bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Environmental Condition (Light Pollution and Radio Interference) of Chinese Astronomical Observatories, Past, Present, and Future
Authors: Yang Jiang Shi 
Published: July 2016

ABSTRACTAlthough China is a backward developing country, the population of many big cities has increased more than 100 percent since 1950. The light and smoke pollution for Shanghai Observatory and Purple Mountain Observatory is very serious, and in Kunming, for Yunnan Observatory, is also quite a problem. Now the only one where the observational condition is still quite good is the optical station of the Beijing Observatory, in XingLong County, Hebei Province. For the future, we plan to do some testing work on the Tibet plateau, where the population if very low, so there is no light pollution at all.
Note on Mercury Light Pollution in Spectroscopic Observations
Authors: Changchun Huang 
Published: July 2016

ABSTRACTMercury light pollution has appeared in our spectroscopic observations of the Comet 1980u made at the Observatoire de Haute Provence and spectroscopic observations of the Nova Andromeda 1986 made at the Purple Mountain Observatory. On spectra of an exposure of about one hour of the comet obtained at the 1.93m telescope of the OHP using the image tube spectrograph D (dispersion of 92 A/mm), the lines 4358, 4047 of Hgl are very strong. In the case of the nova, these lines are quite noticeable on spectra of exposure of 3 hours obtained at the 0.6m telescope of the PMO with the Marly-Nanjing spectrograph (dispersion 40 A/mm).
Economics of Light Pollution
Authors: Hunter Tim B. , Crawford David L. 
Published: July 2016

ABSTRACTLittle attention has been directed toward the environmental and economic costs of light pollution. We estimate that 2.5 percent of the total United States electricity production is expended on nighttime outdoor lighting. About 30 percent of all outdoor nighttime lighting ends up in the night sky. This is equivalent to 17.4 billion kilowatt-hours of electricity, more than the individual electrical production of many countries, including Chile, Cuba, Hungary, Ireland, Indonesia, Israel, Libya, Peru, Syria, or Vietnam. About one half of light pollution arises from direct upward lighting and one half from reflections off the ground and buildings. Light pollution directly costs the country at least a billion dollars a year in unnecessary electricity charges, in addition to the associated environmental harm from the mining and burning of fossil fuels to generate this wasted electricity. The equivalent of 8.2 million tons of coal (or 30 million barrels of oil) are burned annually in the United States simply to light up the night sky. The proper use of full cut-off shielding, timers, and appropriate light levels, if widely instituted, could reduce the overall urban sky glow by at least a factor of four in the next few decades.
The Impact of Light Pollution on Amateur Astronomy and Public Awareness of the Night Sky
Authors: Chester Geoffrey 
Published: July 2016

ABSTRACTWith the growing expansion of urban areas and their associated “domes” of artificial illumination, amateur astronomers have been forced to change many of their observing habits. This is reflected in the instruments today’s amateurs are using: highly portable telescopes of mostly commercial origin. Amateurs must travel further into the field to find dark skies, and this makes the hobby more discouraging. By discouraging the amateurs, an important education resource is lost to the public.
The International Dark-Sky Association, Inc.
Authors: Hunter Tim B. , Crawford David L. , Howell Libby , Knauss Daniel G. 
Published: July 2016

ABSTRACTThe International Dark-Sky Association, Inc. (or IDA, Inc.) is a new tax-exempt, non-profit corporation formed to serve the public and the amateur and professional astronomer communities by providing information, education, and research on light pollution and related topics. IDA will share knowledge of the issue on a local, national, and international basis and will assist with members’ problems. It was organized for the purpose of preserving dark skies for astronomy and for the general public. Solutions to the problem of light pollution will, at the same time, also promote maximum effectiveness for all outdoor lighting and will conserve natural resources.
Threat to Astronomy by Space Art
Authors: Murdin Paul 
Published: July 2016

ABSTRACTThe Light Ring, proposed as a celebration of the centenary of the Eiffel Tower, and now withdrawn by its sponsors, demonstrated the feasibility to launch relatively inexpensive satellites which subtend an appreciable solid angle as seen from earth. Other satellites in the competition organized by the Eiffel Tower proposed configurations under the name of Space Art which could unacceptably increase the night sky background. Satellites of this nature, launched for noble but essentially frivolous motives, pose a threat to optical astronomy.
The Nature of Radio Interference and Some Lines of Defense
Authors: Fisher J. Richard 
Published: July 2016

