bluuebunny/crossref_metadata_2025 huggingface dataset:
Results of the Hα Survey of the Small Magellanic Cloud
Authors: Rosado Margarita , le Coarer Etienne , Georgelin Yvon
Published: July 2016

We present the results of a kinematic survey of the Small Magellanic Cloud, performed with a scanning FP interferometer mainly at Hα. These data allow us to study the overall dynamics of the ionized hydrogen of this galaxy as well as the kinematics of classes of objects. In this presentation we exemplify how the availability of data in several wavelengths can be very useful in establishing the nature of large nebular complexes of the Small Magellanic Cloud. Our kinematic study allows us to discriminate faint shocked nebulae (such as supernova remnants) inside bright HII regions. This is confirmed by recently available radio and X-ray data.
Hα Survey of the Large Magellanic Cloud
Authors: Laval A. , le Coarer E. , Georgelin Y.P. , Marcelin M. , Amram P. , Goldes G. , Carranza G. , Rosado M.
Published: July 2016

The LMC is being surveyed in the Hα emission line with a scanning Fabry-Perot interferometer, attached to the 36 cm telescope of the Observatoire de Marseille. The present results concern the kinematical mapping of bright nebulae; it shows that the kinetic energy involved in the gas motion is closely related to the evolutionary stage of the embedded stars. In particular, in the 30 Dor nebula, a few one-peaked line profiles remain at the boundaries of the shells, among the numerous split areas. The 50-100 pc shells exhibit a relatively usual spherical expansion, with velocities in the same range at the boundaries. On the contrary, the 10-20 pc shells of the central core show different velocities of the one-peak sides of the shells.
Three-Dimensional Fabry-Perot Imaging Spectroscopy of the Crab Nebula
Authors: Lawrence Stephen S. , MacAlpine Gordon M. , Uomoto Alan , Gelderman Richard , Woodgate Bruce E. , Brown Larry W.
Published: July 2016

A three-dimensional model of the [O III] λ5007 line-emitting gas in the Crab Nebula has been developed from imaging spectroscopy taken with the Goddard Fabry-Perot Imager mounted on the McGraw-Hill 1.3m telescope of Michigan-Dartmouth-MIT Observatory. Several interesting morphological features revealed in three-dimensional isophotal displays are discussed.
Hybrid 3-D Spectrophotometry of Emission-Line Nebulae at Ohio State
Authors: Pogge Richard W. , Lame Nancy Joanne
Published: July 2016

A program of 3-D spectrophotometry of emission nebulae being carried out at the Ohio State University will be described. We have had considerable success combining Fabry-Perot imaging, long-slit spectroscopy, and narrowband filter imaging into a hybrid 3-D spectroscopic approach that we have used to obtain detailed spectrophotometric maps of the density, temperature, extinction, and ionization in HII regions and Planetary Nebulae. The centerpiece instrument of this effort, the OSU Imaging Fabry-Perot Spectrograph (IFPS), will be described, and scientific results illustrative of our work will be presented.
3D Observations of the nebula N30 in the LMC
Authors: Laval A. , le Coarer E. , Viale A. , Marcelin M. , Amram P. , Georgelin Y.P.
Published: July 2016

N30 is a 80×330 pc nebula, seen in projection to the North of the LMC. At the position of the nebula, the neutral HI gas is distributed within two layers, with respective heliocentric velocities of 303 km s−1 for the major disk component, and 285 km s−1 for the low-velocity component (Luks & Rohlf 1992). The respective positions of the HI components along the line of sight are not known, nor is the distance between the HI layers, nor their thickness. N30 has been observed with the “survey Hα” equipment of the Observatoire de Marseille (see Rosado et al, and Marcelin et al.,this meeting), giving a 38’ square field (spatial resolution of 9“×9”) and using two scanning Fabry-Perot interferometers, the first one having a spectral sampling step of 15.7 km s−1, and the second one of 4.8 km s−1. No splitting of the line profile is visible, excluding large inner motions. The main emissions measured in N30 and also in all its 8 nearby bright and faint nebulae have heliocentric velocities in the range 302-315 km s−1. Such a velocity shows that all the nebulae are situated inside the HI disk component, following their exciting stars.
Astronomical Observations of Comets and the Io Torus Using Fabry-Perot-Interferometry
Authors: Jockers Klaus
Published: July 2016

Fabry-Perot interferometers have been applied in a focal reducer to observe radiation from atoms and molecules in comets and in the Io torus. Tunable Fabry-Perot interferometers have been used as narrowband filters, and an etalon with fixed airgap in classical arrangement was employed for the measurement of Doppler shifts and for narrow-line photometry.
A Two-Dimensional Spectrometer for Solar Observation and its recent modifications
Authors: Bendlin Cornelia
Published: July 2016

The instrument presented here is based on the combined use of a Universal Birefringent Filter (UBF) and a Fabry-Perot Interferometer (FPI) to obtain narrow-band filtergrams with a CCD. Scanning through a Fraunhofer line with a sufficient number of wavelength settings is accomplished within a few seconds by tuning only the FPI. The two-dimensional spectrometer in the German Vacuum Tower Telescope (VTT)/Tenerife was used to take observations of high spatial, spectral, and temporal resolution, yielding a wide range of results. Since recently, additional information on the solar magnetic field is obtained with it.
An Infrared Multiobject Fiber–Fed Spectrograph for the Calar Alto Observatory
Authors: Herbst T. M. , Pitz E. , Reuther C. M.
Published: July 2016

