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  • Statistical analysis on the current capability to predict the Ap Geomagnetic Index
    New Astron. (IF 1.058) Pub Date : 2021-01-19
    Evangelos Paouris; Maria Abunina; Anatoly Belov; Helen Mavromichalaki

    In this work, forecasting results of the daily Ap geomagnetic index by different Space Weather Prediction Centers (SWPCs) covering the time period from October 2014 up to July 2020, are considered. A three-day forecast of this index obtained from the space weather prediction centers, is analyzed. Standard forecast verification measures, descriptive statistics with correlation coefficients, and error

    更新日期:2021-01-19
  • The regression of effective temperatures in APOGEE and LAMOST
    New Astron. (IF 1.058) Pub Date : 2021-01-06
    Yang Jin-Meng; Wen Xiao-Qing; Zong min

    We use the random forest to regress the surface effective temperatures of stars in APOGEE from SDSS DR16 and LAMOST DR6. When the NUV-u, u-g, g-r, r-i, i-J, J-H, H-K, K-WISE_4_5 magnitudes are used as machine learning features, the coefficient of determination of regression are 94.91% in APOGEE and 90.46% in LAMOST. The standard deviation of the prediction and pipeline temperatures are 93.89K in APOGEE

    更新日期:2021-01-18
  • Sound Speed in Extended Chaplygin Fluid
    New Astron. (IF 1.058) Pub Date : 2021-01-15
    Behnam Pourhassan; Hoda Farahani; Sudhaker Upadhyay

    We consider an extended Chaplygin gas equation of state which is driven from D-brane action and construct a cosmological model based on this equation of state. In this regard, we compute the scale factor of the model under a certain approximation. The conservation equation of this case is a non-linear differential equation which should solve using the special conditions. We also analyze the stability

    更新日期:2021-01-16
  • The overcontact binary RZ Tauri
    New Astron. (IF 1.058) Pub Date : 2021-01-05
    Robert H. Nelson

    The first reliable radial velocity curves for RZ Tau have been obtained. Combined with new light curve (LC) data, simultaneous Roche-based light curve analyses have been carried out using the 2003 version of the Wilson-Devinney code. New values for the masses and radii have been obtained: M1 = 1.53 (4) Mʘ, M2 = 0.57 (2) Mʘ, and R1 = 1.50 (4) Rʘ, R2 = 0.99 (2) Rʘ. Although there is a multitude of spectral

    更新日期:2021-01-12
  • Testing lambert W equation of state with observational hubble parameter data
    New Astron. (IF 1.058) Pub Date : 2020-12-31
    Abdulla Al Mamon; Subhajit Saha

    In this paper, we investigate the possibility that the Universe is driven by a single dark fluid described by a Lambert W equation of state parameter, weff, which is essentially dependent on two parameters ϑ1 and ϑ2 which need to be fixed from observations. We obtain the constraints on these parameters using the latest 51 data points of H(z) measurements, spanning the redshift range 0.07≤z≤2.36. The

    更新日期:2021-01-10
  • Variable relation between string densities
    New Astron. (IF 1.058) Pub Date : 2020-12-24
    S.P. Hatkar; S.D. Katore

    In this work we have proposed a variable relation between densities of cosmic string. Bianchi type II,VIII and IX space time is explored in the context of general relativity. The field equations are solved by assuming that the shear scalar is proportional to expansion scalar. Three different cases are investigated. It is observed that strings contribute significantly in isotropy and acceleration of

    更新日期:2021-01-06
  • Kaluza-Klein FRW dark energy models in Saez-Ballester theory of gravitation
    New Astron. (IF 1.058) Pub Date : 2020-12-26
    R.L. Naidu; Y. Aditya; K. Deniel Raju; T. Vinutha; D.R.K. Reddy

    This article is concerned with the investigation of dynamical behaviour of Kaluza-Klein(KK) FRW type dark energy cosmological models in the framework of a scalar-tensor theory of gravitation formulated by Saez and Ballester (Phys. Lett. A113,467:1986). Three cosmological models, in this theory, are presented by solving the field equations using (i) hybrid expansion law given by Pradhan et al. (Ind

    更新日期:2021-01-06
  • Modeling particle acceleration and non-thermal emission in supernova remnants
    New Astron. (IF 1.058) Pub Date : 2021-01-05
    S. Orlando; M. Miceli; S. Ustamujic; A. Tutone; E. Greco; O. Petruk; F. Bocchino; G. Peres

