Advances in Astronomy The latest articles from Hindawi Publishing Corporation © 2016 , Hindawi Publishing Corporation . All rights reserved. A Hydrodynamical Model of a Rotating Wind Source and Its Effects on the Collapse of a Rotating Core Sun, 27 Dec 2015 11:54:16 +0000 This work presents three-dimensional hydrodynamical simulations with the fully parallel GAGDET2 code, to model a rotating source that emits wind in order to study the subsequent dynamics of the wind in three independent scenarios. In the first scenario we consider several models of the wind source, which is characterized by a rotation velocity and an escape velocity , so that the models have a radially outward wind velocity magnitude given by 1, 2, 4, 6, and 8 times . In the second scenario, we study the interaction of winds emitted from a binary system in two kinds of models: one in which the source remains during the wind emission and a second one in which all the source itself becomes wind. In the third scenario we consider the interaction of a rotating source that emits wind within a collapsing and rotating core. In this scenario we consider only wind models of the second kind built over a new initial radial mesh, such that the angular velocity of the wind is 1, 100, and 1000 times the angular velocity of the core . Guillermo Arreaga-Garcia Copyright © 2015 Guillermo Arreaga-Garcia. All rights reserved. The Impact of KLT Coder on the Image Distortion in Astronomy Tue, 24 Nov 2015 09:27:49 +0000 Presented paper is devoted to the application of Karhunen-Loève transform (KLT) for compression and to study of KLT impact on the image distortion in astronomy. This transform is an optimal fit for images with Gaussian probability density function in order to minimize the root mean square error (RMSE). The main part of the encoder is proposed in relation to statistical image properties. Selected astronomical image processing algorithms are used for the encoder testing. The astrometry and point spread function distortion are selected as the most important criteria. The results are compared with JPEG2000 standard. The KLT encoder provides better results from the RMSE point of view. These results are promising and show the novel approach to the design of lossy image compression algorithms and also suitability for algorithms of image data structuring for retrieving, transfer, and distribution. Petr Pata Copyright © 2015 Petr Pata. All rights reserved. Parameterizing the SFC Baryogenesis Model Tue, 15 Sep 2015 10:40:06 +0000 We have numerically explored the scalar field condensate baryogenesis model for numerous sets of model’s parameters, within their natural range of values. We have investigated the evolution of the baryon charge carrying field, the evolution of the baryon charge contained in the scalar field condensate, and the final value of the generated baryon charge on the model’s parameters: the gauge coupling constant , the Hubble constant at the inflationary stage , the mass , and the self-coupling constants . Daniela Kirilova and Mariana Panayotova Copyright © 2015 Daniela Kirilova and Mariana Panayotova. All rights reserved. Corrigendum to “Regions of Central Configurations in a Symmetric 4 + 1-Body Problem” Sun, 13 Sep 2015 13:52:55 +0000 Muhammad Shoaib Copyright © 2015 Muhammad Shoaib. All rights reserved. The Appearance and Disappearance of Exocomet Gas Absorption Sun, 13 Sep 2015 09:02:13 +0000 CaII K-line (3933 Å) absorption profiles observed towards 15 A-type and two B-type stars with known (or suspected) debris disks, in addition to archival spectral data for three A-type stars, are presented. Inspection of the extracted CaII K-line absorption lines has determined that one late B-type (HD 58647) and four new A-type (HD 56537, HD 64145, HD 108767, and HD 109573) stellar systems exhibit short-term (night-to-night) absorption variation within these profiles. This variability is due to the liberation of gas from falling evaporating bodies (the so-called FEBs activity) on the grazing approach of exocomets towards their parent star. Also we present archival spectra of the FeI λ3860 Å and CaII K-lines towards β Pictoris (HD 39060) that, for the first time, reveal the absorption signatures of FEB activity at similar velocities in both line profiles. FEB-hosting stars seem to be of an earlier type (on average spectral type Al.8 as compared with A3.1) than those where no FEB activity has been observed. This could be due to stellar activity levels (such as chromospheric activity or nonradial pulsations) being