bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Applicability of Fibre-Fed Multi-Object Spectrographs in Flare Star Research
Authors: Szécsényi-Nagy Gábor
Published: July 2016

The 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

We 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

We 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

As 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

A 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

The 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

We 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

By 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

Schmidt 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.
3-D Spectroscopy: The Historical and Logical viewpoint
Authors: Connes Pierre , Coarer Etienne le
Published: July 2016

The present review consists of two parts. The first is mostly of historical interest: the largely-forgotten Lippmann color-photography technique is recalled. The second part is wholly devoted to a critical comparative study of the recently- developed techniques.
Recent progress in the field of optical coatings for Fabry-Perot interferometers and filters
Authors: Pelletier E.
Published: July 2016

During 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

At 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

Imaging 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

I 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

The 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

Observations 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

Spectronebulagraph, 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

Markarian 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

In 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.
Spectral Observations of the Collimated Outflows in LkHα225 and GM1-27
Authors: Magakian T. Yu. , Movsessian T. A.
Published: July 2016

The young emission-line star LkHα225 (V1318 Cyg) with a tiny cometary nebula is located in the small group of very young stars around the well-known Herbig Ae/Be star BD+40°4124. LkHα225 was discovered by Herbig (1960) and studied by several authors (see for references Ibragimov et al., 1988). The star undergoes strong variations of its light (nearly 3 magn.) in visible light as well as in infrared. Spectral type of LkHα225 is very uncertain, but its high luminosity (Lbol=460 L⊙) and mass (5.5 M⊙), as well as the presence of nebulosity suggests that it also belongs to the Herbig Ae/Be class of pre-main sequence (PMS) stars. This small and perhaps variable nebulous appendage on the NW-side of the star can be readily seen on the plates obtained with the 2.6-meter telescope of Byurakan Observatory.
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

We 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.
High-resolution, non-scanning FTS for remote sensing
Authors: Døhlen K. , Cañas A.
Published: July 2016

We present the first results from a portable spectrometer for the visible and very near infrared based upon the principle of heterodyned holographic Fourier transform spectroscopy (HHS) (Dohi and Suzuki 1971, Dohlen 1994). The instrument uses a Michelson interferometer where one of the mirrors is replaced with a grating. This produces a spatially located, frequency-shifted interferogram which is read out by an all-reflective relay lens and a photo-diode array and processed on a portable PC. A battery pack ensures an autonomy of about 7 hours. Instrumental assets include high optical throughput, variable resolving power, and no moving parts.

We have successfully used the instrument in two different remote sensing applications: detection of vegetation reflectance and atmospheric absorption.
Solar Imaging Spectroscopy: Multichannel Subtractive Double Pass Instruments
Authors: Mein P.
Published: July 2016

Several MSDP instruments are used in solar physics to observe simultaneously 2D-fields in a number of wavelengths.

We describe briefly the needs of 3D-data in solar physics, the different spectroscopic methods in use, and the principle of MSDP spectrographs. We discuss the relationships between spectral resolution, field of view and efficiency. We summarize the capabilities of the instruments, either presently working (Meudon, Pic du Midi, Tenerife and Wroclaw), or associated with the THEMIS project.

The solar results take into account the main performances of the MSDP, that is to say the very high spatial resolution and the high speed to cover a wide area on the sun within a short time (coordinated campaigns with space probes).

We conclude by a brief discussion of the capabilities which could be expected from the MSDP in night-time astronomy.
Michelson-Spectro-Interferometry (MSI) of Be stars envelopes with the GI2T Interferometer
Authors: Stee Ph. , Bonneau D. , Lawson P. , Morand F. , Mourard D. , Tallon I. , Vakili F.
Published: July 2016

The GI2T is an optical long-baseline Michelson interferometer which analyses dispersed stellar fringes in the multi-speckle mode with a spectral resolution of one Angstrom while the spatial resolution is about one milliarcsecond. This makes the GI2T a powerful instrument able to perform MSI of extended sources like Be stars or shell stars. In order to interpret these data we have developed a latitude dependent radiative wind model for Be stars. This numerical code enables us to compare directly computed 2D maps in some Balmer lines (Hα and Hβ) with high angular resolution data of some Be stars.
The Nature of Shocks in Molecular Clouds
Authors: Brand Peter W. J. L.
Published: July 2016

