We provide a set of stellar evolution and nucleosynthesis calculations that applies established physics assumptions simultaneously to low- intermediate-mass massive star models. Our goal is an internally consistent comprehensive nuclear production yield data base for applications in areas such as pre-solar grain studies. non-rotating models assume convective boundary mixing where it has been adopted before. include 8 (12) initial masses $Z = 0.01$ ($0.02$). Models are followed either until...

A microprocessor based fault locator is described, which uses novel compensation techniques to improve accuracy. It displays the distance in percent of transmission line length, for facilitating repair and restoration following a permanent fault. Also, it pinpoints weak spots transient faults.

A fundamental basis has been developed for the use of a time-shared stored-program digital computer to perform many electrical power-system protective-relay functions in substation. Logic operations are given detect fault, locate it, and initiate opening appropriate circuit breakers, whether fault is station or on lines radiating from station.

We use three-dimensional hydrodynamical simulations to study the rapid infall phase of common envelope interaction a red giant branch star mass equal 0.88 \msun and companion ranging from 0.9 down 0.1 \msun. first compare results obtained using two different numerical techniques with resolutions, find overall very good agreement. then outcomes those observed systems thought have gone through envelope. The fail reproduce in sense that most donor remains bound at end final orbital separations...

Depending on mass and metallicity as well evolutionary phase, stars occasionally experience convective-reactive nucleosynthesis episodes. We specifically investigate the situation when nucleosynthetically unprocessed, H-rich material is convectively mixed with a He-burning zone, for example in unstable shell top of electron-degenerate cores AGB stars, young white dwarfs or X-ray bursting neutron stars. Such episodes are frequently encountered stellar evolution models extremely low zero metal...

We compare a suite of 3D explosion calculations and stellar models incorporating advanced physics with observational constraints on the progenitor Cassiopeia A. consider binary single stars from 16 to 40 solar masses range energies geometries. The parameter space allowed by observations nitrogen rich high velocity ejecta, ejecta mass, compact remnant 44Ti 56Ni abundances individually as an ensemble is considered. A 15-25 which loses its hydrogen envelope interaction undergoes energetic can...

Despite much effort in the past decades, C-burning reaction rate is uncertain by several orders of magnitude, and relative strength between different channels 12C(12C,alpha)20Ne, 12C(12C,p)23Na 12C(12C,n)23Mg poorly determined. Additionally, conditions a high 12C+12C may lead to lower central temperatures 13C(alpha,n)16O emerging as more dominant neutron source than 22Ne(alpha,n)25Mg, increasing significantly s-process production. This due rapid decrease 13N(gamma,p)12C with decreasing...

Although there is strong support for the collapsar engine as power source of long‐duration gamma‐ray bursts (GRBs), we still do not definitively know progenitor these explosions. Here review current set scenarios GRBs and observational constraints on scenarios. Examining models, find that single stars cannot be only GRBs. Several binary progenitors can match solid also have potential to trends are currently seeing in observations. Type Ib/c supernovae likely produced primarily binaries;...

In recent years, an increasing number of proper motions have been measured for Galactic X-ray binaries. When supplemented with accurate determinations the component masses, orbital period, and donor effective temperature, these kinematical constraints harbor a wealth information on system's past evolution. Here, we consider all this available to reconstruct full evolutionary history black hole binary XTE J1118+480, assuming that system originated in disk has solar metallicity. This analysis...

We report on numerical simulations of the detailed evolution single mode Rayleigh-Taylor [Lord Rayleigh, Scientific Papers II (Cambridge University Press, Cambridge, 1900), p. 200; G. I. Taylor, “The instability liquid surfaces when accelerated in a direction perpendicular to their plane,” Proc. R. Soc. London, Ser. A 201, 192 (1950)10.1098/rspa.1950.0052; S. Chandrasekhar, Hydrodynamic and Hydromagnetic Stability (Oxford Oxford, 1961)] late times high aspect ratios. In contrast established...

An experimental general-purpose process-control digital computer system provides high-speed phase-and ground-distance fault protection of one 230 kV transmission line. The stored program performs all the relaying functions using output an analog-to- converter which reads instantaneous value power- currents and voltages. Model line tests described in a companion paper (II -Test Results) form basis for preliminary performance evaluation. automatic oscillograph diagnostic programs will allow...

We carry out a comprehensive smooth particle hydrodynamics simulation survey of double-degenerate white dwarf binary mergers varying mass combinations in order to establish correspondence between initial conditions and remnant configurations. find that all but one our remnants share general properties such as cold, degenerate core surrounded by hot disk, while least massive pair stars forms only disk. characterize configurations the mass, rotational velocity core, half-mass radius also some...

We provide a description of the SNSPH code—a parallel three-dimensional radiation hydrodynamics code implementing tree gravity, smooth particle hydrodynamics, and flux-limited diffusion transport schemes. descriptions physics parallelization techniques for this code. present performance results on suite tests (both standard new), showing versatility such code, but focusing what we believe are important aspects modeling core-collapse supernovae.