    According to the most popular model for the origin of cosmic rays (CRs), supernova remnants (SNRs) are the site where CRs are accelerated. Observations across the electromagnetic spectrum support this picture through the detection of non-thermal emission that is compatible with being synchrotron or inverse Compton radiation from high energy electrons, or pion decay due to proton-proton interactions

    更新日期:2021-01-05
  • Particle creation and quadratic deceleration parameter in Lyra geometry
    New Astron. (IF 1.058) Pub Date : 2020-12-24
    Binaya K. Bishi; Pratik V. Lepse

    We study the cosmological model of the FRW universe along with particle creation in the framework of Lyra’s geometry. The modified Einstein’s field equations based on Lyra’s geometry are presented and the exact solutions are obtained for dust, stiff matter, vacuum energy and radiation dominated models. The exact solutions are obtained under a specific choice of the particle creation function and quadratic

    更新日期:2020-12-31
  • A study of dynamical effects in the observed second time-derivative of the spin or orbital frequencies of pulsars
    New Astron. (IF 1.058) Pub Date : 2020-12-01
    Dhruv Pathak; Manjari Bagchi

    The observed values of the time-derivatives of the spin or orbital frequency of pulsars are affected by their dynamical properties. We derive thorough analytical expressions for such dynamical contributions in terms of the Galactic coordinates, the proper motion, the pulsar distance, and the radial velocity. We find that the effects of the dynamical terms in the second-derivative of frequencies or

    更新日期:2020-12-21
  • Learning from imbalanced pulsar data by combine DCGAN and PILAE algorithm
    New Astron. (IF 1.058) Pub Date : 2020-12-13
    Mohammed A.B. Mahmoud; Ping Guo

    A pulsar is a rapidly rotating neutron star and transmits periodic oscillations of power to the earth. We introduce a novel method for pulsar candidate classification. The method contains two major steps: (1) make strong representations for pulsar candidate in the image domain by extracting deep features with the deep convolutional generative adversarial Networks (DCGAN) and (2) develop a classifier

    更新日期:2020-12-16
  • The Overcontact Binary BO Arietis
    New Astron. (IF 1.058) Pub Date : 2020-12-04
    Robert H Nelson

    New radial velocity and photometric data for BO Ari have been obtained, and Roche-based simultaneous analysis of RV and light curve data for the system has been accomplished using the 2003 version of the Wilson-Devinney code. Values for the masses and radii have been obtained: M1 = 1.34 (2) Mʘ, M2 = 0.26 (1) Mʘ, and R1 = 1.25 (2) Rʘ, R2 = 0.61 (2) Rʘ. For the luminosities the most likely values are

    更新日期:2020-12-14
  • On the Challenges of Cosmic-Ray Proton Shock Acceleration in the Intracluster Medium
    New Astron. (IF 1.058) Pub Date : 2020-12-02
    Denis Wittor

    Galaxy clusters host the largest particle accelerators in the Universe: Shock waves in the intracluster medium (ICM), a hot and ionised plasma, that accelerate particles to high energies. Radio observations pick up synchrotron emission in the ICM, proving the existence of accelerated cosmic-ray electrons. However, a sign of cosmic-ray protons, in form of γ-rays. remains undetected. This is know as

    更新日期:2020-12-07
  • The analysis of basins of convergence in the regular polygon problem of (N+1) bodies system with spheroidal primaries
    New Astron. (IF 1.058) Pub Date : 2020-10-17
    Rajiv Aggarwal; Md Sanam Suraj; Md Chand Asique; Amit Mittal

    In the present manuscript, we unveil the topology of the basins of convergence in the regular polygon problem of (N+1)-bodies in two different cases, i.e., in case-I, only the central primary creates the Manev-type quasi-homogeneous potential, and in case-II, the peripheral primaries create the Manev-type quasi-homogeneous potential. The regular polygon problem of (N+1)-bodies describes the motion

    更新日期:2020-12-05
  • Quantum gravitomagnetic clock effect in Kerr gravitational field
    New Astron. (IF 1.058) Pub Date : 2020-11-09
    Ahmed Estiak; S.B. Faruque

    We have found an approximate solution of Dirac equation using Foldy-Wouthuysen-Tani Hamiltonian of a Dirac particle in the Kerr gravitational field. We have solved the equation approximately using time-independent perturbation theory for the positive energy states. We have found frequencies by which these states oscillate. Difference of the periods of any of these two states has an identical form of

    更新日期:2020-11-22
  • Possible post-kick jets in SN 1987A
    New Astron. (IF 1.058) Pub Date : 2020-11-11
    Noam Soker

