017477   Gehlot B K;Bagla J S (Kapteyn Astronomical Institute, Groningen Univ, The Netherlands, Email: jasjeet@iisermohali.ac.in) : Prospects of detecting HI using redshifted 21-cm radiation at z <126> 3. J Astrophys Astr 2017, 38(1), 1-9.

Distribution of cold gas in the post-reionization era provides an important link between distribution of galaxies and the process of star formation. Redshifted 21-cm radiation from the hyperfine transition of neutral hydrogen allows us to probe the neutral component of cold gas, most of which is to be found in the interstellar medium of galaxies. Existing and upcoming radio telescopes can probe the large scale distribution of neutral hydrogen via HI intensity mapping. In this paper, we use an estimate of the HI power spectrum derived using an ansatz to compute the expected signal from the large scale HI distribution at z<126>3. We find that the scale dependence of bias at small scales makes a significant difference to the expected signal even at large angular scales. We compare the predicted signal strength with the sensitivity of radio telescopes that can observe such radiation and calculate the observation time required for detecting neutral hydrogen at these redshifts. We find that OWFA (Ooty Wide Field Array) offers the best possibility to detect neutral hydrogen at z<126>3 before the SKA (Square Kilometer Array) becomes operational. We find that the OWFA should be able to make a 3 s or a more significant detection in 2000 hours of observations at several angular scales. Calculations done using the Fisher matrix approach indicate that a 5σ detection of the binned HI power spectrum via measurement of the amplitude of the HI power spectrum is possible in 1000 h (Sarkar et al. 2017).

^iia6 illus, 1 table, 57 ref

017476   Ershkov S V (Sternberg Astronomical Institute, M.V. Lomonosov's Moscow State Univ, 13 Universitetskij Prospect, Moscow 119992, Russia, Email: sergej-ershkov@yandex.ru) : Forbidden zones for circular regular orbits of the moons in solar system, R3BP. J Astrophys Astr 2017, 38(1), 1-4.

Previously, we have considered the equations of motion of the three-body problem in a Lagrange form (which means a - 41 - consideration of relative motions of 3-bodies in regard to each other). Analysing such a system of equations, we considered the case of small-body motion of negligible mass m₃ around the second of two giant-bodies m₁, m₂ (which are rotating around their common centre of masses on Kepler's trajectories), the mass of which is assumed to be less than the mass of central body. In the current development, we have derived a key parameter η that determines the character of quasi-circular motion of the small third body m 3 relative to the second body m₂ (planet). Namely, by making several approximations in the equations of motion of the three-body problem, such the system could be reduced to the key governing Riccati-type ordinary differential equations. Under assumptions of R3BP (restricted three-body problem), we additionally note that Riccati-type ODEs above should have the invariant form if the key governing (dimensionless) parameter η remains in the range 10^-2 Open image in new window 10^-3. Such an amazing fact let us evaluate the forbidden zones for Moon's orbits in the inner solar system or the zones of distances (between Moon and Planet) for which the motion of small body could be predicted to be unstable according to basic features of the solutions of Riccati-type.

1 table, 11 ref

017475   Chatterjee S;Bharadwaj S;Marthi V R (Physics Dep, Indian Institute of Technology Kharagpur, Kharagpur-721 302, Email: suman05@phy.iitkgp.ernet.in) : Simulating the z = 3.35 HI 21-cm visibility signal for the ooty wide field array (OWFA). J Astrophys Astr 2017, 38(1), 1-13.

The upcoming Ooty Wide Field Array (OWFA) will operate at 326.5 MHz which corresponds to the redshifted 21-cm signal from neutral hydrogen (HI) at z = 3.35. We present two different prescriptions to simulate this signal and calculate the visibilities expected in radio-interferometric observations with OWFA. In the first method we use an input model for the expected 21-cm power spectrum to directly simulate different random realizations of the brightness temperature fluctuations and calculate the visibilities. This method, which models the HI signal entirely as a diffuse radiation, is completely oblivious to the discrete nature of the astrophysical sources which host the HI. While each discrete source subtends an angle that is much smaller than the angular resolution of OWFA, the velocity structure of the HI inside the individual sources is well within the reach of OWFA's frequency resolution and this is expected to have an impact on the observed HI signal. The second prescription is based on cosmological N-body simulations. Here we identify each simulation particle with a source that hosts the HI, and we have the freedom to implement any desired line profile for the HI emission from the individual sources. Implementing a simple model for the line profile, we have generated several random realizations of the complex visibilities. Correlations between the visibilities measured at different baselines and channels provides an unique method to quantify the statistical properties of the HI signal. We have used this to quantify the results of our simulations, and explore the relation between the expected visibility correlations and the underlying HI power spectrum.

^iia10 illus, 56 ref

017474   Bhattacharyya S;Bera A;Bharadwaj S;Ramesh Bhat N D;Chengalur J N (Physics Dep, Indian Institute of Technology, Kharagpur-721 302, Email: siddhartha@phy.iitkgp.ernet.in) : FRB event rate predictions for the ooty wide field array. J Astrophys Astr 2017, 38(1), 1-10.

Authors developed a generic formalism to estimate the event rate and the redshift distribution of Fast Radio Bursts (FRBs) in our previous publication (Bera et al. 2016), considering FRBs are of an extragalactic origin. In this paper, we present (a) the predicted pulse widths of FRBs by considering two different scattering models, (b) the minimum total energy required to detect events, (c) the redshift distribution and (d) the detection rates of FRBs for the - 40 - Ooty Wide Field Array (OWFA). The energy spectrum of FRBs is modelled as a power law with an exponent -α and our analysis spans a range -3≤ α ≤ 5. We find that OWFA will be capable of detecting FRBs with α ≥ 0. The redshift distribution and the event rates of FRBs are estimated by assuming two different energy distribution functions; a Delta function and a Schechter luminosity function with an exponent -2≤ y ≤2. We consider an empirical scattering model based on pulsar observations (model I) as well as a theoretical model (model II) expected for the intergalactic medium. The redshift distributions peak at a particular redshift z_p for a fixed value of α, which lie in the range 0.3≤ z_p ≤ 1 for the scattering model I and remain flat and extend up to high redshifts (z≤5) for the scattering model II.

^iia7 illus, 2 tables, 19 ref

017473   Bagheri Z;Davoudifar P;Rastegarzadeh G;Shayan M (NO, Research Institute for Astronomy and Astrophysics of Maraghe, Maraghe, Iran, Email: bagheri.zahra87@gmail.com) : Application of CORSIKa simulation code to study lateral and longitudinal distribution of fluorescence light in cosmic ray extensive air showers. J Astrophys Astr 2017, 38(1), 1-8.

In this paper, we used CORSIKA code to understand the characteristics of cosmic ray induced showers at extremely high energy as a function of energy, detector distance to shower axis, number, and density of secondary charged particles and the nature particle producing the shower. Based on the standard properties of the atmosphere, lateral and longitudinal development of the shower for photons and electrons has been investigated. Fluorescent light has been collected by the detector for protons, helium, oxygen, silicon, calcium and iron primary cosmic rays in different energies. So we have obtained a number of electrons per unit area, distance to the shower axis, shape function of particles density, percentage of fluorescent light, lateral distribution of energy dissipated in the atmosphere and visual field angle of detector as well as size of the shower image. We have also shown that location of highest percentage of fluorescence light is directly proportional to atomic number of elements. Also we have shown when the distance from shower axis increases and the shape function of particles density decreases severely. At the first stages of development, shower axis distance from detector is high and visual field angle is small; then with shower moving toward the Earth, angle increases. Overall, in higher energies, the fluorescent light method has more efficiency. The paper provides standard calibration lines for high energy showers which can be used to determine the nature of the particles.

