Research Projects

Research Project 1

Title: Hot tips of cool dynamic fibrils (for a bachelor’s degree student)

Mentor: dr. Julius Koza (koza@astro.sk)

Institution: Astronomical Institute, Slovak Academy of Sciences, 059 60 Tatranska Lomnica, Slovak Republic

Abstract: Dynamic fibrils (DFs) are the thin jet-like features observed in the solar chromosphere. They usually have a lifetime of 2-4 min and lengths between 1000 and 4000 km. DFs are basically considered for shock-driven phenomena. Magnetoacoustic waves that leak from the lower atmosphere are guided upwards by magnetic fields and they form shocks at chromospheric heights. These shocks then catapult chromospheric material upwards and produce jet-like DFs. They have been suspected for contributing to the heating of upper solar atmosphere, but conclusive evidence was missing. A recent breakthrough in this field is unambiguous evidence for extreme UV emission at tips of DFs suggesting a presence of very hot plasma at coronal temperatures, which likely crowns DFs. The signatures of hot tips of cool DFs can be also identified in the Lyman-alpha images obtained by the Very high Angular resolution ULtraviolet Telescope (VAULT) during its second sub-orbital flight on 14 June 2002 aboard a sounding rocket. However, these unique data have not been analysed in detail. Mastering this topic will arm an applicant with skills and abilities to analyse data expected from the Lyman-alpha Solar Telescope (LST) aboard the Advanced Space-based Solar Observatory (ASO-S), which was launched on 9 October 2022.

An aim of the summer student program is to:

• become familiar with:

− the IDL software including the dedicated IDL SolarSoft package,

− Lyman-alpha images obtained by VAULT,

− LST aboard ASO-S.

• identify DFs with hot tips in VAULT images and to derive their basic parameters.

Preferred qualification: Bachelor student

Requirements:

• a knowledge of programming in any language is essential,

• a keen interest to learn the Interactive Data Language (IDL),

• proficiency in physics and mathematics,

• a basic knowledge of astronomy,

• good verbal and written communication skills in English,

• good motivation with balanced attitude to the work and free-time activities.

Non-mandatory supplementing of application by materials and/or weblinks, documenting knowledge in IDL and/or astronomy, will be considered as an advantage.

Research Project 2

Title: Solar flares by large solar telescopes (for a master’s degree student)

Mentor: dr. Július Koza (koza@astro.sk)

Institution: Astronomical Institute, Slovak Academy of Sciences, 059 60 Tatranska Lomnica, Slovak Republic

Abstract: Solar flares are rapid energy releases within active regions caused by the reconnection of the coronal magnetic field, resulting in plasma heating to temperatures beyond tens of millions of kelvins. They are potential drivers of coronal mass ejections and related disturbances in space weather. Large solar telescopes, hosted at Canary Islands, provide essential high-resolution data on these high-energy events. The 1.5-m GREGOR telescope at Tenerife observed on 16 August 2022 the M5.0-class flare by an ensemble of instruments, including Tenerife Infrared Polarimeter (TIP) and High-resolution Fast Imager (HiFI+). They yielded wealth of spectropolarimetric data and imagery of the flare amounting to tens of terabytes. Earlier, on 10 September 2017, the Swedish 1-m Solar Telescope (SST) accomplished the observation of spectacular flare loops in the aftermath of X8.2-class flare, ranked as the second-largest flare in the past solar cycle 24. This unique dataset involves spectropolarimetry and spectral imaging in prominent chromospheric lines and continua, which provide a solid groundbase for diagnostics of relatively cool flare loops including their magnetic structure.

An aim of the summer student program is to become familiar with:

• the IDL software including the dedicated IDL SolarSoft package,

• flare data from the GREGOR and SST solar telescopes,

• processing and calibration of the flare data,

• flare spectropolarimetry in the Ca II 854.2 nm and the He I 1083 nm spectral lines,

• quantitative diagnostics of flare plasma including inference of magnetic field strength by

the weak field approximation.

