当前期刊: New Astronomy Go to current issue    加入关注   
显示样式:        排序: IF: - GO 导出
我的关注
我的收藏
您暂时未登录!
登录
  • 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:2020-10-19
  • 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:2020-10-19
  • 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:2020-10-19
  • 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:2020-10-19
  • 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
  • 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:2020-10-17
  • 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:2020-10-17
  • 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
  • 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:2020-10-15
  • 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:2020-10-13
  • 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+2lnC and b=ln(1+αr2+βr4). To determine the new constraints, observational

    更新日期:2020-10-13
  • 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
  • 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:2020-09-20
  • 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
  • NGC 2366 : An optical search for possible supernova remnants
    New Astron. (IF 1.058) Pub Date : 2020-08-17
    E.N. Ercan, E. AKTEKİN

    The results of an optical search for supernova remnants (SNRs) in the nearby irregular galaxy NGC 2366 are presented. We took interference filter images and collected spectral data in three epochs with the f/7.7 1.5 m Russian Turkish Telescope (RTT150) at TÜBİTAK National Observatory (TUG) located in Antalya, Turkey. The continuum-subtracted Hα and continuum-subtracted [S ii]λλ6716, 6731 images and

    更新日期:2020-08-17
  • A momentum-conserving N-body scheme with individual time steps
    New Astron. (IF 1.058) Pub Date : 2020-08-16
    Qirong Zhu

    We present an N-body code called Taichi for galactic dynamics and controlled numerical experiments. The code includes two high-order hierarchical multipole expansion methods: the Barnes-Hut (BH) tree and the fast multipole method (FMM). For the time integration, the code can use either a conventional adaptive KDK or a Hamiltonian splitting integrator. The combination of FMM and the Hamiltonian splitting

    更新日期:2020-08-16
  • Compatibility between the scalar field models of tachyon, k-essence and quintessence in f(R, T) gravity
    New Astron. (IF 1.058) Pub Date : 2020-08-13
    Vinod Kumar Bhardwaj; Anirudh Pradhan; Archana Dixit

    We investigate the behavior of the scalar field in f(R, T) gravity (Harko et al., Phys. Rev. D 84, 024020, 2011) inside the structure of a flat FRW cosmological model, where R and T have their usual meaning. The deterministic solution of FEs has been settled by considering the scale factor S(t)=tmekt, where m and k are positive constant. Here we utilize three ongoing imperatives (H0=73.8 and q0=−0

    更新日期:2020-08-14
  • Dynamics of accretion and winds in tidal disruption events
    New Astron. (IF 1.058) Pub Date : 2020-08-14
    T. Mageshwaran, A. Mangalam

    We have constructed self-similar models of a time-dependent accretion disk in both sub and super-Eddington phases with wind outflows for tidal disruption events (TDEs). The physical input parameters are the black hole (BH) mass M•, specific orbital energy E and angular momentum J, star mass M⋆ and radius R⋆. We consider the sub-Eddington phase to be total pressure (model A1) and gas pressure (model

    更新日期:2020-08-14
  • Modeling multiband X-ray light curves of the Crab pulsar with the annular and core gap models
    New Astron. (IF 1.058) Pub Date : 2020-08-13
    Bai Jun-Tao, Xu Xin, Lin Quan-Wei, Zhi Qi-Jun, Shang Lun-Hua, Du Yuan-Jie, Tuo You-Li, Dang Shi-Jun, Wang Shuang-Qiang, Zhao Ru-Shuang, Dong Ai-Jun, Qiao Guo-Jun

    Multiwavelength observation is an effective way to test and constrain theoretical models of pulsars. X-ray observations reveal that the light curve of the Crab pulsar has two sharp peaks, with a phase separation of ~ 0.4 spin periods between its first peak (P1) and second peak (P2). Using observations from the Hard X-ray Modulation Telescope (Insight-HXMT) of China, we studied eight-wavelength (from

    更新日期:2020-08-13
  • Thermonuclear X-ray bursts detected in Cyg X-2 using AstroSat/LAXPC
    New Astron. (IF 1.058) Pub Date : 2020-08-11
    Jincy Devasia, Gayathri Raman, Biswajit Paul