4 illus, 1 table, 10 ref

017472   Agrawal P K;Pawar D D (School of Mathematical Sciences, Swami Ramanand Teerth Marathwada Univ, Nanded-431 606, Email: agrawalpoonam299@gmail.com) : Plane symmetric cosmological model with quark and strange quark matter in f(R, T) theory of gravity. J Astrophys Astr 2017, 38(1), 1-7.

We studied plane symmetric cosmological model in the presence of quark and strange quark matter with the help of f(R, T) theory. To decipher solutions of plane symmetric space-time, we used power law relation between scale factor and deceleration parameter. We considered the special law of variation of Hubble's parameter proposed by Berman (Nuovo Cimento B74, 182, 1983) which yields constant deceleration parameter. We also discussed the physical behavior of the solutions by using some physical parameters.

3 illus, 39 ref

016523   Sharma S K;Ojha S N;Neeraj Kumar (Physics Dep, S.S.V. College, Hapur-245 101, Email: subodhphysicsccs@gmail.com) : Evolution of flare generated magnetohydrodynamic shock in solar wind. Ultra Scient phys Sci-Sect B 2016, 28(5-7), 127-33.

A self-similar spherically symmetric model is constructed to describe a blast wave in the solar wind produced by a solar flare. The shock wave is assumed to advance into a conducting gas streaming with a constant velocity ahead of the shock. Numerical solutions are obtained for the distribution of flow variables within the shocked gas for the special choice of parameters and for uniform and non-uniform distribution of density in ambient solar atmosphere. In particular, the time of transit of the shock at the earth's orbit is calculated. It is observed that the streaming ambient solar atmosphere reducesvariations in flow variables in crossing the shock at earth's orbit.

4 illus, 23 ref

016522   Jayalekshmi G L;Prince P R (Physics Dep, College Univ, Thiruvananthapuram, Email: princerprasad@gmail.com) : Solar activity related periodicities in sea surface temperature. Ultra Scient phys Sci-Sect B 2016, 28(5-7), 134-41.

Sun is a variable star showing a great variety of non-stationary active processes. Such non-stationary and non-equilibrium processes (solar activity) can lead to sporadic acceleration of energetic particles with greatly enhanced flux (solar wind). These processes modify the radiation environment of Earth and cause strong geomagnetic storms through coupling of solar wind and Earth's magnetosphere. This may lead to aurorae and large electric currents that can disrupt communication, power grids and satellite navigation. During active times, Sun's energy output is irregular and highly explosive. Earth's climate is also influenced by solar activity variations. Sea surface temperature is a well known parameter relating to climate change. It can influence air on the near shore atmosphere and its variations can modify Earth's climatein a highly complex way. Present study analyzes sea surface temperature and solar activity variations, in order to find out the presence of solar activity related periodicities in sea surface temperature.Wavelet analysis of global, northern and southern sea surface temperature time series and various solar activity indices were carried out. Major long-term periodicity found common in global, northern and southern sea surface temperature is 17.9 years. Southern hemisphere sea surface temperature variation is shown mainly to follow variations in sunspot activity. However, global sea surface temperature and northern hemisphere sea surface temperature variations are more influenced by asymmetry in the polar magnetic field of the Sun.

3 illus, 1 table, 21 ref

015556   Mathew K;Arya A S;Seth H;Moorthi S M;Babu P N (Space Applications Center, India Space Organisation, Ahmedabad-380 015, Email: kurian_mathew@sac.isro.gov.in) : Correction of mars colour camera images for identification of spectral classes. Curr Sci 2017, 112(6), 1158-64.

Mars Colour Camera on-board the Mars Orbital Mission makes use of a Bayer pattern detector. Spectral response of RGB (red, green and blue) pixels of Bayer detector shows large overlap which reduces the spectral information content of the image. In the present paper, a simple method is suggested to correct the data for spectral overlap. It is shown that correction process significantly increases the spectral information content of the image and enhances the ability of the sensor to identify different target types like dust clouds and water ice clouds.

11 illus, 2 tables, 14 ref

006305   Sreejith K M;Agarwal R;Rajawat A S (Space Applications Center, Indian Space Research Organization (ISRO), Ahmedabad-380 015, Email: asrajawat@sac.isro.gov.in) : Crustal deformation studies using synthetic aperture inteferometry. Proc Indian Natn Sci Acad 2016, 82(3), 737-46.

Satellite based Synthetic Aperture Radar interferometry (InSAR) is a well known remote sensing technique to generate digital elevation models of meter-scale accuracy. The technique also enables to measure ground deformation with subcentimeter level accuracy at a spatial resolution of few meters covering on large areas. In this article we review recent studies from India on crustal deformation related to earthquakes using InSAR technique. We also briefly discuss limitations and recent technological advances of this technique with a future perspective.

9 illus, 40 ref

006304   Chauhan P;Bhardwaj A;Senthil Kumar P;Kaur P; Bhandari N (NO, Space Applications Centre, Ahmedabad, Email: prakash@sac.isro.gov.in) : Understanding our celestial neighbours: an Indian perspective in planetary sciences and exploration. Proc Indian Natn Sci Acad 2016, 82(3), 403-23.

The planetary exploration program of the Indian Space Research Organization is described. The important results obtained from the two successful missions, Mars orbiter Mission (2014) and the earlier Chandrayaan-1 mission (2008-9) to moon are summarized. High-resolution maps of Valles Marineris enabled several surface, aqueous and atmospheric features to be delineated and the highly elliptical orbit of MOM enabled imaging of the surface of the farther side of Deimos as well as study of Mars exospheric constituents. The results from Chandrayaan-1 mission changed many lunar concepts e.g. from dry, passive and inactive to moon to wet, tectonically and volcanically active moon. Some recent results based on the space borne and laboratory based study of Titan, Pluto, Comets and meteorites coming from Mars and Vesta are summarized. The future planetary exploration plans, such as Chandrayaan-2 and second Mars mission are briefly mentioned.

20 illus, 1 table, 96 ref

002151   Sarbadhikari A B;Marhas K K;Sameer;Goswami J N (NO, Physical Research Lab, Ahmedabad-380 009, Email: goswami@prl.res.in) : Water in the lunar interior. Curr Sci 2016, 110(8), 1536-9.

Presence and distribution of water and other volatiles in the lunar interior could have played a key role in the early evolution of the Moon. We report abundance of water along with F and Cl, in apatite present in the Apollo 15 lunar basalt 15555, considered to be the primitive end member of the low-Ti mare basalt suite. Apatites are rare in this basalt and are devoid of significant spatial variation in volatile content. Considering a late-stage crystallization of apatite, we infer 100-160 ppm water, 80-90 ppm fluorine and 10-20 ppm chlorine in the parent magma of 15555. The inferred water content is much lower than that reported for the parent magma of lunar volcanic glasses, as well as in melt inclusions trapped within the glasses that sampled much deeper regions of Moon. This difference suggests a non-uniform distribution of water and other volatiles in lunar mantle source regions, that could have significantly influenced early thermo-chemical evolution of the Moon.

2 illus, 23 ref

020380   Zakharov A F (National Astronomical Observatories of Chinese Academy of Sciences, Datun Road 20A, Beijing, 100 012 China, Email: alex_f_zakharov5@mail.ru) : Possible alternatives to the supermassive black hole at the galactic center. J Astrophys Astr 2015, 36(4), 539-53.

