The origin of chemically peculiar stars and non-zero eccentricity in evolved close binaries have been long-standing problems in binary stellar evolution. Answers to these questions may trace back to an intense mass transfer during AGB binary phase. In this work, we use AstroBEAR to solve the 3D radiation-hydrodynamic equations and calculate the mass transfer rate in asymptotic-giant-branch (AGB) binaries that undergo the wind-Roche-lobe-overflow or Bondi-Hoyle-Lyttleton (BHL) accretion. MESA produces the density and temperature of the boundary condition of the AGB star. To improve the resolution of the dynamics of a circumbinary disk, we implement an azimuthal angle-dependent 3D radiation transfer. We consider optically thin cooling and obtain the number density of the coolants by solving Saha equations. One of the goals of this work is to illustrate the transition from the wind-Roche-lobe-overflow to BHL accretion. Both circumbinary disks and spiral structure outflows can appear in the simulations. Circumbinary disks may form when the optical thickness in the equatorial region increases. The increase of the optical thickness is due to the deflected wind. The resulting mass transfer efficiency in our models is up to a factor of 8 times higher than what the standard BHL accretion scenario predicts, and the outflow gains up to 91% of its initial angular momentum when it reaches 1.3 binary separations. Consequently, some AGB binaries may undergo orbit shrinkage, and some will expand. The high mass transfer efficiency is closely related to the presence of the circumbinary disks.
Context: Observations of asymptotic giant branch (AGB) stars with increasing spatial resolution reveal new layers of complexity of atmospheric processes on a variety of scales. Aim: To analyze the physical mechanisms that cause asymmetries and surface structures in observed images, we use detailed 3D dynamical simulations of AGB stars; these simulations self-consistently describe convection and pulsations. Methods: We used the CO5BOLD radiation-hydrodynamics code to produce an exploratory grid of global "star-in-a-box" models of the outer convective envelope and the inner atmosphere of AGB sta…
With the use of high-resolution ALMA observations, complex structures that resemble those observed in post-AGB stars and planetary nebulae are detected in the circumstellar envelopes of low-mass evolved stars. These deviations from spherical symmetry are believed to be caused primarily by the interaction with a companion star or planet. With the use of three-dimensional hydrodynamic simulations, we study the impact of a binary companion on the wind morphology and dynamics of an AGB outflow. We classifiy the wind structures and morphology that form in these simulations with the use of a classif…
We present a detailed hydrodynamic model that matches the present structure of the well-observed preplanetary nebula OH231.8+04.2. The purpose of the model is to present a physically justified and coherent picture of its evolutionary history from about 100 years of the start of the formation of its complex outer structures to the present. We have adopted a set of initial conditions that are heavily constrained by high-quality observations of its present structure and kinematics. The shaping of the nebula occurs while the densities of the flows are "light": less than the surrounding AGB-wind en…
The Rotten Egg Nebula has at its core a binary composed of a Mira star and an A-type companion at a separation >10 au. It has been hypothesized to have formed by strong binary interactions between the Mira and a companion in an eccentric orbit during periastron passage ~800 years ago. We have performed hydrodynamic simulations of an asymptotic giant branch star interacting with companions with a range of masses in orbits with a range of initial eccentricities and periastron separations. For reasonable values of the eccentricity, we find that Roche lobe overflow can take place only if the perio…
Volume complete sky surveys provide evidence for a binary origin for the formation of isolated white dwarfs with magnetic fields in excess of a MegaGauss. Interestingly, not a single high-field magnetic white dwarf has been found in a detached system suggesting that if the progenitors are indeed binaries, the companion must be removed or merge during formation. An origin scenario consistent with observations involves the engulfment, inspiral, and subsequent tidal disruption of a low-mass companion in the interior of a giant star during a common envelope phase. Material from the shredded compan…
The winds observed around asymptotic giant branch (AGB) stars are generally attributed to radiation pressure on dust, which is formed in the extended dynamical atmospheres of these pulsating, strongly convective stars. Current radiation-hydrodynamical models can explain many of the observed features, and they are on the brink of delivering a predictive theory of mass loss. This review summarizes recent results and ongoing work on winds of AGB stars, discussing critical ingredients of the driving mechanism, and first results of global 3D RHD star-and-wind-in-a-box simulations. With such models …
