bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diffusion Models for Magnetic Ap Stars
Authors: Babel J. 
Published: July 2016

AbstractProgress made in spectroscopy and in the diffusion theory permits now to make severe comparisons, based on line profiles, between theory and observation.We first review transport processes which are present in the atmospheric layers of Ap stars and discuss their relative importance. We then show that mass loss could play a key role for the creation of abundance maps. A mass loss model is proposed for 53 Cam and is compared, by spectrum synthesis, with visible and IUE high resolutions observations. The model accounts well for the line profiles of several elements with an exception for Ti. Furthermore, the abundance stratification predicted by this model gives close agreement with the large variation of the abundances of Cr and Fe found between the visible and UV domains. The diffusion-mass loss model finally permits to give a simple interpretation of the peculiar Ca II K lines observed in many Ap SrCrEu stars and in particular in 53 Cam, β CrB and HD 191742.
CP3 Stars in Open Clusters
Authors: Schneider H. 
Published: July 2016

AbstractAbt published in 1979 frequencies of peculiar stars in open clusters based on published classifications for 661 stars in 14 open clusters and associations. Among others he discussed an age dependence of the frequencies of CP3 stars and found them increasing with age. Furthermore, he suggested a possible age dependence of the rotational velocity of these stars.But the sample he used was rather small: he found eight CP3 stars in 5 open clusters. In the mean time the number of cluster CP3 stars was more than double. Therefore, the findings of Abt shall be examined on the basis of the larger sample.
Variability of 56 Ari
Authors: Czechowski W. , Stȩpień K. 
Published: July 2016

AbstractFrom IUE archival data and visual spectrophotometric observations published by Adelman and Pyper, nearly 20 energy distributions of 56 Ari in different rotational phases were obtained. The light variations in selected spectral bands correlate with spectrum variations. The bolometric flux varies by ˜ 2.5 % over the rotation period.
Polyynes and Polycyclic Aromatic Molecules in C-rich Circumstellar Envelopes
Authors: Omont Alain 
Published: July 2016

The aim of this review is to discuss our knowledge on molecules in the circumstellar environment of evolved stars. In particular the presence and the behaviour of various kinds of molecules with several or many carbon atoms, in relation to C-rich dust, is considered.Such objects include mainly: (i) circumstellar shells of AGB carbon stars, either visible (such as Y CVn) or infrared (such as IRC+10216 (CW Leo)); (ii) planetary nebulae (PNe, e.g. NGC 7027); (iii) pre-planetary nebulae (PPNe, also called post-AGB stars, such as CRL 2688 or the Red Rectangle), probably in an intermediate evolution stage between the two former classes. I will not discuss more peculiar classes, such as R CrB stars and novae, for which very little is known about the presence of such molecular species.
Asteroid Surveys and other CCD Projects Using the Observatoire de la Cote D’Azur (OCA) Schmidt Telescope
Authors: Maury Alain 
Published: July 2016

AbstractA wide field CCD camera has been developed for asteroid searches and has been used at our Schmidt telescope since September 1993. This paper describes this camera and its software as well as the changes it introduced in the type of programs that were requested on the telescope, and changes introduced in the way the telescope is operated.
Astronomy with the Automated Patrol Telescope
Authors: Carter B. D. , Ashley M. C. B. , Bembrick C. S. , Brooks P. W. , Mitchell P. , Storey J. W. V. 
Published: July 2016

AbstractThe Automated Patrol Telescope (APT) is a wide-field CCD imaging telescope operated by the University of New South Wales at Siding Spring Observatory in Australia. The optical design employed resembles that of a Schmidt, but uses a 3-element lens to achieve a wide, corrected field of view. The APT was developed by extensively modifying the optical, mechanical and electronic systems of a Baker-Nunn satellite tracking camera. Telescope motion and operation of the CCD have been placed under computer control, allowing automated observations for longterm survey and monitoring projects. The APT has 0.5 m aperture f/1 optics which produce a 5° flat field, of which a 2°×3° field is covered by the CCD currently installed. The telescope is being used for studies of stellar activity in open clusters and regions of star formation, and comet and minor planet investigations. A number of other projects for the APT are being considered, including searches for novae, supernovae in clusters of galaxies, and brown dwarfs.
Use of CCDs in Schmidt Telescopes for the Investigation of Hα Emission of Flare Stars
Authors: Szécsényi-Nagy Gábor 
Published: July 2016

