bluuebunny/crossref_metadata_2025 huggingface dataset:
Dwarf Galaxies, Cold Dark Matter, and Biased Galaxy Formation
Authors: Dekel Avishai , Silk Joseph
Published: June 2019

The formation of dwarf, diffuse, metal-poor galaxies, as a result of supernova driven winds, is reexamained in view of the accumulating data on dwarfs in the local group and in the Virgo cluster. The observed drop in both surface-brightness and metallicity with decreasing luminosity is not easily understood if the gaseous protogalaxies are self-gravitating (because they swell after gas-loss), but they are produced naturally inside dominant halos, with a mass-radius relation that indicates ‘cold’ dark matter. The theory predicts for the faint dwarfs an M/L that increases with decreasing luminosity up to 10–100, and a corresponding slow decrease in velocity dispersion down to 5–10 km/s.
Anisotropy of the Microwave Background and Cosmological Dark Matter
Authors: Lukash V. N.
Published: June 2019

Both large and small-scale ΔT/T anisotropies of the microwave background are reviewed in the context of the modern theories of the Universe structure origin. A number of primordial perturbation spectra and various types of cosmological missing mass are considered. Theoretical predictions are compared with the observational data. Importance of the ΔT/T measurements on large angular scales (θ > 5°) is emphasized.
Constraints on Dark Matter Density and Axion Mass from the Large-Scale Structure of Spacetime
Authors: Joshi P.S. , Datta B.
Published: June 2019

On the basis of general properties of the large-scale structure of spacetime, we present new and general theoretical upper limits on the density of dark matter in the Universe, assuming a 90% content for the dark matter, and lower limits on the mass of the axion, assuming the dark matter to be made up of axions. These limits are derived in terms of the possible lower limits to the age of the Universe and the Hubble parameter. We find that for the age in the range (8–24) × 109yr, the maximum density of dark matter is in the range (1.25 × 10−28 −1.38 × 10−29) g cm−3 and the minimum value of axion mass in the ranges (0.36–2.39) × 10−5 eV and (1.44–9.51) × 10−5 eV.
Detector developments for small telescopes
Authors: Latham David W. , Geary John C.
Published: June 2019

We describe the performance expected from a new generation of CCD imagers being developed by Tektronix, and we indicate the types of applications, instruments, and computer systems that can best take advantage of these devices on telescopes both large and small. Since these new detectors will be able to reach very faint limits even on small telescopes, we also describe cost-effective television viewing systems suitable for object acquisition and guiding.
TV scanning applied for two dimensional photon counting imaging
Authors: Miyaki Sueo , Isobe Syuzo , Shinchara Nobuo
Published: June 2019

A system with an electronomulitplier of two-stage microchannel plate and a vidicon TV camera is developed for two dimensional photon-counting imaging and is applied for astronomical observations at the Nasmyth focus of the 75cm alt-az telescope of the Sundai Observatory at Kita-Karuizawa (SOK). Some test results are shown here.
Fick Observatory spectrum scanners
Authors: Beavers W. I. , Eitter J. J.
Published: June 2019

Three low-dispersion (15–50A/mm)−1 spectrum scanners have been developed at Fick Observatory as instrumentation for small telescope research and teaching activity. They have been applied in solar eclipse, zodiacal light, stellar, and comet research programs. The two plane grating spectrometers and one holographic grating instrument have been employed on telescopes ranging from 7.6 to 61 cm aperture, generally with f/5 to f/8 configurations. Recently, one of the plane grating instruments has been modified to perform as a four-channel spectrometer for quantitative spectral classification and composite spectra studies. This instrument is also being used to make spatial-spectral studies of the coma of Comet Halley, and other recent comets.
The instrumentation and observing program at Grinnell College's Grant 0. Gale Observatory
Authors: Cadmus R. R. , Melsheimer F. M.
Published: June 2019

Many small observatories are associated with undergraduate colleges at which research programs must be integrated with a broad spectrum of educational programs. The instrumentation and observing programs of Grinnell College's Grant O. Gale Observatory have been designed with this constraint in mind. Although modest by large observatory standards, the instrumentation incorporates contemporary technology such as solid state detectors and microcomputer control. Because a variety of student projects as well as a multi-faceted research program must share the telescope, often during a single night, the auxiliary instrumentation has been designed to eliminate almost all hardware changes associated with changes in observing technique (spectroscopy vs. photometry, for example). The auxiliary instruments are all interfaced to the data acquisition computer, which can also communicate with the telescope control system. Research programs have been selected both on the basis of scientific merit and compatability with our capabilities and constraints. We therefore concentrate on long-term observing programs which cannot be carried out at most large observatories and attempt to take advantage of our flexible instrumentation and computer-processing capability.
The automated patrol telescope
Authors: Cochrane J. W. , Mitchell P. , Payne P. W. , Storey J. W. V. , Webster B. L.
Published: June 2019

A new astronomical system is nearing completion at U.N.S.W. in which a charge coupled device (CCD) array detector is matched to a Schmidt telescope, with the observations completely analyzed on-line. We have modified a Baker-Nunn satellite tracking camera, with its excellent 0.5m, f/1 super-Schmidt optics, converting it into a computer-controlled equatorially-mounted astronomical telescope. The telescope is expected to be located at Siding Spring Observatory in north-western New South Wales.
The optical system of the Mt John one metre telescope
Authors: Nankivell G. R. , Rumsey N. J.
Published: June 2019

The telescope will be used at the Cassegrain focal plane only. Two interchangeable systems of secondary optics are required to give relative apertures of:

(a)

f/13.5 for spectroscopy and photometry over a small field.