We study the sub-Keplerian rotation and dust content of the circumstellar material around the asymptotic giant branch (AGB) star L$_2$ Puppis. We find that the thermal pressure gradient alone cannot explain the observed rotation profile. We find that there is a family of possible dust populations for which radiation pressure can drive the observed sub-Keplerian rotation. This set of solutions is further constrained by the spectral energy distribution (SED) of the system, and we find that a dust-to-gas mass ratio of $\sim10^{-3}$ and a maximum grain size that decreases radially outwards can sat…
Wind mass transfer in binary systems with AGB donor stars plays a fundamental role in the formation of a variety of objects, including barium stars and CEMP stars. We carry out a comprehensive set of SPH simulations of wind-losing AGB stars in binaries, for a variety of binary mass ratios, orbital separations, initial wind velocities and rotation rates of the donor star. The initial parameters of the simulated systems are chosen to match the expected progenitors of CEMP stars. We find that the strength of interaction between the wind and the stars depends on both the wind-velocity-to-orbital-v…
Recent observations of the L2 Puppis system suggest that this Mira-like variable may be in the early stages of forming a bipolar planetary nebula (PN). As one of nearest and brightest AGB stars, thought be a binary, L2 Puppis serves as a benchmark object for studying the late-stages of stellar evolution. We perform global, three-dimensional, adaptive-mesh-refinement hydrodynamic simulations of the L2 Puppis system with AstroBEAR. We use the radiative transfer code RADMC-3D to construct the broad-band spectral-energy-distribution (SED) and synthetic observational images from our simulations. Gi…
Convection and mass loss by stellar winds are two dynamical processes that shape asymptotic giant branch (AGB) stars and their evolution. Observations and earlier 3D models indicate that giant convection cells cause high-contrast surface intensity patterns, and contribute to the origin of clumpy dust clouds. We study the formation and resulting properties of dust-driven winds from AGB stars, using new global 3D simulations. The dynamical stellar interiors, atmospheres, and wind acceleration zones of two M-type AGB stars were modeled with the CO5BOLD code. These first global 3D simulations are …
We present the detection of neutral atomic carbon CI(3 P1 - 3 P0 ) line emission towards omi Cet. This is the first time that CI is detected in the envelope around an oxygen-rich M-type asymptotic giant branch (AGB) star. We also confirm the previously tentative CI detection around V Hya, a carbon-rich AGB star. As one of the main photodissociation products of parent species in the circumstellar envelope (CSE) around evolved stars, CI can be used to trace sources of ultraviolet (UV) radiation in CSEs. The observed flux density towards omi Cet can be reproduced by a shell with a peak atomic fra…
The possibility that mass ejected during Asymptotic Giant Branch (AGB) stellar evolution phases falls back towards the star has been suggested in applications ranging from the formation of accretion disks to the powering of late-thermal pulses. In this paper, we seek to explicate the properties of fallback flow trajectories from mass-loss events. We focus on a transient phase of mass ejection with sub-escape speeds, followed by a phase of a typical AGB wind. We solve the problem using both hydrodynamic simulations and a simplified one-dimensional analytic model that matches the simulations. Fo…
The $s$-process nucleosynthesis in Asymptotic Giant Branch (AGB) stars depends on the modeling of convective boundaries. We present models and s-process simulations that adopt a treatment of convective boundaries based on the results of hydrodynamic simulations and on the theory of mixing due to gravity waves in the vicinity of convective boundaries. Hydrodynamics simulations suggest the presence of convective boundary mixing (CBM) at the bottom of the thermal pulse-driven convective zone. Similarly, convection-induced mixing processes are proposed for the mixing below the convective envelope …
High spatial resolution techniques have given valuable insights into the mass loss mechanism of AGB stars, which presumably involves a combination of atmospheric levitation by pulsation-induced shock waves and radiation pressure on dust. Observations indicate that Al$_2$O$_3$ condenses at distances of about 2 stellar radii or less, prior to the formation of silicates. Al$_2$O$_3$ grains are therefore prime candidates for producing the scattered light observed in the close vicinity of several M-type AGB stars, and they may be seed particles for the condensation of silicates at lower temperature…
Calculations of stellar evolution up to the early white dwarf stage were carried out for stars with mass on the main sequence $M_0=0.82M_\odot$, $0.85M_\odot$, $0.9M_\odot$ and with initial abundances of helium and heavier elements $Y=0.25$ and $Z=10^{-3}$, respectively. For each value of $M_0$ the AGB and post--AGB evolutionary phases were computed with three values of the mass loss parameter in the Blöcker formula: $η_B=0.02$, 0.05 and 0.1. The variable star RU~Cam with pulsation period $Π\approx 22$ day is shown to be in the post--AGB stage and the pulsation amplitude decrease in years 1962…
