Open‐foldable domes with high‐tension textile membranes: The GREGOR dome

Double layers of high‐tensioned textile membranes were applied to the completely open‐foldable dome for the GREGOR telescope for the first time. Simultaneous climate measurements inside and outside the dome have proven the thermalinsulating capability of this double‐layer construction. The GREGOR dome is the result of the continuation of the ESO research on open‐foldable domes with textile structures, followed by the research for the DOT dome with high‐tensioned textile membranes. It cleared the way to extreme stability required for astronomical practice on high mountain sites with heavy storms and ice formation. The storm Delta with 245 km/h 1‐minute mean maximum at the location of the GREGOR caused no problems, nor did other storms afterwards. Opening and closing experiences up to wind speeds of 90 km/h were without problems. New technical developments were implemented and tested at the GREGOR dome, opening the way for application to much larger domes up to the 30 m diameter‐class range (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A space Fresnel imager concept assessment study led by CNES for astrophysical applications

In 2009, the Centre National d??Etudes Spatiales (CNES) carried out an assessment study on a ??Fresnel telescope?? concept based on a two-spacecraftformation flying configuration. This concept uses a binary Fresnel zone plate, and the principle of diffraction focusing, which allows high resolution optical imaging for astrophysics. In addition to CNES, the Laboratoire d??Astrophysique de Toulouse Tarbes (LATT) was deeply involved at two levels: through Research & Technology (R&T) studies to simulate and validate on a test bench the Fresnel concept performance, and through active participation in the CNES team for the optical aspects and to define the astrophysical fields of Fresnel-based space missions. The study was conducted within the technical limitations that resulted from a compromise between the R&T state of the art and the potential scientific domains of interest. The main technical limitations are linked to the size of the primary Fresnel array and to its usable spectral bandwidth. In this framework, the study covers ambitious architectures, correlating the technology readiness of the main critical components with the time-scale and programmatic horizons. The possible scientific topics arise from this range of missions. In this paper, I present a mission launched by a Soyuz, dedicated to astrophysics in the Ultra Violet (UV) band: 120 to 300 nm using a 4-m Fresnel array. It could be competitive in the next fifteen years, whereas a 10-m aperture mission in different bands; UV, visible or Infra Red (IR) (up to 6 ??m) could be achievable in the future. Larger missions, using a primary array larger than 20 m, request technologies not yet available but that will probably be based on new inflatable structures with membranes, as already tested in the USA for other ends.     

THz photometers for solar flare observations from space

The search for the still unrevealed spectral shape of the mysterious THz solar flare emissions is one of the current most challenging research issues. The concept, fabrication and performance of a double THz photometer system, named SOLAR-T, is presented. Its innovative optical setup allows observations of the full solar disk and the detection of small burst transients at the same time. The detecting system was constructed to observe solar flare THz emissions on board of stratospheric balloons. The system has been integrated to data acquisition and telemetry modules for this application. SOLAR-T uses two Golay cell detectors preceded by low-pass filters made of rough surface primary mirrors and membranes, 3 and 7 THz band-pass filters, and choppers. Its photometers can detect small solar bursts (tens of solar flux units) with sub second time resolution. Tests have been conducted to confirm the entire system performance, on ambient and low pressure and temperature conditions. An artificial Sun setup was developed to simulate performance on actual observations. The experiment is planned to be on board of two long-duration stratospheric balloon flights over Antarctica and Russia in 2014–2016.     

Spectral Observations of BIG Objects. III

Results of spectral observations of 66 objects from the BIG (Byurakan IRAS Galaxies) sample made with the 1.93 m telescope at the Observatoire de Haute Provence (OHP, France) are presented. Emission lines are observed from 64 of the galaxies. The red shifts are determined, the radial velocities, distances, and absolute stellar magnitudes are calculated, the spectrum line parameters are determined, diagnostic diagrams are constructed, the objects are classified according to activity type, and their IR and far-IR luminosities are calculated. Of the 66 objects (corresponding to 61 IRAS sources), 6 are Sy2, 2 are LINERs, 8 are AGN (Sy2 or LINER), 10 are composite, 34 are HII, and 4 are Em of undetermined type. It is calculated that IRAS 07479+7832= BIG d141a is a ultraluminous IR galaxy (ULIG), and 21 are LIG. Spectra of several of the galaxies being studied are presented.     

