bluuebunny/crossref_metadata_2025 huggingface dataset:
Out of the Archive: Faint Features of Bright Galaxies
Authors: Malin David , Hadley Brian
Published: July 2016

Simple photographic techniques are used to enhance and combine many images of (mostly) bright galaxies made from plates in the archive of the UK Schmidt Telescope in Edinburgh. The purpose of this project is to reveal extended faint features of these objects that are less than 0.5 % as bright as the night sky. Presented here are the preliminary results of what we intend to be a substantial atlas. The early results suggest that a remarkably large number of apparently normal galaxies reveal unexpected features when very deep images are produced.
Comments on Extragalactic Objective-Prism Work
Authors: Bidelman William P.
Published: July 2016

I much regret not being able to attend this interesting meeting. However, I have two comments concerning useful Schmidt work on galaxies that I would like to pass on to you for further consideration.

Both relate to objective-prism surveys for emission-line galaxies. The first is a suggestion that the work of Wasilewski (1983) should be continued. (Additional studies of his objects have been made by Bothun et al. (1989), Osterbrock & Shaw (1988) and Osterbrock et al. (1992)). This utilized the Burrell Schmidt with a 4° prism that gave a dispersion of some 400 Å/mm in the neighborhood of N1, N2 and Hβ. With this relatively high dispersion one can clearly separate these three lines, giving useful information on their relative strengths and widths that cannot be obtained from lower-dispersion material. It might be worthwhile to employ even somewhat higher dispersions than Wasilewski used, though this would no doubt affect the limiting magnitude somewhat. My second suggestion is that one should carry out objective-prism survey work in longer-wavelength spectral regions than are currently being used. The purpose is the detection of additional extragalactic objects in the z = 3–5 range; this search should utilize the lowest available dispersion.
An Optical Study of a Sample of Active Galaxies
Authors: Surace C. , Comte G. , Guibert J. , (Liege) O. Moreau
Published: July 2016

A new sample of active galaxies was obtained with the ESO Schmidt telescope. We derived quantitative redshifts for 97 emission line galaxies and semi-quantitative photometric and spectro-photometric properties for 62 of them. The results are directly extracted from the Schmidt plates after digitization by the MAMA machine of Observatoire de Paris (C.A.I, INSU Paris).
BVRI CCD Photometry of Galaxies in Abell Clusters: Hubble Types From Undersampled Data
Authors: Moody J. W. , Hintz E. G. , Joner M. D.
Published: July 2016

We have obtained BVRI CCD frames of the inner Abell radius of 14 Abell clusters as part of a survey that will eventually include 45 clusters with 0.03 < z < 0.08. We report on how the colours and surface brightness profiles can be used to identify galaxy Hubble type despite having rather large (2.1 arcsec) pixels and small images.
A Deep Multicolour CCD Survey for Quasar Candidates with the OCA Schmidt Telescope
Authors: Moreau O. , Gosset E. , Royer P.
Published: July 2016

We intend to perform a deep multicolour survey for quasar candidates using the CCD equipment recently installed at the Schmidt telescope of Observatoire de la Côte d’Azur (OCA). As a first step, we will study small areas of 0.3 square degrees but we are especially interested in the forthcoming full coverage of the Schmidt field with a CCD mosaic. In order to prepare the selection of quasar candidates, we have computed their predicted colours on the basis of a composite quasar spectrum.
Imaging and Spectroscopy with Focal Reducers
Authors: Seifert W. , Fürtig W. , Böhnhardt H. , Nicklas H.
Published: July 2016

Focal reducers are nowadays widely used on large telescopes as multi-mode instruments. Some general aspects of the design of focal reducers are discussed. FORS, the focal reducer/low-dispersion spectrograph for the ESO VLT is presented as an example for such a multi-mode instrument on a large telescope.
A Set of Grisms for FORS
Authors: Fürtig W. , Seifert W.
Published: July 2016

The University Observatories of München and Göttingen and the Landessternwarte Heidelberg are building in cooperation with ESO two almost identical FOcal Reducer /low-dispersion Spectrographs (FORS) for the ESO Very Large Telescopes. FORS allows low-dispersion multiobject spectroscopy (19 slits) and longslit spectroscopy in the wavelength range of 330 to 1100 nm. A set of standard grisms with reciprocal dispersions of 45 ...230 Å/mm working in the first order are foreseen. With a slitwidth of 1 arcsec the resulting spectral resolutions range from 180 to 1800.

For further FORS details see Appenzeller and Rupprecht (1992) and Seifert et al. (1994).