Preferred qualification: Master student

Requirements:

• at least basic knowledge of programming in the Interactive Data Language (IDL) or a

keen interest to learn it is essential,

• analytic abilities and self-reliance in problem solving/troubleshooting,

• proficiency in physics and mathematics,

• a basic knowledge of astronomy,

• good verbal and written communication skills in English,

• high motivation with balanced attitude to the work and free-time activities.

Non-mandatory supplementing of application by materials and/or weblinks, documenting

knowledge in IDL and/or astronomy, will be considered as an advantage.

Research Project 3

Ttitle: Spectroscopic analysis and TESS photometry of peculiar early-type stars

Mentor: Mgr. Martin Vaňko, PhD. (vanko@ta3.sk)

Institution: Astronomical Institute, Slovak Academy of Sciences, 059 60 Tatranska Lomnica, Slovak Republic

Abstract: There is a small group of peculiar early-type stars on the main sequence that show different rotation velocities from different spectral lines. This inconsistency might be due to the binary nature of these objects. We aim to verify this hypothesis by a more detailed spectroscopic and photometric (using TESS satellite data) investigation of several such targets: 51 Psc, 53 Aur, HD 47964, CX Leo, HD 138527 and 42 Peg. During the last decade we performed a long-term spectroscopic monitoring of all (six) targets in which binarity has either been established or signs of possible companions have been indicated. The primary goal of the survey is to examine the radial velocities (RVs) variations of the stars published earlier and to study multiplicity of the objects.

Objectives: Determination of the orbital and absolute parameters of the components. Including fine light-curve (LC) effects in the modeling of eclipses and/or pulsation.

Working plan for a student: (i) to obtain LCs for all targets from the TESS archive (ii) to prepare LCs for analysis (phasing, detrending), (iii) to make period analysis of all LCs (iv) interpretation of results comming up from analysis.

Research Project 4

Title: Study of Space Weather Events in Data from Lomnicky Stit Observatory

Mentor: dr. Simon Mackovjak (mackovjak@saske.sk)

Institution: Department of Space Physics, Institute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovak Republic

Abstract: The measurements of secondary cosmic rays at the top of Lomnicky peak in High Tatras represent one of the most exhaustive datasets of space weather conditions obtained in the V4 area over a period of the last 40 years. Thanks to state-of-the-art data science techniques, these data might be reanalyzed for the purpose of automatic detection and classification of signatures of various space weather events. During the internship, the student will become familiar with the physics of space weather events, principles of secondary cosmic rays detection, and data science techniques using Python and its libraries (Pandas, Plotly, TensorFlow, etc.). There will be also a possibility to visit Cosmic Rays Observatory at Lomnicky Stit and discuss the study with senior experts.

Research Project 5

Title: Analysis of different deep learning architectures for segmentation of solar corona structures

Mentor: dr. Peter Butka (peter.butka@tuke.sk)

Institution: Technical University of Košice, Faculty of Electrical Engineering and Informatics, Department of Cybernetics and Artificial Intelligence, Slovak Republic

Abstract: Solar corona structures (like coronal holes and active regions) are the main drivers of space weather processes directly or indirectly affecting the Earth. The most recent space-based solar observatories and their imagers (like Solar Dynamics Observatory with AIA instrument) provides high-resolution EUV images for monitoring of such structures. Automatic detection and segmentation of solar corona structures might bring useful tool for analysis of solar weather processes. Also, deep learning segmentation models became todays de-facto leading machine learning techniques in the area. During the internship, the student will become familiar with the gathering and preprocessing of images for creation of different current state-of-the art deep learning segmentation models using Python and its libraries (Pandas, Sci-kit, Keras,/TensorFlow or PyTorch, etc.), which will be compared by their quantitative and qualitative analysis.

There will be also a possibility to discuss the work and results with the expert from our astrophysics partners from the Institute of Experimental of Physics in Košice. The results of the activity might be interesting for the enhancement of current state in solar corona structures segmentation and thus provide valuable tool for physicists in their research.

Research Project 6

Title: Photometry of transiting exoplanets

Mentor: Mgr. Pavol Gajdoš, PhD (pavol.gajdos@upjs.sk)

Institution: Institute of Physics, Faculty of Science, P. J. Šafárik University in Košice, Slovak Republic

Abstract: This project is concentrated on ground-based observations of exoplanetary transits with small telescopes. The student will select appropriate targets for the observations from known exoplanets according to the equipment used (15 cm telescope). The main goal is observing transits of selected exoplanets at the Astronomical Observatory on the Kolonica saddle. Obtained results will be compared to the data from space telescopes Kepler and TESS.