(b)

f/8 for photography over as wide a field as practicable.
Observational polarimetry programs for small telescopes
Authors: Breger Michel
Published: June 2019

A number of promising observational programs involving linear polarization measurements are discussed after consideration of the observational limits based on telescope size and instrumental accuracy. These projects include studies of interstellar extinction, circumstellar shells and extended envelopes, inhomogeneities on stellar surfaces such as nonradial pulsation, magnetic stars, and interactive binary systems.
Occultations, past and future
Authors: Evans David S.
Published: June 2019

The techniques, advantages and limitations of photoelectric observations of occultations of stars by the Moon are reviewed. The results for timings, lunar limb slopes, double and multiple stars, and the determination of angular diameters of stars are considered. Possible effects of lunar limb irregularities are discussed. Observers are strongly recommended to pursue the upcoming series of occultations of Antares and other important stars.
Occultation studies with small telescopes
Authors: Millis Robert L.
Published: June 2019

Various types of occultations and eclipses offer individuals with access to small telescopes the opportunity to contribute significantly to modern solar system research. In fact, often it is only through the cooperation of several such observers that the desired scientific objectives can be realized. This review discusses three classes of occultations which are of high current interest and which are particularly suitable for investigation with small telescopes.
A search for features in early-type galaxies
Authors: Djorgovski S. , Ebneter K.
Published: June 2019

We are conducting a search for dust lanes, incipient stellar disks and bars, and other deviations from elliptical symmetry in a sample ∼ 250 early-type galaxies. Division by a model galaxy image is a very powerful enhancement technique for this type of work.
CCD scanning with a small telescope
Authors: Gehrels Tom
Published: June 2019

We use a scanning CCD for acquisition and astrometry of new and recovered comets, asteroids and other objects. The CCD is an RCA SID 53612 thinned, buried channel array of 512 × 320 30-micron square pixels that are back-illuminated and refrigerated to −60 C in a vacuum housing. The readout noise is ± 200 electron-hole pairs (ehp) per pixel per readout, the thermal dark current is 50 ehp/pixel/sec, and the scale of our 12-bit analog-to-digital converter is 25 ehp/AD unit. The Newtonian focus of a 91-cm telescope has been modified from f/5 to f/3.85 with a relay lens to give a platescale of 1.73 arcsecs per pixel, a scale chosen for efficient coverage of sky. The CCD is operated in the scanning mode with the telescope drive off, and the rate of transfer of signal charges is tuned to correspond to the rate at which the star images drift across the focal plane. The exposure time (the time the images take to transit the “512” dimension of the CCD) is 60 seconds at the celestial equator, giving a “six sigma” limiting (visual) magnitude of 19.5. A typical scan covers 30 minutes of time in right ascension by 0.156 deg in declination and is stored as a digital array of 14848 × 320 CCD pixels. A set of three 30-minute scans near the opposition point along the ecliptic nets about 5 new main-belt asteroids. Potential moving objects are revealed by determining the positions of all the stellar images in each scan and comparing the results of the three scans. Several potential reference (SAO) stars are in one scan. The reduction from pixel coordinates to apparent topo-centric equatorial coordinates of date involves only three free parameters, making our astrometric reductions simpler than the classical affine transformation of plate coordinates. There is no rotational transformation and the scale in right ascension is defined by the clock. The declination scale is determined from the reference stars. The zero points of R.A. and Dec. are given by the average differences between the pixel coordinates and catalog positions of the reference stars.
Search for variable stars in globular clusters
Authors: Hazen-Liller M. L.
Published: June 2019

A program to search poorly studied southern globular clusters for variable stars is being carried out on the 1-m Yale telescope at CTIO. Recently two galactic bulge clusters of moderately high metallicity have been found to contain RR Lyrae variables; a cluster of similar metallicity a little farther from the galactic center apparently has none.
Astrometry with small telescopes
Authors: Penhallow W. S.
Published: June 2019

At the Quonochontaug Observatory of the University of Rhode Island, we specialize in the development of simple seeing limited optical telescopes. Our main instrument is a heavy Serrier trussed f/10.7, .4-m astrometric reflector which provided the last-minute astrometry in the successful prediction of the occultation of SAO 120774 by Herculina in 1978. It is similar in design to the U. S. Naval Observatory 1.5-m reflector. Its scale of 47.1“/mm makes it potentially more powerful than the Lick .5-m, f/7 astrograph. However, its field of view of 1.3° × 1.7° is insufficient to capture enough AGK3R reference stars which are needed to consistently provide tenth-of-a-second-of-arc accuracy. To solve this problem, a .24-.32-m, f/6.3 lensless Schmidt was developed to provide a 3.8° field at 135”/mm and is mounted on the .4-m telescope. It can be used by itself and/or to provide a secondary reference frame for the main instrument. The measures from the plates and film are reduced by a suite of interactive computer programs which allows one to choose the proper reduction model based on the Eichhorn criterion. Over 100 positions of stars, asteroids, comets and supernovae have been provided with these instruments, and a regular observing program including participation in the IHW is underway.
The use of machine-readable astronomical catalogs at small observatories
Authors: Warren Wayne H.
Published: June 2019