ABSTRACTAs competition for radio spectrum space continues to increase, radio astronomers can expect to put more technical effort into ways of observing in the presence of interference. Much of the spectrum outside of exclusive radio astronomy frequency bands will continue to be available to the science if receivers and antennas are designed to make efficient use of times, frequencies, directions, and coherence envelopes that do not contain sources of interference. The paper outlines the state of the art in antenna sidelobe reduction, high dynamic range spectrometers, and receiver designs for handling large signals. Techniques for excising pulsed interference on very short timescales and a few thoughts on signal canceling techniques are discussed.
Radio Astronomy at WARC MOB-87
Authors: Gergely T. E. 
Published: July 2016

ABSTRACTThe World Administrative Radio Conference for the Mobile Services (WARC Mob-87), held in Geneva in September-October, 1987, took several actions that will have an impact on radio astronomy. Worldwide frequency allocations were made for the Radiodetermination Satellite Service (RDSS) in the 1610 to 1626.5 MHz band. The secondary allocation to radio astronomy in this band has received strong protection, however. The 1660 to 1660.5 MHz band, which radio astronomy shared on a primary basis with the Aeronautical Mobile Satellite Service has been reallocated to the Land Mobile Satellite Service, shared with radio astronomy on a similar basis. The impact that this reallocation will have on radio astronomy is not clear. Since the Radioastronomy Service is primary in the band, Mobile Satellite Systems that evolve will have to provide adequate protection. Perhaps most significantly, WARC Mob-87 recommended that a conference be convened to reallocate all bands in the 1 to 3 GHz range, no later than in 1992. Several other conferences dealing with particular services have been proposed. At first glance, some of these some of these proposals may not appear to have an impact on radio astronomy. They will, however, increase the pressure on the entire radio spectrum. Finally, it is highly likely that a General WARC will be proposed to be held before the end of the 1990s. The radio astronomy community will have to prepare for these conferences.
Far-infrared circumstellar debris shells: Clues to the evolution of massive stars?
Authors: Stencel R.E. , Garmany C.D. 
Published: July 2016

Abstract:A survey of the infrared properties of late-type supergiant stars, using the IRAS database, reveals that about 25% of the stars possess resolved, extended circumstellar shells. These shells are typically several arc minutes in apparent size and therefore on the scale of parsecs at the source. Furthermore, among the resolved sources, there is an inverse correlation between physical size of the infrared shell and B-V color, suggesting that these shells are formed while the objects are red supergiants, but continue to expand ballistically, while the star evolves blueward from that extreme. These shells may be the material swept up into ring nebulae when the central star develops a fast wind.
Pairs of Galaxies in Low Density Regions of a Combined Redshift Catalog
Authors: Charlton Jane C. , Salpeter Edwin E. 
Published: July 2016

AbstractThe distributions of projected separations and radial velocity differences of pairs of galaxies in the CfA and SSRS redshift catalogs are examined. We focus on pairs that fall in low density environments rather than in clusters or large groups. The projected separation distribution is nearly flat, while uncorrelated galaxies would have given one linearly rising with rp. There is no break in this curve even below 50 kpc, the minimum halo size consistent with measured galaxy rotation curves. The significant number of pairs at small separations is inconsistent with the N-body result that galaxies with overlapping halos will rapidly merge, unless there are significant amounts of matter distributed out to a few hundred kpc of the galaxies. This dark matter may either be in distinct halos or more loosely distributed. Large halos would allow pairs at initially large separations to head toward merger, replenishing the distribution at small separations. In the context of this model, we estimate that roughly 10 — 25% of these low density galaxies are the product of a merger, compared with the elliptical / S0 fraction of 18%, observed in low density regions of the sample.
New Data on the Peculiar Galaxy MRK 273
Authors: Asatrian A. S. , Petrosian A. R. , Börngen F. 
Published: July 2016

