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Bachelor & Master Theses

at the University Observatory

For general questions please contact A. Riffeser (arri@usm.lmu.de).
Some Bachelor projects can also be extended in scope and assigned to two students to carry out the work together.

1. Instrumentation and observational projects

Project 1.1 (Bachelor project): Development and measurement of optical components and detectors for new instruments at the Wendelstein observatory (U. Hopp, hopp@usm.lmu.de, F. Grupp, C. Gössl, F. Lang)

Several new instruments and optical measuring devices are being developed for the new 2 m Wendelstein telescope. Optical components such as filters, glass fibres, lenses and electronic detectors (CCDs) have to be measured and tested. Projects in these areas can be assigned according to the student’s interests. They include lab work in Munich, development of small control scripts, as well as analysis and documentation of the measurements.

Project 1.2 (Bachelor project): Literature work relating to astronomic instrument construction (U. Hopp, hopp@usm.lmu.de, F. Grupp)

Documentation of new developments in instrument and telescope construction — including adjustment methods and environmental influence — are often only to be found in poorly available conference proceedings. The task is to critically look at and compile comments spread over many different courses. Current projects focus on SPIE contributions to wind loads of telescopic mounts, the cleaning and coating of telescope and instrumentation mirrors, and methods of mirror adjustment (e.g., Hartmann analysis).

Project 1.3 (Bachelor project): Development of instrument control software (C. Gössl, cag@usm.lmu.de)

Prerequisite for this project is sound knowledge of and interest in programming. The construction of the instrumentation for the 2 m Wendelstein observatory telescope makes the development of sub unit control software necessary. Task: Document the physical approach, the software solution as well as the integration of both in the whole system. Example: Automation of test rigs in the observatory labs or effective organisation of standard star data sets of the 40 cm telescope.

Project 1.4 (Bachelor project): Calibration of Wendelstein observations (A. Riffeser, arri@usm.lmu.de, M. Kluge, C. Gössl, U. Hopp)

The Wendelstein telescopes are used to compile large data sets of objects which are being continuously checked for variability (globular clusters, the galaxy M33, etc.). The analysis of these data sets include their integration into standard flux calibrations as well as into multi-filter analyses. These analyses — at least in the outer regions of the objects — can be made by comparing the observations made with those of other observatories as documented in the databases. The optical observations of the Sloan Digital Sky Survey, as well as the NIR observations of 2MASS will be taken into account, in order to examine the colours of variable AGB stars more exactly.

2. Stars and planets

Project 2.1 (Bachelor project): Analysis of the correlation of the X-ray luminosity and rotation in young stars (T. Preibisch, preibisch@usm.lmu.de)

Existing X-ray luminosity data of stars and literature data of rotation periods for several young star clusters are to be correlated. The correlation of X-ray luminosity and rotation can give insight into dynamo processes forming the basis of the X-ray emission.

Project 2.2 (Bachelor project): Parameter studies on infrared interferometric observations of young stars (T. Preibisch, preibisch@usm.lmu.de)

With the aid of analytical and/or numerical models of the brightness distribution of young stars with circumstellar disks, the impact of certain parameters, (e.g., the strength of scattering on dust particles) on the observables of infrared interferometric observations, are to be examined.

Project 2.3 (Bachelor project): Multi-wavelength observations of star formation regions (T. Preibisch, preibisch@usm.lmu.de)

Students can carry out investigations as part of an ongoing project, e.g., correlation of object lists in different wavelengths ranges (from X-ray to the sub-mm regime). Draft future student lab.

Project 2.4 (Bachelor project): Comoving frame radiative transfer in expanding atmospheres (J. Puls, uh101aw@usm.lmu.de)

The physical parameters of hot stars are mainly determined from a comparison of observed and synthetic spectra, where the latter are calculated by means of so-called model atmosphere codes. One of the most important components of these simulations is the line radiation transport, which, because of the expansion of the outer atmospheres of these stars (= stellar winds), is conveniently solved in the comoving frame and described by a (hyperbolic) partial differential equation. In the numerical codes developed in our institute, a so-called implicit scheme is used, which is characterized by high stability, but relatively low accuracy. In this bachelor thesis, an alternative semi-implicit method allowing for a principally higher accuracy shall be implemented, tested, and compared with the implicit method.