Now there are two basic observational techniques to investigate a gravitational potential at the Galactic Center, namely, (a) monitoring the orbits of bright stars near the Galactic Center to reconstruct a gravitational potential; (b) measuring the size and shape of shadows around black hole giving an alternative possibility to evaluate black hole parameters in mm-band with VLBI-technique. At the moment, one can use a small relativistic correction approach for stellar orbit analysis (however, in the future the approximation will not be precise enough due to enormous progress of observational facilities) while for smallest structure analysis in VLBI observations one really needs a strong gravitational field approximation. We discuss results of observations, their conventional interpretations, tensions between observations and models and possible hints for a new physics from the observational data and tensions between observations and interpretations. We discuss an opportunity to use a Schwarzschild metric for data interpretation or we have to use more exotic models such as Reissner-Nordstrom or Schwarzschild-de-Sitter metrics for better fits.

3 illus, 133 ref

020379   Yeghiazaryan A A;Nazaryan T A;Hakobyan A A (NO, , Byurakan Astrophysical Observatory, 0213 Byurakan, Aragatsotn Province, Armenia, Email: nazaryan@bao.sci.am) : Hα velocity fields and galaxy interaction in the quartet of galxies NGC 7769, 7770, 7771 and 7771A. J Astrophys Astr 2016, 37(1), 1-10.

The quartet of galaxies NGC 7769, 7770, 7771 and 7771A is a system of interacting galaxies. Close interaction between galaxies caused characteristic morphological features: tidal arms and bars, as well as an induced star formation. In this study, we performed the Fabry-Perot scanning interferometry of the system in Ha line and studied the velocity fields of the galaxies. We found that the rotation curve of NGC 7769 is weakly distorted. The rotation curve of NGC 7771 is strongly distorted with the tidal arms caused by direct flyby of NGC 7769 and flyby of a smaller neighbor NGC 7770. The rotation curve of NGC 7770 is significantly skewed because of the interaction with the much massive NGC 7771. The rotation curves and morphological disturbances suggest that the NGC 7769 and NGC 7771 have passed the first pericenter stage, however, probably the second encounter has not happened yet. Profiles of surface brightness of NGC 7769 have a characteristic break, and profiles of color indices have a minimum at a radius of intensive star formation induced by the interaction with NGC 7771.

5 illus, 2 tables, 28 ref

020378   Vujcic V;Jevremovic D;Mihajlov A A;Ignjatovic L M;Sreckovic V A;Dimitrijevic M S;Malovic M (Faculty of Organizational Sciences, Univ of Belgrade and Astronomical Observatory, Volgina 7, 11060 Belgrade 74, Serbia, Email: veljko@aob.rs) : MOL-D: A Collisional database and web service within the virtual atomic and molecular data center. J Astrophys Astr 2015, 36(4), 693-703.

MOL-D database is a collection of cross-sections and rate coefficients for specific collisional processes and a web service within the Serbian Virtual Observatory (SerVO) and the Virtual Atomic and Molecular Data Center (VAMDC). This database contains photo-dissociation cross-sections for the individual ro-vibrational states of the diatomic molecular ions and rate coefficients for the atom-Rydberg atom chemi-ionization and inverse electron-ion-atom chemi-recombination processes. At the moment it contains data for photodissociation cross-sections of hydrogen H₂⁺ and helium He₂⁺ molecular ions and the corresponding averaged thermal photodissociation cross-sections. The ro-vibrational energy states and the corresponding dipole matrix elements are provided as well. Hydrogen and helium molecular ion data are important for calculation of solar and stellar atmosphere models and for radiative transport, as well as for kinetics of other astrophysical and laboratory plasma (i.e. early Universe).

^iia5 illus, 21 ref

020377   Tavabi E;Ajabshirizadeh A;Maralani A R A; Zeighami S (Physics Dep, Payame Noor Univ (PNU), 19395-3697-Tehran, Islamic Republic of Iran, Email: tavabi@iap.fr) : Spicules intenstity oscillations in SOT/HINODE observations. J Astrophys Astr 2015, 36(2), 307-23.

Study the coherency of solar spicules intensity oscillations with increasing height above the solar limb in quiet Sun, active Sun and active region using observations from HINODE/SOT. Existence of coherency up to transition region strengthens the theory of the coronal heating and solar wind, through energy transport and photospheric oscillations. Methods. Using time sequences from the HINODE/SOT in Ca II H line, we investigate oscillations found in intensity profiles at different heights above the solar limb. We use the Fourier and wavelet analysis to measure dominant frequency peaks of intensity at the heights, and phase difference between oscillations at two certain heights, to find evidence for the coherency of the oscillations. The results of fast Fourier transform. (FFT) for the quiet Sun, active Sun and active region show frequency peaks of order 3.6 mHz, 5.5 mHz and 7.3 mHz at four separate heights. The fluctuations of power* are random for the three datasets, i.e., independent from height and solar activity. The wavelet results for quiet Sun, active Sun and active region indicate dominant frequencies similar to FFT results. Results of coherency represent frequencies at about 3.5 mHz and 5.5 mHz for all three datasets. Histograms of frequencies corresponding to maximum coherency for quiet Sun, active region and active sun display frequencies of about 3.5 mHz, 4.2 mHz, 4.6 mHz, 5.3 mHz and 5.8 mHz. The phase speeds of 50-450 kms^-1 are measured for quiet Sun, 50-560 km ^-1 for active region and 50-550 km s^-1 for active Sun. The majority of the measured phase speeds in locations where there is known to be considerable dynamic activity are more than quiet Sun, and the phase speeds obtained from three datasets increase with height. We also find strong evidence for upwardly propagating waves with high coherency in three datasets. Intensity oscillations may result from the presence of the coherent waves, which could provide significant energy to heat the solar atmosphere. Finally, We can calculate the energy and the mass transported by spicules providing energy equilibrium, according to density values of spicules at different heights. To extend this work, we can also consider coherent oscillations at different latitudes and suggest the study of oscillations, which may be obtained from observations of other satellites.

17 illus, 2 tables, 31 ref

020376   Stathopoulos D;Danezis E;Lyratzi E;Antoniou A;Tzimeas D (Astrophysics, Astronomy and Mechanics Dep, Faculty of Physics, Univ of Athens, Panepistimioupoli, Zographou-157 84, Athens, Greece, Email: dstatho@phys.uoa.gr) : Multicomponent analysis of the UV Si IV and C IV broad absorption troughs in BALQSO spectra: The examples of J01225+1339 and J02287+0002. J Astrophys Astr 2015, 36(4), 495-511.

Broad Absorption Line QSOs (BALQSOs) are a subtype of radio-quite QSOs that exhibit complex and unusually broad (FWHM ≥ 2,000 km/s) absorption lines. The existence of these lines in BALQSO spectra raises some questions with respect to the properties, the physical conditions and kinematics of the BAL material as well as the morphology of BAL troughs. In this study, taking into consideration the clumpy structure of the AGN outflow winds, we propose a physical model in order to explain the formation of BAL troughs and we give the mathematical description of this model. We also propose a method for analyzing spec-troscopically the BAL profiles in the UV region of the electromagnetic spectrum. This method consists of the criteria we set during the fitting process of BAL troughs. The purpose of these criteria is to enable us to determine the exact number of components needed to simulate accurately the BAL troughs and guarantee the uniqueness of the fit. We give an application of the model and the method for Si IV and C IV resonance lines in the case of two BALQSOs. From the analysis, we conclude that the BAL material is in the form of clouds (density enhancements) that move radially and intercept the line-of-sight to the central continuum source. Using our method, we find the number of absorption components needed to simulate the BAL profiles, which means the number of clouds in the line-of-sight. We calculate the velocity shifts, the FWHM and the optical depths of the absorption components of BALs and we propose an internal structure for these clouds. Finally, we give some correlations between the properties of absorption components of Si IV and C IV.