Research Project 7

Title:Machine learning and eclipsing binaries

Mentor: assoc. prof. Mgr. Štefan Parimucha, PhD (stefan.parimucha@upjs.sk)

Institution: Institute of Physics, Faculty of Science, P. J. šafárik University in Košice, Slovak Republic

Abstract: Eclipsing binaries (EBs), are variable stars whose light curve analysis allows us to determine the basic parameters of the components, such as their effective temperatures, radii, luminosity, and in combination with radial velocities and/or distances, the masses and mutual separation of the components. EBs are one of the most commonly discovered types of variable stars and archived data from different surveys (KEPLER, TESS, GAIA, SuperWASP, ASASS...) contain tens of thousands of eclipsing binary stars. It is assumed that planned large-scale surveys such as PLATO and/or Vera C. Rubin Observatory (LSST) will discover millions of EBs. Their analysis using up-to-date conventional methods is practically impossible. One of the possible ways of their study is the application of machine-learning techniques to large data sets. The first step in such an analysis should be the automatic classification of different types of EBs and the detection of systems with asymmetric light curves caused by the spots and pulsations. The main task of the student will be to create an artificial dataset and train it with different parameters in order to find the best model describing the real data.

Research Project 8

Title: Characterization of space debris and Near-Earth Objects using own photometric observations

Mentor: dr. Jiří Šilha (jiri.silha@fmph.uniba.sk)

Institution: Comenius University in Bratislava, Faculty of Mathematics, Physics and Informatics, Slovak Republic

Abstract: The primary objective of this work will be to investigate physical and dynamical properties (rotations) of space objects on geocentric, and heliocentric orbits, and in cis-lunar region which will require to perform several observation campaigns of space debris and NEO using AGO70 telescope to extract their color indices, rotation properties, phase functions, albedos, and sizes. The candidate will construct phase functions to perform characterization of space debris according to their surface and shape properties. The candidate will investigate catalogued and newly discovered NEA rotational properties and surface properties using photometric filters.

Research Project 16

Title: High-resolution view of the radio jet in the high-redshift quasar PKS 2215+020

Mentor: Krisztina Perger (and Sándor Frey)

Institution: CSFK Konkoly Observatory, Hungary

Abstract: The quasar PKS 2215+020 (J2217+0220) is a prominent radio-loud active galactic nucleus in the early Universe at redshift z=3.57, also detected in X-rays. The synchrotron radio emission of such objects originates from the relativistic plasma jet emanating from the close vicinity of the central accreting supermassive black hole. These radio jets can be imaged with the technique of very long baseline interferometry (VLBI), providing the highest possible angular resolution. VLBI uses coordinated observations performed by global networks of radio telescopes. At such a high redshift, PKS 2215+020 is known to have an unusually large inner radio jet with low surface brightness, extending to about 80 milliarcsec (corresponding to nearly 600 pc linear size projected onto the sky). The task of the student is to get familiar with the basics of VLBI image reconstruction theory and practice and make images and brightness distribution models of the jet in PKS 2215+020 using archival VLBI data taken at different wavelengths over a long period of time. The goal is to reveal its spectral properties and possibly detect changes in the structure with time. This could lead to the determination of the apparent jet component proper motion, some physical and geometric parameters of this relativistic jet.