AbstractThe use of Schmidt telescopes in their traditional mode for the detection of stellar flares and for the UV and PG photometry of these stars proved to be very productive. The fast optical system and reliable sensitivity of modern photographic emulsions resulted in a photometric time-resolution of several minutes even in the case of distant objects. One of the most important characteristics of flare stars may be the tendency for coexistence with more massive and more luminous member stars of young stellar aggregates (mainly open clusters). Although the vast majority of flare stars discovered seem to belong to clusters, a great many of them are neighbours of our sun. These can be investigated in depth because a sufficient number of their photons can be collected and recorded in narrow photometric bands or even in spectra of good resolution. The direct comparison of solar vicinity flare stars with flare-active members of distant clusters has been almost impossible. However recent developments in silicon-based photon-detecting technology offer the advantage of incredibly high detector quantum efficiency (DQE) in many spectral regions where photographic materials never reached an acceptable level. Hα emission is one of the most characteristic features of flare stars, and the wavelength of Hα photons fits extremely well with the peak of the spectral sensitivity curves of silicon photon detectors. CCD chips placed in the focal surface of Schmidt telescopes seem to be very promising for the future investigation of Hα emission of flare stars.
Multi-Fibre Spectroscopy with Schmidt Telescopes
Authors: Watson F. G. 
Published: July 2016

AbstractLarge Schmidt telescopes are peculiarly well-suited to multifibre spectroscopy. The extent to which the small aperture is compensated by the wide field is illustrated by the fact that the total photon throughput of the 1.2 m UK Schmidt Telescope (UKST) is almost identical to that of the 3.9 m Anglo-Australian Telescope (AAT) in its new 2-degree field (2dF) mode. In the implementation of the technique, Schmidt telescopes have a number of practical advantages, while there is no shortage of scientific problems that can be addressed. However, the instrumentation required to capitalize fully on this potential is costly and, because Schmidts are perceived as “small” telescopes with a specialist following, the required funding is likely to remain elusive.
On the Applicability of Fibre-Fed Multi-Object Spectrographs in Flare Star Research
Authors: Szécsényi-Nagy Gábor 
Published: July 2016

AbstractThe use of optical fibres has recently allowed the full field of some Schmidt telescopes to be accessed for multi-object spectroscopy. The new device: the MOS (multi-object spectrograph) is to revolutionize the field of astronomical spectroscopy. Cosmic objects grouped into aggregates having apparent angular diameters of 1 to 6 degrees and similar apparent brightness in the visual or near infrared spectral range are to be the most probable future targets of MOSs. Flare stars — as it has been demonstrated convincingly by various authors (see Szecsenyi-Nagy 1986, and references therein) — are the most abundant type of variable stars but because of their low luminosity and relatively late discovery we have only very limited amount of spectroscopic data about most of these objects. It is a real bonanza that most of the catalogued flare stars are associated with young open clusters and this fact of course suggests them as really promising targets for wide-field Schmidt cameras equipped with MOSs. In an average open cluster scrutinized for its flare star members some dozen or some hundred representatives of this species are known which are distributed over a sky field of 10–20 square degrees. Fortunately, they are never packed into unresolvable concentrations and even short focal length cameras are able to produce separate images of all cluster member flare stars for an accurate photographic photometry of the objects. The apparent visual brightness of these stars most often fits a 5–7 magnitude range. This seems to be profitable also for the effectiveness of using fibre-fed MOSs in flare star spectroscopy. The first steps of such a program should be the study of radial velocities and the comparison of the measured values with the accepted radial velocity of the cluster. These measurements could provide new and independent arguments for (or against?) the cluster membership of the flare stars observed in the fields of catalogued open clusters. Later, more detailed spectral studies should collect information about the time dependent features of the spectra of flare stars.
Near-Earth Asteroids on Archival Schmidt Plates
Authors: McNaught R. H. , Steel D. I. , Russell K. S. , Williams G. V. 
Published: July 2016