6 illus, 1 table, 56 ref

020375   Smailagic M;Bon E (Astronomical Observatory of Belgrade, Volgina 7, 11060 Belgrade, Serbia, Email: marijana@aob.rs) : Line shapes emitted from spiral structures around symmetric orbits of supermassive binary black holes. J Astrophys Astr 2015, 36(4), 513-27.

Variability of active galactic nuclei is not well understood. One possible explanation is existence of supermassive binary black holes (SMBBH) in their centres. It is expected that major mergers are common in the Universe. It is expected that each supermassive black hole of every galaxy eventually finish as a SMBBH system in the core of newly formed galaxy. Here we model the emission line profiles of active galactic nuclei (AGN) assuming that the flux and emission line shape variations are induced by supermassive binary black hole systems (SMBBH). We assume that the accreting gas inside the circumbinary (CB) disk is photo ionized by mini accretion disk emission around each SMBBH. We calculate variations of emission line flux, shifts and shapes for different parameters of SMBBH orbits. We consider cases with different masses and inclinations for circular orbits and measure the effect to the shape of emission line profiles and flux variability.

^iia8 illus, 1 tables, 76 ref

020374   Singh J;Amuda T O (Mathematics Dep, Faculty of Science, Ahmadu Bello Univ, P.M.B. 2222K Sokoto Road, Samaru, Zaria-Nigeria, Email: teejaymath@gmail.com) : Out-of-Plane equilibrium poins in the photogravitational CR3BP with oblateness and P-R Drag. J Astrophys Astr 2015, 36(2), 291-305.

This paper investigates the motion of a test particle around the out-of-plane equilibrium points in the circular photogravitational restricted three-body problem when the effect of radiation pressure from the smaller primary and its Poynting-Robertson (P-R) drag are taken into account, and the bigger primary is modeled as an oblate spheroid. These points lie in the xz-plane almost directly above and below the center of the oblate primary. The equilibrium points are sought, and we observe that, there are two coordinate points L_6,7 which depend on the oblateness of the bigger primary, and the radiation pressure force and P-R drag of the smaller primary. The positions and linear stability of the problem are investigated both analytically and numerically for the binary system Cen X-4. The out-of-plane equilibrium points are found to be unstable in the sense of Lyapunov due to the presence of a positive real root.

4 illus, 6 tables, 59 ref

020373   Simonia I;Nabiyev S (NO, Ilia State Univ, Cholokashivili Str.3/5, Tbilisi 0162, Georgia) : Nano-metric dust particles as a hardly detectable component of the interplanetary dust cloud. J Astrophys Astr 2015, 36(3), 409-19.

The present work introduces the hypothesis of existence of a hardly detectable component of the interplanetary dust cloud and demonstrates that such a component is a dust formation consisting of the dust particles of nano-metric dimensions. This work describes the main physical properties of such a kind of nano-dust, and its possible chemical and mineralogical peculiarities proposes new explanations related to reddening of the dynamically cold transneptunian objects on account of scattering their light by nano-dust of the hardly detectable component of the interplanetary dust cloud. We propose the relation for the coefficient of absorption by the nano-dust and provide results of the statistical analysis of the TNO color index-orbital inclinations. We also present a critical assessment of the proposed hypothesis.

1 illus, 25 ref

020372   Rosato J;Bufferand H;Capes H;Koubiti M; GodbertMouret L;Marandet Y;Stamm R (AixMarseille Univ, CNRS, PIIM UMR 7345, F-13397 Marseille Cedex 20, France, Email: joel.rosato@univ-amu.fr) : Modeling of stark-zeemean lines in magnetized hydrogen plasmas. J Astrophys Astr 2015, 36(4), 581-8.

The action of electric and magnetic fields on atomic species results in a perturbation of the energy level structure, which alters the shape of spectral lines. In this work, we present the Zeeman-Stark line shape simulation method and perform new calculations of hydrogen Lyman and Balmer lines, in the framework of magnetic fusion research. The role of the Zeeman effect, fine structure and the plasma's non-homogeneity along the line-of-sight are investigated. Under specific conditions, our results are applicable to DA white dwarf atmospheres.

7 illus, 16 ref

020371   Pucha R;Hiremath K M;Gurumath S R (Integrated Science Education and Research Centre (ISERC), Visva-Bharati Univ, Santiniketan-731 235, Email: shashankgurumath@yahoo.in ) : Development of a code to analyze the solar white-light images from the Kodaikanal observatory: Detection of sunspots, computation of heliographic coordinates and area. J Astrophys Astr 2016, 37(1), 1-20.

Sunspots are the most conspicuous aspects of the Sun. They have a lower temperature, as compared to the surrounding photosphere; hence, sunspots appear as dark regions on a brighter background. Sunspots cyclically appear and disappear with a 11 -year periodicity and are associated with a strong magnetic field (<126> 10³ G) structure. Sunspots consist of a dark umbra, surrounded by a lighter penumbra. Study of umbra-penumbra area ratio can be used to give a rough idea as to how the convective energy of the Sun is transported from the interior, as the sunspot's thermal structure is related to this convective medium. An algorithm to extract sunspots from the white-light solar images* obtained from the Kodaikanal Observatory is proposed. This algorithm computes the radius and center of the solar disk uniquely and removes the limb darkening from the image. It also separates the umbra and computes the position as well as the area of the sunspots. The estimated results are compared with the Debrecen photoheliographic results. It is shown that both area and position measurements are in quite good agreement.

10 illus, 2 tables, 33 ref

020370   Peach G (Physics and Astronomy Dep, Univ College London, Gower Street, London WCIE 6BT, UK, Email: g.peach@ucl.ac.uk) : Radio recombination lines of hydrogen. J Astrophys Astr 2015, 36(4), 555-63.

The impact theory of spectral line broadening is used to obtain complete profiles for radio recombination lines perturbed by electron and proton impact. The collisions can be divided into two types: inelastic, where transitions take place between hydrogen levels with different principal quantum number n and elastic, where the transitions are only between degenerate levels for a particular value of n. The widths of the radio lines are essentially determined by inelastic electron collisions and elastic proton collisions with the emitting hydrogen atom occupying either the upper or lower levels of the line. Here, earlier work is extended to examine the contribution from proton collisions to the line width in more detail, and it is shown that the trends in the behaviour of the widths again confirm previous results.

5 tables, 21 ref

020369   Pant N;Ahmad M;Pradhan N (Mathematics Dep, National Defence Academy, Khadakwasla, Pune 411 023, Email: neeraj.pant@yahoo.com) : Einstein-Maxwell field equation in isotropic coordinates: An application to modeling superdense star. J Astrophys Astr 2016, 37(1), 1-11.

We present a charged analogue of Pant et al. (2010, Astro-phys. Space ScL., 330, 353) solution of the general relativistic field equations in isotropic coordinates by using simple form of electric intensity E that involve charge parameter K. Our solution is well behaved in all respects for all values of X lying in the range 0 < X <0.11, K lying in the range 4 <60> K ≤ 6.2 and Schwarzschild compactness parameter u lying in the range 0 <60> u ≤ 0.247. Since our solution is well behaved for wide ranges of the parameters, we can model many different types of ultra-cold compact stars like quark stars and neutron stars. We have shown that corresponding to X = 0.077 and K = 6.13 for which u = 0.2051 and by assuming surface density ρb = 4.6888 x 10¹⁴ g cm^-3 the mass and radius are found to be 1.509M0, 10.906 km respectively which match with the observed values of mass 1.51M0 and radius 10.90 km of the quark star XTE J1739-217. The well behavecl class of relativistic stellar models obtained in this work might have astrophysical significance in the study of more realistic internal structures of compact stars.

