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Bachelor, Master & PhD projects
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The infrared interferometry group at the Max-Planck-Institut für Radioastronomie offers Bachelor, Master, and PhD projects in the following astrophysical areas: |
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Abstracts: see below |
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Contact: Prof. Gerd Weigelt, MPI für Radioastronomie (weigelt@mpifr.de;
0228-525 243) |
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Die Arbeitsgruppe Infrarot-Interferometrie des Max-Planck-Instituts für Radioastronomie in Bonn bietet ab sofort studentische Hilfskraftstellen für Physik- und Astronomiestudenten mit Interesse an digitaler Bildverarbeitung an (22,5 bzw. 45 Std./Monat). |
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Kontakt: | Dr. Dieter Schertl Max-Planck-Institut für Radioastronomie Auf dem Hügel 69, D-53121 Bonn email: ds@mpifr.de Telefon: 0228-525-301 Weiterführende Informationen (inkl. Themen für Bachelor-/Master-/Doktorarbeiten) unter: http://www.mpifr.de/div/ir-interferometry |
| Master, PhD, and postdoc positions |
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Applications are invited for Master, PhD, and postdoc positions in the Infrared Interferometry Group of the Max-Planck Institute for Radio Astronomy in Bonn
(see http://www.mpifr-bonn.mpg.de/div/ir-interferometry). Preference will be given to applicants with experience in one of the following areas: young stellar objects, active galactic nuclei, radiative transfer modeling, or infrared interferometry. Successful applicants will be expected to participate in interferometric observations and their interpretations, or in instrumentation projects (in particular, science software development for the VLTI-MATISSE instrument). The positions offer excellent opportunities for high-resolution studies using the VLT Interferometer. Since our group is a member of the LBT LINC-NIRVANA consortium, we own LBT Guaranteed Observing Time. The appointment is initially for two years and is renewable for up to six years. Applicants should submit a curriculum vitae, list of publications, and brief description of research interests, and arrange for one letter of recommendation to be emailed to weigelt@mpifr.de. The Max-Planck Society is an equal-opportunity employer and aims to employ more disabled people. Applications from disabled persons are, therefore, particularly welcome. |
Master/PhD projects
The abstracts below are a list of currently available Master/PhD projects |
Infrared interferometric studies of protoplanetary disksDescription: Most young stellar objects (YSOs) are surrounded by dusty circumstellar material. Their inner circumstellar environment, at scales of up to a few AU, is usually dominated by accretion disks, in which planets may form. Until recently, the geometry and physical processes in these disks could not be directly studied at infrared wavelengths, because seeing-limited observations can only resolve the outer parts (> 50 AU) of the circumstellar environment of the closest YSOs. The spatial resolution of the ESO Very Large Telescope Interferometer (VLTI), on the other hand, can provide a resolution which corresponds to a few tenths of an AU at a distance of 100 pc and, thus, finally allows the investigation of the structure and processes in the inner circumstellar environment of YSOs. Among the fundamental topics that can be addressed with the VLTI observations are: accretion, dust processing, possibly radial mixing and eventually planet formation. This observational project aims to study the circumstellar environment of YSOs using both current instruments of the VLTI: MIDI, the mid-infrared (8 to 13 micron) two-telescope beam combiner, and AMBER, the near-infrared (1.0 to 2.4 micron) three-telescope beam combiner. The PhD student will work on both the reduction and the scientific interpretation of the interferometric data. To interpret the interferometric observations, the PhD student will confront the data with multi-dimensional radiative transfer models. This analysis will improve the general understanding of the physical processes in YSOs. Contact: Prof. Gerd Weigelt (weigelt@mpifr.de)
Revealing the origin of YSO jets and outflows with high-resolution infrared imaging techniquesInspite of their key role, the origin of the flows themselves remains elusive. While some theoretical models predict that the outflows originate from the star itself, others suggest that the material is launched from the disk. As the acceleration and collimation processes are believed to occur on very small spatial scales (in the inner-most few AU around the star), these theories could not yet be tested with observations. The aim of this project is to use the latest infrared high-resolution imaging techniques, such as speckle interferometry, adaptive optics imaging, and possibly also VLTI long-baseline interferometry, to study the geometry of the outflows very close to their launching region. The student will work on the planning of the observations, data reduction, and the astrophysical interpretation, for which radiative modeling and/or molecular hydrodynamics simulations might also be employed. These studies will provide new insights into the launching, collimation, and propagation of the jets and outflows from young stars. Contact: Prof. Gerd Weigelt (weigelt@mpifr.de)