The development of computer controlled telescopes at small observatories has dramatically increased the demand for and potential usefulness of astronomical catalogs in machine-readable form. The compilation and storage of catalogs containing program and standard stars are obvious necessities for the operation of an automatic telescope, but to date most observers have been collecting their own data and manually entering them into microcomputer disk storage. (This is clear from the small number of machine catalogs distributed by the ADC to smaller observatories.) Astronomical data centers located in several countries around the world currently archive, maintain and disseminate a wide variety of machine catalogs in virtually every discipline of astronomy, and these facilities can provide observers with nearly any kind of data needed for controlling telescopes (positional catalogs), reducing data (catalogs of all types of photometry, spectroscopy, etc.) and providing access to fundamental quantities needed for the interpretation of observations (catalogs of binaries, variables, radial and rotational velocities, etc.). The ADC presently has approximately 450 machine catalogs in its archives and these are available to observatories upon request. Procedures for obtaining data from the ADC and policies for distribution are described in this paper, while a list of all catalogs available can be obtained by contacting the ADC.
Small telescopes and research from space
Authors: Wisniewski W. Z.
Published: June 2019

The number of artificial satellites dedicated to astrophysical research is increasing rapidly. Nearly 30 satellites currently under development or in the early planning stages will be in orbit within 10–12 years and will have more sensitive detectors and better data-processing technology as a result of current research. Many of the galactic and extragalactic objects discovered by the new technology are variable on surprisingly short time scales ranging from sub-seconds to many months. The new variable objects include but are not confined to: neutron and binary stars; quasars (and associated active centers of galaxies); newborn infrared stars and associated clouds; the coronal activity of main sequence stars; cataclysmic variables (white dwarfs in binaries); and novae, supernovae and remnants. We now realize that the short time-scale variations of many unusual stars and active galactic nuclei demand that ground and space data be taken as close in time as possible and that they be carefully planned and coordinated.
Photometric and spectroscopic study of δ2 Lyrae
Authors: Bakos Gustav A. , Tremko Jozef
Published: June 2019

The bright star δ2 Lyr has been observed photoelectrically in the V and B pass bands for three years. The star is a long period variable with an amplitude of 0.2 mag and a period of 83 days. Light changes are coupled with small range velocity changes. On some well-exposed spectrograms the emission features of the H and K lines of CaII appear.
Spectroscopic surveillance of the variable Herbig Ae star AB Aur
Authors: Finkenzeller U. , Schiffer J.G.V. , Mandel H.
Published: June 2019

AB Aur = HD 31293 = BD + 300741 = MWC 93 = HRC 78n is one of the brightest members of a class of pre-main sequence objects introduced by G. Herbig in 1960. The star is characterized by a spectral type of AOVe, L/L⊙ = 70, mv = 7.2 mag, v sini = 140 km/s, and d = 140 pc. Assuming a stellar radius of a main sequence dwarf R/R⊙ = 3.0, one can estimate the rotational period to be on the order of 28 hours if we see the system edge on. Previous work (Praderie et al. (1985) and Finkenzeller (1983)) has focused on high resolution spectroscopy and shown that AB Aur is subject to short term variations. Finkenzeller's observations have indicated that the emission features can disappear completely within a day. Praderie et al. found evidence of a rotational modulation (45 ± 6 hours) of the MgII λ 2795 and FeII UV lines which is interpreted as due to a non-axisymmetric wind interacting with the outer atmosphere.
An off-the-shelf Reticon system
Authors: Honeycutt R. K. , Peery B. F.
Published: June 2019

EG&G Princeton Applied Research produces a Reticon detector system intended for laboratory applications. However, current versions of the system are well-suited to astronomical observations at observatories with modest financial and technical resources.

The detector inputs are intensified by microchannel plates, fiber-optically coupled to a 1024-pixel Reticon. Controller and readout electronics, and software for data pre-processing and graphical display are also available off-the-shelf, enabling the observer to put the system to use without a major development effort.
Spectral classification of eclipsing binaries
Authors: Wolf George W. , Kern Janet T.
Published: June 2019

Approximately 375 classification spectra of 130 Southern Hemisphere eclipsing binary stars were obtained between 1978 and 1982 at Mt. John University Observatory, New Zealand using the 0.6 meter reflector, and at Cerro Tololo Inter-American Observatory, Chile using the 0.4, 0.6, 0.9, and 1.0 meter telescopes. The spectra have been classified by one of us (GWW) using a grid of standards obtained on the various spectrographs at each of the observatories. Since many of the spectra were taken during primary and secondary minima, it has been possible in many cases to classify separately each component in the binaries.
Ion-Molecule Reaction Studies below 80 K by the CRESU Technique
Authors: Marquette J. B. , Rowe B. R. , Dupeyrat G. , Poissant G.
Published: June 2019

The basic principles of the CRESU technique (Cinétique de Réactions en Ecoulement Supersonique Uniforme) are presented. This technique allows ion-molecule reaction rate coefficients under true thermal conditions at interstellar temperatures. Various behaviors of both third-body association and binary reactions with temperature have been observed, including ion-polar molecule reactions whose rate coefficients sharply increase at very low temperatures.
Excitation-Deexcitation of N2+ (B2Σu+, v = 0) Rotational states in a Diffuse Plasma
Authors: Ghosh P. K. , Roy Chowdhury U.K.
Published: June 2019

While sharply different rotational temperature for the lower and higher rotational states of H2 have been observed in astrophysical situations, studies on heavier molecules are less encountered. We report here results of plasma spectroscopic studies on the nitrogen system where the FNS bands (0,0) and (0,1) show much distinctive ‘two-temperature’ phenomena, the departure from the high rotational temperature part (840 ± 50°K and 920 ± 30°K respectively) being perceptible at N' (N' + 1) ≅ 160. the experimental system is an electron beam sustained magnetoplasma at 5 × 10−3 torr, with kTe ≅ 1.5 eV and ne ≅ 4 × 1010 cm−3 obtained from in situ measurements of plasma parameters. Relative excitation-deexcitation rates of the N2+ B2Σu+ rotational states and also in relation to those of H2 are discussed.
Molecular Life-Time against Photodissociation in Dark Interstellar Clouds
Authors: Aiello S. , Barsella B. , Cecchi-Pestellini C. , Mencaraglia F. , Rosolia A.
Published: June 2019

