Cosmochemistry Space Science and Astrophysics-

The Mauritius Radio Telescope (MRT) has been built with the main objective of surveying the southern sky at meter wavelengths. MRT is a Fourier synthesis, T-shaped non-coplanar array. It consists of a2048 m long East-West arm with 1024 fixed helices and a ...

Here we formulate scenario of emergent universe from particle creation mechanism in spatially flat braneworld models. We consider an isotropic and homogeneous universe in Braneworld cosmology and universe is considered as a non-equilibrium thermodynamical system with dissipation due to particle creation mechanism. Assuming the particle creation rate as a function of the Hubble parameter , we formulate emergent scenario in RS2 and DGP models of Braneworld.

ABSTRACT We present the basic concepts of the two-mirror, three-reflection optical system (2MTRT), and discuss the important benefits of such a system for space projects: wide ( 2) correctedand unvignetted FOV, without the use of refractive optics for thefield correction, planarity of the focal surface for an optimizedinstallation of wide area detectors, easy telescope adjustement, small volume and little mass.We also report the results of optical tests made with a 30 cm prototype,equipped with a 2k 2k CCD camera, and give examples of scientific programmes which can be performed from space and in hostile terrestrial sites such as the Antarctic Plateau.

Empirical evidence for both stellar mass black holes M_bh<10^2 M_sun) and supermassive black holes (SMBHs, M_bh>10^5 M_sun) is well established. Moreover, every galaxy with a bulge appears to host a SMBH, whose mass is correlated with the bulge mass, and even more strongly with the central stellar velocity dispersion sigma_c, the `M-sigma' relation. On the other hand, evidence for "intermediate-mass" black holes (IMBHs, with masses in the range 1^2 - 10^5 M_sun) is relatively sparse, with only a few mass measurements reported in globular clusters (GCs), dwarf galaxies and low-mass AGNs. We explore the question of whether globular clusters extend the M-sigma relationship for galaxies to lower black hole masses and find that available data for globular clusters are consistent with the extrapolation of this relationship. We use this extrapolated M-sigma relationship to predict the putative black hole masses of those globular clusters where existence of central IMBH ...

Self-consistent system of spinor, scalar and BI gravitational fields in presence of magneto-fluid and Λ-term is considered. Assuming that the expansion of the BI universe is proportional to the σ_1^1 component of the shear tensor, exact solutions for the metric functions, as well as for scalar and spinor fields are obtained. For a non-positive Λ the initially anisotropic space-time becomes isotropic one in the process of expansion, whereas, for Λ > 0 an oscillatory mode of expansion of the BI model occurs.

We have carried out an intensive study of photometric (Kepler Mission) and spectroscopic data on the system Kepler-2 (HAT-P-7A) using the dedicated software WinFitter. The mean individual data-point error of the normalized flux values for this system is 0.00015, leading to the model's specification for the mean reference flux to an accuracy of ∼0.5 ppm. This testifies to the remarkably high accuracy of the binned data-set, derived from over 1.8 million individual observations. Spectroscopic data are reported with the similarly high-accuracy radial velocity amplitude measure of ∼2 m s^-1. The analysis includes discussion of the fitting quality and model adequacy. Our derived absolute parameters for Kepler-2 are as follows: M_p (Jupiter) 1.80 ± 0.13; R_ 1.46 ± 0.08 × 10^6 km; R_p 1.15 ± 0.07 × 10^5 km. These values imply somewhat larger and less condensed bodies than previously catalogued, but within reasonable error estimates of such literature parameters. We find also tidal, ref...

Plebanski and Demianski [1] presented a large class of solutions of Einstein's equa-tions with a possibly non-zero cosmological constant Λ, which includes, apart from other interesting solutions, the famous Kerr-Newman rotating black hole and hence the Kerr, the Reissner-...

A self-similar solution to the problem of the implosion of a cylindrical shock wave in the presence of a magnetic field has been investigated. A strong shock wave in a cylindrically-symmetric flow travels to the axis of symmetry through a gas of uniform initial density ρ0 and zero-pressure. A comparative study has been made between the results obtained in ordinary gasdynamics and magnetogasdynamics with transverse and axial components of the magnetic field. The value of similarity exponent α has been assigned from that found in the paper of Whitham (1958).

