catalogue as the first example of an all sky coordinated international astrometric project, a considerable number of large photographic catalog projects has been accomplished in the last decades on both hemispheres. The accuracy properties and possible improvements of some catalogs by remeasurement, application of modern reduction techniques and the use of improved reference star catalogs will be discussed.

The optimal use of modern photographic technology and instrumentation for the construction of new global catalogs, capable of positional accuracies on the level of a few 0.01 arcsec, will be outlined with special view to an extension to fainter limiting magnitudes.
A Very Special Catalogue: The Hipparcos Input Catalogue
Authors: Turon C.
Published: June 2019

The various characteristics of the HIPPARCOS Input Catalogue are described:

–

How to select 110 000 stars for HIPPARCOS observation from the 210 000 proposed stars, taking into account the following sometimes conflicting requirements : satisfy a maximum of scientific programmes and respect the observational constraints inherent in the HIPPARCOS satellite operation ?

–

What are the present results regarding the principal astrometric programmes ?

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How to process the specific problems which are raised by the HIPPARCOS observation of double and multiple stars and of stars in dense areas ?

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Which compilations and observations have been undertaken and are in progress within the frame of the Input Catalogue preparation ? What will be the quality of the final data ?

Finally, the contents of the catalogues and annexes that will be published are briefly presented.
The Tarija-Pulkovo Astrographic Catalogue Of The Southern Sky: First Results And Perspectives
Authors: Bystrov N.F. , Polozhentsev D.D. , Potter Kh.I. , Yagudin L.I. , Zelaya J.A. , Zalles R.F.
Published: June 2019

A project of a new photographic catalogue of southern stars was proposed in 1977 by Polozhentsev and Potter (1978). The observations for this catalogue were begun in 1982 with an astrograph (field 5°× 5°) placed at the Bolivian-Soviet observatory near Tarija, Bolivia. The astrograph has an aperture and focal length of 23 and 230 cm, respectively. A total of 6420 plates must be photographed to realize the fourfold coverage of the Southern Hemisphere with a 2° overlap in both coordinates and of these 6405 plates have been taken as of January 1, 1987. V.V. Avramchuk, S.P. Pulyaev, Kh.I. Potter (USSR) and R.F. Zalle, V. Yamaguchi, and E. Espinoza took part in the observations.
A Catalog Of Reference Stars For New Reductions Of The Astrographic Catalog Plates
Authors: Corbin Thomas E. , Urban Sean E.
Published: June 2019

A high density reference star catalog is being compiled at the U. S. Naval Observatory for the purpose of making new reductions of the Astrographic Catalog. The catalog will be a replacement to the SAO catalog and will be derived from the large photographic catalogs and the modern meridian circle catalogs. It is expected that the final catalog will contain 346, 000 stars, with proper motion mean errors generally or less, on a uniform system, the data having been reduced first to FK4 and then to FK5 using the International Reference Stars (IRS).
The Distance Scale of Planetary Nebulae
Authors: Liller Wm.
Published: June 2019

The spectacular success of the so-called Shklovsky method of finding distances to planetary nebulae which are optically thin to the Lyman continuum (Shklovsky 1956; see also Minkowski and Aller 1954) has produced within us a rather breath-taking boldness. Following the careful application of this method to more than 600 planetaries by Cahn and Kaler (1971), we now have the audacity to use planetaries as reliable distance indicators to derive an improved model of our own galaxy (Cahn 1976), trace the evolution of stars in their post-giant stages (O'Dell 1974, Cahn and Wyatt 1976), and even determine distances to other stellar systems (Ford, Jenner, and Epps 1973). At the Tatranská Lomnica meeting 10 years ago, there seemed little hope that one day soon planetary nebulae distances would become reliable. That day is near if not here already.
Advances in Ultraviolet Observations
Authors: Pottasch S.R.
Published: June 2019

Several groups have been involved in recent years in making ultraviolet observations of planetary nebulae from rockets and satellites. About 30 or 40 nebulae have been measured up to the present, some with reasonably high spectral resolution, more with band pass filters of 100 Å or more in width. All measurements have large diaphragms (or slitless systems) so that usually the nebula and the central star are observed together (there are large nebulae for which this is not true). The photometric accuracy of the later observations is quite good, usually better than 20%.
Observations of NGC 7662 from 1300 to 2850 Å
Authors: Bohlin R.C. , Stecher T.P.
Published: June 2019

