A5071518939- Astrophysics and Star Formation Studies
- Stellar, planetary, and galactic studies
- Astro and Planetary Science
- Molecular Spectroscopy and Structure
- Astrophysical Phenomena and Observations
- Atmospheric Ozone and Climate
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Spectroscopy and Laser Applications
- Phase Equilibria and Thermodynamics
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Advanced Chemical Physics Studies
- Astrophysics and Cosmic Phenomena
- Advanced Combustion Engine Technologies
- Atomic and Molecular Physics
- Atmospheric chemistry and aerosols
- Planetary Science and Exploration
- Calibration and Measurement Techniques
- Methane Hydrates and Related Phenomena
- Spacecraft and Cryogenic Technologies
- SAS software applications and methods
- Protein Structure and Dynamics
- Thermal Radiation and Cooling Technologies
Excellence Cluster Origins
2019-2024
Ludwig-Maximilians-Universität München
2015-2024
Excellence Cluster Universe
2014-2023
Stuttgart Observatory
2013-2023
University of Exeter
2010-2023
LMU Klinikum
2023
Bayer (Germany)
2022
Bayerische Staatssammlung für Paläontologie und Geologie
2018
Technical University of Munich
2012-2014
Federal Foreign Office
2011
Context: The global size and spatial distribution of dust is an important ingredient in the structure evolution protoplanetary disks formation larger bodies, such as planetesimals. Aims: We aim to derive simple equations that explain surface density profile upper limit grain which can readily be used for further modeling or interpreting observational data. Methods: have developed a model follows end profile. This calibrated with state-of-the-art simulations evolution, treat growth,...
(Abridged) We present the first radiation-hydrodynamic model of a protoplanetary disc irradiated with an X-EUV spectrum. In where total ionizing luminosity is divided equally between X-ray and EUV luminosity, we find photoevaporation rate 1.4e-8 M_sun/yr, which two orders magnitude greater than case alone. Thus it clear that X-rays are dominant driving mechanism for photoevaporation. This can be understood inasmuch as capable penetrating much larger columns (~1e22 cm^-2) thus effect heating...
(Abridged) We explore the role of X-ray photoevaporation in evolution and dispersal viscously evolving T-Tauri discs. show that wind rates scale linearly with luminosity, such observed range luminosities for solar-type stars (10e28-10e31 erg\s) gives rise to vigorous disc winds order 10e-10-10e-7 M_sun/yr. use solutions from radiation-hydrodynamic models, coupled a viscous model construct population synthesis so we may study physical properties discs so-called `transition discs'. Current...
We present an SPH parameter study of the dynamical effect photoionization from O--type stars on star--forming clouds a range masses and sizes during time window before supernovae explode. Our model all have same degree turbulent support initially, ratio kinetic energy to gravitational potential being set $E_{\rm kin}/|E_{\rm pot}|$=0.7. allow form effects ionizing radiation massive or clusters born within them. find that dense filamentary structures accretion flows limit quantities gas can...
We discuss a hydrodynamical model for the dispersal of protoplanetary discs around young, low mass (<1.5 M_sun) stars by photoevaporation from central object's energetic radiation, which considers far-ultraviolet as well X-ray component radiation field. present analytical scaling relations and derive estimates total mass-loss rates, discussing existence similarity solutions flows primordial with inner holes. Furthermore, we perform numerical calculations, span wide range parameter space...
We model the combined effects of photoionization and momentum--driven winds from O--stars on molecular clouds spanning a parameter space initial conditions. The dynamical are very modest. However, in lower--mass clouds, they influence morphologies HII regions by creating 10pc--scale central cavities.\\ inhomogeneous structures GMCs make them highly permeable to photons, ionized gas supernova ejecta, leaking particular strongly affects their evolution, reducing effectiveness feedback....
Theoretical models of grain growth predict dust properties to change as a function protoplanetary disk radius, mass, age and other physical conditions. We lay down the methodology for multi-wavelength analysis (sub-)mm cm continuum interferometric observations constrain self-consistently structure radial variation properties. The computational architecture is massively parallel highly modular. based on simultaneous fit in uv-plane at several wavelengths with model thermal emission opacity....
The study of photoionized environments is fundamental to many astrophysical problems. Up the present most photoionization codes have numerically solved equations radiative transfer by making extreme simplifying assumption spherical symmetry. Unfortunately very few real astronomical nebulae satisfy this requirement. To remedy these shortcomings, a self-consistent, three-dimensional code has been developed using Monte Carlo techniques. code, mocassin, designed build realistic models having...
We investigate the effect of line sight temperature variations and noise on two commonly used methods to determine dust properties from continuum observations dense cores. One method employs a direct fit modified blackbody SED; other involves comparison flux ratios an analytical prediction. Fitting fluxes near SED peak produces inaccurate spectral index estimates due (and density) variations. Longer wavelength in Rayleigh-Jeans part spectrum (>~ 600 micron for typical cores) may more...