We report the first use of a near infrared multiobject spectrograph that can acquire 1–2.5µm spectra of up to 35 objects in a 1000 arcsecond field.
High Spatial Resolution Integral Field Spectroscopy of extended Ionized Gas around three Quasars
Authors: Durret F. , Pécontal E. , Petitjean P. , Bergeron J.
Published: July 2016

Three quasars, Ton 616, 4C 37.43 and PKS 2251+113 (Stockton and MacKenty 1987) were observed in 1992 at the 3.6 m CFH telescope with the Integral Field Spectrograph TIGER (Courtès et al. 1987, Pécontal 1991) under subarcsecond seeing (0.5 - 0.7”). The spatial sampling was 0.39” in a field 7 by 7 ”, and the spectral resolution 8 ÅFWHM in the Hβ - [OIII]λ 5007 wavelength region (in the rest frame of the objects). The scaling is 4.5, 5.9 and 5.3 kpc.arcsec−1 for Ton 616, 4C 37.43 and PKS 2251+113 respectively (H0 = 75 km.s−1.Mpc−1). The data were reduced with the software developed at Observatoire de Lyon by Rousset, Bacon and Pécontal (Rousset 1992). A detailed account of our results is reported in Durret et al. 1994.
Near-Infrared Spectroscopy of the Surface of Mars Derived from TIGER Spectro-Imaging Data
Authors: Martin P. , Pinet P.C. , Bacon R. , Rousset A.
Published: July 2016

High spectral and spatial resolution telescopic observations of the western hemisphere of Mars, using the integral field spectrograph TIGER at 0.8-1.1 µm, are described.
A Review of Fabry and Perot discoveries
Authors: Georgelin Y.P. , Amram P.
Published: July 2016

It is a great pleasure for us, daily Fabry-Perot interferometer (hereafter referred to as FP) users, to pay homage to the genius inventors of the FP. Each day we are still bewildered by the power of this instrument which mainly consists of two pieces of half-silvered glass. Even if equations of physics are perfectly able to describe multiple-beam interferences (hereafter referred to as MBI), something magic remains in our mind.

We will tackle this paper from a historical point of view. As any discovery, the invention of the FP did not occur just by chance from nowhere. As pointed out by Connes (1986) the invention of the multiple-beam interferometer may be understood as having proceeded from the fortunate convergence of two independent developments: (i) During 2 centuries, MBI has been observed and even computed but its specific and pregnant feature, the fringe sharpening, was not understood before Fabry’s thesis, (ii) A long production of mirrors, leading to the semi-transparent silver film.
Turbulence in Interstellar Clouds
Authors: Falgarone E.
Published: July 2016

Above masses of the order of lOO M⊙, molecular clouds have masses and sizes which scale like those of self-gravitating polytropes bounded by an external pervading pressure. It is unlikely that this scaling is due to mere observational bias. But the physics underlying this behaviour is far from being understood. In particular, the possible contribution of turbulence to both the ambient pressure and the internal pressure (whose dependence with the density would mimic a polytropic behavior) is a difficult and much debated issue. The clouds mass, size and internal velocity dispersion are such that they are observed to be in approximate virial balance between their self-gravity, the surface energy term due to the ambient pressure and their internal energy. The latter is dominated by the kinetic energy of disordered internal motions. However, there has been little evidence so far that these motions are actually turbulent rather than simply disordered. The transition to turbulence in a flow occurs when the non linear advection term in the momentum equation, v.Δv, considerably exceeds the viscous dissipation term, vΔv (wherevis the kinematic viscosity). Non linearities therefore dominate the physics of a turbulent flow and the velocities are not randomly distributed. Most of the previous attempts to determine a well-defined correlation length in the velocity field (Kleiner and Dickman 1985,aandb;Scalo 1984), which is predicted to be close to the scale at which the energy is injected, or to characterize the expected hierarchical structure (Pérault et al. 1986) have been plagued by the lack of dynamical range in the data set and the range of scales over which the correlation functions have been computed. The most plausible determination, that of Kleiner and Dickman (1987) who claim to have found a correlation length of0.2 pcin the Taurus cloud, gives a result which is so close to the angular resolution of the observations that it is doubtful.
The Sharpless 187 Gas Complex : A Study of the Molecular, Atomic, Ionized and Dust Components
Authors: Joncas Gilles , Durand Daniel , Kömpe C. , Roger R.S.
Published: July 2016

Star forming regions are one of the active components of the interstellar medium and as such play an important role in the galactic “ecosystem”. When massive young stars are borned they have a strong impact on their environment through their radiation flux and stellar wind. We are then facing complicated interplays between gas in different states (ionized, atomic and molecular), dust particles and the young stars. The understanding of these interplays can only be done using multifrequency observations. Such an endaveour is already in progress (see Joncas et al. 1988 and Kömpe et al. 1989). We will describe here the young star forming region S187 (Sharpless 1959). This gas complex is nearby (≈1 kpc) thus permitting high spatial resolution with medium size instruments. It contains a faint optically visible HII region ionized by an unidentified BO or BO.5 star. The associated molecular cloud, discovered by Blair et al. (1975), contains a molecular outflow (Bally and Lada 1983) to which an H2O maser is associated (Henkel et al. 1986).
A Theory on the Slope of the IMF
Authors: Zinnecker H.
Published: July 2016

