There is much debate about the origin of crystalline silicates in comets. Silicates protosolar cloud were likely amorphous, however temperature outer solar nebula was too cold to allow their formation this region by thermal annealing or direct condensation. This paper investigates inner hot regions nebula, and diffusive transport out comet zone, using a turbulent evolutionary model nebula. The uses time-dependent surface density profiles generated from 2-D α-disk Hersant et al. (2001). It...

Using the density and temperature profiles resulting from a two-dimensional turbulent model of solar nebula as well an appropriate law for time variation disk accretion rate, we integrate equation diffusion that rules evolution D/H ratio in H2O HCN throughout nebula. By fitting measured LL3 meteorites comets or inferred proto-Uranian proto-Neptunian ices, constrain parameters model, namely, initial rate (0), radius RD, α-coefficient viscosity, find 2 × 10-6 < (0) 10-5 M☉ yr-1, 12.8 RD 39 AU,...

We have developed 1D time-dependent numerical models of accretion discs, using an adaptive grid technique and implicit scheme, in which the disc size is allowed to vary with time. The code fully resolves cooling heating fronts propagating disc. show that radius outer edge fixed produce incorrect results, from probably conclusions about viscosity law been inferred. In particular we outside-in outbursts are possible when a standard bimodal behaviour Shakura–Sunyaev parameter α used. also...

We have developed 1D time-dependent numerical models of accretion discs, using an adaptive grid technique and implicit scheme, in which the disc size is allowed to vary with time. The code fully resolves cooling heating fronts propagating disc. show that radius outer edge fixed produce incorrect results, from probably conclusions about viscosity law been inferred. In particular we outside-in outbursts are possible when a standard bimodal behaviour Shakura-Sunyaev parameter α used. also...

We address the question of relations between black hole's mass, accretion rate, bolometric luminosity, optical luminosity and size Broad Line Region (BLR) in Active Galactic Nuclei, using recent observational data obtained from monitoring campaigns. first show that a standard disc cannot account for observed unless it radiates at super-Eddington rates. This implies existence another, dominant emission mechanism range, which could be due to reprocessing X-rays by system dense clouds, or non...

We demonstrate that the ``sub-keplerian'' rotation curve of maser spots in NGC 1068 can be explained by gravitational attraction disc orbiting central black hole. Possible parameters matching observations are: hole mass 12 million solar masses, outer edge &gt; 1.3 pc, aspect ratio range 0.003 to 0.3, surface density varying approximately as 1/R, and about 9.4 masses. The physical conditions required for excitation masers are fulfilled, would stand a gravitationally marginally stable state.

We present a model for the dwarf nova WZ Sge which does not require assumption of unexplained and unusually low values viscosity α-parameter during exceptionally long quiescent states this system. propose that inner parts accretion disc are disrupted by either magnetic field or evaporation, so is stable (or very close to being stable) in quiescence, as mass transfer rate can sit on cool, lower branch thermal equilibrium curve. Outbursts triggered an enhanced transfer, brings into unstable...

We examine under which conditions one may apply, to steady state Keplerian accretion discs, the β-viscosity prescription has been derived from rotating shear flow experiments (, where Ω is angular velocity at radius R and β a constant of order 10-5; Richard & Zahn [CITE]). Using vertically averaged model, we show that this law be suitable for all three families known systems: in young stellar objects, evolved binary stars Active Galactic Nuclei discs (except their outer gas pressure...

ABSTRACT We aim to unveil the observational imprint of physical mechanisms that govern planetary formation in young, multiple system GG Tau A. present ALMA observations 12 CO and 13 3–2 0.9 mm continuum emission with 0.″35 resolution. The emission, found within cavity circumternary dust ring (at radius &lt;180 au) where no is detected, confirms presence gas near circumstellar disk Aa. outer recently detected hot spot lying at edge are mapped both CO. can be radially decomposed as a series...

We exploit our formula for the gravitational potential of finite size, power-law disks to derive a general expression linking mass black hole in active galactic nuclei (AGN), surrounding disk, its surface density profile (through power index s), and differential rotation law. find that global curve v(R) disk centrifugal balance does not obey law cylindrical radius R (except confusing case s = -2 mimics Keplerian motion), discuss local velocity index. This can help understand how, from...