1 illus, 2 tables, 53 ref

020368   Mura G L;Chiaro G;Ciroi S;Rafanelli P; Salvetti D;Berton M;Cracco V (Dipertimento di Fisica e Astronomia G. Galilei, Univ degli Studi di Padova, Vicolo dell'Psservatorio 3, 35122 Padova, Italy, Email: giovanni.lamura@unipd.it) : Optical couterparts of undertermined type γ-Ray active galactic nuclei with blazar-like spectral energy distributions. J Astrophys Astr 2015, 36(4), 447-55.

During its first four years of scientific observations, the Fermi Large Area Telescope (Fermi-LAT) detected 3033 γ-ray sources above a 4t7 significance level. Although most of the extra-galactic sources arc active galactic nuclei (AGN) of the blazar class, other families of AGNs are observed too, while a still high fraction of detections (<126>30%) remains with uncertain association or classification. According to the currently accepted interpretation, the AGN γ-ray emission arises from inverse Compton (IC) scattering of low energy photons by relativistic particles confined in a jet, which, in the case of blazars, is oriented very close to our line-of-sight. Taking advantage of data from radio and X-ray wavelengths, which we expect to be produced together with γ-rays, providing a much better source localization potential, we focused our attention on a sample of γ-ray Blazar Candidates of Undetermined type (BCUs), starting a campaign of optical spectroscopic observations. The main aims of our investigation include a census of the AGN families that contribute to γ-ray emission and a study of their redshift distribution, with the subsequent implications on the intrinsic source power. We furthermore analyze which γ-ray properties can better constrain the nature of the source, thus helping in the study of objects not yet associated with a reliable low frequency counterpart. Here we report on the instruments and techniques used to identify the optical counterparts of γ-ray sources, we give an overview on the status of our work, and we discuss the implications of a large scale study of γ-ray emitting AGNs.

^iia2 illus, 2 tables, 15 ref

020367   McLaughlin J A (Mathematics and Information Sciences Dep, Northumbria Univ, Newcastle-upon-Type, NE1 8ST, United Kingdom, Email: james.a.mclaughlin@northumbria.ac.uk) : Behaviour of magnetoacoustic waves in the neighbourhood of a two-dimensional null point: Initially cylindrically symmetric perturbation. J Astrophys Astr 2016, 37(1), 1-27.

The propagation of magnetoacoustic waves in the neighbourhood of a 2D null point is investigated for both β ≠ 0 and β ≠ 0 plasmas. Previous work has shown that the Alfven speed, here uA α r, plays a vital role in such systems and so a natural choice is to switch to polar coordinates. For β = 0 plasma, we derive an analytical solution for the behaviour of the fast magnetoacoustic wave in terms of the Klein-Gordon equation. We also solve the system with a semi-analytical WKB approximation which shows that the β = 0 wave focuses on the null and contracts around it but, due to exponential decay, never reaches the null in a finite time. For the β ≠ 0 plasma, we solve the system numerically and find the behaviour to be similar to that of the β = 0 system at large radii, but completely different close to the null. We show that for an initially cylindrically-symmetric fast magnetoacoustic wave perturbation, there is a decrease in wave speed along the separatrices and so the perturbation starts to take on a quasi-diamond shape; with the corners located along the separatrices. This is due to the growth in pressure gradients that reach a maximum along the separatrices, which in turn reduces the acceleration of the fast wave along the separatrices leading to a deformation of the wave morphology.

10 illus, 53 ref

020366   Martinez Aldama M L;Mariziani P;Dultzin D; Sulentic J W;Bressan A;Chen Y;Stirpe G M (Instituto de Astronomia, Univ Nacional Autonoma de Mexico, Aptodo, Postal 70-264, Mexico, D.F. 04510, Mexico, Email: maldama@astro.unam.mx) : Observations of th Ca II IR triplet in high luminosity quasars: Exploring the sample. J Astrophys Astr 2015, 36(4), 457-65.

Authors present a new spectroscopic sample of 11 quasars at intermediate redshift observed with the Infrared Spectrometer and Array Camera (ISAAC) on the ESO Very Large Telescope (VLT), covering O I A8446 and the Ca 11 triplet 8498, 8542, 8662. The new observations - that supplement the sample presented by Martinez-Aldama et al. (2015) -allow us to confirm the constraints on physical conditions and location of the region emitting the low ionization lines, as well as the relation between Ca II and Fe II.

^iia4 illus, 1 table, 30 ref

020365   Majlinger Z;Simic Z;Dimitrijevic M S (Faculty of Humanities and Sociakl Sciences, Univ of Rijeka, 51000 Rijeka, Croatia) : On the stark broadening of Lu III spectral lines. J Astrophys Astr 2015, 36(4), 671-9.

The electron-impact widths for 27 Lu III spectral lines have been calculated by using the modified semiempirical method. Calculations have been also performed with the published relativistic Hartree-Fock oscillator strengths and additionally, with the approximate formula of Cowley. With the obtained results, the influence of Stark broadening on Lu III lines was investigated in the spectra of A-type stars. The obtained data will be included in the STARK-B database, which is part of the Virtual Atomic and Molecular Data Center - VAMDC.

2 illus, 1 table, 18 ref

020364   Kovacevic A;Popovic L C;Shapovalova A I;Ilic D;Burenkov A N;Chavushyan V H (Astronomy Dep, Faculty of Mathematics, Univ of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia, Email: andjelkla@matf.bg.ac.rs) : Time delay evolution of five active galactic nuclei. J Astrophys Astr 2015, 36(4), 475-93.

Here is to investigate light curves of the continuum and emission lines of five type 1 active galactic nuclei (AGN) from our monitoring campaign, to test time-evolution of their time delays. Using both modeled and observed AGN light curves, we apply Gaussian kernel-based estimator to capture variation of local patterns of their time evolving delays. The largest variations of time delays of all objects occur in the period when continuum or emission lines luminosity is the highest. However, Gaussian kernel-based method shows instability in the case of NGC 5548, 3C 390.3, E1821+643 and NGC 4051 possibly due to numerical discrepancies between damped random walk (DRW) time scale of light curves and sliding time windows of the method. The temporal variations of time lags of Arp 102B can correspond to the real nature of the time lag evolution.

7 illus, 4 tables, 39 ref

020363   Kolarski A;Grubor D (Institute for Geophysics, Batajnicki drum 8, 11000 Belgrade, Serbia, Email: aleksandrakolarski@gmail.com) : Comparative analysis of VLF signal variation along trajectory induced by X-ray solar flares. J Astrophys Astr 2015, 36(4), 565-79.

Comparative qualitative analysis of amplitude and phase delay variations was carried out along the trajectory of GQD/22.1 kHz and NAA/24.0 kHz VLF signal traces, propagating from Skelton (UK) and Maine (USA) toward Belgrade, induced by four isolated solar X-ray flare events occurred during the period from September 2005 to December 2006. For monitoring, recording and for storage of VLF data at the Institute of Physics in Belgrade, Serbia, the AbsPAL system was used. For modeling purposes of propagating conditions along GQD and NAA signal propagation paths, LWPCv21 program code was used. Occurred solar flare events induced lower ionosphere electron density height profile changes, causing perturbations in VLF wave propagation within Earth-ionosphere waveguides. As analyzed VLF signals characterize by different propagation parameters along trajectories from their transmitters to the Belgrade receiver site, their propagation is affected in different ways for different solar flare events and also for the same solar flare events.

13 illus, 1 table, 31 ref

020362   Ilic D;Popovic L C;Shapovalova A I;Burenkov A N;Chavushyan V H;Kovacevic A (Astronomy Dep, Faculty of Mathematics, Univ of Belgrade, Studentski trg 16, 11000 Belgrade, Serbia, Email: dilic@matf.bf.ac.rs) : Line shape variability in a sample of AGN with broad lines. J Astrophys Astr 2015, 36(4), 435-45.