of a higher level within the atmospheres of these hotter A-type stars. Barry Y. Welsh and Sharon L. Montgomery Copyright © 2015 Barry Y. Welsh and Sharon L. Montgomery. All rights reserved. Cosmic Rays Report from the Structure of Space Sun, 06 Sep 2015 13:57:49 +0000 Spectrum of cosmic rays follows a broken power law over twelve orders of magnitude. Since ubiquitous power laws are manifestations of the principle of least action, we interpret the spectrum accordingly. Our analysis complies with understanding that low-energy particles originate mostly from rapidly receding sources throughout the cosmos. The flux peaks about proton rest energy whereafter it decreases because fewer and fewer receding sources are energetic enough to provide particles with high enough velocities to compensate for the recessional velocities. Above 1015.6 eV the flux from the expanding Universe diminishes below the flux from the nearby nonexpanding part of the Universe. In this spectral feature, known as the “knee,” we relate to a distance of about 1.3 Mpc where the gravitational potential tallies the energy density of free space. At higher energies particles decelerate in a dissipative manner to attain thermodynamic balance with the vacuum. At about 1017.2 eV a distinct dissipative mechanism opens up for protons to slow down by electron-positron pair production. At about 1019.6 eV a more effective mechanism opens up via pion production. All in all, the universal principle discloses that the broad spectrum of cosmic rays probes the structure of space from cosmic distances down to microscopic details. A. Annila Copyright © 2015 A. Annila. All rights reserved. An Improved Infrared/Visible Fusion for Astronomical Images Wed, 26 Aug 2015 09:34:34 +0000 An undecimated dual tree complex wavelet transform (UDTCWT) based fusion scheme for astronomical visible/IR images is developed. The UDTCWT reduces noise effects and improves object classification due to its inherited shift invariance property. Local standard deviation and distance transforms are used to extract useful information (especially small objects). Simulation results compared with the state-of-the-art fusion techniques illustrate the superiority of proposed scheme in terms of accuracy for most of the cases. Attiq Ahmad, Muhammad Mohsin Riaz, Abdul Ghafoor, and Tahir Zaidi Copyright © 2015 Attiq Ahmad et al. All rights reserved. On the Stability of in the Relativistic R3BP with Oblate Secondary and Radiating Primary Tue, 25 Aug 2015 10:00:47 +0000 We consider a version of the relativistic restricted three-body problem (R3BP) which includes the effects of oblateness of the secondary and radiation of the primary. We determine the positions and analyze the stability of the triangular points. We find that these positions are affected by relativistic, oblateness, and radiation factors. It is also seen that both oblateness of the secondary and radiation of the primary reduce the size of stability region. Further, a numerical exploration computing the positions of the triangular points and the critical mass ratio of some binaries systems consisting of the Sun and its planets is given in the tables. Nakone Bello and Jagadish Singh Copyright © 2015 Nakone Bello and Jagadish Singh. All rights reserved. Nonlinear Stability of the Triangular Libration Points for Radiating and Oblate Primaries in CR3BP in Nonresonance Condition Mon, 24 Aug 2015 11:48:21 +0000 This paper investigates the existence of resonance and nonlinear stability of the triangular equilibrium points when both oblate primaries are luminous. The study is carried out near the resonance frequency, satisfying the conditions , and in circular cases by the application of Kolmogorov-Arnold-Moser (KAM) theory. The study is carried out for the various values of radiation pressure and oblateness parameters in general. It is noticed that the system experiences resonance at for different values of radiation pressures and oblateness parameter. The case corresponds to the boundary region of the stability for the system. It is found that, except for some values of the radiation pressure, and oblateness parameters and for , the triangular equilibrium points are stable. Nutan Singh and A. Narayan Copyright © 2015 Nutan Singh and A. Narayan. All rights reserved. Gamma-Ray Burst in Swift and Fermi Era Mon, 24 Aug 2015 11:16:07 +0000 WeiKang Zheng, Xuefeng Wu, Takanori Sakamoto, Yuji Urata, and Shashi B. Pandey Copyright © 2015 WeiKang Zheng et al. All rights reserved. Utilizing the Updated Gamma-Ray Bursts and