An ultraviolet spectrum of NGC 7662 was obtained with a rocket-borne telescope in a 130 s exposure using a microchannel plate detector and film. In addition to the three strong ultraviolet lines of C III], C IV, and He II seen previously in NGC 7027, a new strong line of [Ne IV] at 2440 Å and a prominent continuum were measured in NGC 7662. The observed fluxes are given for both the lines and the continuum on an absolute basis, with a typical accuracy of about 25 percent. The absolute calibration is based primarily on in-flight observations of the stars α Lyr and α And, which have been well measured in the ultraviolet. This calibration is confirmed by laboratory data and by photoelectric observations from the ANS satellite.
New Absolute Intensities of the Emission Lines of 15 Planetary Nebulae the Members of the Galactic Centre Group
Authors: Vorontsov-Velyaminov B.A. , Kostyakova E.G. , Dukuchaeva O.D. , Arhipova V.P.
Published: June 2019

The new results have been obtained for 15 planetary nebulae, using the new spectrograms obtained at the Abastumany Observatory in 1971. The planetaries belong to the large Galactic centre group, studied by the authors earlier.
Emission Lines in the Near Infrared Spectra of Faint Planetary Nebulae
Authors: Andrillat Yvette , Houziaux Léo
Published: June 2019

We obtained spectra of twelve faint planetary nebulae at the Cassegrain focus of the 193 cm telescope at Haute Provence Observatory (dispersion: 230 Åmm−1 spectral range 8000–11000 Å, receiver: ITT image tube with SI photocathode).
Radio Spectroscopy of Planetary Nebulae
Authors: Chaisson Eric J.
Published: June 2019

The H110α radio recombination line has been observed toward the planetary nebulae NGC 7027, IC 418, and NGC 6543 in order to ascertain the physical characteristics of the bulk nebular gas. The observations of NGC 7027 confirm the earlier findings of Chaisson and Malkan (Ap.J., 210, 108, 1976) and Churchwell, Terzian and Walmsley (A&A, 48, 331, 1976) who reported evidence for a substantial increase in linewidth with principal quantum number. Attributed to electron-ion impact broadening (Stark Effect), the observations imply an electron density Ne ≃ 50,000/cm3. The LTE-derived electron-ion temperature Te ≃ 18,000°K agrees reasonably well with most radio-line analyses, as well as with previous analyses of the radio continuum, of forbidden optical line ratios, and of optical recombination lines and their associated continuum. IC418's HllOa line is also wider than radio lines observed at higher frequencies, suggesting a Stark Effect consistent with Ne < 20,000/cm3; NGC 6543 shows no appreciable line broadening, providing an upper limit to the density Ne < 10,000/cm3. The LTE-derived Te values for IC 418 and NGC 6543 are approximately 14,000 and 7000°K, reasonably consistent with those found by other techniques. On the basis of this and other recent studies, I suggest that the bulkemission in the Hnα recombination lines observed to date, 77 < n < 111, can be explained by a simple model of optically thin planetary nebular gas largely homogeneous in temperature and in density, and only slightly removed from LTE.
Observations of Central Stars
Authors: Lutz Julie H.
Published: June 2019

Central stars of planetary nebulae have long presented a difficult problem for observers because most of them are fainter than tenth magnitude and because emission lines from the nebulosity interfere with spectroscopy of stellar features. With the advent of numerous large telescopes and space telescopes it is possible to obtain detailed observations of many central stars. More observing time devoted to central stars has resulted in accurate observations of emission and absorption features in their optical spectra and in the discovery of binary systems among them. Satellites have made possible observations in the ultraviolet. As usual, recent studies have raised as many questions as they have answered. This review will concentrate on a few topics of current interest. The reader should consult Aller (1976) for a comprehensive review on central stars and for an excellent summary of magnitudes and spectral classifications of individual central stars.
Theoretical Abundances in Planetaries
Authors: Finzi Arrigo , Yahel Raphael
Published: June 2019

A satisfactory model of the formation of planetaries should explain the observations indicating that nitrogen and carbon in planetaries are overabundant by about one order of magnitude. These large abundances imply that substantial fractions of the galactic nitrogen and carbon originate from planetaries; one should then also investigate if the low value of the ratio C13/C12 measured on the Earth is compatible with an assumed dominant rate of the CNO cycle in the formation of planetaries.
Aluminum, Titanium and Magnesium Abundances in Planetary Nebula IC 2149
Authors: Gurzadyan G.A.
Published: June 2019