The standard grisms are located in a grism wheel in the parallel beam between the collimator and the camera. Seven of eight positions are available for grisms. The free diameter of the grisms is 135 mm to cover the whole field of view of FORS. To avoid reflection ghosts the entrance surfaces are all tilted by .
HIFI Survey of Emission-Line Galaxies: recent Results on the Nuclear Superbubble of NGC 3079
Authors: Veilleux S. , Cecil G.
Published: July 2016

The Hawaii Imaging Fabry-Perot Interferometer (HIFI) was used to produce a large data cube of the edge-on SBc galaxy NGC 3079 covering Hα + [NII] λλ6548, 6583. The complete two-dimensional coverage of the Fabry-Perot data allowed us to derive the general flow pattern of the nuclear gas that constitutes the energetic superbubble.
Deep Hα Survey of the Milky Way
Authors: Marcelin M. , Georgelin Y.M. , Amram P. , Georgelin Y.P. , le Coarer E.
Published: July 2016

An Hα Survey of the Milky Way is being led at La Silla with a small telescope equipped with a scanning Fabry-Perot interferometer and IPCS. This Survey gives detailed Hα maps with a 9” spatial resolution and radial velocity maps with a 5km/s resolution. About 200 fields (38’×38’) have been already observed along the galactic plane. They furnish mosaics ranging from galactic longitude 234° to 350°. Combined with distances of exciting stars and radio data our kinematic data of the ionized gas enable to draw precisely the spiral arms of our Galaxy. Examples of the results obtained are given for galactic longitudes 234°, 283°, 290°, 298°, 328° and 338°.
Tridimensional Observations of Nearby Active Galaxies Using OAO Spectronebulagraph
Authors: Yoshida M. , Shimizu Y. , Koyano H. , Kosugi G. , Aoki K. , Ohtani H. , Sasaki T. , Sasaki M.
Published: July 2016

We developed a slit-scanning type 3D-spectroscopic system named as Spectronebulagraph (hereafter SNG; Kosugi et al. 1994) at Okayama Astrophysical Observatory. A detailed description about SNG is presented by Ohtani et al. elsewhere in this colloquium. We present here the results of the 3D-spectroscopy of four nearby active galaxies by using SNG.

This nearby (at distance of 5.4 Mpc) Magellanic irregular galaxy has many H II regions in its main body suggesting violent star-formation activity. We performed tridimensional observations of NGC 4449 using SNG in order to obtain detailed kinematic structure and then to investigate the star-formation mechanism of NGC 4449. Hα intensity map, Hα velocity field are shown in figure 1. As is obvious in lower panel of figure 1, no global rotational motion was detected. Most impressive feature of the velocity field is kpc-scale mosaic structure of low velocity and high velocity components. Also, many filamentary components were newly found in 3D-datacube of the SNG observation.
Integral Field Spectroscopy of Gravitational Mirages
Authors: Angonin-Willaime M.-C. , Vanderriest Christian
Published: July 2016

This paper deals with applications of bi(tri)dimensional spectroscopy methods to some gravitational mirages. Optical fibre devices are well adapted to the study of the structure and geometry of such phenomena. The improvement that brought bidimensional spectroscopy of few mirages is presented and the need to observe the other candidates is discussed.
The integral field spectrograph TIGER: results and prospects
Authors: Bacon R.
Published: July 2016

The integral field spectrograph TIGER, in operation at CFHT since a few years, has been successfully used on a large variety of astrophysical objects, ranging from the planet Mars to distant radio-galaxies and quasars. This review discussed the peculiarities of the TIGER design and gives the main characteristics of the instrument. Two examples of scientific applications are presented to highlight the new possibilities offered by integral field spectrography. Finally the OASIS project dedicated to the CFHT adaptive optics bonnette is briefly presented.
Reconstruction of Spectra obtained with PYTHEAS through Photometric Methods
Authors: Gray M.
Published: July 2016

PYTHEAS is an imaging spectrophotometer giving high spectral and spatial resolutions in joining together several optical concepts (Le Coarer et al 1992, and Georgelin et al. in these Proceedings). It will be shown in this paper that, contrary to other spectrographs using somewhat complex methods of data reduction, the PYTHEAS imaging spectrometer requires simple photometric methods in order to reconstruct the spectra of astrophysical objects.

The CCD image of a continuous spectral energy distribution for a permanent gap between the layers of the Fabry-Perot consists in a series of channelled spectra: each elementary beam, spectrally filtered by the FP interferometer and sampled by a microlens in the frame, gives light to the whole surface of the grism which separates the various F-P orders by displaying them in a line on the detector. Each line or channelled spectrum consists of a series of Fabry pupils (spectral elements), each of them containing the luminous flux emitted on a certain wavelength by the object under investigation. After scanning the FP interferometer across its free spectral range, we obtain a series of shifted channelled spectra whose set provides us with a chart showing the photometric values of flux according to the wavelength. Consequently, some forms of calibration (continuum lamp, spectral lamp) allow the reconstruction of the spectra of the astrophysical object through simple photometric measures.
Low Order Fabry-Perot Low Dispersion Multicolor Large Field Survey System
Authors: Shi-Yang Jiang
Published: July 2016

Crossing a low interference order Fabry-Perot etalon with an objective prism on a Schmidt telescope leads to a simple large field multiband spectrophotometric survey system well-adapted to the study of the spectral energy distribution of faint galaxies and redshift estimates.
3-D Spectroscopy with a Fourier Transform Spectrometer
Authors: Maillard J.P.
Published: July 2016