Molecular clouds are clumpy, and the mass spectrum (dN/dM) of clumps scales with the clump mass M to the -1.5 power, as determined from CO observations of molecular clouds (Blitz 1988, Stutzki et al. 1989). The basic idea is to translate the mass spectrum of clumps into a mass spectrum of stars (that are assumed to form from these clumps) by virtue of a clump-star (i.e. initial-final) mass relation.
Interstellar Wind-Blown Bubbles
Authors: Dyson J. E.
Published: July 2016

‘Classical’ stellar wind-driven bubbles are either energy or momentum driven, and evolve in smooth media containing only radial density gradients. Real bubbles are produced from winds from moving stars and which blow into non-homogeneous media. The resulting mixing of clump material can produce a variety of thermal, dynamical and chemical effects. In this review we discuss some of the modifications to classical bubbles which ensue, using observational examples where appropriate.
Supernova Remnants
Authors: Falle S.A.E.G.
Published: July 2016

In this review I will concentrate on older remnants, by which I mean those in which radiative cooling is important somewhere and the swept up mass is sufficiently large for the details of the initial explosion not to matter. For such remnants it is the optical emission which is crucial since it allows us to deduce a great deal about the physical state of the emitting gas provided we are careful about how we interprete it. Without discussing any particular remnant in detail, I will consider how large and small scale density variations in the ambient medium affect the appearance and energetics of such remnants.
Dust Condensation in the Ejecta of SN 1987A
Authors: Lucy L.B. , Danziger I.J. , Gouiffes C. , Bouchet P.
Published: July 2016

An asymmetry of optical emission lines that appeared in Sept. 1988 is interpreted as evidence of dust condensation within the metal-rich ejecta of SN 1987A. A quantitative analysis of this spectroscopic effect is given and shown to be compatible with the photometric record. Moreover, observational and theoretical estimates of the bolometric light curve come into agreement when the far-IR excess is interpreted as thermal emission by grains in the ejecta. A grain population comprising small silicate grains with an admixture of graphite or amorphous carbon particles is suggested by the data. The relevance of this discovery to suggestions that supernovae are major sources of interstellar dust is briefly discussed.
Infrared Environment of the BE Star 6 Cephei: Interaction of Stellar and Interstellar Winds
Authors: Kun M.
Published: July 2016

Several arclike structures are seen on the high resolution IRAS images (processes via GEISHA system of Groningen) centred on the Be star 6 Cephei, among others an extended bow shock which indicates the rapd motion of the star and the interstellar matter relative to each other. 6 Cephei is embedded in a giant infrared-emitting shell which is thougth to be a three million year old supernova remnant, therefore in this case the presence of the bow shock around the star shows the interaction of a supernova blast wave with the stellar wind of a Be star. In this paper an attempt is made to reveal the history of the interactions of the star with its surroundings during different periods of its life which are recorded on the infrared maps. Some aspects of the formation and evolution of 6 Cephei can be inferred also from its infrared environment.
Near-Infrared Images of the Serpens Molecular Cloud Core
Authors: Eiroa C. , Casali M.
Published: July 2016

Near-infrared images of the Serpens molecular cloud core have been carried out at UKIRT (Mauna Kea Observatory) using the infrared array camera, IRCAM. A large-scale diffuse nebulosity extending over the central part of the core is observed. Over 100 K-sources are detected in the 30 arc min2 cloud core. Some of them are PMS objects which were previously unknown. For the first time, a near-infrared counterpart of the far-infrared source Seroens FIRS1 has been detected. The 2.2 µm source appears as a point like object at the apex of an extended knotty, jet-like nebulosity oriented towards the northwest. In addition, a group of 11 stellar objects is seen in the position of the IR/radio source SVS4. These objects are embedded in a very faint nebulosity and form one of the densest clustering of young stars found in dark clouds.
A CO Search for Molecular Gas in High Mass Post-Main-Sequence Nebulae
Authors: Phillips J.P. , Mampaso A. , Ukita N. , Williams P.G.
Published: July 2016

High mass post-main-sequence nebulae are characterised by a set of unusual, and in certain cases extreme physical characteristics, including large outflow velocities (cf. Phillips and Mampaso, 1988a), extremely compact high emission measure cores (Phillips and Mampaso, 1988b), a high incidence of bipolar morphology (Peimbert and Torres Peimbert, 1982), and evidence for anomalously high levels of shock excited H2 S(l) emission towards both the source cores (Phillips et al 1983, 1985) and nebular peripheries (Zuckerman and Gatley, 1988). The large central star masses also predispose these sources to rapid evolution within the H-R plane (perhaps one or two orders of magnitude more rapid than for typical PN (Schonberner 1981, 1983), and the acquisition of stellar temperatures T* > 105 K, giving rise to correspondingly high levels of nebular excitation.
New Ovro Results Show Disks are Not Necessary for Focussing Bipolar Outflows
Authors: Barsony M.
Published: July 2016

In order to better understand the outflow phenomenon in young, high mass stars, the three sources S87, LkHα101, and S106 were chosen for closer study. High spatial resolution (5” millimeter line 13CO (J=1→0) and CS (J=2→1) maps of these sources were obtained with the Owens Valley Radio Observatory’s (OVRO) millimeter array at 0.15 and 3.0 km s-1 resolutions, respectively.
The Molecular Envolope of Mira
Authors: Planesas P. , Bachiller R. , Martín-Pintado J. , Bujarrabal V.
Published: July 2016

