We use fractional integrals to generalize the description of hydrodynamic accretion in fractal media. The fractional continuous medium model allows the generalization of the equations of balance of mass density and momentum density. These make it possible to consider the general case of spherical hydrodynamic accretion onto a gravitating mass embedded in a fractal medium. The general nature of ...

North part of Japan is one of the heaviest snowfall regions in winter. In a certain case, wet snow accretes to civil engineering structure such as power lines. There is a demand for the prediction that when the snow accretion will occur. General weather forecast is not enough resolution and meteorological variable for estimating snow accretion. By calculating weather condition on our own accoun...

Our X-ray study of the nuclear activity in a new sample of six quiescent early-type galaxies, and in a larger sample from the literature, confirmed (Soria et al., Paper I) that the Bondi accretion rate of diffuse hot gas is not a good indicator of the supermassive black hole (SMBH) X-ray luminosity; in fact, the two quantities appear uncorrelated. Here we suggest that a more reliable estimate o...

A variety of current models for gamma-ray bursts (GRBs) suggest a common engine a black hole of several solar masses accreting matter from a disk at a rate 0.01 to 10 M ⊙ s. Using a numerical model for relativistic disk accretion, we have studied steady-state accretion at these high rates. Outside about 10 cm, the disk is advection dominated; energy released by dissipation is carried in by the ...

We present one of the first physically-motivated two-dimensional general relativistic magnetohydrodynamic (GRMHD) numerical simulations of a radiatively-cooled black-hole accretion disk. The fiducial simulation combines a total-energy-conserving formulation with a radiative cooling function, which includes bremsstrahlung, synchrotron, and Compton effects. By comparison with other simulations we...

In this note we study the accretion disc that arises in hypercritical accretion of Ṁ ∼ 10 MEdd onto a neutron star while it is in common envelope evolution with a massive companion. Such a study was carried out by Chevalier (1996), who had earlier suggested that the neutron star would go into a black hole in common envelope evolution. In his later study he found that the accretion could possibl...

We report on the first dedicated monitoring campaign of spectroscopic variability in young brown dwarfs. High-resolution optical spectra of six targets in nearby star-forming regions were obtained over 11 nights between 2005 JanuaryMarch on the Magellan 6.5m telescope. We find significant variability in Hα and a number of other emission lines related to accretion and outflow processes on a vari...

Planetesimal accretion during planet formation is usually treated as collisionless. Such accretion from a uniform and dynamically cold disk predicts protoplanets with slow retrograde rotation. However, if the building blocks of protoplanets, planetesimals, are small, of order of a meter in size, then they are likely to collide within the protoplanet’s sphere of gravitational influence, creating...

We present new numerical simulations in the thin-disk approximation which characterize the burst mode of protostellar accretion. The burst mode begins upon the formation of a centrifugally balanced disk around a newly formed protostar. It is comprised of prolonged quiescent periods of low accretion rate (typically . 10M⊙ yr ) which are punctuated by intense bursts of accretion (typically & 10M⊙...

Motion parallax, or differential retinal image motion from observer movement, provides important information for depth perception. We previously measured the contribution of shear motion parallax to depth, which is only composed of relative motion information. Here, we examine the roles of relative motion and accretion-deletion information in dynamic occlusion motion parallax. Observers perform...