AbstractOn the basis of direct UBV and spectral observations at Tautenburg (DDR) 2m and Special Observatory (USSR) 6m telescopes respectively the colorimetric and spectral investigations of the megamaser galaxy MRK 273 are carried out. It is seen that: MRK 273 is in a physical group of galaxies, which contains at least five members. Two bright central condensations of MRK 273 are Seyfert nuclei. The area of the main body of MRK 273 which contains both Seyfert nuclei and from which comes out a straight tail, is redder than the remaining part of the galaxy. The tail has a pronounced blue color and most probably radiates in [OIII] λ5007 line. Observed radio continuum, OH and HI absorption features are related to bright “a” nucleus of galaxy. We come to the conclusion that MRK 273 which is the member of the group of the galaxies is itself a close system of two objects with AGNs. The tail, with radiation being of thermal origin, probably is the result of the interaction of these galaxies.
Radio Loud Far-Infrared Galaxies
Authors: Dey Arjun , van Breugel Wil , Shields Joseph C. 
Published: July 2016

AbstractWe present the first results of a multiwavelength study of IRAS galaxies with excess radio emission. The sample was selected by cross-correlating the IRAS Faint Source Survey (for |b| ≥ 50°) and the Point Source Catalogue (for 10° < |b| < 50°) with the Texas radio survey. Recent optical (imaging and spectroscopic) and radio (VLA) observations are discussed. These observations will be used to investigate possible connections between radio galaxy activity, star formation and galaxy interactions.
Central Activity in 60 Micron Peakers
Authors: Heisler Charlene A. , Vader J.P. , Frogel Jay A. 
Published: July 2016

AbstractWe present CCD imaging results of our sample of IRAS galaxies with spectral energy distributions peaking at 60μm (Vader et al 1988). The results support our suggestion that the activity in 60μm peaking galaxies is centrally concentrated, and represents an early stage of dust-embedded nuclear activity. This activity is probably triggered by a recent interaction/merger event as indicated by their peculiar optical morphologies. We propose that 60μm peakers are the precursors of S0’s in the case of amorphous systems, and ellipticals in the case of interacting galaxies.
The Nature of the Emission-line Nebulae in Powerful Far-infrared Galaxies
Authors: Armus Lee , Heckman Timothy M. , Miley George K. 
Published: July 2016

AbstractWe discuss our program of narrow-band (Hα + [Nil]) imaging of a sample of 30 powerful far-infrared galaxies (FIRG’s) chosen to have far-infrared spectral energy distributions similar to the prototype FIRG’s Arp 220, NGC 3690, NGC 6240, and M82. The emission-line nebulae of these IR color-selected sample (ICSS) galaxies as a class are both impressively large (mean half light radius, r ~1.3 Kpc, and mean diameter, D ~16 Kpc) and luminous (LTOT ~108 Lo; uncorrected for internal extinction). The mean total Hα + [Nil] luminosity of the FIRG’s is comparable to that found for pairs of optically selected interacting galaxies (Bushouse, Lamb, and Werner 1988), but is a factor of ~5 greater than that of isolated spirals (Kennicutt and Kent 1983). Only ~25% of the nearby (z ≤ 0.10) FIRG’s have morphologies suggesting that large HII~regions contribuí significantly to their emission-line appearance. The broad-band morphologies of our IR color-selected galaxies fall into three major categories. Nearly 75% are single galaxy systems, with the remaining FIRG’s being either multiple nuclei systems, or members of interacting pairs. Since we see few (10%) currently interacting FIRG’s, yet many (80%) with highly distorted continuum morphologies, our IR color criteria may be preferentially selecting galaxies that have undergone highly inelastic, rapidly merging interactions.
Signs of Interaction of the NGC 1275 Nucleus with the High-Velocity System According to 0,″7 Seeing Observations
Authors: Dudinov V. N. , Tsvetkova V. S. , Novikov S. B. , Pronik I. I. 
Published: July 2016