Evidence is presented to suggest that the shocked molecular hydrogen emission in the brightest part of the Orion outflow is produced in a J-shock and not a C-shock; that this is true throughout the entire flow; that it may be true in many outflow sources; and that this exacerbates problems with current explanations of the very wide velocity profiles observed in molecular hydrogen emission.
An Optical Study of the Star Formation Region NGC 7129
Authors: Castro A.I. Gomez de , Eiroa C.
Published: July 2016

NGC 7129 is a region where many signs of active star formation have been observed. Three water vapor masers, five Herbig-Haro objects, two FIR sources, two molecular outflows and several PMS stars have been detected. We have obtained very deep CCD images of the GGD nebulosities found in the region. The observations have been carried out with the 3.5 m. telescope at the Calar Alto Observatory (Almeria, Spain). The main conclusions inferred from the data are: (1) The Herbig-Haro nature of GGD 32, GGD 34, GGD 35, HH 103 and HH 105 is confirmed, however GGD 33 has shown to be a PMS star, GGD 33a, with a cometary nebulosity, GGD 33b; (2) GGD 32 and HH 103 are embedded in an extended structure (at least as large as 0.465x1.36 pc), where another Herbig-Haro object and an arc connecting GGD 32 and HH 103 have been detected. The whole ensemble seems to be linked to a third molecular outflow which is not well resolved in the available radiomaps; (3) The arc connecting GGD 32 and HH 103 contains low excitation material and probably traces a low density cavity within the molecular cloud; (4) GGD 34 is constituted by three condensations aligned in the East-West direction, the western one is a bow-shock where the cooling region is resolved and has a size of around 2000 AU; (5) the PMS star associated to GGD 35 has been identified. The mass outflow is highly collimated close to the star, but at a distance of 0.072 pc from the star it is deflected by an external agent which deviates it in the direction of the molecular outflow associated to LkHo 234.
Ionization of the Galactic Center Arched Filaments
Authors: Rubin R. , Morris M. , Erickson E.F. , Colgan S. , Simpson J.
Published: July 2016

The remarkable filament system seen in radio observations in the vicinity of the galactic center includes two thin filaments which arch away from the galactic plane (E.G. Yusef-Zadem et al 1984). The brightest part of each of these thermal structures is located at GO.10+0.02 and GO.07+0.04. Morris and Yusef-Zadem (1989) reason that photoionization by OB stars is unlikely on geometrical and morphological grounds. They suggest a magnetohydrodynamic mechanism to account for the radio emission and ionization. Erickson et al. (1968) were able to explain most of their observations of the far infrared (FIR) fine structure line emission from these locations in terms of a photoionization model.
Molecular Disks Around Young Stars
Authors: Sargent Anneila I. , Beckwith Steven V. W.
Published: July 2016

There is now a substantial body of evidence that disk-like structures of gas and dust surround many protostars and young stellar objects (e.g. Rodriguez, these proceedings). We are currently studying a number of these disks to establish whether they have properties compatible with those attributed to the proto-solar nebula, in the early stages of evolution of our solar system. The frequency with which such proto-planetary disks are associated with young stars is also being investigated.
Herbig-Haro Objects
Authors: Böhm Karl-Heinz
Published: July 2016

After a brief introductory discussion of the statistics of known Herbig-Haro (HH) objects we present a survey of recent spectroscopic results in the ultraviolet, the optical and the near infrared range (the latter mostly in connection with H2 observations). We emphasize the importance of the use of spatially resolved line profiles (position-velocity diagrams) in the optical range for the purpose of testing hydrodynamic models of HH objects. Such observations have now been supplemented by the measurement of spatially dependent intensity ratios for a large number of optical lines ~200 in HH 1) and of some ultraviolet lines (including fluorescent H2 lines) which are very useful for diagnostic purposes. The relevance and importance of spectroscopy and imaging in the infrared H2 lines is discussed.
The Spectrum of a Partially Ionized Jet
Authors: Binette L. , Raga A. , Cantó J.
Published: July 2016