    I suggest that the recently observed hot-dust elongated structure that likely engulfs the neutron star (NS) remnant of supernova (SN) 1987A was shaped by jets that the NS launched shortly after it acquired its natal kick velocity. I take the axis of the two post-kick jets to be along the long dimension of the hot-dust elongated structure, which I term the bipolar lobe. The jittering jets explosion

    更新日期:2020-11-16
  • Jeans instability of Eddington-inspired Born-Infield gravitational systems in the context of nonextensive statistics
    New Astron. (IF 1.058) Pub Date : 2020-11-07
    Wei Hong Xiong; Wei Heng Yang; Xiao Chang Chen; Ke Rong He; San Qiu Liu

    Criterion of the Jeans modes for self-gravitational systems in Eddington-inspired Born-Infeld (EiBI) gravity is revisited based on the framework of nonextensive statistics and kinetic theory. The results show the nonextensive parameter q has significant effects on the growth rate and critical wave-number of Jeans instability for the EiBI-gravitational systems. Also, we prove that the standard dispersion

    更新日期:2020-11-12
  • Fractal basins of attraction in a binary quasar model
    New Astron. (IF 1.058) Pub Date : 2020-10-26
    Vinay Kumar; Rajiv Aggarwal; Pankaj Sharma; Bhavneet Kaur

    The present paper investigates the binary system of quasars in the framework of the Circular Restricted Three-Body Problem. The parametric evolution of libration points and the geometry of zero-velocity curves are one of the crucial aspects of our study. The multivariate form of NR method is applied to study the basin of attraction connected with libration points. The algorithm for using the Newton-Raphson

    更新日期:2020-11-09
  • Halo Meteors
    New Astron. (IF 1.058) Pub Date : 2020-11-02
    Amir Siraj; Abraham Loeb

    The stellar halo contains some of the oldest stars in the Milky Way galaxy and in the universe. The detections of ‘Oumuamua, CNEOS 2014-01-08, and interstellar dust serve to calibrate the production rate of interstellar objects. We study the feasibility of a search for interstellar meteors with origins in the stellar halo. We find the mean heliocentric impact speed for halo meteors to be ∼270kms−1

    更新日期:2020-11-09
  • Alternative way to detect and measure parameters of compact dark matter object as a component of a binary system
    New Astron. (IF 1.058) Pub Date : 2020-10-14
    E. Oks

    Various compact dark matter objects (CDOs) were discussed in the literature. Typically parameters of CDOs, such as the mass and the distance, were evaluated by using the gravitational microlensing effect. However, this method has limitations. We propose an alternative method for detecting and measuring parameters of CDOs. It is based on the scenario where there is a star having one planet, such that

    更新日期:2020-11-06
  • f(R,T)Gravity model behaving as a dark energy source
    New Astron. (IF 1.058) Pub Date : 2020-10-26
    Pheiroijam Suranjoy Singh; Kangujam Priyokumar Singh

    Within the limits of the present cosmological observations in f(R,T)gravity theory, we have analyzed a spherically symmetric space-time in 5D setting. The field equations have been carefully studied considering reasonable cosmological assumptions to obtain exact solutions. We have obtained an isotropic model universe undergoing super-exponential expansion. It is predicted that the model universe behaves

    更新日期:2020-11-02
  • Generalized holographic dark energy and cosmic coincidence
    New Astron. (IF 1.058) Pub Date : 2020-10-22
    Ryong Gwang Kim; Chang Hyok Ri

    In this work, we study a generalized interacting holographic dark energy model (GIHDEM) with a parameterized coupling constant in the spatially flat universe filled with the holographic dark energy (HDE) and dark matter (DM). More specifically, we introduce a new coupling parameter ξ(z)between HDE and DM as a function of redshift zwhich is parameterized by the well-known Chevalier-Polarski-Linder (CPL)

    更新日期:2020-11-02
  • Measure of complexity in self-gravitating systems using structure scalars
    New Astron. (IF 1.058) Pub Date : 2020-10-28
    Z. Yousaf; Kazuharu Bamba; M.Z. Bhatti; K. Hassan

    The aim of this paper is to present the definition of complexity for static self-gravitating anisotropic matter proposed in f(G,T)theory, where Gis the Gauss-Bonnet term and Tis the trace of energy momentum tensor. We evaluate field equations, Tolman-Oppenheimer-Volkoff equation, mass functions and structure scalars. Among the calculated modified scalar variables that are obtained from the orthogonal