The spectral variability of active galactic nuclei (AGN) is one of the key features that enables us to study in more detail, the structure of AGN emitting regions. Especially, the broad line profiles that vary both in flux and shape, give us invaluable information about the kinematics and geometry of the broad line region (BLR) where these lines are originating from. We give here a comparative review of the line shape variability in a sample of five type 1 AGNs, those with broad emission lines in their spectra, of the data obtained from the international long-term optical monitoring campaign coordinated by the Special Astrophysical Observatory of the Russian Academy of Science. The main aim of this campaign is to study the physics and kinematics of the BLR on a uniform data set, focusing on the problems of the photoionization heating of the BLR and its geometry, where, in this paper, we give for a first time, a comparative analysis of the variabilty of five type 1 AGNs, discussing their complex BLR physics and geometry in the framework of the estimates of the supermassive black hole mass in AGN.

^iia6 illus, 2 tables, 38 ref

020361   Hill T P;Fox R F (School of Mathematics, Georgia Institute of Technology, Atlanta, GA 30332, USA) : Hubble's law implies benford's law for distances to galaxies. J Astrophys Astr 2016, 37(1), 1-8.

A recent article by Alexopoulos and Leontsinis presented empirical evidence that the first digits of the distances from the Earth to galaxies are a reasonably good fit to the probabilities predicted by Benford's law, the well known logarithmic statistical distribution of significant digits. The purpose of the present article is to give a theoretical explanation, based on Hubble's law and mathematical properties of Ben-ford's law, why galaxy distances might be expected to follow Benford's law. The new galaxy-distance law derived here, which is robust with respect to change of scale and base, to additive and multiplicative computational or observational errors, and to variability of the Hubble constant in both time and space, predicts that conformity to Benford's law will improve as more data on distances to galaxies becomes available. Conversely, with the logical derivation of this law presented here, the recent empirical observations may beviewed as independent evidence of the* validity of Hubble's law.

1 illus, 12 ref

020360   Hegde M;Hiremath K M;Doddamani V H;Gurumath S R (NO, Indian Institute of Astrophysics, Bengaluru-560 034) : Solar wind associated with near equatorial coronal hole. J Astrophys Astr 2015, 36(3), 355-74.

Present study probes temporal changes in the area and radiative flux of near equatorial coronal hole associated with solar wind parameters such as wind speed, density, magnetic field and temperature. Using high temporal resolution data from SDO/AIA for the two wavelengths 193 angstrum and 211 angstrum, area and radiative flux of coronal holes are extracted and are examined for the association with high speed solar wind parameters. We find a strong association between different parameters of coronal hole and solar wind. For both the wavelength bands, we also compute coronal hole radiative energy near the earth and it is found to be of similar order as that of solar wind energy. However, for the wavelength 193 A, owing to almost similar magnitudes of energy emitted by coronal hole and energy due to solar wind, it is conjectured that solar wind might have originated around the same height where 193 angstrum line is formed in the corona.

14 illus, 10 tables, 41 ref

020359   Guo D F;Li K;Hu S M;Jiang Y G;Gao D Y;Chen X (Shandong Provincial Key Lab of Optical Astronomy and Solar-Terrestrial, Institute of Space Sciences, Shandong Univ, Weihai-264 209, China, Email: likai@ynao.ac.cn) : Discovery of a faint eclipsing binary GSC 02265-01456. J Astrophys Astr 2015, 36(3), 399-407.

When observing the transiting extrasolar planets, we found a new eclipsing binary named GSC 02265-01456. The V and R_c observations were carried out for this binary. The photometric light curves of the two bands were simultaneously analyzed using the W-D code. The solutions show that GSC 02265-01456 is an extremely low mass ratio (q - 0.087) overcontact binary system with a contact degree of f = 82.5%. The difference between the two maxima of the light curve can be explained by a dark spot on the primary component.

6 illus, 3 tables, 25 ref

020358   Grzedzielski M;Sukova P;Janiuk A (Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotnikow 32/46 02-668 Warsaw, Poland, Email: mikolaj.grzedzielski@gmail.com) : Deterministic chaos in the X-ray sources. J Astrophys Astr 2015, 36(4), 529-37.

Hardly any of the observed black hole accretion disks in X-ray binaries and active galaxies shows constant flux. When the local stochastic variations of the disk occur at specific regions where a resonant behaviour takes place, there appear the quasi-periodic oscillations (QPOs). If the global structure of the flow and its non-linear hydrodynamics affects the fluctuations, the variability is chaotic in the sense of deterministic chaos. Our aim is to solve a problem of the stochastic versus deterministic nature of the black hole binary variabilities. We use both observational and analytic methods. We use the recurrence analysis and we study the occurence of long diagonal lines in the recurrence plot of observed data series and compare it to the surrogate series. We analyze here the data of two X-ray binaries - XTE J1550-564 and GX 339-4 observed by Rossi X-ray Timing Explorer. In these sources, the non-linear variability is expected because of the global conditions (such as the mean accretion rate) leading to the possible instability of an accretion disk. The thermal-viscous instability and fluctuations around the fixed-point solution occurs at high accretion rate, when the radiation pressure gives dominant contribution to the stress tensor.

^iia6 illus, 19 ref

020357   FerrichaAlami M;Safsafi A;Lahlou L;Chakir H; Bennai M (Lab de Physique de la Matiere Condensee (URACIO), Equipe Physique Quantique et Applications, Faculte des Sciences Ben M'sik, Univ Hassan II, B.P.7955, Casablanca, Maroc, Email: mdbennai@yahoo.fr) : Tree level potential on brane after planck and BICEP2. J Astrophys Astr 2015, 36(2), 269-80.

The recent detection of degree scale B-mode polarization in the Cosmic Microwave Background (CMB) by the BICEP2 experiment implies that the inflationary ratio of tensor-to-scalar fluctuations is r = 0.2_-0.05^+0.07, which has opened a new window in the cosmological investigation. In this regard, we propose a study of the tree level potential inflation in the framework of the Randall-Sundrum type-2 braneworld model. We focus on three branches of the potential, where we evaluate some values of brane tension A. We discuss how the various inflationary perturbation parameters can be compatible with recent Planck and BICEP2 observations.

4 illus, 2 tables, 28 ref

020356   Du L M;Bai J M;Xie Z H;Yi T F;Xu Y B;Xue R; Wang X H (Physics Dep, School of Physics and Electronic Information, Yunnan Normal Univ, Kunming 650 092, People's Republic of China, Email: Leiming_du@ynao.ac.cn) : Scale invarient synchrotron jet of flat spectrum radio quasars. J Astrophys Astr 2015, 36(2), 281-90.

In this paper, the scale invariance of the synchrotron jet of Flat Spectrum Radio Quasars has been studied using a sample of combined sources from FKM04 and from SDSS DR3 catalogue. Since the research of scale invariance has been focused on sub-Eddington cases that can be fitted onto the fundamental plane, while near-Eddington sources such as FSRQs have not been explicitly studied. The extracted physical properties of synchrotron jet of FSRQs have been shown to be scale invariant using our sample. The results are in good agreement with theoretical expectations of Heinz & Sunyaev (2003). Therefore, the jet synchrotron is shown to be scale independent, regardless of the accretion modes. Results in this article thus lend support to the scale invariant model of the jet synchrotron throughout the mass scale of black hole systems.