Mass models of galactic disks traditionally rely on axisymmetric density and rotation curves, paradoxically acting as if their most remarkable asymmetric features, such lopsidedness or spiral arms, were not important. In this article, we relax the axisymmetry approximation introduce a methodology that derives 3D gravitational potentials disk-like objects robustly estimates impacts asymmetries circular velocities in disk midplane. distribution can then be directly fitted to line-of-sight...

We investigate the relationship between circumstellar disks and Taylor-Couette flow. Using Reynolds similarity principle, this results in a number of parameter-free predictions about stability disks, their turbulent transport properties, provided disk structure is available. discuss how latter can be deduced from interferometric observations material. use resulting to compute molecular coefficients, including effect ionization by central object. The control parameter indicates that well into...

In a series of two papers, we present numerical, integral-based methods to compute accurately the self-gravitating field and potential induced by tri-dimensional, axially symmetric fluids, with special regard for tori, discs rings. This first article is concerned fully numerical approach. Complex shapes, small/large aspect ratios, important density gradients compact/extended systems can be accounted for. Loop singularities in Poisson integrals are carefully treated from kernel splitting...

We report an analytical expression for the locations of Lindblad resonances induced by a perturbing protoplanet, including effect disk gravity. Inner, outer and differential torques are found to be enhanced compared situations where keplerian velocity field dynamics both planet is assumed. Inward migration strongly accelerated when gravity only accounted in orbital motion. The addition self-gravity slows down drift but not enough stop it.

Self-gravitating accretion discs have only been studied in a few nearby objects using maser spots at the parsec-scale. We find new spectral window for observing self-gravitating disc super-Eddington accreting Active Galactic Nuclei (AGNs). This is determined by calculating outermost radius () of non and corresponding emission wavelength as function various parameters. that reaches ~ , when (where α, are, respectively, viscosity parameter, gas rate onto central black hole (BH), BH mass...

We demonstrate the high accuracy of density splitting method to compute gravitational potential and field in plane razor-thin, axially symmetric discs, as preliminarily outlined Pierens &amp; Hure (2004). Because residual kernels Poisson integrals are not C^infinity-class functions, we use a dynamical space mapping order increase efficiency advanced quadrature schemes. In terms accuracy, results better by orders magnitude than for classical FFT-methods.

Structure of a quasi-stationary stellar cluster is modelled assuming that it embedded in the gravitational field super-massive black hole. Gradual orbital decay trajectories caused by dissipative interaction with an accretion disc. Gravitational disc constructed and its effect on structure taken into account as axially symmetric perturbation. Attention focused circumnuclear region (r&lt;10^4 radii) where effects central hole dominate over influence outer galaxy. It shown how system becomes...

Aims.The physical properties of the massive disk candidate in star-forming region M 17 are analyzed.

Abstract We present a study of H$_{2}$O maser emission from the LINER, IC 1481, based on single-dish and highly sensitive VLBI observations. The Nobeyama 45-m telescope detected new features near systemic velocity blue-shifted by 124–205 km s$^{-1}$. In addition, known red-shifted $\approx $97–155 s$^{-1}$ were monitored. observations with High Sensitivity Array (HSA) revealed that are distributed along line, gradient, strongly suggesting nearly edge-on molecular gas disk. radius thickness...

We report new calculations of transition matrix elements for more than thirty thousand infrared lines the CO molecule and its isotopomers inside X ground electronic state. These belong to =1, 2, 3 bands involving very high excited states such as 41 133. The have been calculated from an accurate solution Schrödinger equation by using two different theoretical electric dipole moment functions (Werner 1981; Langhoff & Bauschlicher 1995). For low lying levels, our data compare satisfactorily...

The one-dimensional, ordinary differential equation (ODE) by Hur\'e & Hersant (2007) that satisfies the midplane gravitational potential of truncated, flat power-law disks is extended to whole physical space. It shown thickness effects (i.e. non-flatness) can be easily accounted for implementing an appropriate "softening length" $\lambda$. solution this "softened ODE" has following properties: i) it regular at edges (finite radial accelerations), ii) possesses correct long-range properties,...

We compute the structure of a self-gravitating torus with polytropic equation state (EOS) rotating in an imposed centrifugal potential. The Poisson solver is based on isotropic multigrid optimal covering factor (fluid section-to-grid area ratio). work at second order grid resolution for both finite difference and quadrature schemes. For soft EOS (i.e. index n ≥ 1), underlying naturally recovered boundary values any other integrated quantity sensitive to mass density (mass, angular momentum,...