We have mapped the CO J = 2 → 1 and J = 1 → 0 emission of the circumstellar envelope of Mira. Emission in both transitions extends to a distance of ~ 4 x 1016cm from the star. In the inner 2 x 1016cm the lines show the presence of three velocity components. The main component has the intermediate velocity and extends over the whole envelope. From this component we have estimated a mass loss rate of 3 x 107M⊙yr-1 and a total molecular mass of 1.2 x 10-3M⊙. We have shown that, from our data, the only reliable explanation for the lowest and highest velocity components is that they are due to an outflow located within the envelope.
Turbulence in the Orion Nebula
Authors: Castañeda H.O. , O’Dell C.R.
Published: July 2016

We have examined the radial and turbulent velocities of the Orion Nebula at the seeing limit, observing the [OIII]λ5007 line and the [OII]λ3727 doublet with the coudé feed system of the Kitt Peak National Observatory, at very high spatial and spectral resolution.
The Shaping of the Optical Jet of the Galaxy NGC 4258
Authors: Martin P. , Roy J.-R. , Noreau L. , Lo K.-Y.
Published: July 2016

Hα + [NII] and red continuum CCD images as well as high resolution aperture synthesis CO maps were obtained in order to study the optical jet of the barred spiral galaxy NGC 4258. The CO observations show two clouds near the center of the galaxy; these clouds outline a channel and the Hα jet follows this channel. The observations are consistent with the jet being in or making a small angle with the galaxy plane. It is concluded that the interstellar medium may play an important role in making jets detectable optically and in shaping their forms.
Hα-Emission in Directions toward High Velocity 21cm Clouds
Authors: Münch Guido , Pitz Eckhart
Published: July 2016

Measurements of Hα-emission in fields known to emit 21cm radiation at intermediate and high velocities are presented. The observations are partial results of a survey being carried out at the Calar Alto Observatory with a dedicated Fabry-Perot spectrometer of 15cm aperture, providing velocity and angular resolutions of 11km s-1 and 0.5 deg2. The limited material available indicates that the Hα-emission, when detected at a radial velocity nearly the same as that measured in 21cm, appears more extended in the sky than the HI-radiation.
Multiple-Supernova Remnants
Authors: Różyczka M.
Published: July 2016

The present observational and theoretical status of multiple-supernova remnants is briefly reviewed, and evolutionary models of the remnants around OB associations are presented. The remnants are followed for up to almost 30 Myr in various galactic environments (Gaussian or composite disks combined with cold or hot halos). It is found that the presence of a hot halo profoundly modifies the evolution of the remnants, promoting the evaporation of their shells and leading to noneruptive merging of the ejecta with the halo gas. The results also suggest an explanation for the observed deficiency of evolved multiple-supernova remnants.
Clustered Supernovae vs. The Gaseous Disk and Halo: A Rematch
Authors: Heiles Carl
Published: July 2016

Recent developments, both observational and theoretical, require a reevaluation of the effects of clustered supernovae on the two-dimensional porosity parameter Q2D and the rates of mass injection into the halo Ṁ of both cold and hot gas. Clustered supernovae produce two types of bubble. Most clusters produce breakthrough bubbles, which do no more than break through the dense gas disk. But large clusters produce enough energy to make blowout bubbles, which blow gas up into the halo. We calculate area filling factors and mass injection rates into the halo for different types of galaxy. We relate our calculations to two observables, the area covered by H I ‘holes’ and the area covered by giant H II regions. We also reiterate the difficulty of producing the very largest supershells by clusered supernovae.
1/4 Ke V Diffuse Background and the Local Interstellar Medium
Authors: Snowden S.L.
Published: July 2016

The 1/4 keV diffuse X-ray background (SXRB) is discussed in relation to the local interstellar medium (LISM). The most likely source for these soft X-rays is thermal emission from a hot diffuse plasma. The existence of a non-zero flux from all directions and the short ISM mean free path of these X-rays (1020HI cm-2), coupled with ISM pressure constraints, imply that the plasma has a local component and that it must, at least locally (nearest hundred parsecs), have a large filling factor. Our understanding of the geometry and physical parameters of the LISM is therefore directly tied to our understanding of the SXRB.
Solar Variability and its Terrestrial Effects
Authors: Withbroe George L. , Kalkofen Wolfgang
Published: July 2016

The solar output in radiation and particles varies on an eleven-year time scale, affecting terrestrial temperatures and perhaps even climate. We examine some of the data that support this contention.
Total Solar Irradiance Observations from the EURECA and ATLAS Experiments
Authors: Crommelynck Dominique , Domingo Vicente , Fichot Alain , Lee Robert
Published: July 2016

The total solar irradiance was observed by Differential Dual Absolute Radiometers (DIARAD) within the SOVA (SOlar VAriablity) experiment during the EURECA-I mission (EUropean REtrievable CArrier; August 1992 – June 1993) and within the SOLCON (SOLar CONstant) experiment during the ATLAS-1 and 2 missions (ATmospheric Laboratory for Applications and Sciences; March 1992 and April 1993). The results from these observations are presented and the metrology aspect addressed through comparison of the simultaneaous measurements with the two DIARADs on EURECA-I and ATLAS-2, respectively.
Middle Ultraviolet Solar Spectral Irradiance Measurements, 1985-1992, from the SBUV/2 and SSBUV Instruments
Authors: Cebula Richard P. , Hilsenrath Ernest , Deland Matthew T.
Published: July 2016

Solar spectral irradiance measurements from the NOAA-9 and NOAA-11 SBUV/2 instruments and SSBUV are presented and compared. Inter-instrument solar spectral irradiance differences on the order of 5-10% are observed. Internal comparisons of the SBUV/2 solar data suggest instrument sensitivity changes ranging from less than 1% per year near 400 nm to approximately 5% per year near 200 nm.