1 illus, 1 table, 36 ref

020355   Ding G Q;Huang C P (Xingiang Astronomical Observatory, CAS, 150 Science 1-Street, Urumqi-830 011, China, Email: dinggq@xa.ac.cn) : Hard X-ray emission along the Z tracks in GX 17+2. J Astrophys Astr 2015, 36(3), 335-53.

Using the data from the Proportional Counter Array (PCA) and the High-Energy X-ray Timing Experiment (HEXTE) on board Rossi X-Ray Timing Explorer for Z source GX 17+2, we investigate the evolution of its PCA spectra and HEXTE spectra along a 'Z' track on its hardness-intensity diagram. A hard X-ray tail is detected in the HEXTE spectra. The detected hard X-ray tails are discontinuously scattered throughout the Z track. The found hard X-ray tail hardens from the horizontal branch, through the normal branch, to the flaring branch in principle and it contributes <126>(20-50)% of the total flux in 20-200 keV. Our joint fitting results of the PCA+HEXTE spectra in 3-200 keV show that the portion of Comptonization in the Bulk-Motion Comptonization (BMC) model accounts for the hard X-ray tail, which indicates that the BMC process could be responsible for the detected hard tail. The temperature of the seed photons for BMC is <126>2.7 keV, implying that these seed photons might be emitted from the surface of the neutron star (NS) or the boundary layer between the NS and the disk and, therefore, this process could take place around the NS or in the boundary layer.

7 illus, 3 tables, 59 ref

020354   Dimitrijevic M S;Simic Z;Kovacevic A; Valjarevic A;Sahal Brechot S (Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia, Email: mdimitrijevic@aob.bg.ac.rs) : Stark broadening in compact stars: Xe VI lines. J Astrophys Astr 2015, 36(4), 681-91.

This is to will consider Stark broadening of non hydrogenic spectral lines in the impact approximation in compact stars: pre-white dwarf and white dwarf atmospheres. In order to show an example, Stark broadening parameters have been calculated, using the impact semiclassical perturbation approach for four Xe VI spectral lines. Obtained results have been used to demonstrate the influence of Stark broadening in DA and DB white dwarf atmospheres.

1 illus, 1 table, 42 ref

020353   Dimitrijevic M S;Simic Z;Kovacevic A; Valjarevic A;Sahal Brechot S (Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia, Email: mdimitrijevic@aob.rs) : Stark widths of spectral lines of neutral neon. J Astrophys Astr 2015, 36(4), 643-59.

In order to complete Stark broadening data for Ne I spectral lines which are needed for analysis of stellar atmospheres, collisional widths and shifts (the so-called Stark broadening parameters) of 29 isolated spectral lines of neutral neon have been determined within the impact semiclassical perturbation method. Calculations have been performed for the broadening by collisions with electrons, protons and ionized helium for astrophysical applications, and for collisions with ionized neon and argon for laboratory plasma diagnostics. The shifts have been compared with existing experimental values. The obtained data will be included in the STARK-B database, which is a part of the Virtual Atomic and Molecular Data Center - VAMDC.

^iia3 tables, 32 ref

020352   Dhiman J S;Sharma R (Mathematics Dep, Himachal Pradesh Univ, Summerhill, Shimla-171 005, Email: dhiman_jp@yahoo.com) : Gravitational instability of cylindrical viscoelastic medium permeated with non uniform magnetic field and rotation. J Astrophys Astr 2016, 37(1), 1-15.

The self-gravitating instability of an infinitely extending axi-symmetric cylinder of viscoelastic medium permeated with non uniform magnetic field and rotation is studied for both the strongly coupled plasma (SCP) and weakly coupled plasma (WCP). The non uniform magnetic field and rotation are considered to act along the axial direction of the cylinder. The normal mode method of perturbations is applied to obtain the dispersion relation. The condition for the onset of gravitational instability has been derived from the dispersion relation under both strongly and weakly coupling limits. It is found that the Jeans criterion for gravitational collapse gets modified due to the presence of shear and bulk viscosities for the SCP. however, the magnetic field and rotation whether uniform or non uniform has no effect on the Jeans criterion of an infinitely extending axisymmetric cylinder of a self-gravitating viscoelas tic medium.

34 ref

020351   Devereux N (Physics & Astronomy Dep, Embry-Riddle Aeronautical Univ, Prescott. AZ 86301, USA, Email: devereux@erau.edu) : Giant broad line regions in dwarf seyferts. J Astrophys Astr 2015, 36(4), 427-32.

High angular resolution spectroscopy obtained with the Hubble Space Telescope (HST) has revealed a remarkable population of galaxies hosting dwarf Seyfert nuclei with an unusually large broad-line region (BLR). These objects are remarkable for two reasons. Firstly, the size of the BLR can, in some cases, rival those seen in the most luminous quasars. Secondly, the size of the BLR is not correlated with the central continuum luminosity, an observation that distinguishes them from their reverberating counterparts. Collectively, these early results suggest that non-reverberating dwarf Seyferts are a heterogeneous group, and not simply scaled versions of each other. Careful inspection reveals broad H Balmer emission lines with single peaks, double peaks, and a combination of the two, suggesting that the broad emission lines are produced in kine-matically distinct regions centered on the black hole (BH). Because the gravitational field strength is already known for these objects, by virtue of knowing their BH mass, the relationship between velocity and radius may be established, given a kinematic model for the BLR gas. In this way, one can determine the inner and outer radii of the BLRs by modeling the shape of their broad emission line profiles. In the present contribution, high quality spectra obtained with the Space Telescope Imaging Spectro-graph (STIS) are used to constrain the size of the BLR in the dwarf Seyfert nuclei of M81, NGC 3998, NGC 4203, NGC 3227, NGC 4051 and NGC 3516.

^iia2 illus, 1 table, 22 ref

020350   Calafut V;Wiita P J (Physics Dep, The College of New Jersey, 2000 Pennington Road, Ewing, NJ 08628-0718, USA, Email: vc296@cornell.edu) : Modeling the emission from turbulent relativistic jets in active galactic nuclei,. J Astrophys Astr 2015, 36(2), 255-68.

We present a numerical model developed to calculate observed fluxes of relativistic jets in active galactic nuclei. The observed flux of each turbulent eddy is dependent upon its variable Doppler boosting factor, computed as a function of the relativistic sum of the individual eddy and bulk jet velocities, and our viewing angle to the jet. The total observed flux is found by integrating the radiation from the eddies over the turbulent spectrum. We consider jets that contain turbulent eddies that have either standard Kolmogorov or recently derived relativistic turbulence spectra. We also account for the time delays in receiving the emission of the eddies due to their different simulated positions in the jet, as well as due to the varying beaming directions as they turn over. We examine these theoretical light curves and compute power spectral densities (PSDs) for a range of viewing angles, bulk velocities of the jet, and turbulent velocities. These PSD slopes depend significantly on the turbulent velocity, and are essentially independent of viewing angle and bulk velocity. The flux variations produced in the simulations for realistic values of the parameters tested are consistent with the types of variations observed in radio-loud AGN as, for example, recently measured with the Kepler satellite, as long as the turbulent velocities are not too high.

6 illus, 1 tble, 23 ref

020349   Bharadwaj S;Sarkar A K;Ali S S (Physics Dep, Indian Institute of Technology, Kharagpur-721 302, Email: saiyad@phys.jdvu.ac.in) : Fisher matrix predictions for detecting the cosmological 21-cm signal with the ooty wide field array (OWFA). J Astrophys Astr 2015, 36(3), 385-98.