With the advent of bidimensional array detectors the throughput advantage of a Fourier Transform Spectrometer (FTS) can be used to create a new type of 3-D spectrometer. The classical multiplex property in the spectral domain of a FTS is multiplied by the number of pixel of the array. The points of the entrance field are all observed in parallel. After discussing the properties of this instrument, the coupling of the FTS of the CFH Telescope to a camera equipped with a NICMOS 3 array is described. With this combination, spectro-imaging in any bandpass between 1 and 2.5 µm is possible within a circular 24” field of view, with a scale of 0.33”/pixel, at seeing-limited spatial resolution. Any spectral resolution is choosable up to 30,000. Illustrations are given by a study of the dark side of Venus at 1.27 µm and of planetary nebulae at 2 µm. Many other objects can benefit from this observing mode in the near infrared. Further developments of this 3-D technique are discussed.
The Field-Widened SHS: An Extremely High etendue, Unscanned, Michelson-Based Spectrometer
Authors: Harlander John , Roesler F. L. , Reynolds R. J.
Published: July 2016

This poster described a method under development that promises to be useful for 3-D spectroscopic studies of extremely faint, spatially extended astronomical sources. The method, which we call Spatial Heterodyne Spectroscopy (SHS), is a relative of the conventional scanning Fourier Transform Spectrometer (FTS), but is free of any scanning elements. We foresee ground-based and space applications for studies of the interstellar medium and the upper atmospheres of solar system objects. Basic configurations that have been tested in the laboratory were described. The SHS instrument we are currently emphasizing for development is intended for a rocket experiment to measure C IV λ1548,51 doublet emission at a resolving power of 20,000 from the hot ISM. Eventually we hope to provide velocity-resolved all-sky maps of selected FUV lines to complement maps obtained at other wavelengths.
Extensive Molecular Line Survey for Dark Clouds
Authors: Kaifu Norio
Published: July 2016

Since 1984 the molecular line search for dark clouds, mainly TMC1, for wide frequency ranges in the short cm- and mm- waverength regions has been proceeded at Nobeyama Radio Observatory using the 45-m telescope. The main collaborators are: H.Suzuki, M. Ohishi, S. Saito, Y.Yamamoto, K.Kawaguchi, and N.Kaifu.
Molecular Hydrogen Emission from Photodissociation Regions
Authors: Hasegawa Tetsuo
Published: July 2016

We review new observational and theoretical developments of the understanding of the H2 infrared emission in the last 5 years since the discovery of the fluorescent emission in NGC 2023. An excitation analysis of H2 in a variety of Galactic sources has revealed that in many sources the excitation is expressed as a mixture of thermal and fluorescent components. This finding is in good agreement with theories of photodissociation regions, in which the population of H2 changes its character from pure fluorescence to thermal as the density of the region increases. The ortho/para abundance ratio of the fluorescent H2 is observed to lie within a limited range of 1.1 — 1.8 which is well reproduced by depth-dependent model calculations of the ultraviolet excitation and dissociation of H2 molecules. This may be understood as due to the independent self shielding of each of the ortho- and para-H2, rather than the ortho/para abundance ratio of the predissociated H2, a low formation temperature of H2 on grains, or gas phase interchange reactions. A laser emission of molecular hydrogen discovered in the planetary nebula NGC7027 further demonstrates the nonthermal nature of the H2 emission in photodissociation regions.
Star Formation
Authors: Palla Francesco
Published: July 2016

Judging from the poster that the Organizing Committee has selected to announce the celebration of Guido Munch Jubilee, one can easily conclude that the main characteristics of the process of star formation as emerged in recent years through the combined efforts of multiwavelengths studies of molecular clouds, were already known, here in Granada, several centuries ago to the masters who built and enriched the enigmatic palace of the Alhambra. As we can appreciate from a quick inspection of the picture, it is rather obvious to infer that stars are the byproduct of a quite complex series of phenomena, each connected to, and somewhat dependent on, the others. Also, stars do not form in isolation, but rather in clusters or associations, with a strong tendency for the largest ones, also the most massive ones, to sit in the middle of the distribution. Moreover, smaller and less massive stars outnumber their massive counterparts, apparently obeying a power-law distribution. Finally, but with the benefit of doubt, it appears that the idea that the whole process reflects an intrinsic fractal nature was also put forward at the time. With this background in mind, let us now turn to the new emerging aspects of the study of star formation.
Radio Maps of the Regions RCW 57 and W 49
Authors: Sabalisck N.S. , Abrahan Z. , Tateyama C.E.
Published: July 2016

We present maps of the regions RCW57 and W59 in the frequency of 22 GHz with 4.’6 angular resolution. The thermal radio sources RCW57 II are well resolved in the map. RCW57 I presents, at this frequency a diameter twice as large as that reported at 5 GHz, obtained with similar resolution, but coincides with the size of the source at the wavelenght of 1 mm. In the map of the RCW57 region we detected also the supernova remnant G291.0-0.1, of plerionic type. We find a break in the spectrum of this source between 8 and 22 GHz, with the spectral index changing from −0.29 to −0.77. This behaviour is also found in other remnats of the same type.
The Chamaeleon Dark Clouds Complex: Preliminary Analysis of the Colour Excesses E(b-y) Towards the Selected Area 203
Authors: Franco G.A.P.
Published: July 2016