Type Ia Supernovae to Constrain the Cardassian Expansion Model and Dark Energy Mon, 24 Aug 2015 09:07:22 +0000 We update gamma-ray burst (GRB) luminosity relations among certain spectral and light-curve features with 139 GRBs. The distance modulus of 82 GRBs at can be calibrated with the sample at by using the cubic spline interpolation method from the Union2.1 Type Ia supernovae (SNe Ia) set. We investigate the joint constraints on the Cardassian expansion model and dark energy with 580 Union2.1 SNe Ia sample and 82 calibrated GRBs’ data . In ΛCDM, we find that adding 82 high- GRBs to 580 SNe Ia significantly improves the constraint on plane. In the Cardassian expansion model, the best fit is and   , which is consistent with the ΛCDM cosmology in the confidence region. We also discuss two dark energy models in which the equation of state is parameterized as and , respectively. Based on our analysis, we see that our universe at higher redshift up to is consistent with the concordance model within confidence level. Jun-Jie Wei, Qing-Bo Ma, and Xue-Feng Wu Copyright © 2015 Jun-Jie Wei et al. All rights reserved. Physics of Gamma-Ray Bursts Prompt Emission Mon, 24 Aug 2015 08:47:58 +0000 In recent years, our understanding of gamma-ray bursts (GRB) prompt emission has been revolutionized, due to a combination of new instruments, new analysis methods, and novel ideas. In this review, I describe the most recent observational results and current theoretical interpretation. Observationally, a major development is the rise of time resolved spectral analysis. These led to (I) identification of a distinguished high energy component, with GeV photons often seen at a delay and (II) firm evidence for the existence of a photospheric (thermal) component in a large number of bursts. These results triggered many theoretical efforts aimed at understanding the physical conditions in the inner jet regions. I highlight some areas of active theoretical research. These include (I) understanding the role played by magnetic fields in shaping the dynamics of GRB outflow and spectra; (II) understanding the microphysics of kinetic and magnetic energy transfer, namely, accelerating particle to high energies in both shock waves and magnetic reconnection layers; (III) understanding how subphotospheric energy dissipation broadens the “Planck” spectrum; and (IV) geometrical light aberration effects. I highlight some of these efforts and point towards gaps that still exist in our knowledge as well as promising directions for the future. Asaf Pe’er Copyright © 2015 Asaf Pe’er. All rights reserved. Reverse Shock Emission in Gamma-Ray Bursts Revisited Mon, 24 Aug 2015 08:42:57 +0000 A generic synchrotron external shock model is the widely preferred paradigm used to interpret the broadband afterglow data of gamma-ray bursts (GRBs), including predicted observable signatures from a reverse shock which have been confirmed by observations. Investigations of the nature of the reverse shock emission can provide valuable insights into the intrinsic properties of the GRB ejecta. Here we briefly review the standard and the extended models of the reverse shock emission, discussing the connection between the theory and observations, including the implications of the latest observational advances. He Gao and Peter Mészáros Copyright © 2015 He Gao and Peter Mészáros. All rights reserved. GRB 130603B: No Compelling Evidence for Neutron Star Merger Mon, 24 Aug 2015 08:34:59 +0000 The near infrared (NIR) flare/rebrightening in the afterglow of the short hard gamma ray burst (SHB) 130603B measured with the Hubble Space Telescope (HST) and an alleged late-time X-ray excess were interpreted as possible evidence of a neutron star merger origin of SHBs. However, the X-ray afterglow that was measured with the Swift XRT and Newton XMM has the canonical behaviour of a synchrotron afterglow produced by a highly relativistic jet. The H-band flux observed with HST 9.41 days after burst is that expected from the measured late-time X-ray afterglow. The late-time flare/rebrightening of the NIR-optical afterglow of SHB 130603B could have been produced also by jet collision with an interstellar density bump. Moreover, SHB plus a kilonova can be produced also by the collapse of a compact star (neutron star, strange star, or quark star) to a more compact object due to cooling, loss of angular momentum, or mass accretion. Shlomo Dado and Arnon Dar Copyright © 2015 Shlomo Dado and Arnon Dar. All rights reserved. Systematic Spectral Lag Analysis of