The relatively strong emission lines belonging to the singly ionized aluminum, titanium and magnesium are discovered on the shortwave spectrogram of planetary nebula IC 2149 obtained with the help of space observatory “Orion-2”. These lines are: 2669 AIII, 3080 Till and 2800 MgVI. At the same time this is the first evidence on the presence of chemical elements of aluminum, titanium and even magnesium (if we do not have in view the early identification of one very faint line, 4571 Mgl, in the spectrum of NGC 7027) in the composition of the planetary nebulae. As a result, the number of chemical elements discovered in planetary nebulae until now reaches up to 19 (from 16).
Dust in Planetary Nebulae: Observational Considerations
Authors: Balick Bruce
Published: June 2019

The question of dust in planetary nebulae dates back a decade to the first then unexpected discoveries of strong infrared (IR) excesses in planetary nebulae (Gillett et al. 1967; Woolf 1969; Gillett and Stein 1969, 1970; Neugebauer and Garmire 1970; Willner et al. 1972). It has been clear from the outset that a substantial fraction, if not most, of the nebular luminosity is somehow converted to IR radiation by the dust. Two important questions are whether, and to what extent, dust influences the ionization structure and chemical properties of the nebula.
Recombination Lines from Compact HII Regions
Authors: Silverglate Peter , Terzian Yervant
Published: June 2019

Radio recombination lines of hydrogen (H167ot) have been observed from 45 HII regions using the Arecibo telescope. Nine of these sources also show the C167a line, and twenty show H2103 lines. Some of the carbon lines, particularly those from W48 and G62.2 + 0.5, show a significant negative displacement from the H167a velocities. This can be explained if the lines originate in the ionization front or in neutral material swept up by the ionization front. The displacement is 3.8 km/sec for W48, and 5.7 km/sec for G62.2 + 0.5. The source G37.7 + 0.1 ex-hibited two H167a lines, one 25 km/sec wide at 87.3 km/sec and one 16 km/sec wide at 48 km/sec, velocities with respect to the local standard of rest. This may be a case of two HII regions in the same line of sight. Parameters for the HII regions, such as electron temperatures and densities, are derived. (Paper to appear in the Astronomical Journal.)
Planetary Nebulae and the Interstellar Medium
Authors: Salpeter E. E.
Published: June 2019

The requirements of the interstellar medium for ionization, heating and “stirring” are reviewed. The role of planetary nebulae is compared with that of supernova remnants and of OB-stars.
On the Dynamical Evolution of Clusters of Galaxies
Authors: Ostriker Jeremiah P.
Published: June 2019

The theory of the dynamics of star clusters (cf. Spitzer 1975 for a review) is by now so well developed that we have, or think we have, a moderately accurate picture of the physical processes acting in and the overall evolution of spherical systems. in contrast, flattened and/or rotating systems are apparently subject to a variety of ill-understood instabilities which ultimately are a manifestation of the second law of thermodynamics; at given total energy, a system will tend to increase the fraction of its kinetic energy in disordered rather than ordered form. But spherical systems (globular clusters, elliptical galaxies, Morgan cD clusters of galaxies) are relatively smooth and featureless; they show little substructure indicating, presumably, that they are quite stable to perturbations of their fundamental normal modes, and they are normally modeled as rather “hot”, pressure supported systems.
Variability of Magellanic Cloud Supergiants
Authors: Grieve G. R. , Madore Barry F.
Published: June 2019

Statistics on the variability of 127 high-luminosity, intermediate spectral-type supergiants in the Magellanic Clouds are presented.
Red Supergiants in NGC 300
Authors: Graham J.A. , Humphreys Roberta M.
Published: June 2019

Red supergiant stars that are members of the nearby Sc galaxy NGC 300 have been isolated by spectrophotometry and infrared photometry from a blink comparator survey of red stars in the general field of this highly resolved stellar system. Our spectroscopic criterion is the strength of the CaII triplet near λ8500 which is more than twice as strong in red supergiants as in red dwarfs. Red supergiants and dwarf stars also occupy distinct regions in a two-color (J-H) vs (H-K) diagram. Both methods clearly segregate the supergiants which, with visual magnitudes close to 19, must be members of NGC 300. Of the 18 red stars we examined, only 6 are probable members of NGC 300. The other 12 are likely foreground stars belonging to the Galaxy. A principal finding is that, unless special care is taken, contamination by foreground stars can be an important factor when the red stars of an external galaxy are selected only on the basis of their colors in the visual and near infrared spectral region.
Photospheric and “Chromospheric” CIV Lines in B-Main-Sequence Stars
Authors: Castelli Fiorella , Morossi Carlo , Stalio Roberto
Published: June 2019