ABSTRACT Several contemporary modified models of gravity predict the existence of a non-Newtonian Yukawa-type correction to the classical gravitational potential. We study the motion of a secondary celestial body under the influence of the corrected gravitational force of a primary. We derive two equations to approximate the periastron time rate of change and its total variation over one revolution (i.e., the difference between the anomalistic period and the Keplerian period) under the influence of the non-Newtonian radial acceleration. Kinematically, this influence produces apsidal motion. We performed numerical estimations for Mercury, for the companion star of the pulsar PSR 1913+16, and for the extrasolar Planet b of the star HD 80606. We also considered the case of the artificial Earth satellite GRACE-A, but the results present a low degree of reliability from a practical standpoint. KeywordsCelestial mechanics–Orbital and rotational dynamics–Classical field theories

A detailed study of the low-lying electronic states of the H3^+ molecular ion in linear parallel configuration is carried out for B=0-4.414x10^13,in the Born-Oppenheimer approximation. It is shown that the ground state depends on the magnetic field strength. It evolves from the spin-singlet ^1 sigmag for small magnetic fields B<=5x10^8,to the weakly-bound spin- triplet ^3sigmau for intermediate fields and eventually to the strongly-bound spin-triplet ^3piu state for 5 x10^10,G<=B =5 x10^10,G the H3^+ molecular ion is stable towards all possible ionization and dissociation channels.

We consider a self-consistent system of Bianchi type-I (BI) gravitational field and a binary mixture of perfect fluid and dark energy. The perfect fluid is taken to be the one obeying the usual equation of state, i.e., p = ζ, with ζ∈ [0, 1] whereas, the dark energy is considered to be obeying a quintessence-like equation of state. Exact solutions to the corresponding Einstein equations are obtained. The model in consideration gives rise to a Universe which is spatially finite. Depending on the choice of problem parameters the Universe is either close with a space-time singularity, or an open one which is oscillatory, regular and infinite in time.

We discuss the expansion of the universe in the FRLW model assuming that the source of dark energy is either tachyonic scalar field or quintessence. The tachyonic scalar field with exponential and power-law potential (function of homogeneous scalar field ϕ) both gives exponential expansion of the universe. It is found that this behaviour is not distinguishable from the quintessence with respect to these potentials.

The Very Large Telescope (VLT) Observatory on Cerro Paranal (2635 m) in Northern Chile is approaching completion. After the four 8-m Unit Telescopes (UT) individually saw first light in the last years, two of them were combined for the first time on October 30, 2001 to form a stellar interferometer, the VLT Interferometer. The combination in pairs of all four UTs was completed in September 2002. In this article, we will describe the subsystems of the VLTI and the planning for the following years.

By applying Birkhoff's theorem to the problem of the general relativistic collapse of a uniform density dust, we directly show that the density of the dust ρ=0 even when its proper number density n would be assumed to be finite! The physical reason behind this exact result can be traced back to the observation of Arnowitt et al. that the gravitational mass of a neutral point particle is zero: m=0 (PRL, 4, 375, 1960). And since, a dust is a mere collection of neutral point particles, unlike a continuous hydrodynamic fluid, its density ρ = m n=0. It is nonetheless found that for k=-1, a homogeneous dust can collapse and expand special relativistically in the fashion of a Milne universe. Thus, in reality, general relativistic homogeneous dust collapse does not lead to the formation of any black hole in conformity of many previous studies (Logunov, Mestverishvili, Kiselev, Phys.Part.Nucl. 37, 317, 2006; Kisevev, Logunov & Mestvirishvili, Theor. Math. Phys., 164, 972, 2010; Mitra, J....

General integral operator for radiative transfer problems is considered and will be denoted asK τk {g(t)}.General theorems for theK-operator valid to any smooth functiong(t) will be established. The effect of the operator to the functions oftenly occur in transfer problems will also be established analytically and computationally.

... I I I I I 0 1 2 3 4 5 6 7 8 9 100 200 LRS Spectral Index Number of Stars Fig. 2. The spectral indices of featureless spectra of K and early-M stars are consistent with that of the Rayleigh-Jeans law (n = 8), while late-M stars tend to show smaller spectral indices indicating lower ...

We have re-analyzed old photometric UBV data obtained by Papoušek et al. at Skalnaté Pleso, Slovakia (1967–1980) and Brno, Czech Republic (1976–1979) observatories and analyzed new own CCD measurements (Brno, 2003–2005). In both set of photometric data the oscillations in the vicinity of the primary minimum were found. The detected periods are compatible with the previously published ones.