The mission-to-mission accuracy of the SSBUV solar spectral irradiance measurements is better than ±2%. Initial results of our investigation into the feasibility of using SSBUV data to maintain the long-term calibration of the SBUV/2 instruments for solar spectral irradiance monitoring are reviewed.
Photometric Observations of the Sun
Authors: Chapman Gary A.
Published: July 2016

Ground-based calorimetry and photometry of the Sun have been carried out for many years. Following the early years, ground-based photometry has largely replaced ground-based calorimetry, in part due to the advent of airborne and spaceborne detector systems for the broad-band measurement of the solar irradiance and the realization of the difficulty of correcting calorimetry measurements for the effects of the terrestrial atmosphere. Even from spacecraft, recent measurements of the total solar irradiance range from about 1367 to 1374 W/m2. Most of this difference can be ascribed to differences in instrumental scales, while a variation of about 1 to 2 W/m2 appears to be due to solar variability. The quiet Sun may also change, globally, over longer time scales. Using disparate data to understand solar variability will require cooperation between a number of current groups, supported by various governments, covering several zones of longitude.
Variations of Coronal Radiations at Optical Wavelengths
Authors: Altrock Richard C.
Published: July 2016

This paper reviews observations of the variation over long and short time scales of solar coronal flux as observed from ground-based optical observatories. This includes data from Fe X, Fe XIV, Ca XV and the white-light electron corona. The various parameters are compared and contrasted as indicators of global coronal structure and output. The overall envelope of Ca XV minimizes before and during sunspot minimum, begins its slow rise in phase with the solar cycle, but maximizes late with strong 150-day oscillations resulting in values of zero at the local minima. Within the sensitivity of the observations, the increase of the envelope from Cycle minimum to maximum is over a factor of 30. Excluding possible secondary maxima and ignoring strong 150-day oscillations, the general envelope of Fe X appears to indicate a slow decline in intensity following sunspot maximum. Earlier observations indicate a Cycle minimum-to-maximum variation of a factor of 2 to 3. Later observations indicate a factor of 4 to 5. The overall picture for Fe XIV indicates that it varies in phase with the sunspot cycle. However, multiple maxima occur. The amplitudes of all observed Cycles are probably approximately equal, and the increase from Cycle minimum to maximum is approximately a factor of 10. The variation of the polarized and unpolarized white light corona is in phase with the sunspot cycle, although it may have a slower decline to minimum than the sunspot number. The increase from Cycle minimum to maximum is a factor of 2 to 3. Notable periodicities seen in the emission-line corona are (approximately) 27, 150, 180, 220 and 340 days and 3.4 years.
Irradiance Effects of Small-Scale Magnetic Fields on the Sun
Authors: Solanki Sami K.
Published: July 2016

Small-scale magnetic fields affect the solar luminosity mainly on long time scales. To understand their contribution to solar luminosity variations we must know and understand the contribution of a typical small-scale magnetic feature. In this review I briefly outline our theoretical understanding of the processes leading to the enhancement (or reduction) of the brightness of flux tubes. I also present a brief overview of our observational knowledge.
Estimating Solar Forcing of Climate Change during the Maunder Minimum
Authors: Lean Judith , Skumanich Andrew , White Oran R. , Rind David
Published: July 2016

Solar variability models which account for contemporary irradiance variations in terms of modulation by dark sunspots and bright faculae on the solar disk are used to estimate solar radiative output during the Maunder Minimum by postulating the absence of such sources, and additional reduction in the basal solar emission. When the resultant irradiance reduction of 0.25% relative to contemporary mean levels is input to the GISS GCM, the global mean temperature is reduced by 0.46°C. However, as a result of differential heating of the land and oceans, some regions may cool, and others warm, by as much 1°C, in response to the reduced solar irradiance.
Theoretical Interpretation of Magnetic Activity
Authors: Parker Eugene N.
Published: July 2016

Magnetic fields generated and driven by thermal convection are the primary cause of solar activity. There are many facets of the activity, such as plages, flares, sunspots, coronal heating, and the variation of solar luminosity or irradiance whose nature and cause are understood only partially or not at all, although detailed superficial observational descriptions are available. It is suggested that the inferred 105 gauss azimuthal field bundles may be a direct result of the emergence of Ω-loops to form bipolar magnetic regions on the surface in association with an increase in solar irradiance.
A Probable Connection between Solar and Atmospheric Decadal Variability
Authors: Labitzke Karin , Loon Harry van
Published: July 2016

The paper reviews briefly some recent investigations of possible effects of decadal solar variations on the stratosphere and troposphere, drawing attention to the stable, strong correlations between the height of constant pressure levels in the stratosphere and the sunspot cycle.
Solar Activity and Global Temperature
Authors: Friis-Christensen Eigil , Lassen Knud
Published: July 2016