Swift Known- GRBs Mon, 24 Aug 2015 08:33:57 +0000 The difference of photon arrival time, which is known as spectral lag, is well known characteristics of gamma-ray bursts (GRBs). In particular, long duration GRBs show a soft lag which means that high energy photons arrive earlier than soft photons. The lag-luminosity relation is the empirical relationship between the isotropic peak luminosity and the spectral lag. We calculated the spectral lags for 40 known redshift GRBs observed by Swift addition to the previous 31 GRB samples. We confirmed that most of our samples follow the lag-luminosity relation. However, we noticed that there are some GRBs which show a significant scatter from the relation. We also confirm that the relationship between the break time and the luminosity of the X-ray afterglow (so-called Dainotti relation) extends up to the lag-luminosity relation. Yuta Kawakubo, Takanori Sakamoto, Atsumasa Yoshida, and Demos Kazanas Copyright © 2015 Yuta Kawakubo et al. All rights reserved. A New Era of Submillimeter GRB Afterglow Follow-Ups with the Greenland Telescope Mon, 24 Aug 2015 08:30:49 +0000 Planned rapid submillimeter (submm) gamma-ray-bursts (GRBs) follow-up observations conducted using the Greenland Telescope (GLT) are presented. The GLT is a 12-m submm telescope to be located at the top of the Greenland ice sheet, where the high altitude and dry weather porvide excellent conditions for observations at submm wavelengths. With its combination of wavelength window and rapid responding system, the GLT will explore new insights on GRBs. Summarizing the current achievements of submm GRB follow-ups, we identify the following three scientific goals regarding GRBs: (1) systematic detection of bright submm emissions originating from reverse shock (RS) in the early afterglow phase, (2) characterization of forward shock and RS emissions by capturing their peak flux and frequencies and performing continuous monitoring, and (3) detections of GRBs at a high redshift as a result of the explosion of first generation stars through systematic rapid follow-ups. The light curves and spectra calculated by available theoretical models clearly show that the GLT could play a crucial role in these studies. Yuji Urata, Kuiyun Huang, Keiichi Asada, Hiroyuki Hirashita, Makoto Inoue, and Paul T. P. Ho Copyright © 2015 Yuji Urata et al. All rights reserved. Gamma-Ray Bursts as Multienergy Neutrino Sources Mon, 24 Aug 2015 08:10:58 +0000 We review theoretical models for nonelectromagnetic emission, mainly neutrinos and cosmic rays, from gamma-ray bursts (GRBs). In various stages of the relativistic jet propagation, cosmic-ray ion acceleration and subsequent neutrino emission are expected. GRBs are popular candidate sources of the highest-energy cosmic rays, and their prompt phase has been most widely discussed. IceCube nondetection of PeV neutrinos coincident with GRBs has put interesting constraints on the standard theoretical prediction. The GRB-UHECR hypothesis can critically be tested by future observations. We also emphasize the importance of searches for GeV-TeV neutrinos, which are expected in the precursor/orphan or prompt phase, and lower-energy neutrinos would be more guaranteed and their detections even allow us to probe physics inside a progenitor star. Not only classical GRBs but also low-power GRBs and transrelativistic supernovae can be promising sources of TeV-PeV neutrinos, and we briefly discuss implications for the cumulative neutrino background discovered by IceCube. Katsuaki Asano and Kohta Murase Copyright © 2015 Katsuaki Asano and Kohta Murase. All rights reserved. Estimating Finite Source Effects in Microlensing Events due to Free-Floating Planets with the Euclid Survey Thu, 20 Aug 2015 16:12:59 +0000 In recent years free-floating planets (FFPs) have drawn a great interest among astrophysicists. Gravitational microlensing is a unique and exclusive method for their investigation which may allow obtaining precious information about their mass and spatial distribution. The planned Euclid space-based observatory will be able to detect a substantial number of microlensing events caused by FFPs towards the Galactic bulge. Making use of a synthetic population algorithm, we investigate the possibility of detecting finite source effects in simulated microlensing events due to FFPs. We find a significant efficiency for finite source effect detection that turns out to be between 20% and 40% for a FFP power law mass function index in the range [0.9, 1.6]. For many of such events