Molecules in the interstellar space are exposed to interstellar radiation, so that they are destroyed by photodissociation processes, leading to the production of smaller molecules and ions, which in turn can react with other molecular species. Therefore, dissociation rates and dissociation products are important for the chemistry of interstellar molecules. This holds true also for relatively opaque and dense clouds (τ ≲ 10 in the visual), due to the multiple scattering of UV radiation by dust.
High Resolution Spectral Studies of some Diatomic Molecules of Astrophysical Interest
Authors: Balasubramanian T. K. , Bhale G. L. , Gopal Sheila , Krishnamurthy G. , Lakshminarayana G. , Saksena M. D. , Saraswathy P. , Shetty B. J. , Singh Mahavir
Published: June 2019

Laboratory studies have been made on molecules of astrophysical interest such as AlO, CO, CrO, SiS, NH+and OH. Vibrational and rotational constants have been determined more accurately in the various electronic states.
Oscillator Strengths for Visible and Ultraviolet Observations of Interstellar Molecules
Authors: Smith Peter L.
Published: June 2019

The accuracy of the information obtained from observations of optical-wavelength, molecular absorption features in interstellar clouds is directly limited by the accuracy of the rotational-line oscillator strengths used in the analysis of data. This paper briefly discusses optical observations of molecules in interstellar clouds; surveys molecular lifetime and oscillator strengths; and reviews laboratory techniques for obtaining these data.
Evolution of Zero-Metal Clouds
Authors: Villere K. R. , Bodenheimer P. H.
Published: June 2019

Dynamical, chemical and thermal evolution of zero-metal gas clouds has been modeled to study conditions of star formation in the early universe. Numerical results are shown for collapse of a spherical cloud of mass 5 × 105 M⊙. Cooling by H2 lines and by photons emitted in H + e- → H- + hν maintains collapse until formation of an equilibrium protostellar core with mass 0.03 M⊙. the cooling by photons produced with H- is essential for low-mass star formation. If the cloud is fragmented, the evolution of each piece resembles that of the parent cloud.
Radio and Millimetre Observations of Less Complex Molecules
Authors: Guélin Michel
Published: June 2019

Progress in laboratory and astronomical instrumentation has renewed the already large interest for simple astrophysical molecules. On the laboratory side, one of the most notable advances has been the spectroscopic observation of an increasing number of small reactive molecular species. On the astronomical side, the access to submillimetre wavelengths and the completion of millimetric interferometers and large single-dish telescopes, have allowed the detection of many new molecular species and open the way for detailed studies of the distribution of molecules in interstellar and circumstellar clouds.
Formaldehyde Abundances in the Dense Molecular Cores DR 21 and W 3(OH)
Authors: Dickel H. R. , Goss W. M. , Rots A. H.
Published: June 2019

Formaldehyde absorption has been observed with the Very Large Array in both the 6 cm and 2 cm transitions towards a number of ultracompact HII regions which are embedded in the dense cores of molecular clouds. Such data have been compared with the results of radiative transfer calculations to derive the distributions of the molecular hydrogen density and of the abundance of formaldehyde relative to molecular hydrogen. Results are presented for the sources DR 21 and W 3(OH).
A Survey of the Yellow-Red Interstellar Diffuse Spectrum Lines
Authors: McNally D. , Ashfield M. , Baines D.W.T. , Fossey S. , Rees P.C.T. , Somerville W. B. , Whittet D.C.B.
Published: June 2019

A survey of about 100 lines of sight was made using the coudé auxiliary telescope and the coudé spectrograph of the Shane 3m telescope of the Lick Observatory. the data acquisition required 7 observing seasons. the spectra were recorded photographically at 17Ao/mm using a Varo tube intensifier. Each plate was separately calibrated for intensity and wavelength. the plates were measured using the PDS microdensitometer of the Royal Greenwich Observatory, Herstmonceux, and that data reduced on STARLINK using procedures developed by D.W.T. Baines. Care was taken to treat all photographic material in a consistent manner throughout the duration of the survey. the reduced data may therefore be considered self-consistent. the emulsion types used were (principally) Kodak IIIaF and (more rarely) 103aD.
The Distribution of Molecular Hydrogen in Planetary Nebulae
Authors: Storey J. W. V. , Webster B. L. , Payne P. , Dopita M. A.
Published: June 2019

A correlation has been found between strong molecular hydrogen emission and the morphological type of a planetary nebula. Those with an equatorial toroid and bipolar extensions have H2 1−0 S(1) stronger than Brackett γ. H2 maps of several objects, and NGC 2346 in particular, are consistent with a fast stellar wind interacting with an anisotropic medium.
Evidence for a 12 Micron Water-ice Absorption Band in the IRAS LRS Spectra of Protostars and Late type Stars
Authors: de Muizon M. , d'Hendecourt L.B. , Perrier C.
Published: June 2019

We present evidence for a 12 micron absorption band due to the librational mode of the H2O molecule in the form of ice in some IRAS LRS spectra. This identification is based on the 3 micron spectrophotometry of these objects showing the presence of the 3 micron ice band. From these spectra, physical characteristics of the ice can be discussed.
Masers in Circumstellar Shells
Authors: Walmsley C. M.
Published: June 2019