    更新日期:2020-11-02
  • Circular binary star and an interstellar interloper: The analytical solution
    New Astron. (IF 1.058) Pub Date : 2020-09-19
    E. Oks

    We consider an interstellar interloper moving at a relatively large distance from a circular binary star. We use the analytical method of separating rapid and slow subsystems, the rapid subsystem being the binary and the slow subsystem being the interstellar interloper. We show that due to the higher than geometrical symmetry of the problem, in addition to the conservation of the energy and the projection

    更新日期:2020-10-29
  • Anisotropic spheres in f(R,G)gravity with Tolman-Kuchowicz spacetime
    New Astron. (IF 1.058) Pub Date : 2020-10-13
    Mahroz Javed; G. Mustafa; M. Farasat Shamir

    In this paper, we review some anisotropic stellar spheres in the framework of modified f(R,G)gravity. For this purpose, we have capitalized the Tolman-Kuchowicz spacetime Tolman (1939); Kuchowicz (1968). The equations of motion have been formulated by considering anisotropic matter distribution along with metric potentials, a=Br2+2lnCand b=ln(1+αr2+βr4). To determine the new constraints, observational

    更新日期:2020-10-29
  • Scaling relations for width of the power excess of stellar oscillations
    New Astron. (IF 1.058) Pub Date : 2020-10-13
    Ki-Beom Kim; Heon-Young Chang

    Relations between global asteroseismic quantities allow us to derive fundamental stellar parameters. To obtain an insight into solar-like pulsators by an accurate estimate of stellar property requires to explore various scaling relations other than commonly-exploited ones as well as to calibrate the dependence of those over a range of metallicity, mass and evolutionary status of stars. We investigate

    更新日期:2020-10-29
  • Impact of magnetic field on the gas mass fraction of galaxy clusters
    New Astron. (IF 1.058) Pub Date : 2020-10-17
    Sandhya Jagannathan; Sunil Malik; Deepak Jain; T.R. Seshadri

    Magnetic fields have been observed in galaxy clusters with strengths of the order of ~ μG. The non-thermal pressure exerted by magnetic fields also contributes to the total pressure in galaxy clusters and can in turn affect the estimates of the gas mass fraction, fgas. In this paper, we have considered a central magnetic field strength of 5μG, motivated by observations and simulations of galaxy clusters

    更新日期:2020-10-29
  • f(G,T)Gravity with structure scalars
    New Astron. (IF 1.058) Pub Date : 2020-10-19
    M. Farasat Shamir; Madiha Hanif

    Our primary objective in this paper is to analyze structure scalars against the background of f(G,T)gravity. The entire arrangement of conditions executing the structure and the development of self gravitating spherically symmetric dissipative fluids with anisotropic stresses, described as far as structure scalars (scalar functions) are obtained from the orthogonal splitting of the Riemann tensor,

    更新日期:2020-10-29
  • Traversable wormholes supported by non-exotic matter in general relativity
    New Astron. (IF 1.058) Pub Date : 2020-10-19
    Nisha Godani; Gauranga C. Samanta

    Natural horizonless object and its astrophysical signatures have been proposed in various aspects. In this paper, the traversable wormhole solutions are investigated for Einstein’s field equations with cosmological constant. Using redshift function Φ(r)and shape function b(r)as Φ(r)=−1r2and b(r)=r0log(r+1)log(r0+1)in the static and spherically symmetric metric of wormholes, the spherical regions are

    更新日期:2020-10-29
  • KIC 4762887: A near-contact binary or an ellipsoidal variable star?
    New Astron. (IF 1.058) Pub Date : 2020-10-20
    Xu-Zhi Li; Liang Liu

    KIC 4762887 is a variable star with a very small amplitude discovered by Keplerand show the EW-type light curve. We analyzed the light curve of KIC 4762887 by using the 2015 version of the Wilson-Devinney code. The results indicated that it is not a contact binary, maybe not even an eclipsing binary. We also modelled the light curve by the Fourier analysis. The results indicated that the main effect

    更新日期:2020-10-29
  • Signature flipping of isotropic homogeneous space-time with holographic dark energy in f(G)gravity
    New Astron. (IF 1.058) Pub Date : 2020-10-19
    S. H. Shekh; S. D. Katore; V. R. Chirde; S. V. Raut

    Present investigation devoted to the dynamical study of isotropic and homogeneous FRW space-time filled with a Holographic dark energy fluid with cosmic string in the framework of numerous form of f(G)gravity models say linear, quadratic and inverse model. We determine the aspects of the model by considering the hybrid expansion law for the average scale factor that yields power and exponential inflation