Recommended reading:

Lobanov et al. (2001), Astrophys. J., 547, 714 (DOI:10.1086/318391)

Frey & Mosoni (2009), New Astron. Rev., 53, 307 (DOI:10.1016/j.newar.2010.07.005)

Research Project 17

Title: Analysis of planetary surface evolution in the Solar System

Mentor: Ákos Kereszturi

Institution: CSFK Konkoly Observatory, Hungary

Abstract: During the visiting work, spacecrafts acquired datasets of solid planetary surfaces will be analysed, mainly focusing on Mars and Moon, working with images and topographic datasets. The research for Mars aims the identification and survey of fluvial valleys, various sedimentary features for size, topological structure, volume, morphology, and statistical crater analysis based age estimation, as well as comparison to other already surveyed landforms. For the Moon the evaluation of polar regions, comparison of candidate landing sites, estimation of geotechnical parameters of the regolith, statistical analysis of small craters and boulders at different slope angle terrains will be done. The specific topic of the research will be decided together at the beginning of the visit or beforehand. For these works experience in GIS software usage is needed (mainly ArcGIS or QGIS), and knowledge in computer-based handling of large numerical datasets is beneficial. The candidate will work together with the Hungarian team, learn how to use the CraterStat software, and compile a research paper during her/his stay with the support of the scholarship under supervision.

Research Project 18

Title: A study of accretion-related brightness variations of young stars based on the Gaia Science Alerts database

Mentor: Zsófia Nagy

Institution: CSFK Konkoly Observatory, Hungary

Abstract: When they are born, Sun-like stars are surrounded by a disk of gas and dust. The mass transport from the disk onto the star (accretion) builds up the star. This process is time-variable, and as a result, young stars often show time-variable brightness caused by the fluctuating accretion rate. The most extreme variability is observed in young eruptive stars. During the outbursts of these objects, accretion rate may increase by several orders of magnitude. Therefore, observation of such stars is crucial to understand star formation. However, only about 50 young eruptive stars are known. One of the best tools to increase the sample of known young eruptive stars is the Gaia Science Alerts database, which publishes the Gaia light curves of stars showing a rapid change in their brightness. The student's task will be to analyze the optical and infrared variability of Gaia alerted young eruptive star candidates using archival photometric data and new optical / infrared spectroscopic observations. The goal is to study photometric and spectroscopic changes caused by variable accretion and draw conclusions on the physical mechanism of the outburst and its temporal evolution.

Research Project 19

Title: A study of accretion-related brightness variations of known young eruptive stars

Mentor: Ágnes Kóspál, Péter Ábrahám

Institution: CSFK Konkoly Observatory, Hungary

Abstract: When they are born, Sun-like stars are surrounded by a disk of gas and dust. The mass transport from the disk onto the star (accretion) builds up the star and the disks are also the birthplaces of planets. Young stars often show brightness variations caused by the fluctuating accretion rate. The most extreme variability is observed in young eruptive stars. During the outbursts of these objects, accretion rate may increase by several orders of magnitude. The immense energy liberated during outbursts significantly alters the properties of the disk and, consequently, may have a considerable effect on the planet formation. Young eruptive stars are one of the main topics studied in the Konkoly Space Astronomy, Planet and Star Formation Group. The student will join this research group and their task will be to analyze the optical and infrared variability of young eruptive stars using archival data and new observations from Piszkéstető Observatory. They will construct multi-filter light curves and multi-epoch spectral energy distributions and fit them with simple analytical or more complex radiative transfer models. They will study photometric and spectroscopic changes caused by variable accretion and draw conclusions about the physical mechanism of the outburst and its temporal evolution.

Research Project 20

Title: Studying the properties of various types of supernovae

Mentor: Barnabás Barna

Institution: Szeged University, Hungary

Abstract: The research of exploding stars (supernovae) is a dynamically evolving field of modern astrophysics, which received a further boost in the JWST era. Despite the decade-long efforts and various applications (e.g., distance measurements), even fundamental questions, like the exact explosion scenarios, have remained unanswered. Our group studies several aspects of supernovae, e.g., ejecta-CSM interaction, chemical compositions, or dust formation in the ejecta. During the project, the participants will learn the general characteristics of the supernova classes and gain practice in every step of a usual supernova study. Photometric observations will be made from the Observatory of Baja with the 0.8m telescope and processed via the IRAF software package. Former spectroscopic measurements from ESO facilities will be also processed with the EsoReflex pipeline. The data will be the subject of general analysis for the constraining explosion time, distance, ejecta structure, and chemical composition for both thermonuclear and core-collapse supernovae. Finally, the students can participate in an ongoing study aiming for the spectral synthesis of a larger spectroscopic dataset of type Iax SNe. These thermonuclear explosions show a wide range of peak absolute magnitudes. The study will examine the possible correlations of luminosity with other, more easily measured properties. The participant will be the co-author of the future publication, based on their contribution to the study.

