Advances in Astronomy The latest articles from Hindawi Publishing Corporation © 2015 , Hindawi Publishing Corporation . 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. Chemical and Photometric Evolution Models for Disk, Irregular, and Low Mass Galaxies Tue, 20 May 2014 08:47:28 +0000 We summarize the updated set of multiphase chemical evolution models performed with 44 theoretical radial mass initial distributions and 10 possible values of efficiencies to form molecular clouds and stars. We present the results about the infall rate histories, the formation of the disk, and the evolution of the radial distributions of diffuse and molecular gas surface density, stellar profile, star formation rate surface density, and elemental abundances of C, N, O, and Fe, finding that the radial gradients for these elements begin steeper and flatten with increasing time or decreasing redshift, although the outer disks always show a certain flattening for all times. With the resulting star formation and enrichment histories, we calculate the spectral energy distributions (SEDs) for each radial region by using the ones for single stellar populations resulting from the evolutive synthesis model POPSTAR. With these SEDs we may compute finally the broad band magnitudes and colors radial distributions in the Johnson and in the SLOAN/SDSS systems which are the main result of this work. We present the evolution of these brightness and color profiles with the redshift. Mercedes Mollá Copyright © 2014 Mercedes Mollá. All rights reserved. Existence of Resonance Stability of Triangular Equilibrium Points in Circular Case of the Planar Elliptical Restricted Three-Body Problem under the Oblate and Radiating Primaries around the Binary System Thu, 15 May 2014 09:49:09 +0000 This paper analyzes the existence of resonance stability of the triangular equilibrium points of the planar elliptical restricted three-body problem when both the primaries are oblate spheroid as well as the source of radiation under the particular case, when . We have derived Hamiltonian function describing the motion of infinitesimal mass in the neighborhood of the triangular equilibrium solutions taken as a convergent series. Hamiltonian function for the system has been derived and also expanded in powers of the generalized components of momenta. We have used canonical transformation to make the Hamiltonian function independent of true anomaly. The most interesting and distinguishable results of this study are establishing the relation for determining the range of stability at and near the resonance around the binary system. A. Narayan and Amit Shrivastava Copyright © 2014 A. Narayan and Amit Shrivastava. All rights reserved. Damping of Linear Nonadiabatic MHD Waves in a Flowing Prominence Medium Thu, 15 May 2014 06:56:58 +0000 We study the effect of shear flow on the time damping of linear nonadiabatic magnetoacoustic waves in a solar prominence. We consider a homogeneous, isothermal, and unbounded medium permeated by a uniform magnetic field. The adiabaticity is removed by including the optically thin radiative losses, thermal conduction, and heating term in energy equation. We present a local theory of MHD waves to obtain a dispersion relation. The dispersion relation is solved numerically to study the time damping of these waves. It is found that flow influences the damping time and damping per period of both the slow and fast waves significantly. Damping time and damping per period of slow waves are very much higher than the damping time and damping per period of fast waves. Nagendra Kumar, Anil Kumar, Himanshu Sikka, and Pradeep Kumar Copyright © 2014 Nagendra Kumar et al. All rights reserved. Dusty Blue Supergiants: News from High-Angular Resolution Observations Sun, 04 May 2014 12:09:12 +0000 An overview is presented of the recent advances in understanding the B[e] phenomenon among blue supergiant stars in light of high-angular resolution observations and with an emphasis on the results obtained by means of long baseline optical stellar interferometry. The focus of the review is on the circumstellar material and evolutionary phase of B[e] supergiants, but recent results on dust production in regular blue supergiants are also highlighted. W. J. de Wit, R. D. Oudmaijer, and J. S. Vink Copyright © 2014 W. J. de Wit et al. All rights reserved. Imaging FTS: A Different Approach to Integral Field Spectroscopy Tue, 22 Apr 2014 11:17:44 +0000 Imaging Fourier transform spectroscopy (iFTS) is a promising, although technically very challenging, option for wide-field hyperspectral imagery. We present in this paper an introduction to