Observed stellar jets have the following characteristics : a high degree of collimation, a structure of bright, quasi-periodic knots, a very low excitation spectrum (red [S II] to Hα line ratios of 1-10). Assuming that the latter are indicative of the structure of a supersonic jet, we have made a detailed prediction of the emission line spectrum within each radiating knot using the multi-purpose code MAPPINGS which includes all the atomic processes important in low velocity shocks. The structure (density, temperature, ionization) of the stationary, supersonic, nonadiabatic stellar jet was computed separately using a hydrodynamical code developed by A. Raga. An initially overpressured supersonic jet tries to adjust its pressure to the environmental pressure. In this process of pressure adjustment, a series of expansion fans and incident/reflected shock pairs are formed along the jet. We associate the emission from the recombination region behind these crossing shocks with the knots observed in stellar jets. We find that the calculated emission spectrum is of remarkably low excitation.
Inverting the Position-Velocity Diagrams of Molecular Discs
Authors: Richer J.S. , Padman R.
Published: July 2016

The molecular discs around Young Stellar Objects can be detected through high spatial and spectral resolution observations of their position-velocity diagrams. By mapping a high lying transition of a density-tracing molecule (e.g. HON, HCO+, NH3), the lines should be optically thin and we can expect to see the signature of rotation of the protostellar accretion disc. We present single-dish observations of the S106 system which show evidence for the presence of such a rotating disc. We also discuss a simple disc model which predicts the form of the resulting 1-v diagram. With high quality data, we should be able to do the inverse problem that of recovering the disc properties from the 1-v diagram. We discuss approaches to this inverse problem both by a Singular Value Decomposition (least-squares) method, and by a Maximum Entropy Method.
Narrowband Photometry of Photometrically Peculiar Objects
Authors: Mendoza V. Eugenio E.
Published: July 2016

This work is based upon α(16)A(9)-photometry fot 2 Planets, 11 Wolf-Rayet stars and 7 Planetary Nebulae. The results show anomalous α(16) and A(9)-indices for these objects. Thus, they are photometrically peculiar in this system. The main results are:

1) Callisto, Jupiter IV, shows ot(16) and A(9)-indices which can be considered as excellent representatives of solar type stars (G2 V).

2) Uranus and Neptune have anomalous A(9)-index, because of a spectral feature in absorption around λ 7805 Å, most likely due to a carbon compound. Thus, they are off the main sequence in the a(16)A(9)-array.

3) The Hα-line is possibly stronger in Uranus (marginal) and Neptune than in the Sun.

4) Wolf-Rayet stars have anomalous α(16)-inder, because of an extremely wide He II-line (λ 6560 Å), lack of hydrogen and the presence of spectral emission features that fall in the continuum used to determine this index.

5) Most WC stars have anomalous A(9)-index, because the presence of spectral emission features in the short wavelength continuum that defines this index.

6) Some W-R stars show variations in the strength of He II-line (λ 6560 Å).

7) Most WC stars are separated from WN stars in the α(16)A(9)-array.

8) Planetary Nebulae have anomalous α(16)-index, because the continuum around the hydrogen line is probably contaminated by [N II]-lines at λ 6548 Å and λ 6583 Å.

9) Planetary Nebulae have anomalous A(9)-index, because the short wavelength continuum is heavily contaminated by the [Ar III]-line at λ 7751 Å.