The Chamaeleon dark clouds form a large complex of interstellar obscuring material situated at ≈ 15° below the galactic plane. Although it is accepted as being one of the closest low-mass star formation region to the Sun, its distance has been debated issues. The proposed distance is in general dependent on the value assumed for the ratio of total-to-selective extinction, which in the Chamaeleon clouds has proved controversial, leading to distances estimates ranging from 115 to 215 pc.
Interaction Between A Stellar Wind and the Ionized Gas in N120 (LMC)
Authors: Laval A. , Rosado M. , Boulesteix J. , Georgelin Y.P. , Marcelin M. , Greve A. , Larsen J. , Viale A.
Published: July 2016

The western part of the nebula N120, in the LMC, was observed in Hα with the equipment CIGALE at ESO. This equipment consists mainly of a scanning Perot-Fabry interferometer and a two-dimensional photon counting system. The spectral step used here is 0.41 Ǡover free spectral range of 8.24 Ǡ. The total field of view of 7’ x 7’ is covered by 256 x 256 pixels (each pixel being there 2.6” x 2.6”).
On the Nature of the Beta Pictoris Circumstellar Nebula
Authors: Paresce Francesco , Artymowicz Pawel
Published: July 2016

We summarize the observed properties and deduced physical characteristics of the Beta Pictoris circumstellar nebula obtained from a detailed analysis of existing IR and optical data. On the basis of these results, we reject the hypothesis that the observed feature is a bipolar nebula surrounding an evolved star. We claim the nebula is a flattened disk of orbiting particles making up a planetary system in its clearing out phase as small grains collide, erode, and are swept out by radiation pressure.
Molecular Outflows
Authors: Snell Ronald L.
Published: July 2016

The development of millimeter and submillimeter spectroscopy has allowed astronomers to probe the cold, dense component of the interstellar medium. This medium, primarily composed of gas in molecular form, is gravitationally bound into relatively distinct clouds that are sites of star formation within our Galaxy. The most ubiquitous tracers of these molecular clouds are the rotational transitions of carbon monoxide. Observations of CO emission have been commonly used to estimate the size, temperature, mass, and density of molecular clouds; in addition, the spectral line profiles can be used to study the internal dynamics of these clouds. Although the sound speed within molecular clouds is only about 0.2 km s−1, observed CO line widths are more typically 1 to 5 km s−1. Thus, the internal dynamics of molecular clouds are characterized by supersonic gas motions whose nature is poorly understood.
Submillimetre Mapping and Photometry of Bipolar Flows - Evidence for Compact Disks
Authors: Sandell Göran
Published: July 2016

The mm/sub-mm dust emission from bipolar outflow sources is discussed. In nearby outflows the stars driving the flows appear point like and unresolved, i.e. apparent angular sizes < 7” (i.e. 700AU at lOOpc). The spectra are surprisingly flat, suggesting that the dust emission is affected by temperature and density gradients or that the dust surrounding these stars differs from that of the general interstellar medium. If the spectra are characterized with a conventional dust emissivity index, our sample gives an average value of 1.1, rather than the figure of 2, which is usually claimed at these wavelengths for dust in molecular clouds. The total dust and gas masses associated with these stars are a few tenths of a solar mass for nearby low luminosity sources and the gas densities are >107 cm−3, if the gas is in a shell, and the densities could be much higher if the gas densities fall off as a function of radius, or if the mass is distributed in a disk. These masses correspond to extremely high extinctions, which are not observed, and we therefore argue that the mass distribution must be anisotropic, most likely as an inclined disk surrounding the star. Hence, stars driving outflows are surrounded by a dense disk, possibly an accretion disks and/or collimating disk. If these stars are compared to the more evolved T Tauri stars, we find that the difference in disk mass could account for the mass loss observed in these stars. Because of the high gas densities in the disk, most commonly used molecular lines will be optically thick, and molecular observations should be done in rare isotopes and high density tracers in order to yield reliable results of gas densities and gas dynamics.
On the Formation and Propagation of Interstellar Jets
Authors: Tenorio-Tagle Guillermo
Published: July 2016

The flow that results from stationary supersonically converging conical streams is studied by means of two dimensional numerical calculations. Convcrgency leads to a “colimator” conical shock and this to the formation of an underexpanded hydrodynamical jet. The properties of the conical shock and of the collimated stream are summarized for a variety of initial conditions. The resultant jets are followed to large distances (≥ 7.5X1017 cm) away from the injection point, and are shown to develop a complicated structure that eventually approaches a stationary state. Stationary features such as crossing shocks are shown to evolve from working surface shocks, left behind the head of the jet to ensure self-collimation of the beam matter.
The Collimation of Nonadiabatic Winds from Young Stars
Authors: Raga A. C. , Cantó J.
Published: July 2016

Outflows from young stars in many cases show evidence for collimation. For example, bipolar molecular outflows are sometimes quite well collimated (see, e. g., Snell 1982), and stellar jets and Herbig-Haro objects show an even higher degree of collimation (see, e. g., Mundt 1987).
New Young Objects from the IRAS Point Source Catalogue
Authors: Manchado A. , Garcia Lario P. , Sahu K. C. , Pottasch S.R.
Published: July 2016