Over the last 40 years, 12C +12C fusion reaction has been subject of considerable experimental efforts to constrain uncertainties at temperatures relevant for stellar nucleosynthesis. Recent studies have indicated that rate may be higher than currently used in models. In order investigate effect an enhanced carbon-burning on massive star structure and nucleosynthesis, new evolution models their yields are presented exploring impact three different rates. Non-rotating considering five initial...

We present a comprehensive study of white dwarf collisions as an avenue for creating type Ia supernovae. Using smooth particle hydrodynamics code with 13-isotope, {\alpha}-chain nuclear network, we examine the resulting 56Ni yield function total mass, mass ratio, and impact parameter. show that several combinations masses parameters are able to produce sufficient quantities be observable at cosmological distances. find production in double-degenerate ranges from sub-luminous super-luminous,...

We present simulations of the implosion a dense shell in two-dimensional (2D) spherical and cylindrical geometry performed with four different compressible, Eulerian codes: RAGE, FLASH, CASTRO, PPM. follow growth instabilities on inner face shell. Three codes employed Cartesian grid geometry, one (FLASH) polar geometry. While are similar, they employ advection algorithms, limiters, adaptive mesh refinement (AMR) schemes, interface-preservation techniques. find that rate instability is...

Abstract We review existing smoothed particle hydrodynamics setup methods and outline their advantages, limitations, drawbacks. present a new method for constructing initial conditions simulations, which may also be of interest N-body demonstrate this on number applications. This is inspired by adaptive binning techniques using weighted Voronoi tessellations. Particles are placed iteratively moved based proximity to neighbouring particles the desired spatial resolution. can satisfy...

Recent observations with the Chandra X-ray Observatory have provided us capability to discriminate point sources, such as supermassive black hole Sgr A*, from diffuse emission within inner 10'' of Galaxy. The hot plasma producing X-radiation, estimated at ~7.6*10^{31} ergs s^{-1} arcsec^{-2} in 2-10 keV band, has a RMS electron density ~26 cm^{-3} and temperature kT ~= 1.3 keV, total inferred mass ~0.1 solar masses. At least some this gas must be injected into ISM via stellar winds. In most...

High resolution observations of Sgr A* have revealed a wide variety phenomena, ranging from intense rapid flares to quasi-periodic oscillations, making this object an ideal system study the properties low luminosity accreting black holes. In paper, we use pseudo-spectral algorithm construct and evolve three-dimensional magnetohydrodynamic model accretion disk in A*. Assuming hybrid thermal-nonthermal emission scheme, show that MHD turbulence can by itself only produce factor two fluctuations...

An experimental general-purpose process-control digital- computer system described in a companion paper (I-System Description) provides high-speed phase-and ground-distance fault protection of one 230 kV transmission line. The stored program performs all the relaying functions using output an analog-to- digital converter which reads instantaneous value power- currents and voltages. Model line tests here form basis for preliminary performance evaluation. automatic oscillograph diagnostic...

It is suggested in observations of supernova remnants that a number large- and small-scale structures form at various points the explosion. Multidimensional modeling core-collapse supernovae has been undertaken since SN1987A, both simulations suggest/show Rayleigh-Taylor instabilities during explosion main driver for formation structure remnants. We present case study 3D \msol{15} different parameters. investigate effect moderate asymmetries resolutions morphology RT unstable region, take...

Multidimensional simulations of the neutrino-driven mechanism behind core-collapse supernovae have long shown that explosions from this would be asymmetric. Recently, detailed explosion may strongest in a single direction. We present suite modeling these "single-lobe" supernova 15 M☉ red supergiant star, focusing on effect asymmetries gamma-ray emission and mixing explosion. discuss how might explain many observed "asymmetries" supernovae, features both 1987A Cassiopeia A remnant. In...

Gamma-ray burst (GRB) afterglow observations have allowed us to significantly constrain the engines producing these energetic explosions. Te redshift and position information provided by afterglows already limit progenitors of GRBs only a few models. The may also provide another observation that can place further constraints on GRB progenitor: measurements telling about environments surrounding GRBs. Current analyses suggest roughly half long-duration gamma-ray bursts occur in surroundings...

We present the first detailed simulation of interaction between supernova explosion that produced Sgr A East and wind-swept inner ~2 pc region at Galactic center. The passage ejecta through this medium produces an X-ray ridge ~9''-15'' to northeast supermassive black hole Sagittarius A* (Sgr A*). show morphology intensity feature match very well with recently obtained Chandra images, we infer a remnant age less than 2000 yr. This young age—a factor 3-4 lower previous estimates—arises from...

The origin and initial mass function of young stellar clusters near the Galactic center are still poorly understood. Two more prominent ones, Arches Quintuplet clusters, may have formed from a shock-induced burst star formation, given their similar age proximity to each other. Their unusual distribution, however, be evidence contributing role played by other factors, such as capture regions outside themselves. Diffuse X-ray emission these sources provides us with valuable, albeit indirect,...