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Summer Student Program 2021

Due to the current situation related to the COVID-19 epidemic, we are forced to cancel our Summer Student Program also this year. We hope to return with the full program again next year.
However, as a year before, it is still possible to remotely participate in research projects under the supervision of our researchers. Suggested topics are listed below. If you are interested in participating in this type of internship, please contact the selected scientist directly to arrange for the details.


1. "Accretion disk angular momentum transport with non-dipolar stellar field"

Supervisors: dr M. Cemeljic (

Abstract: Results of numerical simulations with star-disk magnetospheric interaction are presently mostly available in the cases with a dipolar stellar magnetic field. Observed stars show more complicated structure of the magnetic field. Performing viscous and resistive simulations with the PLUTO code, we will investigate the transport of angular momentum in star-disk systems with slowly rotating stars with a quadrupole and octupole stellar field. We will also probe their combination with the stellar dipole.

Workplan: The students will learn to use the code PLUTO, and run it in CAMK linux cluster (CHUCK). They will also learn to present and analyze the results with our Python tools. The goal is to find eventual trends in angular momentum transport onto a star in the cases with octupole and quadrupole stellar field, and their combination with a dipole stellar field. The results will then be compared with the trends already found in the purely dipolar field cases. Results of this work will be used in publications about the rotational evolution of stars.

2. "Simulations of a thin accretion disk around a black hole"

Supervisors: dr M. Cemeljic (

Abstract: We will perform numerical simulations of a thin accretion disk around a black hole in pseudo-Newtonian gravitational potential. We will use a recently updated version of the PLUTO code, to obtain the quasi-stationary state in viscous and resistive simulations. Special attention will be paid to finding a good combination of parameters for launching of outflows.

Workplan: The student will first learn to use the PLUTO code, and run it on CAMK linux cluster. Together with learning of the code and Python analysis tools, some basics of the needed physics will be learned in a hands-on approach. A setup with the open magnetic field lines was already initiated in our previous work, now we will search for the conditions for stabilizing the simulations. Results of this work will be the basis for our future work on such disks.


3. "Study of Cepheids in binary systems: discoveries and new methods."

Supervisor: dr hab. B. Pilecki (,

   Cepheids are one of the most important classes of variable stars, being extremely useful in different areas of astrophysics. Because of the relationship between their period and luminosity, they are important distance indicators in the local universe. They are also key objects for testing the predictions of stellar evolution and stellar pulsation theories. In the Araucaria group, we have observed and analyzed many Cepheids in eclipsing and spectroscopically double-lined systems, which let us accurately measure their physical parameters, including the masses and radii. We have also collected hundreds of spectroscopic observations of binary Cepheids in different galaxies. These data, together with publicly available photometry may serve for a multitude of interesting studies of these objects. Two examples are given below, but other projects are possible depending on the interests and skills of the student.
   1) The analysis of spectroscopic data collected for Cepheids suspected for binarity, in the Small Magellanic Cloud. The aim will be to confirm their binarity and to find the orbital periods of the systems. We will also look for the signs of binarity in the O-C diagrams created for available light curves. These would be the first confirmed binary Cepheids in this galaxy.
   2) Spectral Energy Distribution analysis for a selected eclipsing binary system with Cepheid. This study will provide among others such important parameters as temperatures of the components and an independent value of reddening to the system. Combining these data with those already available will provide results of unprecedented quality for these Cepheids. Such a study has never been done before.
   Programming skills will be essential for the necessary analyses and/or visualization.

4. "Physical parameters of eclipsing binary systems in the Milky Way and other galaxies."

Supervisor: dr hab. B. Pilecki (, 

    Detached double-lined eclipsing binary systems are excellent tools to measure the masses and radii of stars with sub-percent accuracy. They also provide one of the best methods for local distance determination in the Universe, which makes possible distance measurements to other galaxies in an almost purely geometrical manner. For example, in the Araucaria group, we have measured the distance to the Large Magellanic Cloud with an accuracy of 1% using observations of binary systems composed of giants. We also work on the calibration of this method using Milky Way systems.
    The goal of the current project will be to obtain orbital and physical parameters of selected rare/interesting binary systems either in the Milky Way or Magellanic Clouds and determine their distances. Various sources of data (TESS, OGLE, ASAS, etc.) and modeling tools (WD, PHOEBE, JKTEBOP) will be used. Alternatively, the student may work on automatic modeling of a larger set of systems using e.g. artificial intelligence for automatic estimation of initial parameters. The aim will be to provide their basic parameters and identify interesting systems for a more detailed analysis. Programming and computer skills will be essential for the successful completion of the project.


5. "Energy of a Strange Quark Star"

Supervisors: F. Kayanikhoo ( & dr M. Cemeljic (

Strange quark stars (SQS) are a new possible type of compact object that may be created after the proto-neutron star state, through a second explosion. The core magnetic field of the quark stars may reach magnetic fields of  ~1018G, with the surface magnetic field ~1014G. The star is deformed due to the strong magnetic field, and it also could release a huge amount of energy.

The purpose of this project is to write a Python code to calculate the total external magnetic field energy for an observer at infinity, Etot = Eint + Eext. Calculation of the internal energy has been carried out in the previous work. In addition, we will calculate the binding energy and study the stability of SQS.


The problem and approach will first be explained in few short lessons. The student will learn the equation of state and the structure parameters of the strange quark stars found in previous work. Next, we proceed with the first version of the code computing the total energy. After testing and first runs, we will work on improvement of the results.


Working knowledge of Python is required.


6. "Constrains on the isolated binary formation of LIGO/Virgo sources"

Supervisors: A. Olejak ( & prof. K. Belczyński (


LIGO/Virgo collaboration detects more and more gravitational wave (GW) signals from double compact object mergers (BH-BH, BH-NS and NS-NS). Estimated parameters (masses, spins) for some mergers seem to be quite unexpected and not trivial to explain based on current theoretical models. The important challenge for the GW community is to determine the actual origin of the GW signals. One of the most promising possibility seems to be the formation of close double compact object mergers via isolated binary evolution, which is however a subject of many uncertainties of stellar and binary physics.

The main goal for the student will be getting familiar with StarTrack population synthesis code and generating a big, public database with synthetic populations of double compact object mergers. Numerical simulations will include many physical models, which in farther steps will be verified by observational constrains and detected population of mergers. Computations will be performed via our citizen-science platform UNIVERSE@HOME, which is one of the largest scientific dispersed computing projects.

The generated open-access database will be useful for our scientific group as well as for the scientists around the world willing to put constrains on the physics of massive binary system evolution and the origin of LIGO/Virgo sources.

Internship will help applicant to become familiar with the population synthesis method and gain experience in massive numerical simulations. Successful student will have a chance to learn about the most important physical processes in stellar and binary star evolution. If the cooperation goes well it will be possible to continue work within our scientific group, prepare thesis or co-author scientific publications based on the generated database.

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