Three new objects have been found, when carrying out a survey of IRAS sources with colours like planetary nebulae, via low resolution spectroscopy. IRAS 14592-6311 and IRAS 07173-1733 are bright cometary nebulae, showing metal line emission very similar to V1331 Cyg (LkHα 120), which is the prototype of a certain number of T Tauri stars. They present strong P-Cygni profiles and some other peculiar characteristics. IRAS 14592-6311 is associated with a molecular cloud at a distance of 2.9 kpc, while IRAS 07173-1733 is located at the edge of the dark cloud KHAV 201. In the case of IRAS 05506+2414, it presents a bipolar structure with Herbig-Haro emission characteristics in one of the lobes, produces by shocked gas, and is located near Orion.
H2 2.12 μm Spectroscopy and Imaging of HH Objects
Authors: Zinnecker H. , Mundt R. , Moneti A. , Geballe T.R. , Zealey W.J.
Published: July 2016

We have obtained high spectral resolution observations of a number of Herbig-Haro (HH) objects in the H2 v=1-0 S(1) line at 2.12μm. Objects observed included HH1/2, HH7-11, HH19, HH32A, HH40, and HH43, all associated with jet-like features or collimated optical outflows. Here we present velocity-resolved 2.12μm spectroscopy for HH40 (an HH-objects moving close to the line of sight) an for HH43B (an HH-object moving close to the plane of the sky). The full set of observations including interpretation is given in Zinnecker et al. (1989). We also present high spatial resolution H2 2.12μm images of HH40 and HH43. The 2.12μm H2 line profiles were obtained with the UKIRT infrared Fabry-Perot system (effective resolution 30-35 km/s) using a diaphragm of diameter 11” for both HH40 and HH43. The H2 images were obtained with the IR-array imager at the CTIO 1.5m telescope through a narrowband filter centred on the v=1-0 S(1) line. The IR-camera used had 58x62 pixels and a resolution of 0.9”/pixel. The exposure time was 2x120sec and 5x60sec for HH40 and HH43, respectively. The images are sky subtracted, but not fiat fielded, and should be viewed as preliminary test images.
Evolution of Clumpy Gas in Galaxies
Authors: Kunze R. , Yorke H.W. , Spurzem R.
Published: July 2016

The basic equations for treating a multicomponent medium: stars, gas clouds and an ambient gas are discussed elsewhere (Yorke, et al., this meeting). Here we apply the 2-D multicomponent code to the problem of explosions in a clumpy medium (cool “clouds” embedded in a warm T ~ 104K or hot T ~ 106K gas). The evolution of supernova remnants and supershells in media of varying degrees of dumpiness are compared and contrasted to the results of earlier calculations.
High-Velocity Absorption Components Toward the LMC
Authors: Vladilo G. , Molaro P. , Monai S. , Centurion M.
Published: July 2016

High-resolution (λ/δλ ⋍ 6 x 104) spectra of R136 (the central object of 30 Dor) and of 2 LMC supergiants obtained at ESO with the 1.4-m telescope have been analysed in order to study the high-velocity absorption components at VLSR ⋍ +60 km s-1 and ⋍ +130 km s-1 first seen in satellite ultraviolet spectra in the general direction of the LMC. Our data have been integrated with previous literature results of SN1987a and of other 4 LMC supergiants obtained from spectra of similar spectral resolution.

At least 6 (possibly 9) interstellar components are found in the range +40 km s-1 ≤ VISR ≤ + 150 km s-1, suggesting that the IUE features at ⋍ +60 km s-1 and ⋍ +130 km s-1 are in fact splitted in several components when observed at higher resolution. Two components originally discovered toward SN1987a (VLSR ⋍ +42 km s-1 and +107 km s-1), are detected for the first time in the Call interstellar spectrum of R136. A component at VLSR ⋍ +49 km s-1 shows significant variations both in Call and in Nal along the different lines of sight. A relatively broad component at VLSR ⋍ +58 km s-1 is present in Call toward R136, but is generally undetected in Nal in the other lines of sight. Also the components in the range +100 km s-1 ≤ VLSR ≤ +150 km s-1 are detected in Call, but not in Nal. Two weak absorptions, detected at +125 km s-1 and +141 km s-1 toward R136, may be associated with the ⋍ +130 km s-1 component characteristic of the ultraviolet spectra.

The almost perfect velocity coincidence of the +107 km s-1, +42 km s-1, +49 km s-1 and +57 km s-1 components along different lines of sight suggests a common origin of the absorbing gas and a location close to our Galaxy. In spite of the low detection limit in our spectra (Wλ ⋍ 5 mÅ), the lack of detection of Nal is compatible with the presence of foreground gas clouds with hydrogen column density N(HI) ≤ 2 x 1019 cm-2, or even greater. The fact that we can detect more easily Call absorptions than the corresponding Nal absorptions indicates a very low value of Call depletion.
Observations of the Galactic Halo
Authors: de Boer Klaas S.
Published: July 2016

After reviewing the history of the early research on gas in the Milky way halo, observational methods to investigate the halo are described. The meaning of the concepts Halo and HVC is discussed and selectional bias in databases is pointed out. The essentials of the interpretation of observed velocities are given. The scanty information on distances of HVCs is reviewed and an outlook is given on the possibilities to firmly settle the distance of at least a few HVCs.
The Violent Interstellar Medium in Messier 31
Authors: Brinks Elias , Braun Robert , Unger Stephen W.
Published: July 2016