    We report the detection of 5 Type-1 thermonuclear X-ray bursts and one burst-like event in the neutron star LMXB source, Cyg X-2 using X-ray data obtained with the Large Area X-ray Proportional Counter (LAXPC) instrument on board AstroSat. We carry out an energy resolved burst profile analysis as well as time resolved spectral analysis for each of the bursts and characterize their properties. All bursts

    更新日期:2020-08-11
  • AB Andromedae – An overcontact eclipsing binary
    New Astron. (IF 1.058) Pub Date : 2020-08-10
    Robert H. Nelson

    In an effort to resolve the discrepancy between two earlier studies, new radial velocity and photometric data have been obtained and analyzed by Roche modelling for AB Andromedae, an overcontact W-subtype eclipsing binary. The new values for the basic data, m1 = 0.60 (3) Mʘ, m2 = 1.14 (3) Mʘ, R1 = 0.81 (1) Rʘ, R2 = 1.08 (1) Rʘ, L1 = 0.73 (6) Lʘ, and L2 = 1.02 (7) Lʘ, mostly lie close to a given set

    更新日期:2020-08-10
  • Accelerating universe with varying Λ in f(R, T) theory of gravity
    New Astron. (IF 1.058) Pub Date : 2020-08-09
    Rishi Kumar Tiwari, Değer Sofuoğlu, Sateesh Kumar Mishra

    In this paper we have investigated Bianchi Type-I cosmological model with varying cosmological constant Λ in f(R, T) theory of gravity. In order to obtain an exact solution of the field equations, we have used a special law of Hubble parameter proposed by Banerjee and Das (Gen Relat Gravit 37 (2005) 1695–1703), which leads to a time dependent deceleration parameter. We have discussed the physical and

    更新日期:2020-08-09
  • Monitoring of transiting exoplanets and their host stars with small aperture telescopes
    New Astron. (IF 1.058) Pub Date : 2020-08-09
    M.A. Salisbury, U.C. Kolb, A.J. Norton, C.A. Haswell

    Exoplanet research is now target rich with a wide diversity of systems making it difficult for high demand observatories to undertake follow up observations over extended periods of time. We investigate the effectiveness of using 0.4m-class telescopes for monitoring transiting hot Jupiters and their host stars. We consider two representative case studies: WASP-52b with 13 new transits, and HAT-P-23b

    更新日期:2020-08-09
  • Capricious basins of attraction in photogravitational magnetic binary problem
    New Astron. (IF 1.058) Pub Date : 2020-08-09
    Vinay Kumar, Md. Arif, M. Shahbaz Ullah

    The present paper deals with the magnetic binary problem in the framework of restricted problem of three bodies. The bigger primary is taken as the source of radiation pressure and smaller primary is taken as point mass. The parametric evolution of the position and existence of libration points are explored. The study of zero velocity curves and the stability of libration points are one of the critical

    更新日期:2020-08-09
  • First lunar occultations results from the Trebur observatory
    New Astron. (IF 1.058) Pub Date : 2020-08-07
    A. Richichi, J.M. Ohlert

    A program of routine observations of lunar occultations has been initiated at the Michael Adrian Observatorium using a 1.2 m telescope equipped with a commercial CMOS camera. The goal is mainly the direct measurement of the angular diameter of late-type stars, as well as of binary stars with small separations. Among the results reported in this first paper, we discuss a measurement of Aldebaran (α Tau)

    更新日期:2020-08-07
  • Anisotropic universe and observational constraint on the dark energy models with the cosmological redshift drift
    New Astron. (IF 1.058) Pub Date : 2020-08-06
    H. Hossienkhani; N. Azimi; S. Gheysari; Z. Zarei

    This study set out to examine the effect of anisotropy on the various dark energy models by using the observational data, including the Sandage-Loeb test, Strongly gravitationally lensing, observational Hubble data, and Baryon Acoustic Oscillations data. In particular, we consider three cases of dark energy models: the cosmological constant model, which is most favored by current observations, the

    更新日期:2020-08-06
  • Self-similar orbit-averaged Fokker-Planck equation for isotropic spherical dense star clusters (i) accurate pre-collapse solution
    New Astron. (IF 1.058) Pub Date : 2020-08-06
    Yuta Ito

    This is the first paper of a series of our works on the self-similar orbit-averaged Fokker-Planck (OAFP) equation to model distribution function for stars in isotropic dense spherical star clusters. At the late stage of the relaxation evolution of the clusters, standard stellar dynamics predicts that the clusters evolve in a self-similar fashion forming collapsing cores. However, the corresponding