Presumably due to a cosmic accident, circumstellar masers are almost exclusively found in oxygen rich stars with [0/C] >1. The exception here is the SiS maser found towards IRC 10216 (Henkel et al. (1985)) but I will ignore this in what follows and concentrate this review upon the circumstellar shells where OH, H2O, and SiO masers are found in profusion. Such objects are thought to be on the asymptotic giant branch (AGB) of the Herzsprung-Russell diagram and show evidence for rapid mass loss. The derived mass loss rates vary from approximately 10−7 solar masses per year for the optically well studied Mira variables in the solar neighbourhood (Distances <1 kpc) to as high as 10−4 solar masses per year for the optically invisible OH-IR stars and for some supergiants. of these objects, the supergiants appear to be more luminous than the rest (105 L rather than 104 L) and their central stars have masses of order 10 M⊙ as compared to most Mira variables whose mass is probably in the range 1–2 M⊙. Most OH-IR stars are likely to be a late stage in the evolution of solar mass type objects where the mass loss rate suddenly increases. As their name indicates, they are characterised by their strong OH-maser (1612 MHz) emission as well as by their radiation at far infrared wavelengths (20–50 μ). They may well be on the way to becoming planetary nebulae (see Pottasch, 1984 for an account of their probable evolution).
Observations of Molecules in Comets
Authors: Feldman P. D.
Published: June 2019

Ultraviolet and visible spectroscopy of comets has identified a large number of species in the coma, most of which appear to be the photodissociation and photoionization products of the “parent” molecules evaporated directly from the cometary nucleus. Analyses of cometary spectra support the icy conglomerate model of the nucleus with H2O as the dominant ice species. Two molecules detected in the ultraviolet, CO and S2, are of particular interest to the study of the cosmogonic evolution of cometary grains. CO appears to be a highly variable constituent from comet to comet, while S2, first observed in comet IRAS-Araki-Alcock in 1983, is found in no other celestial source. Both of these molecules appear to be parent molecules.
Are there Diagnostic Spectral Features of Irradiated Cometary Ices?
Authors: Khare B. N. , Murray B.G.J.P.T. , Sagan C. , Thompson W. R. , Arakawa E. T.
Published: June 2019

There is now evidence that at least some cometary nuclei are dark and red. Cometary ices prepared from combinations of CH4 with H2O and sometimes NH3 were irradiated at 77 K by corona discharge. CH4 - containing ice reddened and darkened at a dose ~1011 erg cm−2 over a period of ~1 hour. Upon evaporation of the now yellowish, irradiated ice, a slightly yellowish colored solid film remains on the walls of the container at room temperature. Transmission measurements of this organic film (called cometary tholin) were made from 0.2 μm to 50 μm wavelength. Strong UV absorption is seen from 0.45 μm to 0.2 μm. Above 0.45 μm, the spectrum remains flat to ~1.3 μm in the near infrared, except for a very small feature near 1.15 μm. A medium sized feature appears centered at 1.4 μm with shoulders at both sides and a nearby weaker feature at 1.52 μm. A strong feature appears at 1.9 μm accompanied by a smaller feature at 1.78 μm. in the region 2.5 μm to 50 μm, the infrared spectrum was taken by dispersing the film in a CsI matrix. Bands are found at 2.92(M), 3.36(S), 3.40(S), 3.46(M), 3.48(M), 5.75(M), 5.99(S), 6.21(M), 6.83(M), 7.30(S), 7.81(W), 8.89(M), 9.26(M), 20.00(W), 22.22(W), and 28.57(W) micrometers, suggesting complex organics including alkane, alkene, aldehyde, and carboxylic acid functional groups. These results are also relevant to UV and cosmic ray processing of interstellar grains, and to icy bodies in the outer solar system.
Reflectance Properties of Irradiated Simulated Cometary Ices
Authors: Arakawa E. T. , Khare B. N. , Murray B.G.J.P.T. , Sagan C. , Thompson W. R.
Published: June 2019

In the prevailing icy conglomerate model of the cometary nucleus, the outer surface is processed by galactic cosmic rays in the Oort cloud. Most ices composed of CH4, along with H2O and/or NH3, studied in our laboratory redden and darken upon charged particle irradiation from a high frequency corona discharge at 77 K. Spectral reflectance relative to a BaSO4 standard in the wavelength interval 0.39 μm to 0.70 μm was measured for incidence angle, i = 0° and emission angle, ε = −4°. CH4-containing ice at 77 K was modified at a dose ~1011 erg cm−2 over a period of ~1 hour. Progressive darkening followed continued irradiation. The ratio of the red to blue reflectance [R(λ = 0.70 μm)/R(λ = 0.40 μm)] changed from 0.9 to ~1.4. Using techniques of ellipsometric polarimetry, we are investigating the detailed optical properties (complex refractive index) of these ices before and after irradiation. These results may then be compared with the properties of cometary coma particles predicted by recent light scattering models to determine which classes of laboratory-produced materials best match the population of dark, reddish particles which seem to be prevalent in some cometary comae.
Observations of the HCN Molecule in Comet Halley
Authors: Despois D. , Forveille T. , Schraml J. , Bockelée-Morvan D. , Crovisier J. , Gérard E.
Published: June 2019

We report here the detection of the J 1-0 rotational line at 88.6 GHz of hydrogen cyanide in comet Halley. Six observational runs were made in the Nov. 19-Dec. 3 1985 period with the IRAM 30-m millimetre radio telescope at Pico Veleta (Spain), when the comet was at rh ~ 1.56 AU from the Sun and Δ ~ 0.63 AU from the Earth.
Laboratory Spectra of 10 K ICEs: A Comparison with Some Astronomical Spectra
Authors: d'Hendecourt L.B.
Published: June 2019