Variable stars in the globular cluster NGC 6362

We report the results of a CCD search for short-period variables in the field of a southern globular cluster NGC 6362. We identified 19 new candidate variables, five of which are cluster RR Lyraes, four are probable SX Phe-type stars and eight are eclipsing binaries. Of the discovered binaries, three are EA-type systems, two of which are located on the cluster CMD in the turn-off region and the third 1 mag above the turn-off point, in the yellow straggler region. Five other systems are of W UMa type, three of which are foreground objects and two are likely cluster members. The remaining two candidates exhibit a modulation of the brightness level with an amplitude of 0.1–0.2 mag; further observations are needed to reveal the nature of their variability. Phased VI light curves for 20 variables (18 RR Lyrae stars and two blue stragglers) located in the central region of the cluster are presented.     

The features of infra-red emission of planetary nebulae in the inner galaxy

414 galactic PN with measured infra-red luminosities (302 of which are located within the sector of galactic longitudes from 345° to 15°) are investigated. All nebulae are subdivided into four mass classes and different distance scales for each class are used. Planetary nebulae located in the inner Galaxy are selected. The galactic radial gradients of infra-red luminosities and excesses are obtained for each nebula mass class. Possible explanations of the effect are discussed.     

Ccd Photometry and Modeling of the Overcontact Binary Systems Nn Vir and Yy CrB

New ground-based BV RI CCD observations of the eclipsing binary systems NN Vir and YY CrB are analyzed and illustrated. New times of minima are given and new ephemerides are proposed. The light curves are analyzed with the Wilson-Devinney light curve synthesis code and new geometric and photometric elements are derived. These elements are used together with the available spectroscopic data to compute absolute elements. The evolutionary status of each system is studied by means of mass-radius diagrams. The systems NN Vir and YY CrB are found to be A-type and W-type W UMa systems, respectively.     

Electrostatic solitons in multispecies electron-positron plasmas

Acoustic solitons are investigated in electron-positron plasmas containing equal hot and cool components of both species. The hot components are isothermal Boltzmann distributed, the cool constituents are modelled by adiabatic fluids. The equations are integrated exactly in terms of a Sagdeev potential. Solitons are shown to be possible, but no double layers, due to the symmetry in the model. Bearing in mind the constraints imposed by the Boltzmann assumption, small amplitude solitons only are found. Such findings are relevant for different kinds of astrophysical plasmas, as well as for other types of similar acoustic solitons.     

Connections between jet physics and the properties of radio-loud and radio-quiet galaxies

Relationships between jet physics and the evolutionary phases of radio galaxies are discussed. This includes the connection between the properties of relativistic jets and the Fanaroff–Riley classes of radio galaxies and the interaction of jets with the interstellar medium in Gigahertz Peak Spectrum and Compact Steep Spectrum Radio Sources. Jets in Seyfert galaxies are compared with those in classical radio galaxies and recent work suggesting that there are major differences between the two types of jets is summarized. The proposed major differences are principally that Seyfert jets are thermally dominated with subrelativistic speeds whereas Radio Galaxy jets are relativistic electron/positron flows. Hence, the production of jets in Seyferts and radio galaxies are fundamentally different.     

The temperature of interstellar porous grains

Free-space equilibrium temperatures for porous interstellar grains are computed for different dust sizes and are compared to those expected for homogeneous normal grains for two material candidates: graphite and a lunar silicate. Relevant differences are found with the former, but are essentially negligible with the latter. The results are discussed in terms of the different optical properties produced by the porosity of the grains. The possible astrophysical implications of these findings are also mentioned.     

The identification and interaction of network,intranetwork, and ephemeral-region magnetic fields

Network magnetic fields, ephemeral active regions, and intranetwork magnetic fields are illustrated and discussed in several contexts. First, they are presented in relation to the appearance and disappearance of magnetic flux. Second, their properties in common with all solar magnetic features are discussed. Third, their distinguishing characteristics are emphasized. Lastly, their interactions are illustrated.Network magnetic fields are no longer considered to be just the aged remnants of active regions. The network is the dynamic product of the merging and cancelling of intranetwork fields, ephemeral regions, and the remnants of active regions. Intranetwork fields are magnetic fields of mixed polarity that appear to originate continuously from localized source sites in between the network. The intranetwork magnetic fields are characterized by flow of successive fragments in approximately radial patterns away from their apparent source sites and by the relative weakness of their magnetic fields. Ephemeral active regions are small, new bipoles that grow as a unit or a succession of bipolar units and whose poles move in opposite directions from their apparent site of origin. Large ephemeral regions are not distinguishable from small active regions.Solar Cycle Workshop Paper.     