We present late-time optical and mid-infrared observations of the Type II supernova 2003gd in galaxy NGC 628. Mid-infrared excesses consistent with cooling dust ejecta are observed 499 to 678 days after outburst accompanied by increasing extinction growing asymmetries emission-line profiles. Radiative-transfer models show that up 0.02 solar masses has formed within ejecta, beginning as early 250 outburst. These formation can be efficient massive-star supernovae could have been major...
We present new models for the X-ray photoevaporation of circumstellar discs which suggest that resulting mass loss (occurring mainly over radial range 10-40 AU) may be dominant dispersal mechanism gas around low pre-main sequence stars, contrary to conclusions previous workers. Our combine use MOCASSIN Monte Carlo radiative transfer code and a self-consistent solution hydrostatic structure irradiated disc. estimate rates assuming sonic outflow at surface where temperature equals local escape...
We present the first 3D Monte Carlo (MC) photoionisation code to include a fully self-consistent treatment of dust radiative transfer (RT) within photoionised region. This is latest development (Version 2.0) gas-only MOCASSIN (Ercolano et al., 2003a), and employs stochastic approach transport radiation, allowing both primary secondary components radiation field be treated self-consistently, whilst accounting for scattering by grains mixed with gas, as well absorption emission gas components....
Transitional disks (TDs) are thought to be a late evolutionary stage of protoplanetary with dust depleted inner regions. The mechanism responsible for this depletion is still under debate. To constrain the models it mandatory have good understanding properties gas content disk. Using X-Shooter broad band -UV NIR- medium resolution spectroscopy we derive stellar, accretion, and wind sample 22 TDs. analysis these allows us put strong constraints on in region very close star (<0.2 AU) which...
We extend our previous smoothed particle hydrodynamics parameter study of the effects photoionization from O-stars on star-forming clouds to include initially unbound clouds. generate a set model in mass range 104–106 M⊙ with initial virial ratios Ekin/Epot = 2.3, allow them form stars and impact photoionizing radiation produced by massive stars. find that, 3 Myr time-scale before supernovae are expected begin detonating, fraction expelled ionizing feedback is very strong function cloud...
The discovery with the {\it Herschel Space Observatory} of bright far infrared and submm emission from ejecta core collapse supernova SN\,1987A has been interpreted as indicating presence some 0.4--0.7\,M$_\odot$ dust. We have constructed radiative transfer models to fit optical far-infrared observations literature at epochs between 615 days 24 years after explosion, determine when where this unexpectedly large amount dust formed. find that by day 1153 are consistent...
Photoevaporation of planet forming discs by high energy radiation from the central star is potentially a crucial mechanism for disc evolution and it may play an important role in formation planetary system. We present here new generation X-ray photoevaporation models solar-type stars, based on set hydrodynamical simulations, which account stellar irradiation via new, significantly improved, parameterisation gas temperatures, detailed photoionisation transfer calculations. This first series...
We present MOCASSIN 2D photoionisation and dust radiative transfer models of a prototypical T Tauri disk irradiated by X-rays from the young pre-main sequence star. The calculations demonstrate layer hot gas reaching temperatures ~10^6 K at small radii ~10^4 distance 1 AU. decrease sharply with depth, but appear to be completely decoupled down column depth ~5*10^21 cm^-2. predict that several fine-structure forbidden lines heavy elements, as well recombination hydrogen helium, should...
We present a new version of the fully 3D photoionization and dust radiative transfer code, mocassin, that uses Monte Carlo approach for radiation.The X-ray enabled mocassin allows geometry independent description low-density gaseous environments strongly photoionized by radiation field extending from radio to gamma rays.The code has been thoroughly benchmarked against other established codes routinely used in literature, using simple plane parallel models designed test performance under...
We present an analysis of the spatial distribution various stellar populations within Large Magellanic Cloud. combine mid-infrared selected young objects, optically samples with mean ages between ~9 and ~1000 Myr, existing cluster catalogues to investigate how structures form evolve LMC. For we use Fractured Minimum Spanning Trees, statistical Q parameter, two-point correlation function. Restricting our massive (OB) stars confirm results obtained for M33, namely that luminosity function...
Aims: Grain growth has been suggested as one possible explanation for the diminished dust optical depths in inner regions of protoplanetary "transition" disks. In this work, we directly test hypothesis context current models grain and transport. Methods: A set evolution with different disk shapes, masses, turbulence parameters, drift efficiencies is combined radiative transfer calculations order to derive theoretical spectral energy distributions (SEDs) images. Results: We find that...
Photoevaporation driven by the central star is expected to be a ubiquitous and important mechanism disperse circumstellar dust gas from which planets form. Here, we present detailed study of disk surrounding nearby TW Hya provide observational constraints its photoevaporative wind. Our new high-resolution (R ~ 30,000) mid-infrared spectroscopy in [Ne II] 12.81 {\mu}m line confirms that this diagnostic traces unbound wind component within 10AU star. From blueshift asymmetry profile, estimate...