A major problem in the determination of the magnitude of a possible solar effect on climate is that no physical parameter of solar energy output exists that has been observed long enough to be used for long-term analyses. Therefore, a number of indirect parameters have been proposed, with the sunspot number as the most commonly used parameter. Recently it has been suggested that climatic effects may be more directly associated with the length of the solar cycle. Whereas the magnitude of the sunspot number is only believed to be reliable back to 1750, determination of solar activity minima may be based on other types of data. A recent reconstructed series of solar cycle lengths back to 1500 gives new information about solar activity in particular before and during the Maunder Minimum. A comparison with reconstructed temperature records has revealed that the good agreement between the solar cycle length and the global temperature found for the modern instrumental temperature record is also characteristic for the total series of reconstructed temperature data. A further result is that the response of the temperature during the pre-instrumental era is the same as for the modern temperature record. This finding confirms the close association beween terrestrial temperature and solar activity measured in terms of the solar cycle length.
Coronal Holes and Photospheric Magnetic Field
Authors: Bumba V. , Klvaňa M. , Sýkora J.
Published: July 2016

Since the reconstruction of the photoelectric magnetograph of the Ondřejov Observatory in 1990 (Klvaňa and Bumba, 1994; Klvaňaet al., 1994), several hundred sets of measurements (mostly in the line FeI 5253.47 Å) have been obtained during 1991 and 1992. The longitudinal magnetic and Doppler velocity fields, as well as the continuum spectral line intensity distribution in more than one hundred areas on the solar surface have been investigated (the measurements of one region were usually repeated several times). Often a relatively large part of the solar disk was studied.

Comparing the measured areas with the distribution of active regions and other activity phenomena on the Hα Synoptic Charts, it has been found that some of the measurements were distributed very favorably around coronal holes, sometimes covering smaller parts and in a few cases even larger parts of their areas.
Magnetic Fields in the Solar Corona as Found from High Spectral Polarization and Spatial Resolution Radio Observations with RATAN-600 Radiotelescope
Authors: Bogod V. M. , Borovik V. N. , Garaimov V. I. , Gelfreikh G. B. , Korzhavin A. N.
Published: July 2016

The results of radio measurements of coronal magnetic field over a large leading sunspot are presented during its passage over the solar disk (August 1992). The ratio of coronal to photosphere field strength was found to be about 0.62, the small decrease in this value being registered during the highest flare activity in the following part of the sunspot group.
Coronal Large-Scale Structure in Odd and Even 11-Year Cycles
Authors: Makarov V. I. , Mikhailutsa V. P. , Fatianov M. P. , Stepanova T. V.
Published: July 2016

Observations of 22 solar eclipses (1914-1991) have been processed. Radial deviations of streamers in the polar and equatorial zones of the Sun in odd and even solar cycles have been studied. An essential difference of the degree of non-radiality of coronal rays at the same latitudes in odd and even cycles has been found. Deviations from the radial direction of streamers are large in the polar zones in the epoch of the maxima of even cycles and in the equatorial zones at the minima of odd cycles. Deviations from radiality at high latitudes are observed mainly in the poleward direction. The results obtained are interpreted in terms of a new model of the cycle, in which the properties of the solar magnetic field depend on the phase of a 22-year solar magnetic cycle.
Coronal Mass Ejections and Solar Filament Disappearances at Solar Maximum
Authors: Dinulescu S. , Maris G.
Published: July 2016

Occurrence of CMEs as a result of solar filament disappearance is discussed over the cycle 22.
Modelling of Quiet Sun Coronal Structures
Authors: Serio S.
Published: July 2016

The 1978 paper by Rosner et al. has set the basis for a new way of understanding thermal stratification in the solar corona, taking into account the constraints of magnetic fields on heat conduction. This paper will review recent progress in modelling of coronal loops, and in particular the effects of deviations from Spitzer conductivity, stationary siphon flows and shocks, thermal stability of the transition region, and possible diagnostics of dynamic heating of the coronal plasma.
Siphon Flows in Stratified Coronal Loops
Authors: Orlando S. , Peres G. , Serio S.
Published: July 2016

We have developed a detailed siphon flow model for coronal loops. We find scaling laws relating the characteristic parameters of the loop, explore systematically the space of solutions and show that supersonic flows are impossible for realistic values of heat flux at the base of the upflowing leg.
Radio Type IV Burst Fine Structures and the Dynamics of the Flare Process
Authors: Aurass H.
Published: July 2016

We present signatures of quasi-periodic release of nonthermal particles in different flare phases. In the decimetric range a characteristic pattern is identified with a recurrence period of 1...3 min accompanied by a slow drift toward lower frequencies. We explain these spectral features as evidence for repeated coronal energy release in a slowly (0.1vA) uprising particle accelerator. The analysis allows quite a new prospect to identify the source of the metric type II burst and its timing in the type IV radio spectrogram.
Numerical Simulation of Chromospheric Spicules Driven by Weakly-Damped Alfvén Waves
Authors: de Pontieu B. , Haerendel G.
Published: July 2016

We perform a time-dependent numerical simulation of the momentum transfer from weakly-damped Alfvén waves to the solar chromospheric plasma in a spatially expanding flux tube. The momentum transfer is due to the effect of ion-neutral collisions on Alfvén waves. By solving one-dimensional and time-dependent hydrodynamic equations, we study the formation of spicules. A realistic model for the solar atmosphere and for both the transport of and momentum-transfer by the Alfvén waves is used. The temperature, density and vertical velocity of the formed structures are very similar to those reported in observational studies of spicules.
Emission Measure of Prominence-Corona Transition Region
Authors: Pojoga S.
Published: July 2016