Research Project 21

Title: A multi-wavelength theoretical study of BLAPs (blue large amplitude pulsators) using MESA

Mentor: László Molnár, Susmita Das

Institution: CSFK Konkoly Observatory, Hungary

Abstract: Classical pulsators are widely used for the estimation of extragalactic distances, thanks to their well-defined period-luminosity relations. However, further kinds of pulsating variables also exist across the Hertzsprung-Russell diagram, one of which is the BLAPs: blue large-amplitude pulsators. This new class of extremely rare pulsators was discovered recently, with phased light curves quite similar to those of RR Lyraes and classical Cepheids but with periods much shorter, in the range of 20-40 min. The evolutionary status of these stars remains unknown; however, pulsation theory predicts that they may be evolved low-mass stars with inflated helium-enriched envelopes. The similarity of light curves of BLAPs with those of classical pulsators makes it possible to reliably model them with current pulsation codes. A few observed light curves of BLAPs are available from OGLE, Gaia, and TESS. A comparison of the theoretical and observed light curves of BLAPs would provide information on the global and structural parameters of the stars. In this project, we plan to compute theoretical multi-wavelength light curves of BLAPs using MESA-RSP in many passbands. The questions we would like to probe are: (i) despite their obvious differences in the evolutionary status from the classical pulsators, what other similarities do they share in addition to the sawtooth nature of their phased light curves? (ii) do they obey a period-luminosity relation? (iii) can we estimate photometric metallicities from their light curves? The study can later be expanded into the evolutionary status of BLAP stars as well.

Research Project 22

Title: Modelling Planet Formation with GPU-assisted Numerical Simulations

Mentor: Zsolt Regály

Institution: CSFK Konkoly Observatory, Hungary

Abstract: Planet formation is one of the hot topics of today's astronomy. An immense theoretical effort is being undertaken to solve the open questions and to better understand how planetary systems and our Solar System are formed. The key aspect of formation theory – confirmed by observations – is that planets emerge in protoplanetary disks from the remnant material of star formation. Physical processes that occur in protoplanetary disks (disk accretion, formation of the building blocks of planets, planet-disk interaction, evolution of planetary orbits, etc.) are governed by hydrodynamical and gravitational phenomena. Due to the complexity of the problem, modelling planet formation requires numerical approaches. The numerical solutions, however, can only be calculated with computing facilities that provide high-performance capabilities such as GPU-accelerated computers. In this summer intern project, we give an overview of the modern concept of planet formation and the numerical methods used for describing protoplanetary disk systems. In addition, a practical introduction is given for the participants to parallel programming techniques focusing on NVIDIA 's CUDA GPU language.

Research Project 23

Title: Radiative transfer processes in circumstellar disks

Mentor: Lei Chen

Institution: CSFK Konkoly Observatory, Hungary

Abstract: A variety of stars are surrounded by circumstellar disks, e.g., protoplanetary disks around young stars, debris disks around Vega-type stars, and the disks around post-AGB stars. In all these disks, the dust component would absorb the stellar light and re-emit the energy in infrared or longer wavelengths. Numerical simulation of such radiative transfer (RT) processes makes it possible to predict the spectral and spatial distribution of the dust emission for given dust distributions, which can be compared with observations. In the three-month summer project, the student will practise this RT simulation procedure with the simulation code RADMC3D, under the supervision of Dr. Lei Chen, and in collaboration with fellow scientists in the group. The project will help the student to gain an understanding of the RT processes, especially how the dust emission (spectra, brightness distribution, etc.) is affected by the dust properties (spatial distribution, grain size distribution, chemical composition, etc.). The student could also practise on the analysis of observational data, e.g., JWST/MIRI spectra of young stars, by comparing the RT simulations with observations. The knowledge gained will be useful in the student's future academic career in the field of circumstellar disk study.