AbstractThe nucleus of the Seyfert galaxy NGC 1275 was observed in the B system on 12-1-1989 with seeing 07 using the Zeiss-1000 telescope on Mount Majdanak in Central Asia. Special methods of processing reveal low-contrast details. The nucleus and circumnucleus are stretched in NW-SE direction. There are two narrow filaments near the nucleus in position angles roughly 340° and 320°. The first is directed near the radio jet of the nucleus, the second has broken details curved to the NW or toward the high-velocity system of NGC 1275.
A Statistical Study of Merging Galaxies-Theory and Observations
Authors: Chatterjee Tapan K. 
Published: July 2016

AbstractA study of the expected frequency of merging galaxies is conducted, using the impulsive approximation. Results indicate that if we consider mergers involving galaxy pairs without halos in a single crossing time or orbital period, the expected frequency of mergers is two orders of magnitude below the observed value for the present epoch. If we consider mergers invovling several orbital periods or crossing times, the expected frequency goes up by an order of magnitude. Preliminary calculation indicate that if we consider galaxy mergers between pairs with massive halos, the merger is very much hastened.
Probing the Tides in Interacting Galaxy Pairs
Authors: Borne Kirk D. 
Published: July 2016

AbstractDetailed spectroscopic and imaging observations of colliding elliptical galaxies have revealed unmistakable diagnostic signatures of the tidal interactions. It is possible to compare both the distorted luminosity distributions and the disturbed internal rotation profiles with numerical simulations in order to model the strength of the tidal gravitational field acting within a given pair of galaxies. Using the best-fit numerical model, one can then measure directly the mass of a specific interacting binary system. This technique applies to individual pairs and therefore complements the classical methods of measuring the masses of galaxy pairs in well-defined statistical samples. The “personalized” modeling of galaxy pairs also permits the derivation of each binary’s orbit, spatial orientation, and interaction timescale. Similarly, one can probe the tides in less-detailed observations of disturbed galaxies in order to estimate some of the physical parameters for larger samples of interacting galaxy pairs. These parameters are useful inputs to the more universal problems of (1) the galaxy merger rate, (2) the strength and duration of the driving forces behind tidally-stimulated phenomena (e.g., starbursts and maybe QSOs), and (3) the identification of long-lived signatures of interaction/merger events.
Dynamical Friction in Pairs of Elliptical Galaxies
Authors: Prugniel Philippe , Combes Françoise 
Published: July 2016

AbstractWe present numerical experiments on dynamical friction in pairs of elliptical galaxies of unequal mass. We confirm that the self-gravity of the response is not important and show the drastic effect of the deformability of the companion which reduces the decay time by more than a factor 2. Almost the same amount of orbital energy is dissipated within the satellite than within the large galaxy. Finally, we discuss the importance of distant encounters for the dynamical evolution of systems of galaxies.
Virial Coefficient and Hidden Mass in the Galaxy Groups
Authors: Anosova J. P. , Orlov V. V. , Kiseleva L. G. 
Published: July 2016

AbstractThe purpose of this work is a verification of the virial mass estimations for small galaxy groups. The dynamical evolution of triple and quintuple galaxies has been studied by the numerical simulations. The dependence of the virial coefficient k(t) versus time was derived. Initially k(0) = 0. The function k(t) has some strong oscillations from 0.02 to 0.99. Generally, these oscillations are quasiperiodical ones. Such a behavior of k(t) is caused by formation in a system of close isolated temporary double subsystems. A strong correlation between the virial coefficient and the least mutual distance in the system is observed.
Stationary Orbits of Satellites of Disk Galaxies
Authors: Polyachenko Valerij L. 
Published: July 2016

AbstractThe satellite of an S-galaxy will experience opposing dynamical-friction forces from the stars of the disk and the halo. If these forces are in balance, the satellite may travel in a stable, near-circular orbit whose radius, for a wide range of physical parameters, should be limited to a zone 1.2 to 1.4 times the disk radius, much as is observed.
Do elliptical galaxies have thick disks?
Authors: Thomson R C , Wright A E 
Published: July 2016