Extreme ultraviolet line intensities obtained with the HCO spectrometer on Skylab are used to study the prominence-corona transition region. The spatial distributions of intensities as well as of EM are found from an almost homogeneous area in a prominence. A possible interpretation is given for the different shape of the EM curves in accordance with different models of subresolution structure.
On the Dynamics of Surge Plasma Knots
Authors: Dermendjiev V. N. , Ökten A. , Madjarska M. S.
Published: July 2016

Plasma knots of a high latitude surge, consisting of only one thin and very long jet are studied over long series of Hα filtergrams. An attempt to evaluate the influence of magnetic flux tube oscillation on the surge plasma was made.
Some Geometrical Characteristics of the Long-Lived Solar Filaments
Authors: Duchlev P. , Mouradian Z. , Dermendjiev V. N.
Published: July 2016

Two basic geometric quantities - the filament length and the height above the limb of the long-lived filaments are studied. Some statistical relations are obtained.
Radio-Wave Diagnostics of the Coronal Plasma
Authors: Hildebrandt J.
Published: July 2016

This review considers possibilities for deriving plasma parameters and source structures of the solar chromosphere, transition region, and lower corona using observations in the centimeter and millimeter wave range. Model calculations for the S-component emission as well as for microwave bursts are described, and their diagnostic capabilities by comparison with observations are discussed.
Structuring, Motions and Shapes of Corona Emission Line Profiles
Authors: Tyagun N. F.
Published: July 2016

The interrelationship of half-widths and intensities for the red, green and yellow lines is considered. This is a direct relationship for the green and yellow line and an inverse one for the red line. The difference in the relationships of half-widths and intensities for different lines appears to be due to substantially dissimilar structuring and to a set of line-of-sight motions in ”hot“ and ”cold“ corona regions.

When diagnosing the coronal plasma, one cannot neglect the filling factor - each line has such a factor of its own.
Solar Wind Acceleration
Authors: Hansteen V. H.
Published: July 2016

The general aspects of solar wind acceleration are well described by considering the thermally driven outflow from an electron – proton corona. However, two puzzling observations remain to be explained: 1) The predicted asymptotic flow velocity is much lower than that observed in high speed streams, and 2) The proton flux observed at 1AU varies considerably less than expected when considering the sensitivity of the proton flux to the coronal temperature predicted by thermally driven models. The solution of the first problem rests upon finding a mechanism which can deposit energy and/or momentum beyond the critical point of the flow. The invariance of the proton flux requires that a mechanism for maintaining a relatively constant proton density scale height in the subsonic region of the flow is found. One such possibility lies in considering the effects of an enhanced coronal helium abundance on the force balance of the subsonic flow. This scenario is discussed in some depth.
Photospheric Vortices and Coronal Heating
Authors: Zirker J. B.
Published: July 2016

We have used the results of a realistic simulation of convection to estimate the power input to coronal loops from the twisting of photospheric magnetic field in intergranular vortices. In this simulation, the vorticity is large (a mean of 0.03 s–1) nearly everywhere in the intergranular lanes, not merely at the corners of three granules. We found the autocorrelation time of vorticity images to be 45 s, but individual vortices last as long as 144 s. Our estimate suggests that field line twisting could supply a substantial fraction, if not all, of the required power to the quiet corona.
Diamagnetic Acceleration of the Solar Wind
Authors: Sekeles B. , Steinitz R.
Published: July 2016

We have developed a new model to account for proton acceleration in the solar wind. The acceleration is a direct result of the diamagnetic effect on the charged particles, and hence on their velocity distribution. Our basic assumptions are: a collisionless plasma, energy conservation and magnetic moment conservation. Through simulation we explore the changes in bulk speed, between 0.3 AU and 1 AU. We find that the diamagnetic effect accounts for the observed velocity increase in bulk speed. Since any form of wave-particle interactions is exluded from our simulations but they fit well the observations, we suggest that the diamagnetic effect also accounts for wind expansion in early type stars, i.e., for stars without convective energy available at their surface.
Long Duration Solar Flare Events and Cosmic Ray Modulation (1969-1992)
Authors: Antalová A. , Kudela K. , Venkatesan D. , Rybák J.
Published: July 2016

We present here the results of the correlation analysis between the galactic cosmic ray intensity decrease p (as observed on Calgary neutron monitor station) and the occurence of SXR long-lasting (LDE-type) solar flares, represented by the LDE-type flare index FI. It is shown, that for the solar cycle with the lower monthly values of FI (the 21-st solar cycle) the correlation coefficient is slighter (about 0.4) comparing to the cycles with the higher LDE-type flare activity (about 0.6, in the 20-th and the 22-nd cycles).
Stepwise Emergence and Development of Microwave Emission of Active Regions – A Fundamental Property of Active Solar Corona
Authors: Smolkov G. Ya. , Nefedyev V. P. , Uralov A. M. , Kardapolova N. N.
Published: July 2016

This paper has two goals: to report the informative merits of the Siberian solar radio telescope (SSRT) for ground-support of the SOHO or some other space mission, and provide a generalized presentation of one of the original results obtained at SSRT that indicates, we believe, a fundamental property of the emission from solar corona active regions (AR).
Synoptic Charts of the Solar Eclipses of 1990 and 1991
Authors: Mouradian Z. , Buchholtz G. , Zlicaric G.
Published: July 2016