the iFTS concept and its advantages and drawbacks, as well as examples of data obtained with a prototype iFTS, SpIOMM, attached to the 1.6 m telescope of the Observatoire du Mont-Mégantic: emission line ratios in the spiral galaxy NGC 628 and absorption line indices in the giant elliptical M87. We conclude by introducing SpIOMM's successor, SITELLE, which will be installed at the Canada-France-Hawaii Telescope in 2014. Laurent Drissen, Laurie Rousseau-Nepton, Sébastien Lavoie, Carmelle Robert, Thomas Martin, Pierre Martin, Julie Mandar, and Frédéric Grandmont Copyright © 2014 Laurent Drissen et al. All rights reserved. First Radio Astronomy Examination of the Low-Frequency Broadband Active Antenna Subarray Tue, 08 Apr 2014 09:57:12 +0000 We present the 25-element active antenna array and its remote control in the framework of the GURT project, the Ukrainian Radio Telescope of a new age. To implement beamforming, the array is phased with the help of discrete cable delay lines in analog manner. The remote control of the array is carried out through the paired encoder and decoder that can transmit parallel data about antenna codes serially. The microcontroller provides the online interaction between personal computer and beamformers with the help of the encoder-decoder system through wires or wireless. The antenna pattern has been measured by radio astronomy methods. A. A. Stanislavsky, I. N. Bubnov, A. A. Konovalenko, A. A. Gridin, V. V. Shevchenko, L. A. Stanislavsky, D. V. Mukha, and A. A. Koval Copyright © 2014 A. A. Stanislavsky et al. All rights reserved. Confirmation of the Luminous Blue Variable Status of MWC 930 Sun, 23 Mar 2014 08:12:19 +0000 We present spectroscopic and photometric observations of the emission-line star MWC 930 (V446 Sct) during its long-term optical brightening in 2006–2013. Based on our earlier data we suggested that the object has features found in Luminous Blue Variables (LBV), such as a high luminosity (~3 105 ), a low wind terminal velocity (~140 km s−1), and a tendency to show strong brightness variations (1 mag over 20 years). For the last 7 years it has been exhibiting a continuous optical and near-IR brightening along with a change of the emission-line spectrum appearance and cooling of the star’s photosphere. We present the object’s -band light curve, analyze the spectral variations, and compare the observed properties with those of other recognized Galactic LBVs, such as AG Car and HR Car. Overall we conclude the MWC 930 is a bona fide Galactic LBV that is currently in the middle of an S Dor cycle. A. S. Miroshnichenko, N. Manset, S. V. Zharikov, J. Zsargó, J. A. Juárez Jiménez, J. H. Groh, H. Levato, M. Grosso, R. J. Rudy, E. A. Laag, K. B. Crawford, R. C. Puetter, D. E. Reichart, K. M. Ivarsen, J. B. Haislip, M. C. Nysewander, and A. P. LaCluyze Copyright © 2014 A. S. Miroshnichenko et al. All rights reserved. Possibility of Detection of Exomoons with Inclined Orbits Orbiting Pulsar Planets Using the Time-of-Arrival Analysis Tue, 25 Feb 2014 12:05:20 +0000 The perturbation caused by planet-moon binarity on the time-of-arrival (TOA) signal of a pulsar with an orbiting planet is derived for the case of the orbit of the planet-moon system inclined of an angle with respect to the plane of the orbit of the planet-moon barycenter around the pulsar. We also consider both the orbits of the moon and the planet-moon barycenter as circular. The signal consists of three sinusoids with frequency, respectively, of , , and , where and are, respectively, the mean motions of the planet and moon around their barycenter and the planet-moon system around the host, respectively. The amplitude of the signal is equal to the fraction of the system crossing time , where and are, respectively, the mass of the planet and the mass of the moon, is their orbital separation, is the distance between the host pulsar and planet-moon barycenter, is the inclination of the orbital plane of the planet, and is the speed of light. Antonio Pasqua and Khudhair A. Assaf Copyright © 2014 Antonio Pasqua and Khudhair A. Assaf. All rights reserved. The Integral Field View of the Orion Nebula Sun, 23 Feb 2014 00:00:00 +0000 This paper reviews the major advances achieved in the Orion Nebula through the use of integral field spectroscopy (IFS). Since the early work of Vasconcelos and collaborators in 2005, this technique has facilitated the investigation of global properties of the nebula and its morphology, providing new clues to better constrain its 3D structure. IFS has led to the discovery of shock-heated zones at the leading working surfaces of prominent Herbig-Haro objects as well as