Project 2.5 (Master project): Modell atmospheres and synthetic spectra for Wolf-Rayet stars (J. Puls, uh101aw@usm.lmu.de)

The model atmosphere code “Fastwind”, developed by our group, is one of the world’s most widely used codes for calculating the optical/IR spectra from massive stars of spectral type O and B. The project presented here aims at stepwise extending the code so that the spectra of so-called Wolf-Rayet stars can be synthesized. The main difference of the atmospheres of these Wolf-Rayet (WR) stars in comparison to those of “normal” stars is a significantly higher wind density (practically all optical lines are formed mainly in the wind) and a different chemical composition: in most cases, the helium and nitrogen abundances (products of the CNO cycle) are greatly increased, whilst the hydrogen abundance is dramatically reduced (until zero). The work presented here requires a strong interest in the implementation of numerical methods.

Project 2.6 (Master project): 3-D radiative transfer in stellar winds of hot stars (J. Puls, uh101aw@usm.lmu.de, J. Sundqvist, jon@usm.lmu.de)

In recent years, substantial progress in the theoretical description of stellar winds from hot stars has been achieved, particularly with regard to the influence of fast rotation and magnetic fields. These theoretical predictions must now be tested by means of observed spectra, which requires a departure from the spherically-symmetric geometry used in current diagnostic methods. Accounting for future developments and already existing computing resources, a treatment in 3-dimensional Cartesian geometry is beneficial. This Master project shall enable the spectrum synthesis of wind lines, based on such a geometry and a so-called two-level atom, whilst two different methods (short or long characteristics) shall be compared. The achieved accuracies can be determined, for special cases, by comparison with already existing 1-D spherically symmetric calculations. This project constitutes a first building block for models and spectrum synthesis calculations in three-dimensional expanding atmospheres, and a future coupling with hydrodynamic models.

Project 2.7 (Bachelor project): Correlation of X-ray emission and fundamental parameters of hot stars (T. Hoffmann, hoffmann@usm.lmu.de, A. W. A. Pauldrach)

A possible correlation between the intensity of the X-ray emission and fundamental stellar parameters is to be carried out. This entails the simultaneous comparison of a sample of existing observed X-ray and UV spectra of hot stars with model spectra which will need to be calculated. This analysis will help to better understand the dynamic processes that lead to the production of X-ray radiation in these atmospheres.

Project 2.8 (Bachelor project): Calculation of mass loss rates of extremely massive stars (A. W. A. Pauldrach, T. Hoffmann, hoffmann@usm.lmu.de)

Using a largely already existing program, mass loss rates are to be calculated for a model grid of extremely massive stars such as might arise in dense star clusters through collisions and merging processes. Such stars could conceivably have masses of up to a few thousand solar masses (see http://www.usm.uni-muenchen.de/people/adi/RevBer/HotStars-OForT-Mod.html). The data obtained represent important quantities for describing the evolution of such objects and to compute their spectra, and thereby check for the possible existence of such stars in present-day starburst clusters.

Project 2.9 (Bachelor project): Extension of existing UV observations of samples of central stars of planetary nebula with FUSE data (A. W. A. Pauldrach, uh10107@usm.lmu.de, T. Hoffmann)

The objective is to extend observed UV spectra of a selected sample of central stars of planetary nebula with FUSE (Far Ultraviolet Spectroscopic Explorer) data. Data from the MAST archive (http://archive.stsci.edu/) are to be edited and combined with existing UV spectra. Finally, a comparison of these extended observations with existing calculated synthetic spectra (Pauldrach et al. 2004) should lead to new findings.

3. Galaxies

Project 3.1 (Bachelor project): Dynamos in galaxies (H. Lesch, lesch@usm.lmu.de)

All galaxies are magnetized. Where do galactic magnetic fields come from, how are they maintained and how are they structured? These are the questions we wish to answer. In this project we will develop a model for the amplification of galactic magnetic fields based on analytic calculations.

Project 3.2 (Bachelor project): Propagation of cosmic rays in the Galaxy (H. Lesch, lesch@usm.lmu.de)

Cosmic rays represent a small but high-pressure part of the interstellar medium. Through their pressure on the magnetic fields, cosmic rays contribute considerably to the galactic dynamo. In this project we will analyse the properties of Galactic cosmic rays and their impact on gamma-ray emission.

Project 3.3 (Bachelor project): The age of a galaxy (R. Saglia, saglia@usm.lmu.de)

How do we measure the age of a galaxy? The bachelor thesis should summarize the methods that have been developed to reach this goal and their uncertainties. If there is enough time, one can also derive a spectroscopic age from data available for a selected number of objects.

