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Summer Student Program 2022

Despite the unclear situation with the COVID pandemic the Nicolaus Copernicus Astronomical Center will organize the summer student program this year in a hybrid form. That means that we will allow the students to come to CAMK building to work on the projects, but we will not be able to provide accommodation. The exact form of the collaboration is up to the project supervisor and is indicated in the project description, but in the case of the on-site form the project supervisor is expected to be available on-site for the student. On-line form of the program is also possible.

We invite 2nd, 3rd, or 4th year undergraduate physics or astronomy students (in exceptional circumstances we would accept younger students). The duration of an individual programme should be 4-6 weeks. Suggested topics are listed below. If you are interested in participating in the internship in the on-line only form, please contact the selected scientist directly to arrange for the details. For on-site form please first contact the supervisor and fix the exact time and duration of the project and then send your application (the supervisor's name, date of the project, scientific CV). Applications should be submitted in PDF form to praktyki@camk.edu.pl. There is no deadline for applications and they will be considered once submitted. The successful candidates will be informed by email. Please be aware that the on-site form is limited to EU citizens only.

 

PROJECTS


Measuring the structure of relativistic jets in numerical simulation results.

Relativistic jets are powerful collimated magnetized outflows from black holes in active galaxies. Their detailed structure depends on the outcome of several physical mechanisms: launching, acceleration, collimation, stability, energy dissipation. Investigating these mechanisms requires performing numerical simulations, the results of which are rich in detail. The candidate will be given an opportunity to explore basic results of general relativistic magnetohydrodynamical (GRMHD) simulation of relativistic jets launched from magnetically arrested disk (MAD).

 

Supervisors: Krzysztof Nalewajko (CAMK PAN Warsaw, knalew@camk.edu.pl), Agnieszka Janiuk (CFT PAN).

Form: on-line.

Project duration: July-September, flexible.


Numerical simulations of star-planet magnetospheric interaction

Abstract: Interaction of a planetary magnetosphere with the magnetic field
of its host star defines the atmospheric outer boundary conditions on the
planet and modulates the radio emission from the planet. Using state-of
the-art numerical simulations, we will investigate magnetospheric interaction
of small, rocky planets and Neptune-type gas giants orbiting various types of
stars, from stellar giants to Sun-like stars, white dwarf and neutron-star
like objects.
Workplan: Students will learn to use the PLUTO code with the star-planet setup,
and run it on a laptop and CAMK linux cluster (CHUCK). The goal is to develop
suite of simulations which could later be used to model particular cases from
the exoplanet surveys. Students will also learn to present and analyze the
results of numerical simulations using Paraview and Python tools. Results of
this work will be used in publications on star-planet magnetospheric interaction
in our international collaboration, in which students will possibly become
co-authors.

 

Supervisors: Miljenko Čemeljić (CAMK PAN Warsaw, miki@camk.edu.pl), J. Varela (UC3 Madrid)

Form: on-site or on-line.

Project duration: July-September, flexible.


Mock Observations of Eclipsing Binaries in Simulated Star Clusters

Variable stars have been extremely useful in understanding stellar formation and evolution. Observations of eclipsing binaries in dense stellar systems like globular clusters provide direct distance estimates and can also help to constrain the turn-off masses in these systems. In this project, the student will work on simulating mock observations of results of numerical star cluster simulations using the COCOA code. The main task of the project will be to further develop the COCOA code by accurately computing changes in magnitude for binary stars that will eclipse each other during periodic observations.

COCOA creates synthetic observational data from the projected snapshot of a star cluster simulation, it can also be used to create a sequence of projected snapshots in which positions of stars in binaries can be tracked. When these positions of stars in some these binaries will overlap during the eclipses, the total magnitude of the binary will decrease which will be detectable through photometry of the mock observations. By doing this, it will be possible to compare the population of eclipsing binaries in simulated star cluster models with real observations. Programming experience particularly in Python along with knowledge of reducing photometric observations will be particularly helpful for the implementation of this task.


Supervisor: Mirosław Giersz (CAMK PAN Warsaw, mig@camk.edu.pl).

Form: on-line.

Time: July-September, flexible.


The study of Cepheids in binary systems.

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. One of the possibilities is to perform the Spectral Energy Distribution analysis for a selected eclipsing binary system with a Cepheid to obtain, e.g, the temperatures of the components. Other projects are also possible depending on the interests and skills of the student. Programming skills will be essential for the successful completion of the project.

Supervisor: Bogumił Pilecki (CAMK PAN Warsaw, pilecki@camk.edu.pl), https://users.camk.edu.pl/pilecki/

Form: on-site or on-line.

Time: July to mid-September (4 weeks) TBD.


Spectra of eclipsing binaries taken during total eclipses.