The presence in the far-UV spectra of early-type stars of spectral lines of superionized atoms is argument of controversial debate among astronomers. Presently there is agreement on the non-radiative origin of these ions but not on the proposed mechanisms for their production nor on the proposed locations in the stellar atmosphere where they are abundant. Cassinelli et al. (1978) suggest that the Auger mechanism is operative in a cool wind blowing above a narrow corona to produce these ions; Lucy and White (1980) introduce radiative instabilities growing into hot blobs distributed across the stellar wind; Doazan and Thomas (1982) make these ions to be formed in both pre- and post-coronal, high temperature regions at low and high velocity respectively.
S Doradus Type; Hubble-Sandage Variables
Authors: Wolf B.
Published: June 2019

The luminous S Dor variables or Hubble-Sandage variables have gained considerable interest during the past few years for their exceptional (if compared to normal luminous hot stars) stellar wind properties. They seem to represent a short intermezzo in the evolution of the very massive stars prior to becoming WR stars. More recent results on S Dor variables (mainly of the LMC) are briefly summarized. Since most of the data have been or are going to be published elsewhere only an outline will be presented here.
A Large Sample of Emission-Line Stars in the Large Magellanic Cloud: Their Location in the Hertzsprung-Russell Diagram
Authors: Bohannan Bruce
Published: June 2019

The paths that massive stars follow in their evolution can potentially be determined by studying a homogeneous collection of luminous stars. In this investigation, mass-losing stars in a galaxy are studied through a sample of 59 H alpha emission-line stars in the Large Magellanic Cloud (LMC). The most luminous, most massive stars in the LMC, like their counterparts in the Galaxy, are losing mass at a rate that significantly alters their spectroscopic appearance and that affects their evolution.
The Average X-Ray Lifetime of Massive X-Ray Binaries
Authors: Hellings Paul
Published: June 2019

Massive X-ray binaries may be powered by two mechanisms generating X-radiation: accretion of stellar wind material of the O-star, or Roche lobe overflow (RLOF). The evolution of RLOF powered X-ray binaries has been studied by Savonije (1978). For massive binaries the duration of the RLOF powered stage is less than 100 years for binaries evolving through case B of mass transfer, and 5000 to 10 000 years for case A. On this basis Savonije concluded that the majority of the X-ray binaries should evolve through case A of mass transfer, in order to explain the observed number of active sources in massive binaries. In this study we compute the transition from compact+P systems into X-ray binaries, with emphasis on the wind powered stage.
New Stellar Associations in M31
Authors: Efremov Yu. N. , Ivanov G. R. , Nikolov N. S.
Published: June 2019

About twenty years ago van den Bergh (1964) recognized 188 OB associations in the Andromeda Nebula. He used plates taken by the 52-inches Tautenburgh Schmidt telescope in GDR. Later on Richter (1971) added 7 new associations in the south-western periphery of M31. Now we have the opportunity to continue the search of stellar associations in M31 with the 2m Ritchey-Chrétien (RC) telescope of the Bulgarian National Astronomical Observatory. The limiting magnitude of this telescope is approximately the same as that of the Tautenburg 2m Schmidt telescope but it possesses somewhat smaller field (1°x1°) with plate-scale 12.8 mm−1. That is why a new search of stellar associations in M31 by means of the 2m RC telescope is very efficient. Indeed, some previous inspections of the RC plates (Efremov, 1982) indicated some new associations in M31.
The Associations OB 110 and OB 112 in M 33 Galaxy
Authors: Kunchev P.Z. , Nikolov N.S.
Published: June 2019