the first attempt to determine the chemical composition of Orion protoplanetary disks, also known as proplyds. The analysis of these morphologies using IFS has given us new insights into the abundance discrepancy problem, a long-standing and unresolved issue that casts doubt on the reliability of current methods used for the determination of metallicities in the universe from the analysis of H II regions. Results imply that high-density clumps and high-velocity flows may play an active role in the production of such discrepancies. Future investigations based on the large-scale IFS mosaic of Orion will be very valuable for exploring how the integrated effect of small-scale structures may have impact at larger scales in the framework of star-forming regions. Adal Mesa-Delgado Copyright © 2014 Adal Mesa-Delgado. All rights reserved. Chemodynamical Simulations of Dwarf Galaxy Evolution Mon, 17 Feb 2014 09:43:28 +0000 In this review I give a summary of the state of the art for what concerns the chemo-dynamical numerical modelling of galaxies in general and of dwarf galaxies in particular. In particular, I focus my attention on (i) initial conditions, (ii) the equations to solve; (iii) the star formation process in galaxies, (iv) the initial mass function, (v) the chemical feedback, (vi) the mechanical feedback, (vii) the environmental effects. Moreover, some key results concerning the development of galactic winds in galaxies and the fate of heavy elements, freshly synthesised after an episode of star formation, have been reported. At the end of this review, I summarise the topics and physical processes, relevant to the evolution of galaxies, that in my opinion are not properly treated in modern computer simulations of galaxies and that deserve more attention in the future. Simone Recchi Copyright © 2014 Simone Recchi. All rights reserved. Probable Value for the Next Sunspot Minimum Wed, 05 Feb 2014 13:53:08 +0000 Gumbel’s first distribution is applied to smoothed monthly mean sunspot numbers for solar cycles 10 to 24. According to that, the next minimum for solar cycle 24-25 transition would be the deepest solar minimum of the last 150 years. This study provides an additional insight about changes in the Sun which are currently happening. Virginia Mabel Silbergleit Copyright © 2014 Virginia Mabel Silbergleit. All rights reserved. Observing and Reducing IFUs: INTEGRAL and PMAS—Properties of the Ionized Gas in HH 202 Wed, 05 Feb 2014 09:32:22 +0000 The reduction of integral field spectroscopy (IFS) data requires several stages and many repetitive operations to convert raw data into, typically, a large number of spectra. Instead there are several semiautomatic data reduction tools and here we present this data reduction process using some of the Image Reduction and Analysis Facility (IRAF) tasks devoted to reduce spectroscopic data. After explaining the whole process, we illustrate the power of this instrumental technique with some results obtained for the object HH202 in the Orion Nebula (Mesa-Delgado et al., 2009). Luis López-Martín Copyright © 2014 Luis López-Martín. All rights reserved. HCO+ and Radio Continuum Emission from the Star Forming Region G75.78+0.34 Wed, 22 Jan 2014 16:52:38 +0000 We present 1.3 and 3.6 cm radio continuum images and a HCO+ spectrum of the massive star forming region G75.78+0.34 obtained with the Very Large Array (VLA) and with the Berkley Illinois Maryland Association (BIMA) interferometer. Three structures were detected in the continuum emission: one associated with the well-known cometary H ɪɪ region, plus two more compact structures located at 6′′ east and at 2′′ south of cometary H ɪɪ region. Using the total flux and intensity peak we estimated an electron density of ≈1.5 × 104 cm−3, an emission measure of ≈6 × 107 cm−6 pc, a mass of ionized gas of ≈3 M⊙, and a diameter of 0.05 pc for the cometary H ɪɪ region, being typical values for an ultracompact H ɪɪ region. The HCO+ emission probably originates from the molecular outflows previously observed in HCN and CO. Rogemar A. Riffel and Everton Lüdke Copyright © 2014 Rogemar A. Riffel and Everton Lüdke. All rights reserved. Properties of the HII Regions Derived Using Integral Field Spectroscopy Tue, 17 Dec 2013 16:05:31 +0000 Here we review some of our more recent results on the observed properties of HII regions using Integral Field Spectroscopy. In particular, we illustrate the use of this technique to study in detail the ionization conditions across the nebulae for galactic HII regions (focused on the Orion Nebula) and the statistical study of large samples of extragalactic HII regions. We review the