    更新日期:2020-08-06
  • Dynamical analysis with thermodynamic aspects of anisotropic dark energy bounce cosmological model in f(R, G) gravity
    New Astron. (IF 1.058) Pub Date : 2020-08-02
    S.H. Shekh

    Present analysis dedicated to the dynamical investigation of anisotropic dark energy LRS Bianchi type-I cosmological model in the context of modified gravity in which Langrangian be the arbitrary function of Ricci scalar and Gouss-Bonnet invariant say f(R, G) gravity in the way of anisotropic fluid. The classification of the field equations towards f(R,G)=f0RmG1−m make available that the model is purely

    更新日期:2020-08-02
  • Non-commutative wormhole solutions in exponential gravity with matter coupling
    New Astron. (IF 1.058) Pub Date : 2020-08-01
    M. Farasat Shamir, G. Mustafa, Anum Fazal

    In the present article, we use non-commutative geometry to investigate the wormhole solutions in modified f(R, T) theory of gravity. In particular, we consider Gaussian and Lorentzian source with f(R,T)=f1(R)+λT model to discuss the wormhole solutions existence. We choose two different models of f1(R) i.e. f1(R)=R−αγ(1−e−Rγ) known as exponential gravity model and f1(R)=R−αγtanh(Rγ) known as Tsujikawa

    更新日期:2020-08-01
  • Irregular emission cycles in the Oe star HD 60 848
    New Astron. (IF 1.058) Pub Date : 2020-07-30
    Gregor Rauw; Yaël Nazé; Fran Campos; Joan Guarro Fló; Umberto Sollecchia

    We analyse the spectroscopic and photometric variability of the Oe star HD 60 848 over the last twenty five years. The spectra reveal recurrent, but irregular cycles of increased circumstellar emission lines. These cycles are highly asymmetric displaying a slow increase over about 6 years, followed by a fast decay within about 6 months. Our analysis focuses on the most recent cycle (2013 – 2020). The

    更新日期:2020-07-30
  • The late-type detached binary DU Leonis
    New Astron. (IF 1.058) Pub Date : 2020-07-29
    Robert H. Nelson

    New radial velocity and photometric data for DU Leonis have been obtained, and Roche-based simultaneous analysis of RV and light curve data for DU Leo has been accomplished for the first time, using the 2003 and 2015 versions of the Wilson-Devinney code. Values for the masses and radii have been obtained: M1 = 0.937 (5) Mʘ, M2 = 0.921 (5) Mʘ, and R1 = 1.25 (1) Rʘ, R2 = 1.21 (1) Rʘ. For the luminosities

    更新日期:2020-07-29
  • Reaction rate calculation of d(α, γ)6Li process at low energy in framework of effective field theory
    New Astron. (IF 1.058) Pub Date : 2020-07-27
    S. Nahidinezhad, H. Sadeghi, M. Khoddam

    Reaction rate of the process d(α, γ)6Li has been calculated in the framework of Effective Field Theory (EFT) at low energy. Deuteron is assumed as a dibaryon in the initial state. The reaction amplitude for the initial P-wave states of deuteron-alpha and reaction rate for sum of E1 and E2 transitions are found in the framework of EFT up to NLO. Our results are in good agreement with the recent experimental

    更新日期:2020-07-27
  • Dynamics of some cosmological solutions in modified f(R) gravity
    New Astron. (IF 1.058) Pub Date : 2020-07-26
    Adnan Malik, M. Farasat Shamir

    This paper is devoted to investigate the modified f(R) theory of gravity, where R represents the Ricci scalar respectively. For our current work, we consider the Friedmann-Robertson-Walker (FRW) space-time for finding solutions of field equations. Furthermore, some numerical solutions are examined by taking the Klein-Gordon Equation and using distinct values of the equation of state (EoS) parameter

    更新日期:2020-07-26
  • Exact analytic solution of an unsolvable class of first Lane–Emden equation for polytropic gas sphere
    New Astron. (IF 1.058) Pub Date : 2020-07-24
    Rafael Torres-Córdoba, Edgar A. Martínez-García