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；Institute for Frontiers in Astronomy and Astrophysics, Beijing Normal University（北京师范大学天文与前沿科学研究院）；Yunnan Observatories, Chinese Academy of Sciences (CAS)（中国科学院云南天文台）；University of Chinese Academy of Sciences（中国科学院大学）；Henan Normal University（河南师范大学）
A significant fraction of isolated white dwarfs host magnetic fields in excess of a MegaGauss. Observations suggest that these fields originate in interacting binary systems where the companion is destroyed thus leaving a singular, highly-magnetized white dwarf. In post-main-sequence evolution, radial expansion of the parent star may cause orbiting companions to become engulfed. During the common envelope phase, as the orbital separation rapidly decreases, low-mass companions will tidally disrupt as they approach the giant's core. We hydrodynamically simulate the tidal disruption of planets an…
We present a radiation hydrodynamics simulation of the formation of a massive star using a Monte Carlo treatment for the radiation field. We find that strong, high speed bipolar cavities are driven by the radiation from the protostar, and that accretion occurs stochastically from a circumstellar disc. We have computed spectral energy distributions and images at each timestep, which may in future be used to compare our models with photometric, spectroscopic, and interferometric observations of young massive stellar objects.
We report a spectropolarimetric study of the post-AGB binary system 89 Herculis, based on data acquired with the high-resolution Catania Astrophysical Observatory Spectropolarimeter, the HArps-North POlarimeter and the Echelle SpectroPolarimetric Device for the Observation of Stars. The linear polarization clearly detected across single atmospheric lines in absorption is characterized by complex Q and U morphologies that are variable with the orbital period of the system. Gauss-level magnetic fields, continuum depolarization due to pulsations, hot spots and scattering in the circumstellar envi…
Evolutionary tracks of stars with masses on the main sequence $0.84M_\odot\le M_\textrm{ZAMS}\le 0.95M_\odot$ and initial metal abundances $Z=0.006$ and $Z=0.01$ were computed under various assumptions about the mass loss rate at the red giant stage as well as at the AGB and the post--AGB stages. Among 160 evolutionary sequences we selected nearly 30 sequences where the final thermal flash of the helium shell source occurs in the early post--AGB stage when the ratio of the hydrogen envelope mass to the stellar mass ranges from 0.01 to 0.08. Selected evolutionary sequences were used for calcula…
We investigate mass transfer and the formation of disc in binary systems using a combination of numerical simulations and theory. We consider six models distinguished by binary separation, secondary mass and outflow mechanisms. Each system consists of an asymptotic-giant-branch (AGB) star and an accreting secondary. The AGB star loses its mass via a wind. In one of our six models, the AGB star incurs a short period of outburst. In all cases, the secondary accretes part of the ejected mass and also influences the mass-loss rate of the AGB star. The ejected mass may remain gravitationally bound …
The material lost through stellar winds of Asymptotic Giant Branch (AGB) stars is one of the main contributors to the chemical enrichment of galaxies. The general hypothesis of the mass loss mechanism of AGB winds is a combination of stellar pulsations and radiative pressure on dust grains, yet current models still suffer from limitations. Among others, they assume chemical equilibrium of the gas, which may not be justified due to rapid local dynamical changes in the wind. This is important as it is the chemical composition that regulates the thermal structure of the wind, the creation of dust…
Carbon-enhanced metal-poor stars, CH stars and barium stars, among other classes of chemically peculiar stars, are thought to be products of the interaction of low- and intermediate-mass binaries which occurred when the most evolved star was in the asymptotic giant branch (AGB) phase. Binary evolution models predict that if the initial orbital periods of such systems are shorter than a few thousand days, their orbits should have circularised due to tidal effects. However, observations of the progeny of AGB binaries show that many of these objects have substantial eccentricities, up to about 0.…
This work is part of an ongoing effort aiming at identifying the actual wind-drivers among the dust species observed in circumstellar envelopes. In particular, we focus on the interplay between a strong stellar radiation field and the dust formation process. To identify critical properties of potential wind-driving dust species we use detailed radiation-hydrodynamical models which include a parameterized dust description, complemented by simple analytical estimates to help with the physical interpretation of the numerical results. The adopted dust description is constructed to mimic different …