A series of experiments in which mixtures of ices are irradiated with ultraviolet light have been performed. the evolution of these simulated interstellar grain mantles is followed by infrared spectroscopy. the appearance of new bands is observed and possible identifications of these bands are discussed.
Identification of Polycyclic Aromatic Hydrocarbons
Authors: Léger A. , D'Hendecourt L.
Published: June 2019

The nature of the Very Small Grains evidenced by K. Sellgren (1985) is discussed. Their stability suggests that they are graphitic material and specifically Polycyclic Aromatic Hydrocarbons (PAHs). The expected IR emission of a typical PAH, coronene, gives an impressive spectroscopic agreement with the five observed “Unidentified IR Emission Features”, leading to an unambiguous identification. Those PAHs are the most abundant organic molecules detected to this date (f ~ 10−5).
Astrochemistry — A Summary
Authors: Dalgarno A.
Published: June 2019

A brief summary of the content of the papers comprising the symposium is presented.
Observations of Molecules in Stellar Atmospheres - Chemistry Near Thermal Equilibrium
Authors: Lambert David L.
Published: June 2019

A general review is given of the astrophysical information obtainable from observations of molecules in stellar photospheres. Through selected examples, the use of molecules as thermometers (e.g., the OH 3 μm V-R lines in the Sun and α Ori) and as probes of the isotopic (e.g., iMg in metal-poor dwarfs, 12C/13C in cool carbon stars) and elemental abundances (e.g., CNO in red giants) is sketched. All of the (carefully) selected analyses assume that local thermodynamic equilibrium (LTE) prevails.
The First Byurakan Survey (FBS) and Search Problems for AGN
Authors: Lipovetsky V.A. , Markarian B.E. , Stepanian J.A.
Published: June 2019

The history of the First Byurakan Survey carried out to search for AGN is shortly described. The sample completeness for different classes of objects: Sy1, Sy2, QSO, BL Lac objects is estimated as 0.6, 0.4, 0.4 and 0.6, respectively. The lack of radioquiet BL Lac objects as a whole class is shown. Different search procedures of AGN are compared, their perspectives are evaluated.
The Second Byurakan Spectral Sky Survey
Authors: Markarian B.E. , Stepanian J.A. , Erastova L. K.
Published: June 2019

The method of the Second Spectral Survey carried out with the Byurakan 1-m Schmidt telescope is discussed. The limiting magnitude is fainter in comparison with the First Byurakan Survey at about 2–3m.

The results of low dispersion (500 objects) and slit spectroscopy (300 objects) based on observations with the 6-m telescope of Special Astrophysical Observatory for four fields of the Second Survey are presented.

The luminosity function of faint UV galaxies is discussed. The completeness of AGN of the Second Survey and their surface and space densities are also estimated. The surface density of QSO and ELG is estimated and these data are compared with the results of other surveys.

New observational data obtained with the 6-m telescope are compared with the new data of different deep surveys carried out during last years.
UV-Galaxies
Authors: Khachikian E. Ye.
Published: June 2019

At the present time the previously used term “Peculiar galaxy” is gradually being replaced by the term “active” galaxy. This is quite natural, because the overwhelming majority of “peculiar” galaxies turned out to be “active” at the same time. The opposite is not correct: there are a lot of examples where a galaxy looking normal is physically active.
The Byurakan Classification and the Colours of the Central Parts of Spiral Galaxies
Authors: Tovmassian H.M. , Hakopian S.A.
Published: June 2019

The statistical study of the U-B, B-V colours of the central regions of galaxies of different Byurakan classes show the presence of UV-excess emission in the nuclear regions of the majority of galaxies of types 5 and 2s.
Spectral Variability in Seyfert Galaxies
Authors: Peterson B.M.
Published: June 2019

Recent observations of spectral variability in active galactic nuclei have established the connection between the broad emission-line and optical continuum flux changes. The inferred size of the broad-line region is at least an order of magnitude smaller than conventional estimates based on photoionization models, which leads to new conclusions about the nature of the broad-line region.
1–3-Day Variations of the Broad Emission Lines of Seyfert Nuclei
Authors: Bochkarev Nikolay G.
Published: June 2019

One of the principal problems of investigation of AGNs is to understand the nature of the central objects and the physical processes which yield their gigantic luminosities. This requires us to consider the innermost parts of AGNs (3–30 gravitational radii, i.e. ≲ 1016 cm: angular size less than 1 milliarcsecond).

1–3d variations of the relative shape of broad emission line profiles of active galactic nuclei (AGN) are perhaps the most informative probe of the innermost parts of AGNs (r = 1015–16 cm from the centre). Optimal objects for these observations are Sy 1.5 with strong variations of the non-thermal continuum (e.g. NGC 4151). The expected amplitude of the variations ranges from a few percent to 10–20%. The optimal spectral resolution is 0.5–5 Å. It is very desirable to complement spectral observations with photometric data. The results of the first set of such observations with the 6-meter telescope are reported.
Unity and Diversity Among Jets in Active Galaxies
Authors: Keel William C.
Published: June 2019

Jets, and more general kinds of directed flow, are increasingly seen as important aspects of the activity of galactic nuclei. Their frequent presence, on scales from parsecs to megaparsecs, in radio galaxies implicates jets in the production of radio lobes, and instances have been found of jets apparently “frustrated” and disrupted in gas-rich galactic disks. Jet-like emission is occasionally found on small scales around Seyfert nuclei, with some observations suggesting links to nuclei at yet lower levels of (radiative) activity.
VLBI Observations of NGC4151 at 6 cm Wavelength
Authors: Preuss E. , Alef W. , Pedlar A.
Published: June 2019