Radiative transfer modeling of YSO circumstellar disksDescription: Stars form from collapsing clouds which are composed of gas and dust, likely via circumstellar accretion disks. These disks are at the focus of the current astronomical research, not only because they are an integral part of the star formation process, but also because they provide the stage where planet formation is taking place. In this project, we aim for a better theoretical understanding of the structure and the physical conditions in the inner-most regions of these protoplanetary disks. For this, we will use radiative transfer simulations to investigate the influence of dust chemisty effects (such as grain growth or dust settling), planet-disk interactions, or active accretion on the disk structure. Besides theoretical work on disk theory and code development for our numerical dust radiative transfer computations, the student might also decide to work on incorporating gas radiative transfer in the simulations. Models, such as those developed in the course of this project, will be crucial in the near future to constrain the spatial structure as well as the kinematics of protoplanetary disks using spectroscopic and high-angular resolution imaging observations (i.e. provided by infrared or sub-millimeter interferometry). Contact: Prof. Gerd Weigelt (weigelt@mpifr.de)
Probing the circumstellar environment of AGB stars with infrared long-baseline interferometryDescription: The vast majority of all stars in the universe which have passed the main sequence phase are of low and intermediate mass and evolve through the AGB phase. These luminous, frequently pulsating and heavily mass-losing AGB stars form an important stellar population which contributes considerably to the light, chemistry and dynamics of galaxies, and the envelopes of AGB stars are the major factories of cosmic dust. Accordingly, AGB stars are heavily enshrouded by dust. In addition, the conditions in the inner region of the circumstellar environment of these stars are suitable for the formation of layers of different types of molecules. Hence, AGB stars are ideal laboratories for investigating the interplay between various physical and chemical processes. For the study of AGB stars and their circumstellar matter, infrared long-baseline interferometry with its high spatial and spectral resolution is a key technique since it provides information about the chemical composition and the spatial distribution of molecules and dust around these stars. Moreover, interferometry with three or more telescopes and high spatial resolution even allows the detailed study of stellar surface inhomogeneities. The project aims to study the circumstellar environment of AGB stars using both current instruments of ESO's Very Large Telescope Interferometer: MIDI, the mid-infrared two telescope beam combiner operating in the N band between 8 and 13 micron, and AMBER, the near-infrared three-telescope beam combiner operating in the J, H, and K bands between 1.0 and 2.4 micron. The PhD student will work on both the reduction and the scientific interpretation of the interferometric data obtained with MIDI and AMBER. To interpret the interferometric observations, in particular the wavelength dependence of the apparent sizes, the PhD student will confront the data with state-of-the-art model atmospheres and multi-dimensional radiative transfer models. This analysis will provide important information about the formation of the circumstellar gas and dust chemistry around AGB stars and will improve our general understanding of the mass-loss process in these evolved stars. Contact: Dr. Keiichi Ohnaka (kohnaka@mpifr.de), Prof. Gerd Weigelt (weigelt@mpifr.de)
Unveiling the innermost region of the enigmatic Luminous Blue Variable Eta CarinaeDescription: The enigmatic object Eta Carinae is one of the most luminous and most massive unstable Luminous Blue Variables suffering from an extremely high mass loss of the order of 1/1000 solar masses per year. With a mass of the order of 100 solar masses, it is one of the most massive stellar objects known to date. Eta Car, which has been subject to a large variety of studies over the last few decades, is surrounded by the expanding bipolar Homunculus nebula ejected during the so-called Great Eruption in 1843. Eta Carinae is a fascinating object in many respects. Spectroscopic studies of the Homunculus nebula showed that the stellar wind of Eta Carinae is aspherical and latitude-dependent. Very recently, the first near-infrared spectro-interferometric observations of Eta