10) Planetary Nebulae lie far apart from all kind of stellar objects in the α(16)A(9)-diagram.
Star Formation in Galactic Nuclei
Authors: Terlevich Roberto
Published: July 2016

The term AGN or Active Galactic Nucleus, although with rather ill-defined boundaries, signifies extragalactic systems with non-stellar nuclear activity. Non-stellar activity indicators are: high luminosity, presence of broad emission lines, variability, nuclear UV excess, x-ray emission, radio emission, variable polarization, jets, etc.
A Plasmon Driven Bowshock Model for the Narrow Line Region of NGC 5929
Authors: Taylor D. , Dyson J. E. , Axon D. J. , Pedlar A.
Published: July 2016

Close links appear to exist between the optical narrow line region (NLR) in Seyfert galaxies and the nuclear non-thermal radio emission. Both occur on similar scales (~ 102 —103 pc), and correlations have been found between the 21 cm radio power and both the [OIII] λ5007Å luminosity and linewidth (de Bruyn & Wilson 1978; Whittle 1985). Approximate balance appears to exist between the thermal pressure of the NLR gas and the relativistic and magnetic pressure of the radio components (de Bruyn & Wilson 1978; Unger et al. 1985; Pedlar, Dyson & Unger 1985). There are also several examples of a direct spatial association between the optical and radio components, for example Mkn 78 (Pedlar et al. 1988).
Ultraviolet Observations of Halo Clouds
Authors: Danly Laura , Blades Chris
Published: July 2016

Since the earliest optical absorption line studies of Munch and Zirin (1961) identified clouds of gas located at large distances from the galactic plane, considerable effort has gone into trying to understand the origin and nature of Milky Way halo gas. Subsequent high resolution optical absorption studies (Albert 1981; Blades et al 1989) have expanded on the early results, demonstrating clearly that (1) halo clouds are more likely to have velocities outside the range allowed by galactic rotation and (2) halo clouds show smaller depletion of refractory elements compared to their disk counterparts (i.e. the Spitzer-Routley effect).
Galactic Winds
Authors: Völk Heinrich J. , Breitschwerdt D. , McKenzie J. F.
Published: July 2016

In the sequel we will be discussing that - apart from all other halo flows - it is highly probable that our Galaxy has a systematic mass loss; most other galaxies should behave in a similar way. This mass loss should occur in the form of a supersonic galactic wind provided the intergalactic pressure is low enough. We will investigate this possibility mainly for our Galaxy. We shall argue [1] that the energetic particle component of the interstellar medium, the cosmic rays (CRs), is basically responsible for driving a wind for typical gas temperatures below 106 K. Thus for asymptotic wind velocities of the order of the escape velocity, the mass flux is essentially determined by the observable CR energy loss from the Galaxy. Galaxies with very hot gas on the other hand hardly need the CR component and drive a wind almost exclusively through their thermal pressure.
The Intermediate Velocity Cloud IVC86+38.5-45, Related to High Velocity Clouds?
Authors: Herbstmeier U.
Published: July 2016

Examining the high velocity cloud complex C and its possible interaction with gas of the galactic disk we became aware of a dust cloud located at galactic longitude l = 86° and latitude b = 38°.5 seen in the l00µm image of the IRAS. This cloud consists of a cucumber shaped core surounded by a horseshoe shaped halo opening towards larger galactic coordinates. At very low 100µm intensities dust lanes starting at the core or the ends of the horseshoe can be traced for about 5° towards high galactic latitude and longitude.
Galactic Fountains
Authors: Kahn F. D.
Published: July 2016

The intercloud medium (ICM) is kept hot and supplied with gas by supernova remnants of Type II. The rate at which mass is added balances the rate at which gas flows away from the ICM into the galactic halo. A fountain is thus formed, since the gas only has enough energy to escape from the disk, but not from the Galaxy as a whole. The upward flow must be followed by the descent of the gas, in the form of a shocked sheet: the return flow seems to be observed in the form of intermediate velocity clouds.
Deterministic Self-Propagating Star Formation
Authors: Palouš Jan
Published: July 2016

The evolution of large scale expanding structures in differentially rotating disks is studied. High column densities in some places may eventually lead to molecular cloud formation and initiate also star-formation. After some time, multi-structured arms evolve, where regions of intensive star-formation are separated from each other by regions of atomic gas or molecular clouds. This is due to the deterministic nature and to the coherence of this process. A simple model of galactic evolution is introduced and the different behaviour of Sa, Sb, and Sc galaxies is shown.
The Milky Way Disk Warp
Authors: Florido E. , Battaner E. , Alfaro E. , Sanchez-Saavedra M.L.
Published: July 2016