Project 3.4 (Bachelor/Master project): Dynamical modeling of stellar disks (R. Saglia, saglia@usm.lmu.de, J. Thomas, jthomas@mpe.mpg.de)

Three-dimensional galaxies are often modeled using the Schwarzschild approach. One computes stellar orbits in a given gravitational potential and superposes them to reproduce the available dataset. The modeling of two-dimensional objects like galaxies with stellar disks poses some yet unsolved questions. How well can one compute the gravitational potential using spherical harmonics? What is the optimal amount of regularization? How well can one describe real galaxies? During the thesis answers to these questions will be tested and implemented.

Project 3.5 (Bachelor project): The masses of supermassive black holes at the centers of galaxies (R. Saglia, saglia@usm.lmu.de)

How do we measure the masses of supermassive black holes at the centers of galaxies? What are their uncertainties? How much mass is hidden in supermassive black holes? The results of the recent research should be critically summarized and discussed.

Project 3.6 (Master project): Dark Matter in dwarf elliptical galaxies (R. Saglia, saglia@usm.lmu.de)

Giant elliptical galaxies are embedded in massive dark matter halos. Not much is known, however, about the dark matter halos of dwarf ellipticals, because their low velocity kinematics are difficult to measure. Thanks to our new high-resolution two-dimensional spectrograph VIRUS-W we were able to obtain high quality spectra for a number of dwarf ellipticals in the Virgo cluster. Goal of the master thesis is the reduction and analysis of these data, their dynamical modeling and the determination of the dark matter density in these objects.

4. Cosmology

Project 4.1 (Bachelor project): Distances to supernovae in various cosmological models (J. Weller, weller@usm.lmu.de)

The student will derive the correlation between distance and red shift for different Friedmann Models. Boundary conditions to cosmological parameters will be derived by comparison with supernova data. These analyses are made with the aid of so-called Monte Carlo Markov chains. If there is enough time, the analysis can be extended to models with extra dimensions.

Project 4.2 (Bachelor project): The size evolution of galaxies (R. Saglia, saglia@usm.lmu.de)

The size of a galaxy changes during its life. Goal of the thesis is to summarize the results of the last years of published research. How do we measure the size of a galaxy? What is the rate of change of the size of a galaxy with time? Does it depend of the mass of the galaxy? What are the mechanisms that drive the size change of galaxies?

Project 4.3 (Bachelor project): Distance determinations of galaxies using Cepheids and other methods (M. Kodric, kodric@usm.lmu.de, A. Riffeser, arri@usm.lmu.de)

The distance determination using the period-luminosity relation (PLR) of Cepheids is a cornerstone of distance determination of distant galaxies. The calibration of the PLR is generally done with the low-metallicity Magellanic Clouds, although the influence of metallicity on the PLR is not exactly known. At present a curvature of the PLR, that was assumed to be a linear relationship until now, is discussed in the literature, which of course would have consequences for the distance determination. In this bachelor thesis the distance determination method should be reviewed and the underlying problems of the PLR calibration discussed. The thesis should also deal with other distance determination methods for nearby galaxies, by means of which the PLR can be calibrated.

5. Numerical Astrophysics

Bachelor- und Masterarbeiten auf dem Gebiet der numerischen und theoretischen Astrophysik können prinzipiell jederzeit in folgenden Bereichen angeboten werden:

  • Die Struktur der turbulenten interstellaren Materie (ISM) und die Entstehung von Molekülwolken
  • Entstehung von Planeten, Sternen und Sternhaufen
  • Sterne und deren Einfluss auf die umgebende interstellare Materie
  • Strahlungstransport
  • Galaxienentstehung und -evolution im kosmologischen Kontext (lokale Galaxien bis zu hoher Rotverschiebung, Galaxienhaufen, kosmisches Web, schwarze Löcher, selbstregulierende Sternentstehung)
  • Galaktische Dynamik
  • Aktive galaktische Kerne (AGN)
  • Ursprung und Natur der Gaswolke G2, nahe dem Zentrum der Milchstraße
  • Die Struktur und Entstehung von Dunkle-Materie-Halos
  • Magnetfelder und deren Rolle von kleinen bis zu kosmischen Skalen
  • Nutzung und Weiterentwicklung von Simulationssoftware auf parallelisierten CPUs oder GPUs (Grafikkarten): unsere hydrodynamischen Codes basieren auf Teilchen (SPH/N-Body), Gitter (Grid), oder dem Moving-Mesh- oder Meshless-Verfahren
  • Software zur dreidimensionalen Datenvisualisierung

Konkrete Themen werden in der Regel im Zusammenhang mit laufenden Forschungsprojekten gewählt. Mehr Informationen über aktuelle und abgeschlossene Projekte finden sich auf der Homepage der CAST-Gruppe.

Last updated 2016 January 14 11:01 by Webmaster (webmaster@usm.uni-muenchen.de)