it will also be possible to measure the angular Einstein radius and therefore constrain the lens physical parameters. These kinds of observations will also offer a unique possibility to investigate the photosphere and atmosphere of Galactic bulge stars. Lindita Hamolli, Mimoza Hafizi, Francesco De Paolis, and Achille A. Nucita Copyright © 2015 Lindita Hamolli et al. All rights reserved. Astronomy and Climate-Earth System: Can Magma Motion under Sun-Moon Gravitation Contribute to Paleoclimatic Variations and Earth’s Heat? Thu, 13 Aug 2015 12:12:05 +0000 Paleoclimate data have yielded variations with periods of ~23, ~40, and ~100 ky. Thermodynamic changes resulting from orbital eccentricity, obliquity, and precession have been ascribed as the cause of the variations although processes within the oceans and atmosphere may have too short memory to explain such variations. In this work, the dynamics of Sun-Moon gravitation (SMG) were explored for a rotating Earth and were determined to have a long memory in magma, a mostly ignored geophysical fluid with a mass ~3,400 times that of the atmosphere plus the oceans. Using the basic motion and gravitation (including obliquity) of the Sun and the Moon, we determined that SMG-induced magma motion could produce paleoclimatic variations with multiple periods (e.g., ~23, ~40, ~80, and ~100 ky), with considerable power for Earth’s heat. Such “reproducible” power could possibly maintain an energetic Earth against collapse, radioactivity, and cooling. Zhiren Joseph Wang and Xiaopei Lin Copyright © 2015 Zhiren Joseph Wang and Xiaopei Lin. All rights reserved. TEC Data Forecasting Using a Novel Nonlinear Model Wed, 29 Jul 2015 09:09:50 +0000 A novel nonlinear TEC forecasting model is proposed in the paper; the main produces of the model are as follows: first the EOF decomposition of TEC data is made, then the genetic algorithm is used to establish the nonlinear time field model, and finally the decomposed space field and the predicted time field are reconstructed to achieve the purpose of forecasting the TEC data. Experiments indicate that the performance of the novel forecasting model is effective and superior to the direct forecasting and linear forecasting models. Jun Wang, Bihua Zhou, and Shudao Zhou Copyright © 2015 Jun Wang et al. All rights reserved. UGC 7639: A Dwarf Galaxy in the Canes Venatici I Cloud Tue, 28 Jul 2015 13:27:36 +0000 We want to get insight into the formation mechanism and the evolution of UGC 7639, a dwarf galaxy in the Canes Venatici I Cloud (CVnIC). We used archival multiwavelength data to constrain its global properties. Ultraviolet images show that UGC 7639 inner regions are composed mostly by young stellar populations. In addition, we used smoothed particle hydrodynamics simulations with chemophotometric implementation to account for its formation and evolution. UGC 7639 is an example of blue dwarf galaxy whose global properties are well matched by our multiwavelength approach, that is, a suitable approach to highlight the evolution also of these galaxies as a class. We found that the global properties of UGC 7639, namely, its total absolute B-band magnitude, its whole spectral energy distribution, and morphology, are well matched by an encounter with a system four times more massive than our target. Moreover, the current star formation rate of the simulated dwarf, ≈0.03 M⊙ yr−1, is in good agreement with our UV-based estimate. We derived a galaxy age of 8.6 Gyr. Following our simulation, the ongoing star formation will extinguish within 1.6 Gyr, thus leaving a red dwarf galaxy. L. M. Buson, D. Bettoni, P. Mazzei, and G. Galletta Copyright © 2015 L. M. Buson et al. All rights reserved. Coronal Holes in Global Complexes of Activity Wed, 22 Jul 2015 10:48:14 +0000 We propose a new concept that considers the global complexes of activity as a combination of global and local fields. Traditionally, the complexes of activity have been identified from observations of active regions (ARs). Here, we show that a complex of activity comprises both (AR) and coronal holes (CHs). Our analysis is based on observations of magnetic fields of various scales, SOHO/MDI data, and UV observations of CH. The analysis has corroborated the existence of complexes of activity that involve AR and equatorial CH. Both AR and CH are embedded in an extended magnetic region dominated by the magnetic field of one sign, but not strictly unipolar. It is shown that the evolution of CH and AR is a single process. The relationship between the fields of