The associations OB 110 and OB 112 in M 33 galaxy (Humphreys and Sandage, 1980) form a powerful group of young stars. This rich star cloud is situated far (∼6 kpc) from M 33 nucleus. The abundance of hot stars and its huge dimensions (900 × 1500 pc) make it similar to the association OB 78 (400 × 800 pc) in the Andromeda galaxy. We use distance modulus (m-M)v = 25.35 given by Sandage and Carlson (1983) and EB-V = 0.03.
CCD Observations of Young Stellar Associations and Multiple Systems in the Magellanic Clouds
Authors: Lortet M. C. , Heydari-Malayeri M. , Testor G.
Published: June 2019

The nebular and stellar observations were carried out by G. T. at the Cassegrain focus of the Danish 1.50m telescope at the ESO La Silla Observatory in August and September 1984, using a RCA CCD (512 × 320 pixels) with a pixel size of 0.47”. The frames were reduced using the VAX/MIDAS software at ESO Garching and Meudon Observatory (INVENTORY automatic program).
Neutral Hydrogen Observations of DI Galaxies in the Virgo Cluster
Authors: Hoffman G. L. , Salpeter E. E. , Helou G.
Published: June 2019

We are in the midst of obtaining 21 cm observations of late-type (Sdm through ImV, including BCD) dwarf galaxies in the Virgo Cluster, selected from the Binggeli, Sandage and Tammann catalog (1985, in press). To date, we have observed 174 of these objects; the sample is nearly complete to BT = 17.0. 114 have been detected, and 37 of the strongest emitters have been mapped at 119 spacing to determine HI diameters and rotation curves.
Contributions to the Local Gravitational Field from beyond the Local Supercluster
Authors: Yahil A.
Published: June 2019

IRAS 60μ sources are used to map the local (≲200h−1 Mpc, Ho =100h km s−1 Mpc−1) gravitational field, and to determine its dipole component, on the assumption that the infrared radiation traces the matter. The dipole moment is found to point in the direction of the anisotropy of the microwave background radiation. Comparison of the two anisotropies, using linear perturbation theory, yields an estimate of the cosmological density parameter, Ω =0.85±0.16, with nonlinear effects increasing Ωo by ∼15%. The quadrupolar tidal field within the Local Supercluster, due presumably to the same density inhomogeneities, is detected in a kinematical study of the velocity field.
Cosmological Consequences of an Unstable Heavy Neutrino
Authors: Padmanabhan T. , Vasanthi M. M.
Published: June 2019

In a recent paper Simpson has reported evidence for a heavy neutrino of about 17.1 kev mass. Cosmological bounds on stable neutrino species imply that this neutrino [νH] must be unstable. The most likely decay mode νH→νL+f where νL is a light neutrino and f is a scalar boson leads to a cosmological scenario which is quite different from the conventional picture. In this scenario universe becomes matter dominated at a redshift of z ∼ 107 and becomes radiation dominated [by the decay product νL of νH] at z ∼ 310. The kinematic constraints on the lifetime of νH do not lead to any contradictions. On the other hand, growth of baryonic perturbations is severely limited in this model due to two reasons: (i) virtually no growth can take place in the radiation dominated region z ≤ 310. (ii) Decay of νH is likely to disrupt and smoothen out past growth by a large factor. It is doubtful whether a simple way out of this difficulty exists.
CCD instrumentation at Capilla Peak Observatory
Authors: Laubscher B. E.
Published: June 2019

The astronomers at the University of New Mexico are applying the finishing touches to their CCD project. We addressed many issues during the course of this project, such as whether to build or buy the CCD camera system, what upgrades our telescope and observatory were in need of, and what kind of image processing capability the instrument demanded. Our decisions and solutions are presented as a guide to other institutions which may be considering CCD instrumentation for their small telescopes, especially since most face the same constraints that we do: limited money and manpower.
A new polarimeter for stellar polarisation measurement
Authors: Saxena A. K.
Published: June 2019

A polarimeter for the measurement of Stokes' parameters for stellar and quasi stellar objects in specific wavelength regions has been reported. The variable retardation and dispersive property of a small angle Babinet Compensator has been exploited for such measurement. The theoretical basis of the method is given in detail.
CCD camera for the 60cm telescope at Kagoshima Space Center
Authors: Takagishi K. , Matsuoka M. , Omodaka T.
Published: June 2019

A CCD detector has been developed for photometry and image detection with the 60cm reflector at Kagoshima Space Center. The structure and the manipulation of the instrument were simpified by the use of Peltier devices for cooling the CCD in order to eliminate thermal noise. A micro-computer system is used to control the instrument and process the data. A test observing run has demonstrated that a photometric sensitivity of 20th magnitude in the W band(3800-7000 Å) can be achieved in a 3600sec exposure.
To upgrade a telescope?
Authors: White Nathaniel M.
Published: June 2019