VLTI/PIONIER imaging of post-AGB binaries. An INSPIRING hunt for inner rim substructures in circumbinary discs
KU Leuven（荷鲁文大学）；Macquarie University（麦考瑞大学）；European Southern Observatory（欧洲南方天文台）；Observatorio Astronómico Nacional (OAN-IGN)（国家天文观测台（OAN-IGN））；Georgia State University（佐治亚州立大学）
本文利用VLTI/PIONIER干涉成像技术，研究后AGB双星系统的内 rim 结构，揭示可能的子结构，发现四个目标存在异常亮度增强，可能由辐射或动力学响应或流体不稳定性引起。
Dimtri Mihalas' textbooks in the 70's and 80's on "Stellar Atmospheres" and "Foundations of Radiation Hydrodynamics" helped lay the early groundwork for understanding the moving atmospheres and winds of massive, luminous stars. Indeed, the central role of the momentum of stellar radiation in driving the mass outflow makes such massive-star winds key prototypes for radiation hydrodynamical processes. This paper reviews the dynamics of such radiative driving, building first upon the standard CAK model, and then discussing subtleties associated with the development and saturation of instabilities…
(abridged) In the inner regions of AGB outflows, several molecules have been detected with abundances much higher than those predicted from thermodynamic equilibrium (TE) chemical models. The presence of the majority of these species can be explained by shock-induced non-TE chemical models, where shocks caused by the pulsating star take the chemistry out of TE in the inner region. Moreover, a non-uniform density structure has been detected in several AGB outflows. A detailed parameter study on the quantitative effects of a non-homogeneous outflow has so far not been performed. We implement a p…
Nearly all energy generated by fusion in the solar core is ultimately radiated away into space in the solar atmosphere, while the remaining energy is carried away in the form of neutrinos. The exchange of energy between the solar gas and the radiation field is thus an essential ingredient of atmospheric modeling. The equations describing these interactions are known, but their solution is so computationally expensive that they can only be solved in approximate form in multi-dimensional radiation-MHD modeling. In this review, I discuss the most commonly used approximations for energy exchange b…
We present a set of new numerical methods that are relevant to calculating radiation pressure terms in hydrodynamics calculations, with a particular focus on massive star formation. The radiation force is determined from a Monte Carlo estimator and enables a complete treatment of the detailed microphysics, including polychromatic radiation and anisotropic scattering, in both the free-streaming and optically-thick limits. Since the new method is computationally demanding we have developed two new methods that speed up the algorithm. The first is a photon packet splitting algorithm that enables …
Stellar evolution calculations for population II stars with initial composition $Y_0=0.25$, $Z_0=10^{-3}$ and the initial stellar mass $M_0 = 0.82M_\odot$ were carried out from the main sequence to the white dwarf stage. Twelve AGB and post--AGB evolutionary sequences were computed with different values of the parameter in the Blocker mass loss rate formula ($0.01\leη_B\le 0.12$). Selected models of evolutionary sequences with masses $M=0.536M_\odot$, $0.530M_\odot$ and $0.526M_\odot$ that experience the loop in the Hertzsprung--Russel diagram due to the final helium flash were used as initial…
We present results from combining a grid-based radiative transfer code with a Smoothed Particle Hydrodynamics code to produce a flexible system for modelling radiation hydrodynamics. We use a benchmark model of a circumstellar disc to determine a robust method for constructing a gridded density distribution from SPH particles. The benchmark disc is then used to determine the accuracy of the radiative transfer results. We find that the SED and the temperature distribution within the disc are sensitive to the representation of the disc inner edge, which depends critically on both the grid and SP…
In low-mass binary systems, mass transfer is likely to occur via a slow and dense stellar wind when one of the stars is in the AGB phase. Observations show that many binaries that have undergone AGB mass transfer have orbital periods of 1-10 yr, at odds with the predictions of binary population synthesis models. We investigate the mass-accretion efficiency and angular-momentum loss via wind mass transfer in AGB binary systems. We use these quantities to predict the evolution of the orbit. We perform 3D hydrodynamical simulations of the stellar wind lost by an AGB star using the AMUSE framework…
There has been tremendous progress in the degree of realism of three-dimensional radiation magneto-hydrodynamic simulations of the solar atmosphere in the past decades. Four of the most frequently used numerical codes are Bifrost, CO5BOLD, MANCHA3D, and MURaM. Here we test and compare the wave propagation characteristics in model runs from these four codes by measuring the dispersion relation of acoustic-gravity waves at various heights. We find considerable differences between the various models. The height dependence of wave power, in particular of high-frequency waves, varies by up to two o…