The analysis of detached eclipsing binaries (DEBs) provides the most precise and accurate data on fundamental stellar properties, e.g. masses, radii, effective temperatures, luminosities, metallicites, ages, etc. However, the atmospheric parameters, (like Teff, [M/H], log(g)) may be directly estimated mainly from the high-resolution, high-SNR spectra, which in case of DEBs are composed of two individual stellar spectra, mixed together with variable proportions, and shifted by a different value in each observing epoch. Their decomposition is possible, but is very often risky, as it leads to systematic uncertainties, and relies on input information that may be inaccurate or hard to obtain. The knowledge of proper values of atmospheric parameters is necessary for further analysis, such as age and evolutionary status determination, or testing evolutionary models.
One possible way to work the problem around is to observe a DEB during a total eclipse, meaning in a moment when light from only one star is being recorded. This allows one to determine the parameters of one component more easily, and greatly simplifies the decomposition process.
The student will work on a sample of such spectra, and will be tasked to provide a set of basic stellar atmospheric information, possibly with abundances of individual elements. The student will get familiar with the ESO data products, and will earn experience in spectral analysis by working with a modern spectral analysis tool (most likely iSpec). Depending on the time constraints and student's performance, it will also be possible to run spectral decomposition codes (FD3), and/or compare the obtained results with stellar models (PARSEC, MESA).

 

Supervisor: Krzysztof Hełminiak (CAMK PAN Torun, xysiek@ncac.torun.pl).

Form: on-line.

Time: July-September, flexible.


Sub-stellar bodies around detached eclipsing binaries.

Planets and brown dwarfs (BDs) in non-sigle stellar environments are still statistically rare, mainly due to historical limitations of detection methods, and target selection biases. Most of the currently known cases are limited to circumstellar bodies, i.e. those orbiting one component of a (usually wide) binary system. Some circumbinary objects have been detected with various techniques, and those found around detached eclipsing binaries (DEBs) are among the most valuable, as the host binary may be precisely and accurately characterized, leading to a better knowledge on the planet itself.
The student will learn about some of the techniques to search for circumbinary planets, i.e. radial velocities, eclipse timing variation, direct imaging. Depending on the student's preferences, and availability of the data, the student will work on at least one from the following sets: (i) photometry (both ground- and satellite-based) and eclipse timing variations, (ii) radial velocities from high-resolution spectrographs, (iii) direct imaging and integral field spectroscopy from extreme-AO instruments with coronagraphs. Computational skills will be very welcome.

 

Supervisor: Krzysztof Hełminiak (CAMK PAN Torun, xysiek@ncac.torun.pl).

Form: on-line.

Time: July-September, flexible.


Role of net magnetic flux in truncated accretion discs.

Long-term X-ray observations of black hole X-ray binaries have shown that these systems undergo outbursts lasting for a few months to years, during which they also exhibit spectral-temporal variability. In the low/hard state, the luminosity of these systems is low, and their energy spectrum peaks in the hard X-ray band. As the outburst progresses, this peak in the energy spectrum gradually shifts to the soft X-ray band. Phenomenological models associate this transition with the change in the geometry and dynamics of the accretion flow, although the cause of this transition is not completely understood. Begelman & Armitage 2014 put forth a model based on the idea that thick discs/thin discs advect/diffuse the magnetic field lines, thus increasing/decreasing the net magnetic flux and thereby the turbulence which causes a transition to thin/thick discs.
In this project, the student will perform GRMHD simulations of truncated black hole accretion discs to test the hypothesis mentioned above for state transitions. The initial setup includes a two-component accretion flow around a moderately spinning black hole (a= 0.5) with the spin axis aligned to the disc. The disc is threaded with the vertical magnetic field, and the numerical simulations will be performed using the code Cosmos++. The simulation data will then be used to analyze the advection and diffusion of the magnetic field in the geometrically thick and thin disc regions and study the net magnetic flux accumulation. If time permits, the student will also perform a similar study for a disc misaligned with the spin axis of the black hole and compare the results with the untitled disc simulations.

 

Supervisors: Wlodek Kluźniak (CAMK PAN Warsaw, wlodek@camk.edu.pl), Deepika Bollimpalli (MPI)

Form: on-line.

Time: July-September, flexible.


The last stable orbit of a neutron star - quark star binary.

Quark stars (QS) are hypothetical stellar remnants that are more compact than neutron stars (NS). They may be formed after accretion of mass onto a neutron star, or a proto-neutron star, depending on the astrophysical situation. The associated gravitational implosion may be accompanied by a luminous ejection of the envelope that is called a Quark-Nova. The existence of quark stars is related to the fundamental question of the stability of baryonic matter.

One possible way of detecting quark stars would be by observing their coalescence with a binary companion. The gravitational waves detected by the LIGO-VIRGO detectors carry information about the interior material of compact and about the deformation of components in the last orbit of the binary system. The last stable orbit separates the binary phase from the coalescence, and as such its radius and orbital frequency are important to know. The student will rigorously compute the parameters of the last stable orbit and the interior structure of the QS and NS in general relativity, using the numerical code LORENE.

Work plan

The problem and approach will first be explained in a few lessons. The student will learn the LORENE library (https://lorene.obspm.fr), the equation of state, and structure parameters of the SQS found in previous works for single SQS.  We will proceed with the LORENE code for binary neutron stars with a simple equation of state. Next, we will work on the improvement of the run and make a model of binary SQS-NS with the defined equation of state for SQS companion.

Requirement

Working knowledge of C++ or/and Python is required.

 

Supervisors: Fatemeh Kayanikhoo (CAMK PAN Warsaw, fatima@camk.edu.pl), Miljenko Čemeljić (CAMK PAN Warsaw, miki@camk.edu.pl)

Form: on-line, hybrid, or on-site.

Time: July-September, flexible.

 

 

 

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