reported new scaling relation between the local mass density and the oxygen abundance across the disk galaxies and the recently discovered universal gradient for oxygen abundances. We update our previous results the lack of a dependence of the Mass-Metallicity relation with the starformation rate, including new unpublished data. Finally we discuss on the relation between the ionization conditions in the nebulae and the underlying stellar population. All together our results indicate that disk galaxies present a chemical enrichment dominated by an inside-out growth scenario, with a less evident effect of radial migrations and/or outflows. Sebastian F. Sánchez Copyright © 2013 Sebastian F. Sánchez. All rights reserved. On the Effects of Viscosity on the Shock Waves for a Hydrodynamical Case—Part I: Basic Mechanism Thu, 05 Dec 2013 13:02:46 +0000 The interaction of shock waves with viscosity is one of the central problems in the supersonic regime of compressible fluid flow. In this work, numerical solutions of unmagnetised fluid equations, with the viscous stress tensor, are investigated for a one-dimensional shock wave. In the algorithm developed the viscous stress terms are expressed in terms of the relevant Reynolds number. The algorithm concentrated on the compression rate, the entropy change, pressures, and Mach number ratios across the shock wave. The behaviour of solutions is obtained for the Reynolds and Mach numbers defining the medium and shock wave in the supersonic limits. Huseyin Cavus Copyright © 2013 Huseyin Cavus. All rights reserved. Incorporation of 36Cl into Calcium-Aluminum-Rich Inclusions in the Solar Wind Implantation Model Wed, 04 Dec 2013 13:57:16 +0000 We consider the short-lived radionuclide (SLR) 36Cl in calcium-aluminum-rich inclusions (CAIs) found in primitive meteorites with the solar wind implantation model. In this model, SLRs are produced via nuclear reaction with solar energetic particles (SEPs) interacting with gaseous targets in the protosolar atmosphere in T-Tauri stars. These SLRs are captured by the solar wind and then implanted in CAI precursor materials, which have dropped from the funnel flow leading onto the protostar. This method of incorporating SLRs into solar system materials is currently active in our solar system and has been measured with SLRs from the solar wind being implanted on the lunar surface. T-Tauri stars are capable of SEP fluxes ~105 greater than contemporary SEP fluxes. Here we scale the production rate of 36Cl to the ancient SEP activity. From the enhanced production rates and the refractory mass inflow rate at 0.06 AU from the protosun, we model the ancient 36Cl content in CAIs. We find the initial isotopic ratio of 36Cl/35Cl to range from about 1 × 10−5 to 5 × 10−5 and the concentration of 36Cl to range from about 3 × 1013 to 1.5 × 1014 atoms g−1. Glynn E. Bricker and Marc W. Caffee Copyright © 2013 Glynn E. Bricker and Marc W. Caffee. All rights reserved. A Numerical Simulation of Chern-Simons Inflation Tue, 03 Dec 2013 14:05:20 +0000 We present results of numerical simulations of the Chern-Simons inflation model proposed by Alexander, Marciano, and Spergel. According to this model, inflation begins with a fermion condensate interacting with a gauge field. Crucial to the success of this mechanism is the assumption that the Chern-Simons interaction would drive energy from the initial random spectrum into a narrow band of frequencies at superhorizon scales. In this work, we numerically confirm this expectation. These gauge fields and currents, when combined with the Friedmann equations, were broken into a system of hyperbolic equations and numerically simulated. It was found in our simulation that, by including the effects of the chiral anomaly for the axial vector current, inflation can end satisfactorily after approximately 60 e-folds. David Garrison and Christopher Underwood Copyright © 2013 David Garrison and Christopher Underwood. All rights reserved. The Mitchell Spectrograph: Studying Nearby Galaxies with the VIRUS Prototype Sun, 01 Dec 2013 16:09:23 +0000 The Mitchell Spectrograph (a.k.a. VIRUS-P) on the 2.7 m Harlan J. Smith telescope at McDonald Observatory is currently the largest field of view (FOV) integral field unit (IFU) spectrograph in the world (). It was designed as a prototype for the highly replicable VIRUS spectrograph which consists of a mosaic of IFUs spread over a diameter FOV feeding 150 spectrographs similar to the Mitchell. VIRUS will be deployed on the 9.2 meter Hobby-Eberly Telescope (HET) and will be used to conduct the HET Dark Energy Experiment (HETDEX). Since seeing first light in 2007 