Research Project 24

Title: Routine operations of GRBAlpha: challenges for time-domain high energy astrophysics

Mentor: András Pál

Institution: CSFK Konkoly Observatory, Hungary

Abstract: GRBAlpha is the first 1U CubeSat mission providing gamma-ray burst monitoring of the sky, built and operated by a joint Hungarian–Slovakian–Czech–Japanese collaboration. Since its launch, it detected and characterized several dozens of gamma-ray bursts and other types of high energy transients (such as solar flares and soft gamma-ray repeaters), demonstrating the viability of astrophysics on such a small spacecraft. Currently, the operations of the project follow a well-established scheme. Namely, the Hungarian team oversees the payload-side support, the preparation for future on-board software upgrades allowing the increase the downlink data volume as well as manages the downlink satellite reception network; the Slovakian members support the satellite commanding, radio subsystems and platform-side software support; the Czech group manages the data processing and scientific interpretation while the Japanese participants provide further calibration data and particle physics simulations of the detector array. The aim of our proposal now is to extend this networking of ours with in-house experiences by sharing the knowledge of different groups for students involved in the whole project – aiding not just the smoother operations and the way towards higher data volume but providing further effort for the upcoming projects such as GRBBeta and optimizing the utilization of VZLUSAT-2, another spacecraft having onboard a similar type of gamma detector system.

Research Project 25

Title: Disks, envelopes, and outflows of eruptive young stars with ALMA

Mentor: Fernando Cruz Saenz De Miera

Institution: CSFK Konkoly Observatory, Hungary

Abstract: Stars are born surrounded by a protostellar disk, and deeply embedded in a thick envelope. Accretion is the physical process that moves material from the outer edges of the disk towards the inner radii and then onto the star so that it reaches its final mass. Two additional effects this mechanism can have in these young stellar objects are the depletion of the enveloping material and the ejection of bipolar molecular outflows. Most of these forming stars have stable mass accretion rates, but there is a subset of them that experiences episodes in which the mass accretion rate increases suddenly by orders of magnitude. These are called eruptive young stars. Our research group is working towards understanding the effects these accretion outbursts have on the circumstellar disks and their surroundings, and to do this we are using observations taken with the ALMA radio antenna array in Chile. Your collaboration with us will be by learning how to work with this type of data then measuring the amount of material in the disks and envelopes surrounding the protostars and studying the kinematics of their molecular outflows to estimate how much mass and momentum are being injected back into the star-forming region.

Research Project 26

Title: Hunting for jets in eruptive young stars with MUSE

Mentor: Fernando Cruz Saenz De Miera

Institution: CSFK Konkoly Observatory, Hungary

Abstract: Stars are born surrounded by a protostellar disk, and deeply embedded in a thick envelope. Accretion is the physical process that moves material from the outer edges of the disk towards the inner radii and then onto the star so that it reaches its final mass. An astrophysical phenomenon thought to be a by-product of accretion are the high velocity jets. Most of the forming stars have stable mass accretion rates, but there is a subset of them that experiences episodes in which the mass accretion rate increases suddenly by orders of magnitude. These are called eruptive young stars. Our research group is working towards searching what is the relationship between the accretion outbursts and the ejection of jets, and to do this we are using observations taken with the MUSE instrument of the VLT in Chile. Your collaboration with us will be by learning how to work with integral field spectroscopy and then carrying out a deep search for faint jet emission. You will follow up by calculating the excitation temperature and electron density of the jets you discover, and then estimate their kinematic age to correlate with the accretion history of the star.

Research Project 27

Title: Stellar merger model for the progenitor of supernova SN1987A

Mentor: Dr. Ondrej Pejcha

Institution: Charles University, Prague, Czech Republic

Abstract: Supernova 1987A was the brightest and closest supernova in the last 400 years and consequently is one of the most studied objects in the Universe. About 20 neutrinos from the formation of the neutron star were detected on Earth. SN1987A had a very peculiar light curve and puzzling properties of its progenitor star, which was a blue supergiant surrounded by three nebular rings. The leading explanation is that the supernova progenitor experienced binary star merger ~20000 years before the supernova explosion. In the past few years there have been stellar mergers witnessed in real time and these events have been modelled in great detail. The goal of this project is to re-interpret the matter distribution around SN1987A in the light of new evidence on stellar mergers using (radiation) hydrodynamical simulations. Other projects involving hydrodynamical simulations, transport of radiation, and complex models of data focused on binary stars are also possible