A warped disk in our own galaxy is evident by means of HI, HII, γ-rays and dust observations, but unexistent when star distributions are considered, specially those of late type stars. This fact is in disagreement with the theories which assume a gravitational origin of warps, for instance a tidal interaction with the Magellanic Clouds. We tried to find the z-distribution of open clusters of different ages, for which a warp distribution was neither found nor rejected. Assuming an intergalactic magnetic field origin of the warp, we obtain a direction of the field in the Milky Way neighborhood given by (b,1) = (45°, 74°).
The Solar Spectral Irradiances from X-Ray to Radio Wavelengths
Authors: White Oran R.
Published: July 2016

Sources of new measurements of the solar EUV, UV, and visible spectrum are presented together with discussion of formation of the solar spectrum as a problem in stellar atmospheres. Agreement between the data and a modern synthetic spectrum shows that observed radiative variability is a minor perturbation on a photosphere in radiative equilibrium and LTE. Newly observed solar variability in 1992 defines a magnetic episode on the Sun closely associated with changes in both spectral irradiances and the total irradiance. This episode offers the opportunity to track the relationship between radiation and magnetic flux evolution.
Response of the Middle Atmosphere to Solar Variability — Model Simulations
Authors: Huang Theresa Y. W. , Brasseur Guy P.
Published: July 2016

Solar flux variations could affect the middle atmosphere through modulating the photolysis of chemical series and solar heating rates. Indirect feedback effects from chemical, radiative, and dynamical interactions could provide additional sources for perturbations in the middle atmosphere. In this paper, recent developments in modeling the effect of solar variability on the middle atmosphere is described. For the 27-day solar rotational cycle, the temperature and ozone response in the stratosphere predicted by one- and two-dimensional models compares well with data analyses. For the 11-year solar cycle, model simulations suggest a non-negligible ozone/temperature response compared to changes produced by anthropogenic perturbations in the stratosphere. There is no sufficient long-term atmospheric dataset to establish a statistically significant correlation with the 11-year solar cycle. But in general, agreement between the observational analysis (for periods of one to two solar cycles) and model simulations of the long-term solar variability effect is unsatisfactory.
Some Problems in Understanding the Solar Corona
Authors: Gabriel A. H.
Published: July 2016

The development of the physics of the solar atmosphere during the last 50 years has been greatly influenced by the increasing capability of observations made from space. Access to images and spectra of the hotter plasma in the UV, XUV and X-ray regions provided a major advance over the few coronal forbidden lines seen in the visible and enabled the cooler chromospheric and photospheric plasma to be seen in its proper perspective, as part of a total system. In this way space observations have stimulated new and important advances, not only in space but also in ground-based observations and theoretical modelling, so that today we find a well-balanced harmony between the three techniques.
Structure and Evolution of Coronal Magnetic Fields
Authors: van den Oord G. H. J.
Published: July 2016

A review is presented on the structure and evolution of coronal magnetic fields. The force balance and the energy partitioning of the field is discussed together with a number of MHD invariants and their implications. Various solutions of the MHD equations are reviewed along with their applicability to the actual boundary value problem posed by the photospheric driver. The importance of topological studies in understanding the creation of small scales is emphasized.
Evolution of Large-Scale Coronal Structures
Authors: Ambrož P.
Published: July 2016

The large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.

Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.
Coronal Holes and Background Magnetic Fields on the Sun
Authors: Stepanian N. N.
Published: July 2016

Size, lifetime and rotational rate of coronal holes (CH) and their connection with background magnetic field (BMF) structures were studied on the base of Solar Geophysical Data (1977-1987).

Mean sizes of CH are (1-3) × 1011cm, changing with solar cycle and latitude. Mean life time is 5 rotations. Only small part of CH has rigid rotation. Most of them show differential rotation. CH appear in structures of BMF with the sign of polar magnetic field of corresponding hemisphere about 5-10 rotations after polar field reversal. Rotation rates of CH and BMF near the solar equator are almost the same. Rotational rate of BMF falls with latitude faster than the CH rate. Rotation differential of CH changes with solar cycle, BMF has no such connection.