various scales in the course of a cycle is discussed. Vladimir N. Obridko and Bertha D. Shelting Copyright © 2015 Vladimir N. Obridko and Bertha D. Shelting. All rights reserved. Equilibrium Points and Related Periodic Motions in the Restricted Three-Body Problem with Angular Velocity and Radiation Effects Mon, 06 Jul 2015 09:35:33 +0000 The paper deals with a modification of the restricted three-body problem in which the angular velocity variation is considered in the case where the primaries are sources of radiation. In particular, the existence and stability of its equilibrium points in the plane of motion of the primaries are studied. We find that this problem admits the well-known five planar equilibria of the classical problem with the difference that the corresponding collinear points may be stable depending on the parameters of the problem. For all planar equilibria, sufficient parametric conditions for their stability have been established which are used for the numerical determination of the stability regions in various parametric planes. Also, for certain values of the parameters of the problem for which the equilibrium points are stable, the short and long period families have been computed. To do so, semianalytical expressions have been found for the determination of appropriate initial conditions. Special attention has been given to the continuation of the long period family, in the case of the classical restricted three-body problem, where we show numerically that periodic orbits of the short period family, which are bifurcation points with the long period family, are connected through the characteristic curve of the long period family. E. A. Perdios, V. S. Kalantonis, A. E. Perdiou, and A. A. Nikaki Copyright © 2015 E. A. Perdios et al. All rights reserved. Stability of the Moons Orbits in Solar System in the Restricted Three-Body Problem Sun, 28 Jun 2015 11:31:02 +0000 We consider the equations of motion of three-body problem in a Lagrange form (which means a consideration of relative motions of 3 bodies in regard to each other). Analyzing such a system of equations, we consider in detail the case of moon’s motion of negligible mass around the 2nd of two giant-bodies , (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. Under assumptions of R3BP, we obtain the equations of motion which describe the relative mutual motion of the centre of mass of 2nd giant-body (planet) and the centre of mass of 3rd body (moon) with additional effective mass placed in that centre of mass , where ξ is the dimensionless dynamical parameter. They should be rotating around their common centre of masses on Kepler’s elliptic orbits. For negligible effective mass it gives the equations of motion which should describe a quasi-elliptic orbit of 3rd body (moon) around the 2nd body (planet) for most of the moons of the planets in Solar System. Sergey V. Ershkov Copyright © 2015 Sergey V. Ershkov. All rights reserved. Influence of the Atmospheric Mass on the High Energy Cosmic Ray Muons during a Solar Cycle Wed, 27 May 2015 10:13:59 +0000 The rate of the detected cosmic ray muons depends on the atmospheric mass, height of pion production level, and temperature. Corrections for the changes in these parameters are importance to know the properties of the primary cosmic rays. In this paper, the effect of atmospheric mass, represented here by the atmospheric pressure, on the cosmic ray was studied using data from the KACST muon detector during the 2002–2012 period. The analysis was conducted by calculating the barometric coefficient () using regression analysis between the two parameters. The variation of over different time scales was investigated. The results revealed a seasonal cycle of with a maximum in September and a minimum in March. Data from Adelaide muon detector were used, and different monthly variation was found. The barometric coefficient displays considerable variability at the interannual scale. Study of the annual variations of indicated cyclic variation with maximums between 2008 and 2009 and minimums between 2002 and 2003. This variable tendency is found to be anticorrelated with the solar activity, represented by the sunspot number. This finding was compared with the annual trend of for the Adelaide muon detector for the same period of time, and a similar trend was found. A. H. Maghrabi, R. N. Alotaibi, M. M. Almutayri, and M. S. Garawi Copyright © 2015 A. H. Maghrabi et al. All rights reserved. Hydrodynamic Modeling of the Interaction of Winds within a Collapsing Turbulent