AbstractWe describe our routine identification of images of asteroids and comets on plates and films in the U.K. Schmidt Telescope archive. The asteroids of most interest to us are those which approach the Earth, and whenever such an object is found (by anyone) we perform backintegrations in order to determine whether the object may have been recorded on any UKST plate taken since 1973. In many cases the object is found (‘precovered’) and measured, allowing an accurate orbit to be determined soon after its discovery; other studies such as long-term dynamical investigations, or predictions of future close approaches to the Earth, are then possible. Similar programs using other wide-field plate archives are to be encouraged, since valuable scientific results may be derived.
Guide Star Catalog Revisited - The Determination of Proper Motions
Authors: Röser S. , Bastian U. , Kuzmin A. V. 
Published: July 2016

AbstractWe are compiling a catalogue of positions and proper motions of 4 million stars, based on the Guide Star Catalogue (GSC) and the Astrographic Catalogue (AC). The GSC is re-reduced by a method described in this paper. The AC has been newly reduced recently by us for the determination of positions and proper motions of the PPM catalogue.The expected accuracy of the proper motions of the GSC-AC catalogue ranges between 5 and 6 mas/year. Having an average star density of 100 per square degree, this catalogue will be a useful tool for the reduction of CCD frames.
Proper Motion Survey in the Pleiades
Authors: Souchay J. , Schilbach E. 
Published: July 2016

AbstractAs a first step of our open cluster programme a catalogue of proper motions and photographic U, B, V, R magnitudes for stars up to 18 mag within a region centered near Alcyone is presented. The catalogue is based on MAMA measurements of plates taken with Tautenburg and OCA (CERGA) Schmidt telescopes. The photometric survey includes ca. 65000 stars and covers a total field of about 25 square degrees. Proper motions have been obtained for ca. 40000 stars within a central 17 square degree region of this field. For the majority of stars in the survey an accuracy of 0.08 mag and 2 mas/year has been estimated for photometric data and proper motions, respectively. The results of the determination of the Pleiades membership up to 18th magnitude is presented.
Determination of the C/M5+ Ratio in the Galactic Disk
Authors: Fuenmayor Francisco J. 
Published: July 2016

AbstractA determination of the C/M5+ ratio, as a function of the galactocentric distance, in the galactic disk is presented. These results are based upon previous determinations of the space density for cool carbon stars and for late giant M stars in the Milky Way. Most of these results were obtained from objective-prism surveys in the near infrared using mainly Schmidt-type telescopes. The ratio C/M5+ appears to increase from 0.05 to 0.25 in the galactic disk, from the galactic center outwards. A mean value of 0.15 of this ratio for the Galaxy is suggested. Correlations between the C/M5+ ratio and currently known metal abundance gradients in the galactic disk are discussed.
The Michigan 10-Degree Blue Spectral Survey as a Basis for Future Deep Schmidt Surveys
Authors: Houk N. , Hippel T. von 
Published: July 2016

AbstractThe Henry Draper stars are being systematically classified on the MK System, using the Curtis and Burrell Schmidt telescopes with photographic spectra having a dispersion of 108 Å/mm. Over 156,000 stars south of δ = +5°, have been classified leaving about 69,000 yet to do. The project is expected to be completed around the year 2004. This all-sky network of consistently classified spectra of very good quality should serve as a basis for future deep surveys. Such surveys will almost certainly be automated because of the huge number of stars to be dealt with. Von Hippel et al. at Cambridge plan to scan at least 150,000 of the spectra classified by Houk, using her plates to serve as a ‘training’ set for automatic classification using artificial neural networks. The same data can also be utilized for other methods of automatic classification including the metric-distance methods used by Kurtz and La Sala (Kurtz 1983). Even at lower dispersions, significantly more information can be obtained from Schmidt spectra than by doing Schmidt photometric colour surveys alone, though these are also valuable, especially when used in conjunction with spectra. We urge that large Schmidts not currently having prisms or other dispersive elements consider adding this equipment.
The Search For Stellar Variability In M67: Ensemble Photometry with the Burrell Schmidt Telescope
Authors: Joner Michael D. , Hintz Eric G. , Stephens Thomas , Nelson Kenneth A. , Moore Helen , Moody J. Ward 
Published: July 2016

AbstractWe have analyzed time-series data for 160 stars in the old open cluster M67. Approximately 400 CCD frames from two nights on the Burrell Schmidt have been reduced differentially relative to an ensemble of seventeen stable stars. We present data on two new variables and evidence of four new suspected variable stars in M67.
Merger in M31’s Bulge & 3-D Accretion – A BVRI CCD Study at Kiso –
Authors: Sofue Yoshiaki 
Published: July 2016