We conduct three-dimensional hydrodynamical simulations of two opposite jets launched obliquely to the orbital plane around an asymptotic giant branch (AGB) star and within its dense wind, and demonstrate the formation of a `messy' planetary nebula (PN), namely, a PN lacking any type of symmetry (highly irregular). In building the initial conditions we assume that a tight binary system orbits the AGB star, and that the orbital plane of the tight binary system is inclined to the orbital plane of the binary system and the AGB star (the triple system plane). We further assume that the accreted ma…
The late evolutionary stages of low- and intermediate-mass stars are characterised by mass loss through a dust-driven stellar wind. Recent observations reveal complex structures within these winds, that are believed to be formed primarily via interaction with a companion. How these complexities arise, and which structures are formed in which type of systems, is still poorly understood. Particularly, there is a lack of studies investigating the structure formation in eccentric systems. We aim to improve our understanding of the wind morphology of eccentric AGB binary systems by investigating th…
Beyond the main sequence solar type stars undergo extensive mass loss, providing an environment where planet and brown dwarf companions interact with the surrounding material. To examine the interaction of substellar mass objects embedded in the stellar wind of an asymptotic giant branch (AGB) star, three dimensional hydrodynamical simulations at high resolution have been calculated utilizing the FLASH adaptive mesh refinement code. Attention is focused on the perturbation of the substellar mass objects on the morphology of the outflowing circumstellar matter. In particular, we determine the p…
Spherical asymmetries are prevalent within the outflows of AGB stars. Since binary interaction with a stellar or planetary companion is thought to be the underlying mechanism behind large-scale structures, we included the effects of UV radiation originating from a stellar companion in our chemical kinetics model. The one-dimensional model provides a first approximation of its effects on the chemistry throughout the outflow. The presence of a close-by stellar companion can strongly influence the chemistry within the entire outflow. Its impact depends on the intensity of the radiation (set by th…
Low- and intermediate mass stars experience a significant mass loss during the last phases of their evolution, which obscures them in a vast, dusty envelope. Although it has long been thought this envelope is generally spherically symmetric in shape, recent high-resolution observations find that most of these stars exhibit complex and asymmetrical morphologies, most likely resulting from binary interaction. In order to improve our understanding about these systems, theoretical studies are needed in the form of numerical simulations. Currently, a handful of simulations exist, albeit they mainly…
Motivated by recent theoretical work on tidal disruption events and other peculiar transients, we present moving-mesh radiation-hydrodynamic simulations of radiative luminosity emitted by a central source being reprocessed by a wind-like outflow. We couple the moving-mesh hydrodynamic code JET with our newly-developed radiation module based on mixed-frame grey flux-limited diffusion with implicit timestep update. This allows us to study the self-consistent multi-dimensional radiation-hydrodynamic evolution over more than ten orders of magnitude in both space and time in a single run. We simula…
We present the newly-incorporated gray radiation hydrodynamics capabilities of the FLASH code based on a radiation flux-limiter aware hydrodynamics numerical implementation designed specifically for applications in astrophysical problems. The newly incorporated numerical methods consist of changes in the unsplit hydrodynamics solver and adjustments in the flux-limited radiation diffusion unit. Our method can treat problems in both the strong and weak radiation-matter coupling limits as well as transitions between the two regimes. Appropriate extensions in the "Helmholtz" equation of state are …
We use multi-frequency radiation hydrodynamics (rad-HD) to simulate radiative acceleration of a spherically symmetric stellar wind. We demonstrate the rad-HD capabilities of Athena++ for a series of test problems with multi-group radiation transfer. We then model the radiative transfer of a single spectral line through a spherically symmetric, isothermal, "CAK"-type line driven wind. We find that correctly accounting for the Doppler shift of the absorbed radiation, the force is well described by the analytic Sobolev line transfer in the supersonic parts of the solution where the flow is statio…