The effectiveness of existing telescopes can often be greatly enhanced through upgrading. Two important questions which should be answered in the planning stage are discussed, based on recent experience in upgrading two Lowell Observatory telescopes.
Asteroseismology with small telescopes
Authors: Kurtz D. W.
Published: June 2019

Study of the solar interior through analysis of solar oscillations, a field now referred to as helioseismology, has generated interest in the development of asteroseismology, the study of the interior of pulsating stars through the analysis of their oscillations. Some progress has been made in the study of the Rapidly Oscillating Ap stars, cool magnetic Ap stars which pulsate in high overtone, low degree non-radial p-modes with periods between 4 and 15 minutes. Since all of these stars found so far are bright (V<10), their light variations can be studied with small telescopes; most of the work done has been with a 0.5-m telescope. Their light variations are extremely complex, however, which means that they must be intensively observed, something which can only be done with small telescopes. Due to aliasing problems, multisite observing programs of the Rapidly Oscillating Ap stars are often necessary in order to decipher their frequency patterns. A collaborative observing program is suggested.
uvby photometry with a CCD
Authors: Anthony-Twarog Barbara J.
Published: June 2019

Initial observations using uvby filters with a CCD detector were completed in June of 1985, using the Cerro Tololo 4m PFCCD system. It has been possible to derive all Strömgren indices (b-y, m1 and c1) for V<18 from frames with acceptable integration times. For fields in the open cluster IC 4651, averages of 2 to 3 frames with exposure times of 15, 20, 40, and 500 seconds for the y, b, v, and u filters, yielded high precision magnitudes and indices for V<15. Exposure times up to 5 times longer were required for the v and u filters in order to derive c1 indices of sufficient precision for stars with V between 15 and 16. One result of our survey is the apparent absence of main sequence stars below V = 15.
The empirical period-radius relation for pulsating stars: a synthesis based on photometric and radial velocity measurements
Authors: Burki G.
Published: June 2019

The relation existing between the radius and the period for the pulsating stars of a given class constitutes a powerful test for the theory of stellar evolution and for the identification of the pulsation modes. In recent years, several authors have determined the mean radius of a lot of pulsating stars of various classes by applying the Baade-Wesselink method. Fig. 1 presents the resulting general logP - logR diagram grouping these determinations. The sources for the radii are given by Burki and Meylan (1986). The variable stars in known binaries have been excluded since the presence of a companion biases the radius calculation (Burki, 1984). The determinations marked by arrows are based on the radial velocities by CORAVEL (1m telescope at the Haute-Provence Observatory, France) or/and on the photometry in the Geneva system (40cm and 70cm telescopes at La Silla Observatory, Chile).
A new B-subdwarf eclipsing binary with an extremely short period
Authors: Menzies J W , Marang F
Published: June 2019

The B-type Subdwarf BD-07°3477 has been found to be an eclipsing binary with a period of about 2h48m. A preliminary analysis of the light curve reveals the system to be fully detached. It appears to be similar in many respects to the O-Subdwarf binary AA Dor which is thought to be the remnant of a system which has undergone a common envelope phase of evolution.
Photometry of selected Cepheids
Authors: Moffett Thomas J.
Published: June 2019

Cepheids with periods around 15 days sometimes show a reversal, or dip, in their light curves near phase 0.85. The theoretical interpretation of this feature is still in doubt. We present a list of suspected dip Cepheids, accessible to small telescopes, which need additional photometry to verify the dip.
A description of a catalogue of bright uvbyβ standard stars
Authors: Perry Charles L. , Crawford David L.
Published: June 2019

A description is given of an all-sky catalogue of bright standard stars for the uvbyβ photometric systems.
Instrumentation for low-resolution spectroscopy
Authors: Phillips M. M.
Published: June 2019

Instrumentation presently in use for low resolution, digital spectroscopy on 1 meter class telescopes at three observatories - Lick, Kitt Peak, and Cerro Tololo - is reviewed. A detailed comparison is made between the performance of a typical two-dimensional photon counter, the “2D-Frutti”, and currently-available CCDs. Prospects for further detector advances center on large-format, low-noise, uvsensitive CCDs.