The fraction of Seyfert galaxies containing linear radio sources is quite substantial and may be more than 50% (Ulvestad and Wilson 1984). About 20 of the well resolved Seyfert galaxies show double or triple structure on the arcsec scale. In this respect these objects are very reminiscent of the classical radio galaxies, but they are typically smaller than these by several orders of magnitude, both with regard to power ∼ 1039–1041 erg/s and linear extent kpc (Wilson, this volume). They are basically confined in the wider nuclear environment. The central small scale () radio sources in Seyfert galaxies are very weak, mJy at 6 cm wavelength, and have therefore hardly been observed with VLBI (see, e.g. Preuss 1984).
The Primeval Hadron: Origin of Rotation and Magnetic Fields in the Universe
Authors: Muradian R.M.
Published: June 2019

The problem of the origin of celestial bodies - stars, galaxies and their clusters - is discussed proceeding from the concept of superheavy strongly interacting elementary particles termed superhadrons.

Starting from generalized Regge law the universal relationship between mass and intrinsic angular momentum of cosmic objects has been established. Expressions are obtained for parameters of stars and Universe via fundamental constants. The prediction of the global rotation of the Universe is discussed and the problems of cosmic magnetic fields and energy problem in active galaxies are considered.
Low-Luminosity Active Nuclei in Elliptical Galaxies
Authors: Sadler Elaine M.
Published: June 2019

The results of a sensitive radio and optical survey of nearby early-type galaxies show that most (perhaps all) bright ellipticals have ‘active’ nuclei. These are characterized by a central non-thermal radio source and a weak LINER-like optical emission spectrum. There appears to be a smooth continuity in optical and radio properties from the weakest nearby sources to strong radio galaxies. Galaxies with radio sources usually show optical emission lines, but there is no simple relationship between gas content and radio power.
VLBI Observations of the M81–M82 Pair of Galaxies
Authors: Bartel Norbert , Ratner Michael , Shapiro Irwin , Rogers Alan
Published: June 2019

VLBI observations show that the center of the nearby (~ 3.3 Mpc distant) spiral galaxy, M81, consists of a single elongated radio core, of dimensions 1000 × 4000 AU, with the major axis aligned, in projection, within 3° (<1σ) of the galaxy's rotation axis. This morphology can be interpreted in terms of an active galactic nucleus (AGN) with either a core-jet structure residing in M81's center or an accretion disk filling out the broadline region of this center. In contrast, the radio structure in the companion galaxy, M82, is very complex. VLBI observations of M82 yield the diameters and spectral index distribution of the hot spots, and the morphology and expansion velocity of the brightest hot spot, 41.9+58. Our results argue against the hot spots being core and jet condensations, or young supernovae (SNe), or typical supernova remnants (SNRs). We suggest that the hot spots in M82 are the remnants of stellar events that yielded some combination of SNRs and “exotic” objects.
Theory of bipolar flows and jets from young stars
Authors: Norman Colin A.
Published: June 2019

Current thinking on the origin, evolution and stability of stellar jets and bipolar flows is reviewed. Particular emphasis is given to the driving mechanisms of bipolar molecular and ionised gas outflows from young stellar objects. General constraints on both hydrodynamic and magnetohydrodynamic flows are presented. The interrelationship between the protostellar outflows and others such as those associated with powerful, highly collimated outflows in active galactic nuclei are discussed. Intimately connected phenomena such as maser sources and Herbig-Haro objects are briefly treated and finally, areas of potentially interesting future research are indicated.
Radio emission from young stellar objects in the Rho Ophiuchi cloud
Authors: André Ph. , Montmerle T. , Feigelson E.D. , Stine P.
Published: June 2019

Following an Einstein X-ray survey of the rho Oph molecular cloud, uncovering several dozen young stellar objects (YSO) (Montmerle et al. 1983), an extensive radio continuum VLA(C) survey was conducted in 1983 to look for counterparts to these sources at 1.4 and 5 GHz (André et al. 1986) To shed light on emission mechanisms, we performed follow-up VLA(A/B) observations of identified radio stars in March 1985 at 1.4, 5 and 15 GHz.
Hypersonic jets from young stars in molecular clouds
Authors: Blome Hans-Joachim , Kundt Wolfgang
Published: June 2019

We argue that the narrow jets which are sometimes seen to escape from YSOs into an ambient molecular cloud consist of e±-plasma which can be created in stellar magnetospheric discharges and subsequently centrifugally post-accelerated. This high-pressure pair plasma is squeezed into two jets which ram cocoons into the molecular cloud, observed in the form of molecular lobes (outflows).
A precessing jet in L1551
Authors: Lightfoot J. F.
Published: June 2019

An analysis of published observations of the L1551 optical jet leads to the conclusion that the driving region is very small, possibly little larger than the star itself. Further the data suggest that the jet is precessing.
Molecular outflows and mass loss in pre-main-sequence stars
Authors: Levreault Russell M.
Published: June 2019

We have conducted a survey for molecular outflows toward 71 pre-main-sequence stars using the J = 2 → 1 transition of CO. Outflows were detected and mapped toward 20 of these objects and in an additional six background sources not included in the original survey. The outflow sources range in mass from 0.5 to 30 M⊙, in luminosity from 4 to 1.1 × 105 L⊙, and in age from < 104 to ~ 106 years. In the H-R diagram, the outflow sources form a distinct band running across the top of the diagram.