AbstractBy contrast-enhancing and colour-excess analyses of BV RI CCD images of the central 12’.5 × 12’.5 region of M31 taken with the Kiso 105 cm Schmidt telescope, we found a “face-on” spiral feature of dark clouds, which are associated with Hα spirals. The feature can be understood as being due to accretion of gas clouds from companion galaxies and/or from a merger galaxy in the past 108–9 years.
Schmidt Telescopes and Quasar Surveys
Authors: Hewett Paul C. 
Published: July 2016

AbstractSchmidt telescopes have, for some three decades, provided one of the most important sources of data for studies of the quasar population at all wavelengths. In the 1980s the combination of Schmidt telescope plate material and automated scanning machines such as COSMOS and APM allowed a new generation of projects to be undertaken, the results from which are largely responsible for our present understanding of the evolution of the optically–selected quasar population. The digitisation of photographic plates coupled with the computer–based selection of candidate quasars has meant that quantitative calculation of survey selection functions can be accomplished. The first results from surveys with such selection functions are beginning to appear, and progress is being made in constraining the form of the evolution of the quasar luminosity function at high–redshifts, a regime where there has been much disagreement over the nature of evolution. The (still) unique wide–field capability of Schmidt telescopes, coupled with the application of analysis techniques developed using the automated scanning machines, will ensure that Schmidt telescopes continue to make an important contribution to quasar–astronomy over the next ten years.
Recent progress in the field of optical coatings for Fabry-Perot interferometers and filters
Authors: Pelletier E. 
Published: July 2016

AbstractDuring the last years, considerable improvements occurred in the field of multidielectric spectral filters. Nowadays we can conceive and realize practically any filtering system meeting extremely precise requirements necessary for optical instruments and particularly for astronomy. We will give here a short overview of the multiple factors leading to these improvements.
Photometry with Fabry-Perot Spectrometers
Authors: Bland-Hawthorn J. 
Published: July 2016

AbstractAt optical and infrared wavelengths, imaging Fabry-Perot devices are used in three different ways: (i) to obtain a single spectrum of a diffuse source which fills a large fraction of the aperture, (ii) to obtain a monochromatic image within a field defined by the Jacquinot spot, and (iii) to obtain a spectrum at each pixel position over a wide field by tuning the etalon. We review the theoretical basis for Fabry-Perot photometry and summarize the calibration procedures for the different applications. We discuss methods for recognizing and dealing with artefacts (scattered light, atmospheric effects, etc.) which can seriously comprise the photometric integrity of the data if left untreated.
Observations of Extragalactic Objects with the Hawaii Imaging Fabry-Perot Interferometer (HIFI)
Authors: Tully R. Brent 
Published: July 2016

AbstractImaging Fabry-Perot interferometers have a particularly useful role to play in studies of the extended regions of anomalous emission in active galaxies. It becomes possible to study the velocity and excitation structure of warm gas with full coverage of large fields. Observations and modeling of several good examples of transient activity will be described as a way of demonstrating the power of an operational facility.
Hot Shocked Gas Along the Helical Jets of NGC 4258
Authors: Cecil G. 
Published: July 2016

AbstractI summarize the results of our multifrequency study of the helically twisted jets in the Seyfert galaxy NGC 4258. [N II], Hα, and [O III] Fabry-Perot datacubes obtained with the HIFI system on the U. Hawaii 2.2m telescope form the basis of this work. ROSAT x-ray multiband images (HRI & PSPC), CO spectra, and unpublished VLA 6 and 20 cm maps are correlated with these spectral grids. Together these data reveal clear signatures of high-velocity (> 300 km s−1) shocks along the jets that suggest efficient entrainment of ambient molecular gas.
TAURUS 2 Observations of Giant Extragalactic HII Regions
Authors: Castañeda Héctor O. 
Published: July 2016