TAURUS observations in the line of Hα and VLA HI mapping of the HII complex No. 722 in M31, reveal what seems to be a spherical cavity 330 pc in diameter blown out by a stellar association of over 20 × 106 year old. Evidence of induced star formation which was initiated less than 5 × 106 years ago is present in the form of bright HII emission and numerous O, B and Wolf-Rayet stars which are found within the shell surrounding the cavity. The energy necessary to create the HI shell is estimated to be about 5 × 1051 erg.
Contributions of Supernovae to the Chemical and Dynamical Evolution of the ISM
Authors: Trimble Virginia
Published: July 2016

Supernovae of Types Ia, Ib, and II contribute, on average, 1051 ergs of turbulent energy to the interstellar medium for each 2 Mo of new heavy elements. This permits a dynamical extension of the homogeneous one-zone model (with constant IMF and instantaneous recycling) that is familiar from studies of galactic chemical evolution. Chemically possible scenarios predict current kinetic energy inputs ranging from 1039 to 1040 erg yr−1 per solar mass of interstellar gas. Dynamical studies might narrow this.
Solar Monitoring has a Past and Present: Does it have a Future?
Authors: Willson Richard C.
Published: July 2016

Intrinsic variations of total solar irradiance have, after nearly a century of sustained effort, been demonstrated by flight experiments during solar cycles 21 and 22. This accomplishment has been the result of a collaborative effort on behalf of several groups of researchers in both the United States and Europe. The overriding concern at this point of time is whether the integrity of the precision long-term solar total irradiance database, which began at the maximum of solar cycle 21 and continues in the present, will be lost in the late 1990’s, prior to the inception of experiments planned for the NASA Earth Observing System beginning in 2002. Experiments are not currently in place to prevent an unbridgeable discontinuity in the precision total solar irradiance database.
Irradiance Observations of the Sun
Authors: Fröhlich Claus
Published: July 2016

Measurements of the total solar irradiance during the last 14 years from satellites show variations over time scales from minutes to years and decades. The most important variance is in the range from days to several months and is related to the photospheric features of solar activity: decreasing the irradiance during the appearance of sunspots, and increasing it by faculae and the bright magnetic network. Long-term modulation by the 11-year activity cycle is observed conclusively with the irradiance being higher during solar maximum. The accuracy of the determined variability and its interpretation in terms of manifestations of activity related features on the photosphere is discussed. Besides the direct influence of the spots, faculae and magnetic network more profound changes in the thermal transport seem to influence the behaviour of the solar photospheric radiation on the solar cycle and longer time scales.
Irradiance Observations from the UARS/SOLSTICE Experiment
Authors: Rottman Gary J. , Woods Thomas N. , White Oran R. , London Julius
Published: July 2016

The Solar/Stellar Irradiance Comparison Experiment (SOLSTICE) is one of the two ultraviolet spectrometers on the Upper Atmosphere Research Satellite (UARS) measuring the full disk solar irradiance. This spectrometer covers the spectral range of 119 to 421 nm and typically makes ten full spectral scans per day. The instrument was designed to monitor changes in the solar radiation with a relative accuracy of better than 1%. To achieve this goal the spectrometer makes repeated observations of a number of bright blue stars; stars that individually should vary by only small fractions of a percent over time periods of thousands of years. The calibration stars are observed with the same optics and detectors used for the solar observations and any drift in the instrument response is directly determined by changes in the ensemble average flux from these calibration stars. The instrument performance and calibration are described and solar data from the first year of the UARS mission are presented. These UARS data show significant solar activity during late 1991 and early 1992 and then clearly mark a decrease as we move off the maximum of solar cycle 22. We are optimistic that an extended UARS mission, perhaps as long as ten years, is now possible.
Photometric Variations of Solar Type Stars
Authors: Radick Richard R.
Published: July 2016

High precision measurements of photometric variability among solar type stars have now been made since 1980. These observations clearly show that year-to-year brightness variations connected with magnetic activity are a widespread phenomenon among such stars. They also suggest that the Sun’s potential for long-term white light variability may be significantly understated by measurements of solar total irradiance during the 1980s.
The Variability of Stellar Magnetic Flux, Related Surface Structures and Activity
Authors: Saar Steven H.
Published: July 2016

I review information from a variety of sources, including magnetic field measurements, Doppler imaging, and various photometric and spectroscopic survey and monitoring programs for clues concerning the physical properties, spatial structure, variability and evolution of magnetic regions and associated activity on cool stars. Based on these data, I sketch a scenario of what the surfaces of cool stars look like as a function of spectral type and age/rotation/activity level.
Solar Rotation, Irradiance Changes and Climate
Authors: Nesme-Ribes Elizabeth , Sokoloff Dmitry , Sadourny Robert
Published: July 2016