Roughly half of the observed outflows are bipolar at some level; the rest show a rich variety of morphologies. In addition to the CO (J = 2 → 1) data, we have obtained CO (J = 1 → 0) and 13CO (J = 1 → 0) observations that enable us to estimate the excitation temperature and optical depth in each outflow, leading to the derivation of outflow masses. The observed outflows range in mass from 0.01 to 56 M⊙, in size from < 0.07 to ~ 5 pc, and in age from ~ 103 to 5 × 105 years old.

Simple momentum conservation arguments are then used to derive the mass loss rates necessary to produce the observed outflows. The results range from ~ 10−8 to ~ 10−3 M⊙ yr−1. Correlation of these mass loss rates with other parameters shows that pre-main-sequence mass loss goes as the square root of the bolometric luminosity and as the 1.7 power of the stellar mass. Implications for these findings on the nature of the pre-main-sequence mass loss mechanism, for self-regulated low-mass star formation, and for formation of the terrestrial planets are discussed.
V645 Cyg - On the structure of a YSO
Authors: Schulz A. , Black J.K. , Lada C.J.
Published: June 2019

In the CO(J=3−2) line we observe a bipolar outflow in V645 Cyg. The physical properties of the neutral flow gas and its geometry put new constraints on the structure of this YSO.
Star formation in the southern complex region NGC 3576
Authors: Persi P. , Perrari-Toniolo M. , Spinoglio L.
Published: June 2019

NGC 3576 (RCW 57) is a very bright optically visible nebula (~10' in size) located near the galactic plane at a distance of 3.6kpc. The region is associated with the HII region G291.28–0.71 (Retallack & Goss), and with a giant molecular cloud of M≃9×104 M⊙ (Cheung et al.1980) The source is reported in the IRAS Small Scale Structure Catalog. From the observed far-IR fluxes we derive a total luminosity of L(FIR)≃7×105 L⊙, suggesting that at least seven possible 07–09 stars could ionize the entire observed region. A cluster of five IR sources and extended 10μm emission were found by Frogel & Persson (1974). IRS 1 is a very compact object (<3'), while IRS 2–5 show diffuse infrared emission. In addition IRS 2, very close to IRS 1, is coincident with the radio emission peak. An H2O maser source and NH3 emission are present in the complex region.

We present multidiaphragm photometry from 1 to 20μm of 1RS 1, IRS 3 and IRS 4 and CVF observations between 2-μm and 8–13μm of IRS 1, collected at the 1m and 3.6m ESO telescopes.
An observational study of the Herbig Ae star VV Serpentis, and of R-stars associated with its dark cloud
Authors: Chavarría-K. C. , Ocegueda J. , de Lara E. , Finkenzeller U. , Mendoza E.
Published: June 2019

In this work we give a revised distance (250 ± 20 pc) to the star VV Serpentis and its associated dark cloud complex, redetermine its spectral type (= A2e, see also Herbig, 1960, ApJ Suppl. 4, 337), and report on observations of previously unknown associated emission line stars, and of stars with associated reflection nebulosity (R-stars) belonging to the same region.
Stellar wind flows in T Tauri stars
Authors: Sá C. , Lago M.T.V.T. , Penston M.V.
Published: June 2019

Following the successful modelling of the wind from RU Lupi using data at moderate and high dispersion we report on similar observations of other T Tauri stars where the general pattern of the wind, as deduced from the widths of the emission lines of the various species, seems to be similar.
The circumstellar environments and variability of RY and RU Lup
Authors: Hutchinson M. G. , Evans A. , Davies J. , Bode M. , Whittet D. , Kilkenny D.
Published: June 2019

The variability of the two T Tauri stars RY and RU Lup has been monitored between 1980 and 1984 at both optical and infrared wavelengths. We present here a preliminary analysis of the data and suggest possible mechanisms for the observed variability.
Near-IR observations of the SSV 13, SSV 9, SSV 5 sources in NGC 1333
Authors: Busso M. , Persi P. , Robberto M. , Scaltriti F. , Silvestro G.
Published: June 2019

The sources (1) SSV 13 (identified with the IRAS (2) source 03259+3105), SSV 9 (IRAS 03256+3107), SSV 5 (IRAS 03262+3108) were observed photometrically in the JHKL bands with the In-Sb photometer at the Italian IR Telescope (TIRGO, Gornergrat, Switzerland). In addition CVF spectrophotometry between 2.0 and 2.4 μm of SSV 13 was carried out. We present a study of the energy distribution between 1 and 100 μm, including both our photometry and IRAS data.
GSS 31: Another T Tauri star with an infrared companion
Authors: Zinnecker Hans , Chelli Alain , Carrasco Luis , Cruz-Gonzales Irene , Perrier Christian
Published: June 2019

Using a rapid slit scan technique in the infrared (JHKL), the source GSS 31 (alias EL 22 or Do-Ar 24E), a T Tauri star in the Ophiuchus dark cloud, was discovered to be double at a projected separation of 1.“95±0.”10 (i.e. 320 AU). The position angle is almost exactly north-south. This is the second discovery of its kind, and the first in the southern hemisphere, the only previous case known being T Tauri itself (Dyck et al. 1982, Schwartz et al. 1984). The important point is that we were able to secure infrared photometry separately for both components while for T Tau the separation into two components was model-dependent due to their small separation (0.6). IR-photometry for the joint system GSS 31 had previously been obtained by Grasdalen, Strom & Strom (1973) and Elias (1978), while Chini (1981) obtained UBVRI photometry.