the Mitchell Spectrograph has been widely used, among other things, to study nearby galaxies in the local universe where their internal structure and the spatial distribution of different physical parameters can be studied in great detail. These observations have provided important insight into many aspects of the physics behind the formation and evolution of galaxies and have boosted the scientific impact of the 2.7 meter telescope enormously. Here I review the contributions of the Mitchell Spectrograph to the study of nearby galaxies, from the investigation the spatial distribution of dark matter and the properties of supermassive black holes, to the studies of the process of star formation and the chemical composition of stars and gas in the ISM, which provide important information regarding the formation and evolution of these systems. I highlight the fact that wide field integral field spectrographs on small and medium size telescopes can be powerful cost effective tools to study the astrophysics of galaxies. Finally I briefly discuss the potential of HETDEX for conducting studies on nearby galaxies. The survey parameters make it complimentary and competitive to ongoing and future surveys like SAMI and MANGA. Guillermo A. Blanc Copyright © 2013 Guillermo A. Blanc. All rights reserved. Anomalous Microwave Emission: Theory, Modeling, and Observations Mon, 25 Nov 2013 11:54:00 +0000 Clive Dickinson, Roberta Paladini, and Laurent Verstraete Copyright © 2013 Clive Dickinson et al. All rights reserved. Studying the Interstellar Medium of H II/BCD Galaxies Using IFU Spectroscopy Sun, 24 Nov 2013 15:20:29 +0000 We review the results from our studies, and previous published work, on the spatially resolved physical properties of a sample of H II/BCD galaxies, as obtained mainly from integral-field unit spectroscopy with Gemini/GMOS and VLT/VIMOS. We confirm that, within observational uncertainties, our sample galaxies show nearly spatially constant chemical abundances similar to other low-mass starburst galaxies. They also show He II  4686 emission with the properties being suggestive of a mix of excitation sources and with Wolf-Rayet stars being excluded as the primary ones. Finally, in this contribution, we include a list of all H II/BCD galaxies studied thus far with integral-field unit spectroscopy. Patricio Lagos and Polychronis Papaderos Copyright © 2013 Patricio Lagos and Polychronis Papaderos. All rights reserved. The Study of Nebular Emission on Nearby Spiral Galaxies in the IFU Era Wed, 13 Nov 2013 09:00:41 +0000 A new generation of wide-field emission-line surveys based on integral field units (IFU) is allowing us to obtain spatially resolved information of the gas-phase emission in nearby late-type galaxies, based on large samples of HII regions and full two-dimensional coverage. These observations are allowing us to discover and characterise abundance differentials between galactic substructures and new scaling relations with global physical properties. Here I review some highlights of our current studies employing this technique: (1) the case study of NGC 628, the largest galaxy ever sampled with an IFU; (2) a statistical approach to the abundance gradients of spiral galaxies, which indicates a universal radial gradient for oxygen abundance; and (3) the discovery of a new scaling relation of HII regions in spiral galaxies, the local mass-metallicity relation of star-forming galaxies. The observational properties and constrains found in local galaxies using this new technique will allow us to interpret the gas-phase abundance of analogue high-z systems. Fernando Fabián Rosales-Ortega Copyright © 2013 Fernando Fabián Rosales-Ortega. All rights reserved. Are Wolf-Rayet Stars Able to Pollute the Interstellar Medium of Galaxies? Results from Integral Field Spectroscopy Thu, 10 Oct 2013 18:08:58 +0000 We investigate the spatial distribution of chemical abundances in a sample of low metallicity Wolf-Rayet (WR) galaxies selected from the SDSS. We used the integral field spectroscopy technique in the optical spectral range (3700 Å–6850 Å) with PMAS attached to the CAHA 3.5 m telescope. Our statistical analysis of the spatial distributions of O/H and N/O, as derived using the direct method or strong-line parameters consistent with it, indicates that metallicity is homogeneous in five out of the six analysed objects in scales of the order of several kpc. Only in the object WR404 is a gradient of metallicity found in the direction of the low surface brightness tail. In contrast, we found an overabundance of N/O in spatial scales of the order of hundreds of pc associated with or close