Magnetic activity cycles for solar-type stars are believed to originate from non-uniform internal rotation. To determine this depthwise angular velocity distribution, helioseismology is a valuable source of information. Surface rotation, as traced by sunspot motion, is a well-observed parameter with data going back to the beginning of the telescopic era. This long sunspot series can be used in understanding the behaviour of the Sun’s surface rotation, the connection with its internal rotation, and thereby its magnetic activity. Apparent solar diameter is another important parameter. This is related to the structure of the convective envelope and how it reacts to the presence of magnetic fields. Both these parameters are related to the solar output, and can provide a surrogate for total solar irradiance, by way of a theoretical modeling of the response of the convective zone to the emergence of periodic magnetic fields. The impact of solar variability on the terrestrial climate is also addressed.
Large-Scale Coronal Magnetic Structure and Its Variations during an 11-year Solar Cycle
Authors: Ivanov E. V.
Published: July 2016

Maps of coronal magnetic fields at different heights calculated under potential approximation, have been used to reconstruct the corona shape in different phases of solar cycles 21 and 22. The shape of the solar corona depends on the maximum heliolatitudes and the structure of the heliospheric current sheet (HCS) that, in turn, are determined by space-time variations of the 3 main components of the global magnetic field of the Sun: 1) the axial dipole component; 2) the inclined dipole component; and 3) the quadrupole component. Variations of theHCSmaximum heliolatitudes and the width of the corona at 2.5R⊙during a solar cycle are compared with variations of the global magnetic field indices in the photosphere and at the source surface. The role of the solar cycle reference points and the global magnetic field indices in the corona shape variations over a solar cycle are discussed.
White-Light Coronal Structures: Streamers and CMEs
Authors: Hildner E.
Published: July 2016

Over the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.
Observed Large-Scale East-West Asymmetries in the Solar Corona
Authors: Noëns J. C. , Pech B. , Xanthakis J. , Mavromichalaki H. , Tritakis V. , Petropoulos V. , Paliatsos A.
Published: July 2016

Some new results are presented and discussed about the problem of the asymmetries in the observed corona between the east and west limbs. “Local effects” are analysed. Relations within one eleven-year solar activity cycle are shown.
Large-Scale Coronal Magnetic Field and Density Structures
Authors: Gibson S. , Bagenal F.
Published: July 2016

We have modelled the large-scale magnetic field and density structures in the corona using the magnetostatic model of Bogdan and Low (1986) and white light images from both NASA’s Solar Maximum Mission (SMM) Coronagraph/Polarimeter and the High Altitude Observatory Mark III (MkIII) K-coronameter (Bagenal and Gibson, 1991; Gibson and Bagenal, 1992.)

We have used the magnetostatic model to calculate the magnetic field, density, pressure, and temperature distribution in the corona. Moreover, we have studied how, if at all, photospheric magnetic field observations could be used to improve predictions of coronal fields.

We are at present examining the implications of our predictions of magnetic field and density structures have for coronal heating and solar wind acceleration. We are also analysing the robustness of these predictions, studying both observational and model related errors.
Coronal Mass Ejections and the Critical Velocity Ionization Phenomenon
Authors: Golbraikh E. , Filippov M. , Steinitz R.
Published: July 2016

We propose a new viewpoint concerning the mechanism for coronal mass ejection (CME) formation in the solar corona. According to developed approach the origin of CME is connected with high-speed movement in the transition zone or lower. The high-speed flows of neutral gas are able to produce explosive events (EEs) and jets in the chromosphere by the critical ionization velocity (CIV) mechanism. They can be sources of eruptive prominences. In this case CIV phenomenon results in ion and electron heating up to tens of eV. In turn high-energy electrons can cause weak flares. The eruptive prominences generate CMEs with velocities ≥ 100 km s−1. Thus, the following chain of phenomena appears to form the observed CME: high-speed movements of neutral gas – its ionization due to CIV phenomenon – eruptive prominences (weak flares) – CMEs.
Filling of Magnetic Loops by an Electric Current
Authors: Gopasyuk S. I.
Published: July 2016

Results of investigations of the magnetic fields and electric currents in the active region are presented. The calculations based on the observational data showed that the electric currents are more concentrated in lower magnetic loops. The cause of this is the magnetic loop stretching. For a stretching magnetic loop the self-inductance increases and the current decreases.
Flaring Coronal Structures
Authors: Watanabe T.
Published: July 2016

The highlights of the Japanese solar mission,Yohkoh, are presented, with emphasis on flaring structures in the solar corona. Definitive evidences of the magnetic reconnection in the solar corona are observationally confirmed for the first time. New insights in the location of hard X-ray sources are obtained. Completely blueshifted line emissions from highly ionized plasmas are seen at the very initial phase of solar flares. It is revealed that the solar corona is very dynamic in various time scales in X-ray intensities. Ample evidences of numerous flare-like activity like microflares and X-ray jets conclude that they are also the manifestation of the magnetic reconnection.
The Superthermal Electrons in Flare Loops
Authors: Karlický M.
Published: July 2016

In this paper the collisional, return current, mirroring and wave-particle interaction effects on the propagation of superthermal electrons in flare loops are reviewed. Moreover, the electron bombardment of dense layers of the solar atmosphere and corresponding atmospheric response are presented. The accompanied X-ray, radio and Hαemissions during the evaporation process are discussed.
Can Soft X-Rays Be Used as a Proxy for Total Energy Injected by a Flare into the Interplanetary Medium?
Authors: Smith Z. K. , Dryer M. , Armstrong M.
Published: July 2016

