Showing papers in "New Astronomy in 2019"

TL;DR: In this article, the authors use well-established observational evidence to draw conclusions about the fundamental nature of the viscosity in accretion discs, and conclude that the value of α is readily amenable to reliable estimation and that the observations are consistent with the hypothesis that α ∼ 0.2 − 0.3.

TL;DR: In this article, the authors explored the Tsallis holographic dark energy (THDE) model admitting the mutual interaction between dark matter and dark energy, from the statefinder perspective.

TL;DR: In this article, the existence and stability of the libration points are explored and analysed numerically, under the effect of non-isotropic mass variation of the fifth body (test particle or infinitesimal body).

TL;DR: In this paper, it was shown that the Jacobian integral is a constant in two special cases, which can be used to determine the regions of motion from the zero velocity surfaces.

TL;DR: In this paper, a new holographic dark energy (NHDE) model with new infrared cut-off (IR) has been investigated in Bianchi-III anisotropic model with the matter.

TL;DR: By considering the time-varying deceleration parameter (DP), this article investigated Tsallis holographic dark energy (THDE), infrared cut-off with the Hubble horizon proposed by Tavayef, et al. in the framework of Friedmann Robertson Walker universe.

TL;DR: In this paper, the clean numerical simulation (CNS) strategy was used to obtain the first collisionless free-fall 3-body orbits of chaotic dynamic systems, including the three collisionless periodic orbits of the freefall triple system.

TL;DR: In this article, the cosmological dynamics of holographic dark energy in a DGP braneworld in which the holographic parameter c2 is slowly varying with time was studied.

TL;DR: In this paper, the authors studied the motion of a test particle in the Robe's circular restricted three-body problem (CR3BP) when the fluid of the first primary is assumed to be viscous and the shape of the second primary is considered as an oblate spheroid.

TL;DR: In this article, the influence of the anisotropy on the evolution of the universe was studied using the supernovae type Ia (SNIa) data and compared with 6 representative parametrizations of the recent Hubble expansion history H(z).

TL;DR: In this article, the authors present new CCD VI photometry of the distant globular cluster Pal 13, which reveals the variability of a red giant cluster member and three probably non-member stars; two RRab stars and one W Virginis star or CW.

TL;DR: In this paper, a spatially homogeneous and anisotropic Bianchi type-III space-time model is proposed to obtain exact solutions of Einstein's field equations under the purview of the assumption of two fluid, barotropic fluid, and dark energy.

TL;DR: In this article, a solution of the Four Poisson-Laplace equation of gravitation (CPL) was used to explain the anomalous flat rotation curves of spiral galaxies, and the proposed solution does not invoke the exotic hypothesis of darkmatter but makes the assumption that our existing Laws of Gravitation need to be amended.

TL;DR: In this article, a multivariate version of Newton-Raphson iterative scheme is introduced for determining the basins of attraction in the configuration (x, y) plane.

TL;DR: In this article, the spectral features of the blazar Mrk 501 indicate an EHBL nature of the source, whereas, the temporal characteristics with fast variability during the high activity state of a source in X-ray and γ-ray energy bands are not compatible with the behaviour of EH BL Lac (EHBL) type of blazars.

TL;DR: In this article, the authors investigated the anisotropic Locally Rotationally Symmetric (LRS) Bianchi type-I metric with dark energy in modified f(R, T) theory of gravity, where R is the Ricci scalar and T is the trace of stress energy momentum tensor.

TL;DR: In this article, an effective dynamical sound speed may resolve the nonisomorphism of the critical and the sonic points in low angular momentum axially symmetric accretion flow maintained in hydrostatic equilibrium along the vertical direction.

TL;DR: In this paper, the scale factor a (t ) = [ t k exp ( t ) ] 1 n (k, k) as the generalized Hybrid expansion law which yields the time-dependent deceleration parameter (DP), speaking to a class of models which produce the transition of the universe from the early decelerating stage to the ongoing accelerating stage.

TL;DR: In this article, the authors studied the restricted four body problem, where the three primary bodies are moving in elliptic orbits always maintaining the configuration of an equilateral triangle, and the forces affecting the motion of the bodies are the mutual gravitational attractions of the primaries, however the effect of the fourth body of infinitesimal mass is assumed to be negligible.

TL;DR: In this article, a cosmological model of spatially homogeneous and isotropic accelerating universe which exhibits a transition from deceleration to acceleration is proposed and derived using Friedmann Robertson Walker (FRW) metric.

TL;DR: In this paper, a morphological study of two extended open clusters in the sky, Melotte 22 and Melotte 25 using J, H, and Ks photometry with Gaia DR2 and PPMXL proper motions is presented.

TL;DR: Nyambuya et al. as mentioned in this paper made the attempt to revive Nordstrom's relativistic theory of gravitation which was rejected on the basis of it contravening observational reality in that it failed to account for the periastron precession of the planet Mercury and as well as the gravitational bending of starlight barely grazing the limb of a massive gravitational object such as the Sun.

TL;DR: In this paper, the authors report the results of a long-term spectral and timing study of the first transient magnetar, XTE J1810-197 which was discovered in 2003, when its X-ray luminosity increased by 100 fold.

TL;DR: In this article, the magnetic activity properties for a sample of M-type stars in Kepler field by using the two light-curve-based magnetic proxies, iAC and Reff, were studied.

TL;DR: In this article, the authors reviewed and analyzed the time series of light curve observations to search for period evolution of R Scuti star and found that the irregular behavior of the light curve was investigated by power spectral density (PSD) and fast Fourier transform (FFT) techniques.

TL;DR: In this paper, a double-lined eclipsing binary star in the field of the high metallicity old open cluster NGC 6791 was analyzed using high-precision Kepler photometry and high-resolution UVES and GIRAFFE spectroscopy from ESO Science Archieve.

TL;DR: In this article, the authors present the recent evolution of the Be disk in this system thanks to spectra collected by amateur spectroscopists since the end of 2013, showing that the emission linked to the be disk nearly disappeared in January 2014, but the disk has recovered, with a line strength now reaching levels only seen during the active phase of 1950-1990.

TL;DR: In this paper, the authors argue that the simulations that do not include magnetic fields are unable to capture the correct physics, in particular the high value of the magnetic Prandtl number, and the low value of magnetic diffusivity.

TL;DR: In this paper, the authors used the Wilson-Devinney (W-D) program with cool star-spots to analyze the first four-color (BVRcIc) light curves of NSVS 10441882.

TL;DR: In this article, the authors extend Pasetto et al. (2012) on a single composite-stellar population (CSP) to multiple CSPs, including also a phase-space description of the CSP concept.