Generalizations of the Jacobian integral

The restricted problem of three bodies is generalized to the restricted problem of 2+n bodies. Instead of one body of small mass and two primaries, the system is modified so that there are several gravitationally interacting bodies with small masses. Their motions are influenced by the primaries but they do not influence the motions of the primaries. Several variations of the classical problem are discussed. The separate Jacobian integrals of the minor bodies are lost but a conservative (time-independent) Hamiltonian of the system is obtained. For the case of two minor bodies, the five Lagrangian points of the classical problem are generalized and fourteen equilibrium solutions are established. The four linearly stable equilibrium solutions which are the generalizations of the triangular Lagrangian points are once again stable but only for considerably smaller values of the mass parameter of the primaries than in the classical problem.     

Flows in clumpy planetary nebulae

The dynamics of clumps observed in planetary nebulae are considered. The possibility that SiO maser spots in evolved stars and the planetary nebula clumps are formed by the Parker instability behind shocks in pulsating stars' atmospheres is raised. Molecular observations of the clumps are suggested. The effects of the ablation of clumps on the global flow structure of a more tenuous plasma in which they are embedded are reviewed.     

Spatial structure of gravity waves in the solar photosphere

Observations of the Fe I line are used to simulate spatial and temporal pressure variations in the solar photosphere. The local internal gravity waves, which are essentially structures that are quasi-periodic in space (on granular and mesogranular scales) and time and propagate along inclined paths at subsonic velocities, are isolated by appropriate filtering. The phase and group velocities of the wave trains are orthogonal; their z-projections are of the opposite sign.     

The evolution of the surface temperature of Mars

Changes in the average surface temperature of Mars are studied as a function of the time that has elapsed since the origin of the planet. Time variations in the factors influencing the surface temperature are investigated: and approximate methods for computing the effect of such variations are discussed. Three possible degassing sequences are postulated, and their likely effects for the presence of liquid water on the Martian surface are assessed.     

Detection and computation of the amount of atmospheric wave-front tilt in the application of adaptive optics technology to lunar laser ranging

For dealing with the problem of too few photons in the return wave in lunar laser ranging, the effect of the atmospheric turbulence is studied. The principles of the two tracking algorithms, cross correlation and absolute difference are studied and programs are written, which are tested with solar data. Collected image data of the interested area on the lunar disc are given. The integrated tilt signals of the atmospheric wave front obtained are treated by different methods under different conditions and the algorithms are compared as to their effectiveness.     

Asteroid rotation: IV. 1979 observations

Results of photoelectric lightcurve observations made during 1979 are reported. Of a total of 53 asteroids observed, reliable rotation periods are reported for 22 asteroids for which no previous values are known, 7 periods are reported which are revisions of previously reported values, and for 12 other asteroids periods are suggested which are admittedly of low reliability and those objects should be reobserved. In addition, phase relations are presented for many of the asteroids, fitted to the theoretical phase function of Lumme and Bowell (Astron. J., 86, 1705, 1981). Adopting their formalism, mean absolute magnitudes at zero phase angle, $\text{V}\text{(0°)}$, for 52 asteroids, and values of the multiple scattering parameter, Q, for 22 asteroids are reported. For comparison purposes, the absolute magnitude, V(1,0) and the linear phase coefficient, βv, in the traditional system are computed. In the appendixes (1) the methods of observation and data reduction are discussed, which are recommended to other lightcurve observers in the hope of standardizing reporting practices as much as possible; and (2) a cumulative index of all asteroid rotation data of which the authors are aware is presented.     

Numerical extrapolation of periodic solutions

Numerical procedures are established for the continuation of families of periodic solutions of non-integrable dynamical systems. They are based on the use of the previous known members of a family for non-linear prediction of the next member to be determined. Both symmetric and asymmetric periodic solutions are considered. The procedures are applied and compared in the case of the restricted three-body problem. They are shown to lead to considerable saving of computer time.     

恒星临边昏暗系数的测定

介绍一种新的一级挖和二级近似描述恒星大气临边昏境现象方法,其临边昏境系数可通过有关物理量的直接测量或测量流量和辅助量恒星表面温度的方法间接给出。与太阳观测比较和数值模型大气方法比较,均显示新方法能够以很精确的方式描述恒星临边昏境关系,或确定其相应系数 方法对太阳观测的１７６个数据比较了统计方差,其中直接法的一级挖和二级挖分别为０．３８％和０．２６％;间接法的方差与此相近而略大;与数值模型大气比较其     

Some observed characteristics of solar radar echoes and their implications

The results of a series of radar studies of the sun at 38.2 MHz are presented. The echoes imply ever-present compressional waves in the corona, and these waves are likely associated with coronal heating. Some echoes are refracted by plasma clouds high in the corona. Other echoes are reflected by dense plasma irregularities moving outward very slowly at 0 to 20 km/sec. These are sometimes found as far out as three solar radii from the sun's center. Suggestions for future solar radar experiments and the need for them are outlined.