Authors have used the Fisher matrix formalism to quantify the prospects of detecting the z = 3.35 redshifted 21-cm HI power spectrum with the upcoming radio-imterferometric array OWFA. OWFA's frequency and baseline coverage spans comoving Fourier modes in the range 1.8 x 1(10^-2 ≤ k ≤ 2.7 Mpc^-1. The OWFA HI signal, however, is predominantly from the range k ≤ 0.2Mpc^-1. The larger modes, though abundant, do not contribute much to the HI signal. In this work, we have focused on combining the entire signal to achieve a detection. We find that a 5 - σ detection of A_HI is possible with <126>150h of observations, here A_HI² is the amplitude of the HI power spectrum. We have also carried out a joint analysis for A_HIand β the redshift space distortion parameter. Our study shows that OWFA is very sensitive to the amplitude of the HI power spectrum. However, the anisotropic distribution of the k modes does not make it very suitable for measuring β.

7 illus, 3 tables, 35 ref

020348   Bensch K;DelOlmo A;Sulentic J;Perea J; Marziani P (Instituto de Astrofisica de Andalucia, IAA-CSIC, Glorieta de la Astronomia, s/n, 18008, Granada, Spain, Email: kasia@iaa.es ) : Measures of the soft X-ray excess as an eigenvector 1 parameter for active galactic nuclei. J Astrophys Astr 2015, 36(4), 467-74.

Authors present a preliminary analysis of X-ray data of quasars in the context of the 4D eigenvector 1 parameter space (Sulentic et al. 2000a, b). 4DE1 serves as a surrogate H-R diagram for representing empirical diversity among quasars and identifying the physical drivers of the diversity. The soft X-ray spectral index (Γ_soft) was adopted as one of the key 4DE1 that correlates contrasting extremes in Type 1 properties. 4DE1 motivated the hypothesis of two quasar populations (A and B) divided by L/L_EDD ≈ 0.2. Pop. A is a largely radio-quiet population with FWHM Hβ <60> 4000 km/s and often showing a soft X-ray excess. Pop. B is a mix of radio-quiet and a majority of RL quasars shows only a hard X-ray power-law SED. The X-ray separation was based upon earlier ROSAT and ASCA data but we now confirm this dichotomy with large samples of X-ray spectra obtained with XMM-Newton and SWIFT. One popular idea connects the soft excess in Pop. A quasars as a signature of thermal emission from a hot accretion disk in sources radiating close to the Eddington limit.

4 illus, 3 tables, 17 ref

020347   AlGhafri K S (NO, College of Applied Sciences- Ibri, P.O. Box 14, 516 Ibri, Oman, Email: khalil.ibr@cas.edu.com ) : Standing slow MHD waves in radiatively cooling coronal loops. J Astrophys Astr 2015, 36(2), 325-34.

The standing slow magneto-acoustic oscillations in cooling coronal loops are investigated. There are two damping mechanisms which are considered to generate the standing acoustic modes in coronal magnetic loops, namely, thermal conduction and radiation. The background temperature is assumed to change temporally due to optically thin radiation. In particular, the background plasma is assumed to be radiatively cooling. The effects of cooling on longitudinal slow MHD modes is analytically evaluated by choosing a simple form of radiative function, that ensures the temperature evolution of the background plasma due to radiation, coincides with the observed cooling profile of coronal loops. The assumption of low-beta plasma leads to neglecting the magnetic field perturbation and, eventually, reduces the MHD equations to a 1D system modelling longitudinal MHD oscillations in a cooling coronal loop. The cooling is assumed to occur on a characteristic time scale, much larger than the oscillation period that subsequently enables using the WKB theory to study the properties of standing wave. The governing equation describing the time-dependent amplitude of waves is obtained and solved analytically. The analytically derived solutions are numerically evaluated to give further insight into the evolution of the standing acoustic waves. We find that the plasma cooling gives rise to a decrease in the amplitude of oscillations. In spite of the reduction in damping rate caused by rising the cooling, the damping scenario of slow standing MHD waves strongly increases in hot coronal loops.

3 illus, 24 ref

020346   Aklonizan N;Qindeel R;Ben Nessib N; SahalBrechot S;Dimitrijevic M S (Physics and Astronomy Dep, College of Science, King Saud Univ, P.O.Box 2455, Riyadh 11451, Saudi Arabia, Email: nalonizan@ksu.edu.sa) : Stark broadening parameters for neutral oxygen spectral lines. J Astrophys Astr 2015, 36(4), 661-9.

Stark broadening parameters for nine neutral oxygen (O I) lines have been determined within the impact approximation and the semiclassical perturbation method. The atomic data have been taken from the TOPbase and NIST atomic databases. The electron and proton Stark widths and shifts and ion broadening parameter values for these O I lines have been calculated for electron density of 10¹⁶ cm^-3 and for 4 different electron temperatures in the range of 5000 K to 40000 K. These Stark broadening parameters are compared with our previous results (Ben Nessib, N. et al. 1996, Physica Scripta, 54, 603-613), where we calcu lated Stark broadening parameters for only four O I spectral lines and where Stark widths and shifts were compared with experimental and theoretical data available in the literature. In the present paper, we have also compared our results with the Griem's book (Griem, H. R. 1974, Spectral line broadening by plasmas) and VALD (Ryabchikova, T. et al. 2015, Physica Scripta, 90, 054005) values.

^iia3 tables, 17 ref

019151   Lasue J (NO, , Institute de Recherche en Astrophysique et Planetologie Observatoire Midi-Pyrenees, 9 Avenue Colonel Roche, Toulouse, FR) : Mars exploration today. Sci Cult 2015, 81(7-8), 167-74.

Since the beginning of the space age with the launch and success of Sputnik 1 in 1957, the exploration of our neighbouring planets has demonstrated the diversity of environments available around the Sun. More recently, the current extent of exoplanet discoveries - with more than a thousand planets confirmed by the Kepler mission in January 2015 - has lead us to a better understanding of how the planetary systems and planets within them are formed. It also made us realise that other habitable worlds may be quite common. But as we tackle the complexity of our own planet, a definite answer to the questions of how early Earth originated and evolved to support life requires a deeper understanding of the solar system as a whole, and more specifically how Mars evolved so differently. Whether Mars harbours life or did in the past remains the most important driver of Mars exploration.

8 illus, 1 table, 6 ref

018162   Singh T P (NO, Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai-400 005, Email: tpsingh@tifr.res.in) : General relativity, torsion and quantum theory. Curr Sci 2015, 109(12), 2258-64.

Recall some of the obstacles which arise when one tries to reconcile the general theory of relativity with quantum theory. We consider the possibility that gra- vitation theories which include torsion, and not only curvature, provide better insight into a quantum theory of gravity. We speculate on how the Dirac equation and Einstein gravity could be thought of as limiting cases of a gravitation theory which possesses torsion.

14 ref

018161   Padmanabhan T (NO, Inter-University Centre for Astronomy and Astrophysics, une University Campus, Ganeshkhind, Pune-411 007, Email: paddy@iucaa,ernet.in) : Gravity is thermodynamics. Curr Sci 2015, 109(12), 2236-42.

The equations of motion describing all physical systems, excluding gravity, remain invariant if a con- stant is added to the Lagrangian. In the conventional approach, gravitational theories break this symmetry exhibited by all other physical systems. Restoring this symmetry to gravity and demanding that gravitational field equations should also remain invariant under the addition of a constant to a Lagrangian, leads to the in- terpretation of gravity as the thermodynamic limit of the kinetic theory of atoms of space. This approach selects, in a very natural fashion, Einstein's general relativity in d = 4. Developing this paradigm at a dee- per level, one can obtain the distribution function for the atoms of space and connect it up with the thermo- dynamic description of spacetime. This extension relies on a curious fact that the quantum spacetime endows each event with a finite area but zero volume. This approach allows us determine the numerical value of the cosmological constant and suggests a new perspective on cosmology.

22 ref