Gas Cloud Wed, 20 May 2015 06:38:28 +0000 By using the particle-based code Gadget2, we follow the evolution of a gas giant molecular cloud, in which a set of gas particles representing the wind are created by a Monte Carlo scheme and suddenly move outwards from the cloud’s center. The particles representing the gas cloud initially have a velocity according to a turbulent spectrum built in a Fourier space of 643 grid elements. The level of turbulence and the temperature of the cloud are both adjusted so that a gravitational collapse of the cloud is initially induced. All the winds are activated in a very early stage of evolution of the cloud. We consider only two kinds of winds, namely, one with spherical symmetry and the second one of a bipolar collimated jet. In order to assess the dynamical change in the cloud due to interactions with the winds, we show isovelocity and isodensity plots for all our simulations. We also report on the accretion centers detected at the last simulation time available for each model. Guillermo Arreaga-García and Julio Saucedo-Morales Copyright © 2015 Guillermo Arreaga-García and Julio Saucedo-Morales. All rights reserved. Regions of Central Configurations in a Symmetric 4 + 1-Body Problem Thu, 05 Mar 2015 11:55:42 +0000 The inverse problem of central configuration of the trapezoidal 5-body problems is investigated. In this 5-body setup, one of the masses is chosen to be stationary at the center of mass of the system and four-point masses are placed on the vertices of an isosceles trapezoid with two equal masses at positions and at positions . The regions of central configurations where it is possible to choose positive masses are derived both analytically and numerically. It is also shown that in the complement of these regions no central configurations are possible. Muhammad Shoaib Copyright © 2015 Muhammad Shoaib. All rights reserved. Evaluation of the Effective Temperature of Sunspots Using Molecular Parameters of AlF Thu, 29 Jan 2015 07:27:10 +0000 The physical conditions of celestial objects can be analyzed using the spectrum of atoms or molecules present in the object. The present work focuses on the spectroscopic analysis of astrophysically significant molecule AlF. The evaluation of Franck-Condon (FC) factors and -centroids is done by a numerical integration procedure using the suitable potential energy curves for , , , and band systems of AlF molecule. The intensity of various bands is discussed with the help of derived FC factors. The band degradation and the nature of potential energy curves are studied using -centroid values. The vibrational temperature of sunspot is estimated to be around 1220 ± 130 K which falls in the reported temperature range of cold sunspots. K. Balachandrakumar, V. Raja, B. Karthikeyan, S. P. Bagare, and N. Rajamanickam Copyright © 2015 K. Balachandrakumar et al. All rights reserved. Variations in EUV Irradiance: Comparison between LYRA, ESP, and SWAP Integrated Flux Mon, 09 Jun 2014 06:53:15 +0000 The Sun Watcher Using Active Pixel System Detector and Image Processing (SWAP) telescope and Large Yield Radiometer (LYRA) are the two Sun observation instruments on-board PROBA2. SWAP extreme ultraviolet images, if presented in terms of the integrated flux over solar disk, in general, correlate well with LYRA channel 2–4 (zirconium filter) and channels QD and 18 of EVE/ESP on-board SDO between 2010 and 2013. Hence, SWAP can be considered as an additional radiometric channel. We compare in detail LYRA channel 2–4 and SWAP integrated flux in July 2010 and in particular during the solar eclipse that occurred on July 11, 2010. During this eclipse, the discrepancy between the two data channels can be explained to be related to the occultation of active region 11087 by the Moon. In the second half of July 2010, LYRA channel 2–4 and SWAP integrated flux deviate from each other, but these differences can also be explained in terms of features appearing on the solar disk such as coronal holes and active regions. By additionally comparing with timeline of EVE/ESP, we can preliminarily interpret these differences in terms of the difference between the broad bandpass of LYRA channel 2–4 and the, relatively speaking, narrower bandpass of SWAP. Mehmet Sarp Yalim and Stefaan Poedts Copyright © 2014 Mehmet Sarp Yalim and Stefaan Poedts. All rights reserved. Metals in 3D: A Cosmic View from Integral Field Spectroscopy Wed, 21 May 2014 06:28:35 +0000 Jorge Iglesias-Páramo Copyright © 2014 Jorge Iglesias-Páramo. All rights reserved.