    更新日期:2020-10-29
  • Gravitational collapse of a self-gravitating unidirectional fluid flow
    New Astron. (IF 1.058) Pub Date : 2020-10-19
    Umber Sheikh; M.Z. Bhatti; Z. Yousaf

    This paper explores the collapsing process of a unidirectional isotropic matter configuration. The junction conditions for a static exterior geometry and the non-static interior geometry are expressed in terms of the cosmological constant. The time-lapse for the appearance of the black hole and the cosmological horizon is calculated. It is observed that in the de-Sitter space, the unidirectional perfect

    更新日期:2020-10-29
  • On the recent detection of new oscillations in rapidly oscillating Ap star HD 137949—Final result
    New Astron. (IF 1.058) Pub Date : 2020-10-20
    C.N. Ofodum; P.N. Okeke; B.I. Okere

    We present the result of additional high-speed photometric observation of HD 137949. The Johnson-B photometric data were obtained on five nights between 2013 July 31, and August 19, using 0.5-m optical telescope of the South African Astronomical Observatory (SAAO). Frequency analysis of our nightly data sets as well as combination of all data sets reveal no new oscillation besides the well-known principal

    更新日期:2020-10-29
  • The role of some collisional processes in AGNs: Rate coefficients needed for modeling
    New Astron. (IF 1.058) Pub Date : 2020-10-21
    Milan S. Dimitrijević; Vladimir A. Srećković; Ljubinko M. Ignjatović; Bratislav P. Marinković

    The importance of some atom hydrogen collisions in AGN has been investigated. The results are useful for better estimation of the hydrogen Balmer lines fluxes, which usage for effective temperature diagnostics in astrophysical plasma is limited by errors from the line formation models. The data could be also useful for modeling cooler and denser parts of AGN BLR clouds, as well as for the investigation

    更新日期:2020-10-29
  • EFFECTS OF TRIAXIALITY OF PRIMARIES ON OBLATE INFINITESIMAL IN ELLIPTICAL RESTRICTED THREE BODY PROBLEM
    New Astron. (IF 1.058) Pub Date : 2020-10-21
    Poonam Duggad; S. Dewangan; A. Narayan

    This paper examines the effects of triaxiality of both the primaries on the position and stability of the oblate infinitesimal mass in the neighborhood of triangular equilibrium points in the framework of Elliptical restricted three body problem. We have found the solutions for the locations of triangular equilibrium points. We have investigated the stability of infinitesimal mass around the triangular

    更新日期:2020-10-29
  • Tsallis HDE with an IR cutoff as Ricci horizon in a flat FLRW universe
    New Astron. (IF 1.058) Pub Date : 2020-10-09
    Umesh Kumar Sharma; Vandna Srivastava

    The THDE (Tsallis HDE) model using an IR cut off as Ricci horizon has been investigated in the context of a flat Friedmann-Lemaı^tre-Robertson-Walker Universe by describing an accelerated expansion stage which Universe is experiencing. Evolution of Universe from decelerated (earlier) to the accelerated (current) phase exhibits by deceleration parameter (DP) attained in the model of THDE. The good behavior

    更新日期:2020-10-17
  • Advances in deep space exploration via simulators & deep learning
    New Astron. (IF 1.058) Pub Date : 2020-10-02
    James Bird; Linda Petzold; Philip Lubin; Julia Deacon

    The NASA Starlight and Breakthrough Starshot programs conceptualize fast interstellar travel via small relativistic spacecraft that are propelled by directed energy. This process is radically different from traditional space travel and trades large and slow spacecraft for small, fast, inexpensive, and fragile ones. The main goal of these wafer satellites is to gather useful images during their deep

    更新日期:2020-10-15
  • Conformable fractional isothermal gas spheres
    New Astron. (IF 1.058) Pub Date : 2020-09-30
    Eltayeb A. Yousif; Ahmed M.A. Adam; Abaker A. Hassaballa; Mohamed I. Nouh

    The isothermal gas sphere is well known as a powerful tool to model many problems in astrophysics, physics, chemistry, and engineering. This singular differential equation has not an exact solution and solved only by numerical and approximate methods. In the present paper and within the framework of the Newtonian hydrostatic equilibrium, we have developed general analytical formulations for the fractional