These results speak about different nature of BMF and CH, and the different depth of their sources. The source of CH is located deeper than that of the background magnetic field.
Formation of Coronal Holes and the Global Magnetic Field Distribution
Authors: Bumba V. , Klvaňa M. , Rušin V. , Rybanský M. , Buyukliev G. T.
Published: July 2016

The photoelectric magnetograph of the Ondřejov Observatory was reconstructed in 1990 (Klvaňa and Bumba, 1994; Klvaňaet al, 1994). During 1991 and 1992, several hundred sets of measurements were obtained, mostly in line Fel 5253.47 Å. It has been found that some of the measurements are distributed very favorably around coronal holes, sometimes covering smaller parts and in a few cases even larger parts of their areas.

Both 1991 and 1992 were exceptional as regards their relation to the phase of the ending solar activity cycle (No 22): while the period of the secondary cycle maximum (mainly the southern solar hemisphere) took place in 1991, the year 1992 coincided with the initial stage of its declining branch. Since the formation of coronal holes is in close relation to the dynamics of the global distribution of solar magnetic fields, we thought that before starting to investigate the detailed connections of the individual coronal holes with particular local magnetic fields, it might be interesting to study their mutual relations also on a large scale.
Spatial and Temporal Distribution of Evolutionary Regimes of the Green Corona Brightness During the Cycles 20-21
Authors: Badalyan O. G. , Kuklin G. V.
Published: July 2016

The distributions of the green corona brightness in the cycles 20-21 are analysed using the principal component method. Four regimes of the evolution of brightness distributions were detected. A “latitude-time” diagram was constructed and compared with the specific points of the cyclic Wolf numbers curve.
Wave Properties in the Upper Chromosphere and at the Base of the Corona
Authors: Bocchialini K. , Vial J.-C. , Koutchmy S.
Published: July 2016

From a 83 min long sequence of observations of Ca II K and He I (1083 nm) line profiles, some dynamical properties of the main components of the quiet upper chromosphere are derived: for both the magnetic network and the internetwork, amplitude and phase spectra of the Doppler velocities are presented.
Rotational Characteristics of the Green Solar Corona: 1947-1991
Authors: Rybák J. , Rušin V. , Rybanský M.
Published: July 2016

Fe XIV 530.3 nm coronal emission line observations have been used for the estimation of the green solar corona rotation. A homogeneous data set, created from measurements of the world-wide coronagraphic network, has been examined with a help of correlation analysis to reveal the averaged synodic rotation period as a function of latitude and time over the epoch from 1947 to 1991.

The values of the synodic rotation period obtained for this epoch for the whole range of latitudes and a latitude band ±30° are 27.52±0.12 days and 26.95±0.21 days, resp. A differential rotation of green solar corona, with local period maxima around ±60° and minimum of the rotation period at the equator, was confirmed. No clear cyclic variation of the rotation has been found for examinated epoch but some monotonic trends for some time intervals are presented.

A detailed investigation of the original data and their correlation functions has shown that an existence of sufficiently reliable tracers is not evident for the whole set of examinated data. This should be taken into account in future more precise estimations of the green corona rotation period.
Long-Term Corona Features Associated with Schwabe-Cycle Phases
Authors: Storini M. , Sýkora J. , Felici A. , Bavassano B. , Parisi M.
Published: July 2016

Six-month averages of the green corona intensity (spectral line: FeXIV 530.3 nm) determined for each five degrees of heliographic latitude in the period 1943-1992 are used to evaluate corona features during Schwabe-cycle phases. Differences between odd and even cycles are investigated by examining the ascending and descending phases of each solar cycle and taking into account sunspot numbers. Results from cycle 18 to 22 show different time behaviour of coronal features when we compare odd and even cycles in the range of middle and equatorial heliolatitudes.
Evidence of Asymmetric Variation of the Emissions of the Solar Corona
Authors: Xanthakis J. , Mavromichalaki V. , Tritakis V. , Petropoulos B. , Paliatsos A. , Noëns J. C. , Pech B.
Published: July 2016