Carinae were obtained with AMBER, the beam combiner instrument of ESO's Very Large Telescope Interferometer. The spectrally dispersed AMBER interferograms allowed the investigation of the wavelength dependence of the visibility, differential phase, and closure phase of Eta Carinae's aspherical and optically thick wind region with a spatial resolution as high as 5 milli-arcseconds and spectral resolutions up to 12,000. The PhD student will reduce and interpret new observations obtained with both bispectrum speckle interferometry at ESO telescopes and long-baseline interferometry using VLTI/AMBER. The interferometric observations will be confronted with recent theoretical predictions for anisotropic winds from fast-rotating, luminous hot stars. Contact: Prof. Gerd Weigelt (weigelt@mpifr.de)
Infrared interferometry of nearby AGNDescription: The presence of an optically thick parsec-scale dusty torus surrounding the central engines of Active Galactic Nuclei (AGN) is the cornerstone of the unification scheme for AGN. Depending on the torus inclination relative to the line-of-sight, the central accretion disk and Broad Line Region are either visible or obscured by the torus. This viewing-angle effect is able to explain the difference between type 1 and type 2 AGN. The gas and dust within the torus are believed to be accreted from larger kpc-scale regions, while the torus itself supplies the accretion disk with matter. Thus, the torus plays a key role in fueling and regulating the AGN activity. The dust content of the torus absorbs most of the optical and UV radiation from the AGN, leading to thermal NIR and MIR reemission. Due to the small scales involved, detailed studies require high angular resolution and are only possible with new interferometric and adaptive optics instrumentation. The proposed project focuses on NIR and MIR interferometry with the AMBER and MIDI instruments of ESO's Very Large Telescope Interferometer and imaging with adaptive optics using the NaCo, SINFONI, and VISIR instruments of the ESO Very Large Telescope. Radiative transfer modeling with available codes will be used for the quantitative interpretation of the observations. Contact: Dr. Makoto Kishimoto (mk@mpifr.de), Prof. Gerd Weigelt (weigelt@mpifr.de)
Infrared signatures of AGN fuelingDescription: The presence of an Active Galactic Nucleus (AGN) in galaxies is often accompanied by intense star formation in the inner galaxy in the form of starburst rings or more scattered regions of star formation. The transport of matter on scales less than 1 kpc from star-forming regions to the nucleus can nowadays be studied with adaptive optics imaging and integral field spectroscopy with the ESO VLT instruments NaCo, SINFONI, and VISIR. Tracers of the molecular and ionized ISM and dust absorption structures will be investigated to track the AGN fueling processes like stellar bars, spiral shocks in the ISM, or enhanced turbulence in the gaseous disks. The kinematical information from spectroscopy together with the distribution of stellar, gaseous, and dust components derived from multi-wavelength imaging allows the construction and testing of dynamical models for the circumnuclear region. The fueling of the nuclear region is directly related to and crucial for the formation of dusty tori surrounding the central engine, which play a key role in AGN unification schemes. Contact: Dr. Makoto Kishimoto (mk@mpifr.de), Prof. Gerd Weigelt (weigelt@mpifr.de)
Exploring the parsec-scale environment of active galactic nuclei in the mid-infraredDescription: New instruments at the world's largest optical observatories enable us, for the first time, to study the innermost regions of active galaxies in the thermal infrared (mid-infrared). At these wavelengths, the emission is dominated by dust which surrounds the central supermassive black hole and accretion disk. This "dust torus" absorbs and re-emits parts of the radiation coming from the accretion disk. The torus seems to play a fundamental role in providing the fuel to feed the central accretion disk and the black hole. Current interferometric facilities allow us to measure the size of the dust torus at different IR wavelengths. In addition, a large sample of AGN tori can be observed with state-of-the-art mid-infrared spectro-photometric instruments. Such observations at high angular resolution enable us to study the emission from the torus without significant contamination by the surrounding host. The proposed project is focused on high angular resolution, mid-infrared observations in the 5-30 micron regime. The PhD student will work in an international collaboration and will contribute to the following projects: (1) development of techniques to reduce and calibrate Q-band observations (18-30 micron) obtained with the ESO VLT and (2) interpretation of VLT and Spitzer data with radiative transfer models. Contact: Dr. Makoto Kishimoto (mk@mpifr.de), Prof. Gerd Weigelt (weigelt@mpifr.de)
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