    This article provides for the first time a general analytical solution to the Lane-Emden equation of the first kind. So far only three known analytical solutions are found in the literature, for the following values of n: 0, 1 and 5. A common feature these three solutions share is their boundary conditions: θ(ξ)∣ξ=0=1 and dθ(ξ)dξ∣ξ=0 =0. If a third boundary condition d2θ(ξ)dξ2∣ξ=0,= −1 is used, only

    更新日期:2020-07-24
  • GalRotpy: a tool to parametrize the gravitational potential of disc-like galaxies
    New Astron. (IF 1.058) Pub Date : 2020-07-22
    Andrés Granados, Daniel Torres, Leonardo Castañeda, Lady Henao, Santiago Vanegas

    GalRotpy is a Python3-based tool, intended to determine the contribution of each mass component to the gravitational potential of disc-like galaxies by means of their rotation curve. Besides, GalRotpy allows to perform a parametric fit of a given rotation curve, which relies on a MCMC procedure implemented by using emcee package. Here the gravitational potential of disc-like galaxies is built from

    更新日期:2020-07-22
  • The study of runaway candidate stars in the 30 Doradus region: Using Gaia DR2 data
    New Astron. (IF 1.058) Pub Date : 2020-07-22
    Yikdem Mengesha Gebrehiwot, Berhe Tewelde Teklehaimanot

    We explore the Gaia DR2 relative proper motions of seven young, massive, OB type runaway candidate stars presented by Platais et al. (2018) in the 30 Doradus (30 Dor) region of the Large Magellanic Cloud (LMC). The stars are slow runaways in the tangential plane of the 30 Dor region with relative proper motions μ≤0.4masyr−1 that correspond to a tangential velocity of 100 kms−1 with respect to their

    更新日期:2020-07-22
  • Absolute parameters of the W UMa binaries CSS J223614+311343, V523 Aur and V783 And
    New Astron. (IF 1.058) Pub Date : 2020-07-18
    Diana Kjurkchieva; Raul Michel; Shijie Zhao; Carmen Ayala-Loera; Luis C. Bermudez-Bustamante; Velimir A. Popov

    Photometric BVRc observations of the stars CSS J223614+311343, V523 Aur and V783 And were carried out and their absolute parameters (masses, radii and luminosities) were determined based on light curve modeling and Gaia distances. The main results are: (i) The components of CSS J223614+311343 and V783 And are of K spectral type while those of V523 Aur are G stars; (ii) The three systems have middle

    更新日期:2020-07-20
  • A new approximate coupling function: The case of Forbush decreases
    New Astron. (IF 1.058) Pub Date : 2020-07-17
    L. Xaplanteris, M. Livada, H. Mavromichalaki, L. Dorman

    We attempt the derivation of a new coupling function between ground level and primary cosmic rays for the case of Forbush decreases. The calculations for the new function are based on basic Quantum Field Theory theoretical tools, something that has not been attempted till now in other widely used cosmic ray coupling functions. The use of Quantum Field Theory calculations in cosmic rays events in general

    更新日期:2020-07-17
  • New photometric analysis of hot Jupiter: WASP-135b
    New Astron. (IF 1.058) Pub Date : 2020-07-17
    Oğuz Öztürk, Ahmet Erdem

    We report photometric follow-up observations of WASP-135b obtained using the 1.23-m telescope at Calar Alto Observatory and 1.00-m telescope at TÜBİTAK National Observatory during the 2017 and 2018 observational seasons. Eight new transit light curves of WASP-135b were analyzed with jktebop code. The ratio of the planet radius to radius of host star, fractional radius of host star, and orbital inclination

    更新日期:2020-07-17
Contents have been reproduced by permission of the publishers.
导出
全部期刊列表>>
Springer 纳米技术权威期刊征稿
全球视野覆盖
施普林格·自然新
chemistry
3分钟学术视频演讲大赛
物理学研究前沿热点精选期刊推荐
自然职位线上招聘会
欢迎报名注册2020量子在线大会
化学领域亟待解决的问题
材料学研究精选新
GIANT
ACS ES&T Engineering
ACS ES&T Water
屿渡论文,编辑服务
ACS Publications填问卷
阿拉丁试剂right
西北大学
大连理工大学
湖南大学
华东师范大学
王要兵
浙江大学
隐藏1h前已浏览文章
课题组网站
新版X-MOL期刊搜索和高级搜索功能介绍
ACS材料视界
天合科研
x-mol收录
陆军军医大学
李霄鹏
廖矿标
试剂库存
down
wechat
bug