    更新日期:2020-10-11
  • Stability of P-type orbits around stellar binaries: An extension to counter-rotating orbits
    New Astron. (IF 1.058) Pub Date : 2020-10-02
    Chaelin Hong; Maurice H.P.M. van Putten

    Continuing advances in observational astronomy may detect exoplanets around exotic systems such as a binary of a compact object - white dwarf, neutron star or black hole - with a stellar companion. Their formation history includes tidal capture, familiar from studies of X-ray binaries, that may put exoplanets on co- or counter-rotating P-type orbits of the resulting binary. We here revisit the essential

    更新日期:2020-10-11
  • Modelling the quenching of star formation activity from the evolution of the colour-magnitude relation in VIPERS
    New Astron. (IF 1.058) Pub Date : 2020-10-02
    G. Manzoni; M. Scodeggio; C.M. Baugh; P. Norberg; G. De Lucia; A. Fritz; C.P. Haines; G. Zamorani; A. Gargiulo; L. Guzzo; A. Iovino; K. Małek; A. Pollo; M. Siudek; D. Vergani

    We study the evolution of the colour-magnitude relation for galaxies in the VIMOS Public Extragalactic Redshift Survey (VIPERS) by introducing the concept of the bright edge, and use this to derive constraints on the quenching of star formation activity in galaxies over the redshift range 0.5 < z < 1.1. The bright-edge of the colour-magnitude diagram evolves with little dependence on galaxy colour

    更新日期:2020-10-11
  • Photometric study of three contact binary systems
    New Astron. (IF 1.058) Pub Date : 2020-09-29
    Massimiliano Martignoni; Francesco Acerbi; Carlo Barani

    The first complete light curves of two eclipsing binaries in Camelopardalis, NX Cam and V584 Cam, are here presented together with the new observations of the system NSVS 2643686 obtained in 2014. The light curves were modelled using the latest version of the Wilson-Devinney code. Our results show that all the three systems have an extreme mass ratio q < 0.2, two of them, NX Cam and NSVS 2643686, having

    更新日期:2020-10-11
  • On the modified circular restricted three-body problem with variable mass
    New Astron. (IF 1.058) Pub Date : 2020-09-30
    Md Sanam Suraj; Rajiv Aggarwal; Md Chand Asique; Amit Mittal

    In the present work, we shall show an exhaustive numerical analysis of the dynamical behavior of the test particle in the modified restricted three-body problem with variable mass in which the extra effect of the three-body interaction is also taken into account. This additional force ingredient appears in the potential of the classical problem as a new extra term. As the main results, we determine

    更新日期:2020-10-08
  • Comparing X-ray color selection in separating X-ray binary classes using color-color-intensity diagrams
    New Astron. (IF 1.058) Pub Date : 2020-10-08
    N. Islam; S.D. Vrtilek; Bram Boroson; D.-W. Kim; E. O’Sullivan; M.L. McCollough; G. Fabbiano; C. Anderson; D.J. Burke; R. D’Abrusco; A. Fruscione; J.L. Lauer; D. Morgan; A. Mossman; A. Paggi; G. Trinchieri

    X-ray binaries exhibit a wide range of properties but there are few accepted methods to determine the nature of the compact object. Color-Color-Intensity diagrams have been suggested as a means of distinguishing between systems containing black holes from those containing neutron stars. However, this technique has been verified with data from only one instrument (RXTE/ASM) with a single set of X-ray

    更新日期:2020-10-08
  • Viability bounds in f(R, G) gravity with energy conditions
    New Astron. (IF 1.058) Pub Date : 2020-10-01
    Rameshwar Singh

    In the present work, we discuss the viability bounds arising from the energy conditions in the context of an extended gravitational theory namely f(R, G) gravity, where R stands for the curvature scalar and G represents the Gauss-Bonnet invariant. Two specific forms of f(R, G) have been taken into account to examine the validity of the general inequalities obtained by the weak energy condition (WEC)

    更新日期:2020-10-02
  • Michel accretion onto a non-commutative black hole
    New Astron. (IF 1.058) Pub Date : 2020-09-23
    G. Abbas; A. Ditta

    The matter accretion onto a noncommutative (NC) inspired Schwarzschild black hole is addressed for a polytropic fluid and results are compared with Schwarzschild black hole. The flow parameters - critical velocity u(r), sonic speed cs2 and accretion rate M˙ are derived from the NC static black hole and are related to the outcomes acquired for the standard Schwarzschild black hole. Due to the effect