Solar flares are a source of impulsive energy releases on the Sun that can inject energy into the interplanetary medium. Some of these energy injections drive interplanetary shocks that can, in turn cause disturbances in Earth’s environment. In an attempt to quantify these energy releases using readily available observational data, we explore the possibility of using, as a proxy, the solar flare signatures observed in soft X-ray data. Our motivation has been prompted by the real-time operational requirements of NOAA and U. S. Air Force to provide estimates of arrival times and strengths of shocks that impact Earth’s magnetosphere. The luxury of extensive,ex post factostudies of flare total energy outputs is not possible in an operational context. This study is restricted to flares associated with shocks seen in the corona as metric type II radio bursts. Using GOES data, the energy released in the 1-8Å X-ray wavelength band is computed and then compared to the estimates made from a numerical model based on two-dimensional, time-dependent MHD modeling of flare-initiated interplanetary shocks. We find that the proxy energy estimates computed from the GOES data provideno advantageover the estimates made using the MHD-based numerical model.
Type II Solar Radio Bursts over Solar Cycle 21
Authors: Maris G. , Tifrea E.
Published: July 2016

The type II solar radio bursts produced by a shock wave passing through the solar corona are one of the most frequently studied solar activity phenomena. The scientific interest in this type of phenomenon is due to the fact that the presence of this radio event in a solar flare is an almost certain indicator of a future geophysical effect. The origin of the shock waves which produce these bursts is not at all simple; besides the shocks which are generated as a result of a strong energy release during the impulsive phase of a flare, there are also the shocks generated by a coronal mass ejection or the shocks which appear in the interplanetary space due to the supplementary acceleration of the solar particles.
Fine Structure of Prominences and Filaments
Authors: Mein P.
Published: July 2016

The fine structures of prominences and filaments are involved in many phenomena such as formation and magnetostatic support, instabilities and eruptions. After a short introduction (Section 1), we concentrate on quiescent prominences, and we review some recent results about resolved structures (Section 2), statistical properties of “threads” (Section 3), and detailed analysis of average line profiles (Section 4). We mention magnetic field measurements (Section 5) and thermal problems (Section 6). New magnetostatic models (Section 7) are very promising. We discuss briefly the problem of the scale of fine structures, and we suggest some directions for further works (Section 8).
Cold Matter in Filament Channels
Authors: Engvold O.
Published: July 2016

The formation of cold filaments in the low corona is a central research area in solar physics. Their basic properties are not well understood, but they may be crucial for the mass and magnetic flux balance in the solar corona. The review discusses multi-wavelength observational results and theoretical modelling of filament channels and quiescent filaments.
Remarks on Two-Dimensional Magnetic Arcade Models of Coronal Structures
Authors: Anzer U.
Published: July 2016

A critical evaluation of some recent models for coronal structures using two-dimensional magnetic arcades will be given. We discuss prominences with inverse polarity as well as the evolution of sheared arcades.
On the Motion of Eruptive Prominences
Authors: Molodensky M. M. , Vial J.-C.
Published: July 2016

The increase of current in filaments can be evidenced by the variation of its twist. We show two examples of such a current increase, the last stage of which is the filament eruption and the flare. We suggest a theory of the equilibrium and the eruptive motion including the interaction of the filament current with the magnetic fields of the active region and the mirror current. We take into account the curvature of filament.
Line Formation and Intensity Enhancement of the He II 304Å Line in the Solar Atmosphere
Authors: Jordan S. D.
Published: July 2016

Observations of He II 304Å line profiles from the Goddard solar EUV sounding rocket flight of May 9, 1991 are analyzed to determine lower limits on the small scale non-thermal velocities in the regions observed. In the quiet Sun, a lower limit of 30 km/s is obtained over much of the spectrograph slit. It is argued that a sufficient fraction of the He II ions will survive in their upward motions, before collisional excitation to produce a 304Å photon, to enhance the computed line intensity up to the observed values, in contrast to earlier theoretical results that yield total line intensities generally smaller than observed values.
The Excitation Equilibrium in the Solar Corona and Non-Maxwellian Electron Distributions
Authors: Dzifčáková E.
Published: July 2016

We demonstrate the influence of an electron non-Maxwellian distribution function on the collisional excitation coefficient and, as an example, on the excitation equilibrium of Fe XIV in the solar corona. The results can be used for specific applications in the solar corona, especially in the active corona, where deviations from Maxwellian distribution can be significant.
Dissipation of Coronal Waves
Authors: Edwin P. M. , Laing G. B.
Published: July 2016

The dissipation of ducted, fast magnetoacoustic waves by ion viscosity, electron heat conduction and radiation in a cold plasma is re-considered. The results are compared with earlier ones and it is now found, contrary to previous belief, that the ducted waves are not readily dissipated in the solar corona and are therefore unlikely to play a role in the heating of the solar atmosphere.
Total Solar Eclipses, 1994 – 1999
Authors: Pasachoff J. M.
Published: July 2016

I summarize total solar eclipses that will occur during the 1990s, as part of the coordinating task of the Working Group on Eclipses of the International Astronomical Union. These eclipses will provide several favorable opportunities to provide coronal and other solar observations not only for intrinsic data reduction but also to compare with observations obtained from a variety of spacecraft.