We attempt to present clear evidence that the east coronal hemisphere appears brigther than the west in the green and the red spectral emissions as well as in the white light of the solar corona. In addition, a simple scenario which could explain optical inequalities between the east and the west solar hemisphere has been formulated.
Soft X-ray Imaging of TY Pyx Binary System. Possible Presence of Interconnecting Stellar Loop
Authors: Siarkowski M. , Sylwester J. , Preś P.
Published: July 2016

Using a new 3D deconvolution technique we analyze the X-ray light curve of TY Pyx eclipsing binary to model the corona around the system. Our result indicates the possible presence of an interstellar loop connecting the stars.
Coronal Loop Interaction Observed at Visible Wavelengths
Authors: Smartt R. N. , Zhang Z. , Kim I. S. , Reardon K. P.
Published: July 2016

Coronal loops, as recorded in images of the emission from the 5303Å (Fe XIV) and 6374Å (Fe X) lines, display transient, localized brightenings, commonly evident in post-flare loop systems. Such brightenings apparently occur also in quiet coronal loop systems, but only in the lower range of energies that characterize these coronal events. Brightening is observed to occur in regions where two loops come into contact, with resultant heating of the common plasma volume, and subsequent cooling. The observations show systematically that a brightness maximum in the cooler (6374Å) line lags that of the hotter (5303Å) line, as also for Ha material relative to the red line, the sequence revealing cooling of the plasma following initial heating. Coalescence is evident in that the brightness can extend away from the overlapping region along the adjacent parts of the loops. Brightenings are found to be a common phenomenon in post-flare loop systems.
Manifestation of Multiple Energy Release on the Evolution of Flares in the Diagnostic Diagrams
Authors: Sylwester B. , Sylwester J. , Reale F. , Serio S.
Published: July 2016

In the present contribution we advance the investigation of evolution of flares in the emission measure-temperature diagrams. Models are considered in which the flare heating consists of a pair of elementary heating episodes (EHE) taking place in separate loops within flaring region. The parameters of the modelling are: the time profile of heating within individual episode, the time elapsed between individual energy releases and the amount of energy released. Earlier, we have shown that some of the X-ray flares observed by theBCSonSMMdisplay evolutionary patterns in the emission measure-temperature diagrams which are hard to interpret in the framework of model with single energy episode. Present analysis offers a possibility to interpret some of these patterns.
Fast Drift Bursts, Spikes, and Continua Observations in the 100-4200 MHz Band
Authors: Jiřička K. , Karlický M. , Kepka O. , Tlamicha A.
Published: July 2016

New Ondřejov solar radio observational system consisting of a high-time resolution 3000 MHz receiver and of a 100-4200 MHz radiospectrograph is described and some results of observation of fast drift bursts, spikes, and continua are presented.
Effects of Ambipolar Diffusion on Prominence Thread Models
Authors: Rovira M. G. , Fontenla J. M. , Vial J.-C. , Gouttebroze P.
Published: July 2016

We have improved previous model calculations of the prominence-corona transition region including the effect of the ambipolar diffusion in the statistical equilibrium and energy balance equations. We show its influence on the different parameters that characterize the resulting prominence theoretical structure. We take into account the effect of the partial frequency redistribution (PRD) in the line profiles and total intensities calculations.
Prominence Oscillations and Stability
Authors: Vršnak B. , Ruždjak V.
Published: July 2016

A number of high-amplitude prominence oscillations of different modes, triggered by various perturbations, are presented and classified as membrane-like, string-like, sausage-like and elastic-spring-like oscillations.
Spectroscopy of a Solar Prominence with the Narrow-Bandpass Filter
Authors: Rudawy P.
Published: July 2016

Observations and analysis of a quiescent prominence above the solar limb are presented. The set of quasi-monochromatic images of the prominence made in a few wavelengths of Hα, Hβand D3lines have been used for reconstruction of the coarse line profiles. Two-dimensional maps of the main physical parameters of the prominence matter-macroscopic and turbulent velocities, electron temperature, density and optical thickness have been constructed. Presented method of low-resolution spectroscopy is useful for investigations of the variety of large-scale solar phenomena.