The study of post asymptotic giant branch (post-AGB) stars is a valuable tool to study still poorly known aspects of the evolution of the stars through the AGB. This is due to the accurate determination of their surface chemical composition and to the peculiar shape of the SED: the emission from the central star can be easily disentangled from the contribution from the dusty shell, which can then be characterized. The goal of the present study is to reconstruct the dust formation process and more generally the late phases of the evolution of O-rich stars across the AGB phase. This is performed…
We investigate the general stability of 1D spherically symmetric ionized Bondi accretion onto a massive object in the specific context of accretion onto a young stellar object. We first derive a new analytic expression for a steady state two temperature solution that predicts the existence of compact and hypercompact HII regions. We then show that this solution is only marginally stable if ionization is treated self-consistently. This leads to a recurring collapse of the HII region over time. We derive a semi-analytic model to explain this instability, and test it using spatially converged 1D …
A truncated moment formalism for general relativistic radiation hydrodynamics, based on the Thorne's moment formalism, is derived. The fluid rest frame is chosen to be the fiducial frame for defining the radiation moments. Then, zeroth-, first-, and second-rank radiation moments are defined from the distribution function with a physically reasonable assumption for it in the optically thin and thick limits. The source terms are written, focusing specifically on the neutrino transfer and neglecting higher harmonic angular dependence of the reaction angle. Finally, basic equations for a truncated…
Recent observations of strikingly well-defined spirals in the circumstellar envelopes of asymptotic giant branch (AGB) stars point to the existence of binary companions in these objects. In the case of planet or brown dwarf mass companions, we investigate the observational properties of the spiral-onion shell wakes due to the gravitational interaction of these companions with the outflowing circumstellar matter. Three dimensional hydrodynamical simulations at high resolution show that the substellar mass objects produce detectable signatures at 100 AU distance, for the wake induced by a Jupite…
Radiation controls the dynamics and energetics of many astrophysical environments. To capture the coupling between the radiation and matter, however, is often a physically complex and computationally expensive endeavour. We develop a numerical tool to perform radiation-hydrodynamics simulations in various configurations at an affordable cost. We build upon the finite volume code MPI-AMRVAC to solve the equations of hydrodynamics on multi-dimensional adaptive meshes and introduce a new module to handle the coupling with radiation. A non-equilibrium, flux-limiting diffusion approximation is used…
We investigate the effect of including diffuse field radiation when modelling the radiatively driven implosion of a Bonnor-Ebert sphere (BES). Radiation-hydrodynamical calculations are performed by using operator splitting to combine Monte Carlo photoionization with grid-based Eulerian hydrodynamics that includes self-gravity. It is found that the diffuse field has a significant effect on the nature of radiatively driven collapse which is strongly coupled to the strength of the driving shock that is established before impacting the BES. This can result in either slower or more rapid star forma…
We present a formulation for multigroup radiation hydrodynamics that is correct to order $O(v/c)$ using the comoving-frame approach and the flux-limited diffusion approximation. We describe a numerical algorithm for solving the system, implemented in the compressible astrophysics code, CASTRO. CASTRO uses an Eulerian grid with block-structured adaptive mesh refinement based on a nested hierarchy of logically-rectangular variable-sized grids with simultaneous refinement in both space and time. In our multigroup radiation solver, the system is split into three parts, one part that couples the ra…
We describe the development of a flux-limited gray radiation solver for the compressible astrophysics code, CASTRO. CASTRO uses an Eulerian grid with block-structured adaptive mesh refinement based on a nested hierarchy of logically-rectangular variable-sized grids with simultaneous refinement in both space and time. The gray radiation solver is based on a mixed-frame formulation of radiation hydrodynamics. In our approach, the system is split into two parts, one part that couples the radiation and fluid in a hyperbolic subsystem, and another parabolic part that evolves radiation diffusion and…
Context: Radiative feedback plays a crucial role in the formation of massive stars. The implementation of a fast and accurate description of the proceeding thermodynamics in pre-stellar cores and evolving accretion disks is therefore a main effort in current hydrodynamics simulations. Aims: We introduce our newly implemented three-dimensional frequency dependent radiation transport algorithm for hydrodynamics simulations of spatial configurations with a dominant central source. Methods: The module combines the advantage of the speed of an approximate Flux Limited Diffusion (FLD) solver with th…