The synoptic charts of solar rotations 1831 and 1844 have been drawn up, corresponding to the eclipses of 22 July 1990 and 11 July 1991. These charts contain the active regions and the filaments, and show the position of the solar limb, at the time of the eclipse. They are for use in studying the coronal structures observed during these eclipses. The variation of these structures is given in the table. The last section of the article contains a formula for identifying the structures out of the limb.
FeXIV Line Emission Polarization of the July 11, 1991 Solar Corona
Authors: Sýkora J. , Rybák J. , Ambrož P.
Published: July 2016

High resolution images, obtained during July 11, 1991 total solar eclipse, allowed us to estimate the degree of solar corona polarization in the light of FeXIV 530.3 nm emission line and in the white light, as well. Very preliminary analysis reveals remarkable differences in the degree of polarization for both sets of data, particularly as for level of polarization and its distribution around the Sun’s limb.
On the Eclipse E-Corona Observations by the Fabry-Perot Technique
Authors: Kim I. S. , Smartt R. N.
Published: July 2016

Interpretations of the eclipse Fabry-Perot interferograms obtained by different authors are compared particularly in point of view of velocity measurements. Advantages and disadvantages of the instrumentation consisting of a Fabry-Perot etalon and a narrow band interference filter are discussed when a coronal emission is imposed on steep gradient coronal continuum. A list of optical and near infrared emission coronal lines is analyzed and a recommendation for employment of the Fe XIV (5303Å) and Fe XI (7892Å) is given. An optical sketch of the Fabry-Perot instrumentation is suggested. It allows to select both the instrumental and coronal continuum contributions to get reliable data on the field velocity.
Solar Flare Energetic Neutral Emission Measurements in the Project Coronas-I
Authors: Baláž J. , Dmitriev A. V. , Kovalevskaya M. A. , Kudela K. , Kuznetsov S. N. , Myagkova I. N. , Nagornikh Yu. I. , Rojko J. , Ryumin S. P.
Published: July 2016

The experiment SONG (SOlar Neutron and Gamma rays) for the low altitude satellite CORONAS-I is described. The instrument is capable to provide gamma-ray line and continuum detection in the energy range 0.1 – 100 MeV as well as detection of neutrons with energies above 30 MeV. As a by-product, the electrons in the range 11 – 108 MeV will be measured too. The pulse shape discrimination technique (PSD) is used.
Astrophysical consequences of the screening of nuclear reactions
Authors: Isern J. , Hernanz M.
Published: July 2016

The rate of nuclear reactions depends on the influence of the surrounding particles that compose the plasma. At high densities the situation is far from being satisfactory and the influence of electron polarization has not been completely elucidated. In particular, it is shown that the possibility of an accretion induced collapse of a carbon-oxygen white dwarf instead of a supernova explosion completely depends on the screening factors and pycnonuclear rates that are adopted. Similarly, the possibility of detecting isolated neutron stars that accrete matter from the interstellar medium depends on the adopted pycnonuclear rates. Low rates allow the formation of a metastable layer that can release energy explosively and produce aγ-ray burst. Nevertheless, current rates seem to prevent such a situation.
Non Crystallized Regions of White Dwarfs. Thermodynamics. Opacity. Turbulent Convection
Authors: Mazzitelli I.
Published: July 2016

The evolution of White Dwarf stars along their cooling sequences is governed not only by their thermal content, but also by the rate at which heat flows through the external, partially degenerate and non-isothermal layers. In particular, cooling is found to be largely influenced both by the optical atmosphere, and by the convective envelope. The first one, in fact, determines the internal density stratification, down to the point at which electron degeneracy takes over, while the second one affects the temperature stratification in the same layers. The reliability of the present generation of models of White Dwarf envelopes is discussed, on the grounds of the main physical inputs (thermodynamics, opacity, convection theory), for both H-rich and He-rich surface chemical compositions. The conclusion is that, below Log L/L⊙ ≤ −3, we can build little more than test models
Evris
Authors: Baglin A.
Published: July 2016

The EVRIS experiment is an exploratory mission devoted to stellar seismology. It will observe approximately ten bright stars, for 20 days each, during the cruise of the Russian MARS 94 mission. The photometer will be able to detect amplitudes of modes as small as a few 10−6 magnitude. Some objects of masses lower than the solar one will allow to test the thermodynamics.
PRISMA: A Mission to Study Interior and Surface of Stars
Authors: Lemaire P.
Published: July 2016

New technics such as asteroseismology are able to sound the deep interior of stars and to provide the data that will constrain the modelisation of the core. This information will be combined with data collected from the stellar surface which give direct access to measurements of the radiative losses, angular momentum losses and distribution of active structures. From the two sets of data, the key role of the convection zone will be clarified, as the convection zone excites the waves that propagate through the whole star and generates the magnetic field that structures the stellar surface. The PRISMA mission was developed to collect the data needed for detecting the oscillations by very accurate photometry (micromagnitude) and to derive the surface activity and rotation from accurate ultraviolet spectroscopy. A short description of the model payload is given with the observational constraints related to the needed accuracy of measurements. Following the non-selection by ESA in may 1993, some following perspectives are described.
Modified Adiabatic Approximation for A Hydrogen Atom Moving in A Magnetic Field
Authors: Bezchastnov V.G. , Potekhin A.Y.
Published: July 2016

Motion of a hydrogen atom across the magnetic field shifts center of electron density distribution. For strong magnetic fields, the radiative transitions can be considered in the modified adiabatic approximation in which the shifts are taken into account. The method is illustrated by calculating the photoionization cross sections.