AbstractWe discuss new evidence which supports the existence of thick disks in elliptical/S0 galaxies. Numerical simulations of weak interactions with thick disk systems produce shell structures very similar in appearance to those observed in many shell galaxies. We think this model presents a more plausible explanation for the formation of shell structures in elliptical/S0 galaxies than does the merger model and, if correct, supports the existence of thick disks in elliptical/S0 galaxies.
The Multi-Telescope Telescope Project: An Inexpensive Spectroscopic Facility
Authors: Bagnuolo W.G. , Furenlid I.K. , Gies D.R. , Barry D.J. , Hopper C.H. , McAlister H.A. , Hartkopf W.I. 
Published: July 2016

AbstractWe have constructed a new facility at the Georgia State University Hard Labor Creek Observatory, consisting of a telescope and a fiber-fed spectrograph and detector. The Multi-Telescope Telescope (MTT) is an inexpensive one-meter light-collecting telescope whose ‘primary’ mirror consists of nine 33.3 cm mirrors. Each mirror of the MTT focuses light into a separate optical fiber, thus avoiding light losses of conventional fiber bundles. The optical fibers feed a modified ‘slightly’ off-plane Ebert-Fastie spectrograph. The detector is a CCD with low thermal noise characteristics, cooled to 200 K. The CHARA spectroscopic facility will be used for high precision radial velocity observations of binary orbits, tomographic separation of binary spectra, and observations of nonradial pulsations of Be stars.
Spectroscopic Binaries in the Open Cluster M67
Authors: Latham David W. , Mathieu Robert D. , Milone Alejandra A.E. , Davis Robert J. 
Published: July 2016

AbstractFor almost 400 members of M67 we have accumulated about 5,000 precise radial velocities. Already we have orbital solutions for more than 32 spectroscopic binaries in M67. Many of these orbits were derived by combining the Palomar and CfA observations, thus extending the time coverage to more than 20 years. The distribution of eccentricity versus period shows evidence for tidal circularization on the main sequence. The transition from circular orbits is fairly clean. Excluding the blue stragglers, the first eccentric orbit has a period of 11.0 days, while the last circular orbit has a period of 12.4 days. For longer periods the distribution of eccentricity is the same as for field stars. The blue straggler S1284 has an eccentric orbit despite its short period of 4.2 days.
Spectroscopic Binaries in the Halo
Authors: Latham David W. , Mazeh Tsevi , Stefanik Robert P. , Davis Robert J. , Carney Bruce W. , Torres Guillermo , Laird John B. 
Published: July 2016

AbstractFor almost 1500 stars in the Carney-Latham survey of proper-motion stars we have accumulated about 20,000 precise radial velocities. Already we have orbital solutions for more than 150 spectroscopic binaries in this sample, and about 100 additional binary candidates with variable velocity. We find that among the metal-poor halo field stars in this sample the frequency of short-period spectroscopic binaries is indistinguishable from that of the disk. The distribution of eccentricity versus period shows evidence for tidal circularization on the main sequence. For the binaries more metal poor than [m/H] = −1.6 there is a clean transition from circular to elliptical orbits at a period of about 19 days. For longer periods the distribution of eccentricity is the same as for stars in the disk of the Galaxy.
TODCOR: A Two-Dimensional Correlation of a Composite Spectrum to Derive the Radial Velocities of its Components
Authors: Mazeh Tsevi , Zucker Shay 
Published: July 2016

Cross correlation is a frequently used technique to obtain the Doppler shifts of digitized celestial spectra. This method, suggested by Tonry & Davis (1979), cross correlates the observed spectrum against an assumed template, and obtains the stellar radial velocity by the location of the correlation maximum (Wyatt 1985). The technique finds the correct radial velocity even for extremely low S/N spectra.Spectra composed of two components present a potential difficulty to this technique. The cross correlation of these spectra usually displays a double peak which can not be resolved whenever the relative velocity of the two components is small. To overcome this difficulty, we developed TODCOR — a new TwO-Dimensional CORrelation algorithm which can simultaneously derive the Doppler shifts of the two components.TODCOR assumes that the observed spectrum is a combination of two known spectra with unknown shifts. Following the one-dimensional technique, the algorithm calculates the correlation of the observed spectrum against a set of combinations of two templates, with all possible shifts. The correlation, thus, is a two-dimensional function, whose two independent variables are the radial velocities of the two components. The location of the maximum of this function corresponds to the actual Doppler shifts of the two components.