    更新日期:2020-09-28
  • Effect of Moon perturbation on the energy curves and equilibrium points in the Sun–Earth–Moon system
    New Astron. (IF 1.058) Pub Date : 2020-09-23
    Ashok Kumar Pal; Elbaz I. Abouelmagd; Ram Kishor

    In this paper, we have considered that the Moon motion around the Earth is a source of a perturbation for the infinitesimal body motion in the Sun–Earth system. The perturbation effect is analyzed by using the Sun–Earth–Moon bi–circular model (BCM). We have determined the effect of this perturbation on the Lagrangian points and zero velocity curves. We have obtained the motion of infinitesimal body

    更新日期:2020-09-28
  • The first light curve solutions and period study of two contact binary systems: V1370 Tau and QQ Boo
    New Astron. (IF 1.058) Pub Date : 2020-09-19
    Jabar Rahimi; Elahe Lashgari; Morteza Ghanbarzadehchaleshtori; Amin Boudesh; Fatemeh Davoudi; Ahmad Farahani; Filip Walter; Bohuslav Hladík; Peter Nosal; Atila Poro

    The first light curve solutions of the binary systems V1370 Tau and QQ Boo are presented. The periodic changes are calculated, and a new ephemeris presented for each of these two binary systems. O-C analysis is performed using the MCMC method in OCFit code. The changing rate of period was measured as dP/dt= 0.2423 days/year for V1370 Tau and dP/dt= -0.1363 days/year for QQ Boo. The light curve solutions

    更新日期:2020-09-23
  • The comparative analysis of dense stellar models governed by quadratic and linear equations of state
    New Astron. (IF 1.058) Pub Date : 2020-09-21
    Kiran Pant; Pratibha Fuloria

    In the present article we construct physically viable models of anisotropic charged compact stellar objects admitting quadratic equation of state and linear equation of state. We analyze the physical behavior of compact star models 4U1538-52, LMCX-4, and Vela X-1 with in the frame work of general relativity. Our stellar models are free from singularities, satisfy all energy conditions and exhibit physically

    更新日期:2020-09-23
  • Improving performance of zoom-in cosmological simulations using initial conditions with customized grids
    New Astron. (IF 1.058) Pub Date : 2020-09-18
    Gillen Brown; Oleg Y. Gnedin

    We present a method for customizing the root grid of zoom-in initial conditions used for simulations of galaxy formation. Starting from the white noise used to seed the structures of an existing initial condition, we cut out a smaller region of interest and use this trimmed white noise cube to create a new root grid. This new root grid contains similar structures as the original, but allows for a smaller

    更新日期:2020-09-22
  • A novel early dark energy model
    New Astron. (IF 1.058) Pub Date : 2020-09-18
    Luz Ángela García; Leonardo Castañeda; Juan Manuel Tejeiro

    We present a theoretical study of an early dark energy (EDE) model. The equation of state ω(z) evolves during the thermal history in a framework of a Friedmann-Lemaitre-Robertson-Walker Universe, following an effective parametrization that is a function of redshift z. We explore the evolution of the system from the radiation domination era to the late times, allowing the EDE model to have a non-negligible

    更新日期:2020-09-22
  • Plane-symmetric dark energy model with a massive scalar field
    New Astron. (IF 1.058) Pub Date : 2020-09-20
    Y. Aditya; U.Y. Divya Prasanthi; D.R.K. Reddy

    Investigation of dark energy models in the presence of scalar fields are attracting several kinds of research because they play a vital role in the discussion of a new scenario of accelerated expansion of the universe. In this paper, we obtain an exact plane-symmetric dark energy cosmological model in the presence of an attractive massive scalar field by solving Einstein field equations using some

    更新日期:2020-09-22
  • A Rare Low-mass Short-period Eclipsing Binary Candidate With A Close-in Non-coplanar Stellar Companion
    New Astron. (IF 1.058) Pub Date : 2020-09-16
    B Zhang; S-B Qian; Zejda Miloslav; Q-J Zhi; A-J Dong; L-Y Zhu

    First multi-colour light curves (LCs) of the short-period contact eclipsing binary (CEB) 1SWASP J224747.20-351849.3 (hereafter J2247) are presented and analyzed by using the 2013 version of the Wilson-Devinney (W−D) code in this paper. We found that J2247 was a low-mass W-subtype medium CEB. Third light was detected and the average luminosity contribution (l3/Lall) was as high as 67.89%. Until now

    更新日期:2020-09-20
  • On the event rate and luminosity function of superluminous supernovae
    New Astron. (IF 1.058) Pub Date : 2020-09-16
    Wen-Chang Zhao; Xiao-Xin Xue; Xiao-Feng Cao

