We investigate the hydrodynamics of threedimensional classical Bondi-Hoyle accretion. A totally absorbing sphere of different sizes (1, 0.1 and 0.02 accretion radii) moves at different Mach numbers (0.6, 1.4, 3.0 and 10) relative to a homogeneous and slightly perturbed medium, which is taken to be an ideal, nearly isothermal, gas ( = 1:01). We examine the influence of Mach number of the flow an...

Abstract The transonic phenomenon of black hole accretion and the existence photon sphere characterize strong gravitational fields near a horizon. Here, we study spherical flow onto general parametrized spherically symmetric spacetimes. We analyze process for various perfect fluids, such as isothermal fluids ultra-stiff, ultra-relativistic, sub-relativistic types, polytropic fluid. influences a...

We present a model for the equilibrium of solid planetary cores embedded in a gaseous nebula. From this model we are able to extract an idealized roadmap of all hydrostatic states of the isothermal protoplanets. The complete classification of the isothermal protoplanetary equilibria should improve the understanding of the general problem of giant planet formation, within the framework of the nu...

In our previous study, (Eur Phys J Plus 135:362, 2020 & Eur 135:637, 2020), we have discussed the possible existence of dark-matter-admixed pulsars, located in dwarf as well massive spiral galaxies (based on Singular Isothermal Sphere dark-matter density profile) and Milky Way galaxy Universal Rotational Curve profile). this article, use Navarro–Frenk–White (NFW) profile to get analogous re...

ABSTRACT We consider the possibility that Milky Way’s dark matter halo possesses a non-vanishing equation of state. Consequently, we evaluate contribution due to speed sound, assuming content galaxy behaves like fluid with pressure. In particular, model distribution via an exponential sphere profile in galactic core, and inner parts whereas compare three widely used profiles for halo, i.e. Eina...

In previous studies we identified two classes of starless cores, thermally subcritical and supercritical, distinguished by different dynamical behavior and internal structure. Here we study the evolution of the dynamically-unstable, thermally-supercritical cores by means of a numerical hydrodynamic simulation that includes radiative equilibrium and simple molecular chemistry. From an initial st...

ABSTRACT General circulation models (GCMs) provide context for interpreting multiwavelength, multiphase data of the atmospheres tidally locked exoplanets. In current study, non-hydrostatic THOR GCM is coupled with HELIOS radiative transfer solver first time, supported by an equilibrium chemistry (FastChem), opacity calculator (HELIOS-K), and Mie scattering code (LX-MIE). To accurately treat rad...

see through the wall radar, is a relatively new small range radar that uses electromagnetic waves to detect targets behind wall. because of its symmetry, a conducting sphere is often used as a reference scatterer to calibrate radars. in this paper, to simulate received signal for see through the wall radar, scattering model of a conducting sphere in free space is presented. then using a dielect...