to the positions of the WR stars in 4 out of the 6 galaxies. We exclude possible hydrodynamical causes, such as the metal-poor gas inflow, for this local pollution by means of the analysis of the mass-metallicity relation (MZR) and mass-nitrogen-to-oxygen relation (MNOR) for the WR galaxies catalogued in the SDSS. Enrique Pérez-Montero, Carolina Kehrig, Jarle Brinchmann, José M. Vílchez, Daniel Kunth, and Florence Durret Copyright © 2013 Enrique Pérez-Montero et al. All rights reserved. Signature of Plausible Accreting Supermassive Black Holes in Mrk 261/262 and Mrk 266 Sun, 29 Sep 2013 19:16:14 +0000 We address the neutrino radiation of plausible accreting supermassive black holes closely linking to the 5 nuclear components of galaxy samples of Mrk 261/262 and Mrk 266. We predict a time delay before neutrino emission of the same scale as the age of the Universe. The ultrahigh energy neutrinos are produced in superdense protomatter medium via simple (quark or pionic reactions) or modified URCA processes (G. Gamow was inspired to name the process URCA after the name of a casino in Rio de Janeiro). The resulting neutrino fluxes for quark reactions are ranging from to , where is the opening parameter. For pionic and modified URCA reactions, the fluxes are and , respectively. These fluxes are highly beamed along the plane of accretion disk, peaked at ultrahigh energies, and collimated in smaller opening angle . Gagik Ter-Kazarian and Lusine Sargsyan Copyright © 2013 Gagik Ter-Kazarian and Lusine Sargsyan. All rights reserved. Geometry of the Universe and Its Relation to Entropy and Information Mon, 16 Sep 2013 12:56:57 +0000 In an effort to investigate a possible relation between geometry and information, we establish a relation of the Ricci scalar in the Robertson-Walker metric of the cosmological Friedmann model to the number of information and entropy . This is with the help of a previously derived result that relates the Hubble parameter to the number of information . We find that the Ricci scalar has a dependence which is inversely proportional to the number of information and entropy . Similarly, a nonzero number of information would imply a finite Ricci scalar, and therefore space time will unfold. Finally, using the maximum number of information existing in the universe, we obtain a numerical value for the Ricci scalar to be . Ioannis Haranas and Ioannis Gkigkitzis Copyright © 2013 Ioannis Haranas and Ioannis Gkigkitzis. All rights reserved. Anomalous Microwave Emission from Star Forming Regions Tue, 30 Apr 2013 13:25:26 +0000 The evidence for microwave emission from spinning dust grains has been strengthened considerably by its detection in a number of discrete astrophysical objects associated with star formation. These detections, in combination with statistical constraints on its presence on large angular scales in the diffuse ISM, have provided strong observational confirmation of an emission mechanism still referred to as anomalous. This emission has a peaked spectrum with a maximum in the microwave band; the present review discusses the continuum radio emission mechanisms which can contribute to this region of the electromagnetic spectrum, collects published results on the prevalence of anomalous microwave emission in a variety of star formation regions, presents the overall conclusions that may be drawn from the detections so far, and discusses the prospects for future research on the anomalous microwave emission attributed to spinning dust within star forming regions. Anna M. M. Scaife Copyright © 2013 Anna M. M. Scaife. All rights reserved. Retrograde versus Prograde Models of Accreting Black Holes Tue, 16 Apr 2013 08:22:15 +0000 There is a general consensus that magnetic fields, accretion disks, and rotating black holes are instrumental in the generation of the most powerful sources of energy in the known universe. Nonetheless, because magnetized accretion onto rotating black holes involves both the complications of nonlinear magnetohydrodynamics that currently cannot fully be treated numerically, and uncertainties about the origin of magnetic fields that at present are part of the input, the space of possible solutions remains less constrained. Consequently, the literature still bears witness to the proliferation of rather different black hole engine models. But the accumulated wealth of observational data is now sufficient to meaningfully distinguish between them. It is in this light that this critical paper compares the recent retrograde framework with standard “spin paradigm” prograde models. David Garofalo Copyright © 2013 David Garofalo. All rights reserved.