    We calculate the rate per unit volume of hydrogen-poor superluminous supernovae (SLSNe-I) based on the 17 events discovered with the Pan-STARRS1 Medium Deep Survey (PS1 MDS). Two forms of the luminosity function (LF) are assumed : a log-normal form and a single power-law form, respectively. The rate of SLSNe-I is assumed to be proportional to the cosmic star formation rate with an additional redshift

    更新日期:2020-09-20
  • Solar Wind Turbulence: Connections with Energetic Particles
    New Astron. (IF 1.058) Pub Date : 2020-09-15
    Sean Oughton; N. Eugene Engelbrecht

    For the solar wind, a wealth of observational evidence indicates that turbulence is an important dynamical process for velocity (v), magnetic (b), and other related fluctuations at MHD (fluid) scales. Here we review such observations and turbulence features, including discussion of when wave or turbulence descriptions can (or cannot) explain the observations. The relevance of properties of MHD turbulence

    更新日期:2020-09-15
  • The Detached Binary TW Coronae Borealis
    New Astron. (IF 1.058) Pub Date : 2020-08-26
    Robert H. Nelson

    New radial velocity and photometric data for TW CrB have been obtained, and Roche-based simultaneous analysis of RV and light curve data for the system has been accomplished for the first time, using the 2003 version of the Wilson-Devinney code. Values for the masses and radii have been obtained: M1 = 1.31 (6) Mʘ, M2 = 1.22 (4) Mʘ, and R1 = 1.50 (1) Rʘ, R2 = 1.42 (1) Rʘ. For the luminosities the most

    更新日期:2020-08-26
  • On the rate of core collapse supernovae in the milky way
    New Astron. (IF 1.058) Pub Date : 2020-08-26
    Karolina Rozwadowska, Francesco Vissani, Enrico Cappellaro

    Several large neutrino telescopes, operating at various sites around the world, have as their main objective the first detection of neutrinos emitted by a gravitational collapse in the Milky Way. The success of these observation programs depends on the rate of supernova core collapse in the Milky Way, R. In this work, standard statistical techniques are used to combine several independent results.

    更新日期:2020-08-26
  • Kind of Robe’s restricted problem with heterogeneous irregular primary of N-layers when outer most layer has viscous fluid
    New Astron. (IF 1.058) Pub Date : 2020-08-25
    Abdullah A. Ansari

    This paper deals with the properties of the motion of the test particle (third body) which is moving in the outer layer of the heterogeneous body filled with the viscous fluid, under the influence of the heterogeneous body and the point mass. We have determined the gravitational potential between the heterogeneous body and the test particle and then evaluated the equations of motion of the test particle

    更新日期:2020-08-25
  • Accretion discs with non-zero central torque
    New Astron. (IF 1.058) Pub Date : 2020-08-21
    C.J. Nixon; J.E. Pringle

    We present analytical and numerical solutions for accretion discs subject to a non-zero central torque. We express this in terms of a single parameter, f, which is the ratio of outward viscous flux of angular momentum from the inner boundary to the inward advected flux of angular momentum there. The standard “accretion” disc, where the central boundary condition is zero-torque, is represented by f=0

    更新日期:2020-08-21
  • Constraining f(T, B) teleparallel gravity from energy conditions
    New Astron. (IF 1.058) Pub Date : 2020-08-20
    Snehasish Bhattacharjee

    f(T, B) teleparallel gravity is a recently proposed straightforward generalization of the popular f(T) teleparallel gravity by the incorporation of a boundary term B=2e∂i(eTi)=▽iTi where T denote the torsion scalar (Bahamonde et al., 2015). In this work, I investigate the viability of some well motivated f(T, B) teleparallel gravity models of the forms f=αBn+βTm, f=αBnTm and f=αlog(B)+βT where α, β

    更新日期:2020-08-20
  • Dilaton-Axion Black Hole under the Solar System Tests
    New Astron. (IF 1.058) Pub Date : 2020-08-19
    Amna Ali; Sabiruddin Molla; Farook Rahaman; Ruhul Amin; Gurudas Mandal; Saibal Ray

    In the present paper we study the static and spherically symmetric dilaton-axion black hole in the testing ground of the Solar system. We constrain the parameters of the string motivated dilaton-axion form of the classical tests of general relativity, viz., the perihelion precession of the planet Mercury and the deflection of light by the Sun. In this case we have two free parameters: the dilaton strength

    更新日期:2020-08-19
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