AbstractThe use of TAURUS 2, a Fabry-Perot imaging spectrograph, for the study of the kinematics and the dynamics of giant extragalactic HII regions in nearby galaxies is discussed. The technical aspects of the instrument, together with the procedures adopted for data analysis and reduction, and some of the first scientific results of our programme are also presented.
New Methods to Measure HII Regions Diameters
Authors: Fuentes-Masip O. , Castañeda H. O. , Muñoz-Tuñón C. 
Published: July 2016

AbstractObservations of the giant irregular galaxy NGC 4449 are being used to study the correlations between the diameter or luminosity and the velocity dispersion of its giant HII regions (GHRs), understanding as GHRs those HII regions with supersonic velocity dispersions. In the central part of this galaxy the HII regions overlap, and also there is a strong, morphologically diffuse emission that permeates the main body of NGC 4449, both effects making difficult the detection, identification and separation of HII regions. We have developed new techniques to solve these problems, obtaining HII regions parameters equivalent to the ones that would be got if the HII regions did not overlap and if the diffuse emission did not exist.
The O.A.O. Spectronebulagraph and the Kyoto 3D Spectrograph
Authors: Ohtani Hiroshi 
Published: July 2016

AbstractSpectronebulagraph, an automated observation system of tridimensional spectroscopy with a long slit spectrograph, is now in operation at the 188 cm telescope of the Okayama Astrophysical Observatory. This system is based on the local area net work of personal computers which control the telescope, the autoguider, the Cassegrain spectrograph and its CCD camera. Effects of variable atmospheric transmission during scans of target objects are removed by performing a set of two orthogonal scans and the data processing.A new spectrograph is now under development for the telescope. This instrument has multiple modes for tridimensional spectroscopy, i.e., the filter imagery mode, the imaging Fabry-Perot interferometer mode, a slit spectrograph mode for Spectronebulagraph, and the microlens array spectrograph (TIGER) mode. For the last mode, a dual preoptics to get simultaneously the sky background is introduced and achromatization of the microlenses is tried. This project is a part of development of a prototype instrument for the SUBARU telescope.
Integral Field Spectrography of the double AGN merging system Markarian 463
Authors: Chatzichristou E. 
Published: July 2016

AbstractMarkarian 463, a system of 2 interacting/merging galaxies (E and W) has been observed with SILFID at CFHT in sub-arcsec resolution conditions. We found that both nuclei are AGNs, with the W component being a Sy 2 or LINER and the E component, hitherto known to be a “hidden” Seyfert 1, having essentially Sy 2 characteristics. The bipolar collimated emission originating from the E nucleus is a conspicuous feature in the [OIII]5007 and Hα reconstructed images, as well as in the V – R color map. In velocity maps some previously undetected kinematical features are detected, most notably a sharp velocity gradient (more than 300 km s−1) within 2″ NE of the E nucleus. In addition, in the direct imaging mode a bright optical jet extending ~ 1.2″ S from the E nucleus and a fuzzy blue component 0.8″ W of the W nucleus were seen. Both were also discovered on HST images. Detailed ionization maps reveal individual regions with distinct physical conditions, which constrain the mechanism(s) responsible for the ionization of the gas.
Simultaneous Bidimensional Spectroscopy of Extened Objects Using Optical Fibers: Application to Seyfert Galaxies
Authors: Arribas S. , Mediavilla E. , Marín A. García , Lorenzo B. García , Rasilla J. L. 
Published: July 2016

AbstractIn this communication we summarize the main characteristics of three optical fiber systems, namely HEXAFLEX, HEXAFLEX-II, and 2D-FIS, developed for performing simultaneous bidimensional spectroscopy of extended objects. They have been used at the 4.2m William Herschel (WHT) and the 2.5m Nordic Optical Telescope (NOT), which are sited at the Observatorio del Roque de los Muchachos. These systems have been used to observe the circumnuclear regions of several Seyfert galaxies. They show clear advantages over other instruments based on more classical techniques, at least for these complex objects of small angular size on the sky. Some examples will be given to illustrate this.
K’-Band Spectro-imagery of AFGL 2688 and NGC 7027
Authors: Cox Pierre , Maillard Jean-Pierre , Huggins P.J. , Forveille T. , Bachiller R. , Guilloteau S. , Omont A. 
Published: July 2016

AbstractWe report high spatial and spectral resolution near-infrared mapping results in the K’–Band obtained with BEAR towards the protoplanetary nebula AFGL 2688 and the planetary nebula NGC 7027.