Research Project 28

Title: Interaction of expanding envelopes of supernovae with the surrounding circumstellar medium

Mentor: Dr. Petr Kunfuerst

Institution: Masaryk University, Brno, Czech Republic

Abstract: We propose to study the interactions of expanding supernova (SN) ejecta with different morphologies of the surrounding dense circumstellar medium (CSM) formed before the SN explosion. Many possible mechanisms can lead to violent eruptions of huge amounts of matter from potential SNe progenitors long or shortly before the SN explosion itself; the nature of these processes is still not completely clear. After the explosion, the propagation of the SN shock wave through such an environment leads to significant effects that fundamentally increase the luminosity of the light curve and can create spectra of a characteristic aspherical pattern. We can use advanced multidimensional hydrodynamic codes developed in our department to simulate gas dynamics during such interactions and calculate the light curves and spectral profiles of several SN-CSM configurations. Based on our calculations, we can also estimate the amount and spatial distribution of the original ejected mass, which can contribute to the understanding of pre-explosive eruptive mechanisms. We also use our department's Monte Carlo radiative transfer code and compare the calculated observables with the real ones from observed SNe.

Research Project 29

Title: Magnetospheres of rotating hot stars

Mentor: Dr. Petr Kunfuerst

Institution: Masaryk University, Brno, Czech Republic

Abstract: Hot, massive, early-type stars are essential objects for a steady and long-term supply of circumstellar matter (CSM) with new "fresh" material. The transfer of material from stars to their surroundings is also accompanied by a corresponding transfer of angular momentum. Many early-type stars have strong magnetic fields that are thought to be of fossil origin. These magnetic fields substantially affect the rate of mass loss and the rate of angular momentum loss by stellar winds. The outflowing mass via the stellar winds can be more or less captured by the magnetospheres, leading to significant changes in the mass distribution around the star. This can also lead to a significant reduction in the rate of mass loss due to the backward movement of material along magnetic field lines in strong magnetic fields. Magnetic compression of circumstellar matter also leads to an aspherical distribution of circumstellar material that can alter the profiles of the observed light curves. Using our magnetohydrodynamic code, we can calculate the hydrodynamic behavior of the CSM, its structure, and subsequently estimate the observable characteristics of such magnetic stars depending on the assumed magnetic field intensity and morphology.

Research Project 30

Title: Hydrodynamic simulations of supernovae interacting with their environment

Mentor: Dr. Richard Wunsch

Institution: Astronomical Institute of the Czech Academy of Sciences, Prague, Czech Republic

Abstract: The project offers a general introduction to astronomy-related hydrodynamic simulations. The participants can learn about the core structure and the most important modules of the 3D mesh-refinement code FLASH, including the use of the hierarchical data format (HDF5) file structure and post-processing scripts. By the use of FLASH and FLASH-related codes, the participants can gain practice in both Fortran and Python programming languages. The participants will create and run simulations following the evolution of expanding, high-velocity gaseous shells (e.g. supernova explosions) in various astrophysical environments. A further goal is studying the interaction of the shell with the circumstellar/interstellar matter or nearby objects. The students will create a method to transform the simulation outputs of FLASH into synthetic observables at the optical / IR / radio wavelengths. The project also aims to motivate the participants (and via them, their home institutes) for further involvement in using and developing hydrodynamic simulations.

Research Project 31

Title: Calibration of the “unaltered” amount of cold gas in galaxies with a machine learning classifier.

Mentor: Dr. Boris Deshev

Institution: Astronomical Institute of the Czech Academy of Sciences, Prague, Czech Republic

Abstract: The cold gas content of galaxies determines their star formation rate and with that their overall evolution. There are numerous physical processes, both internal and external, which can affect the gas content of galaxies. All those processes work on relatively long time scales and their direct observation is difficult. For that reason we want to do statistical studies of large samples of galaxies.

For this kind of studies it is important to have a reliable method for assigning an “undisturbed” amount of cold gas to the galaxies based on their other observable properties like e.g. stellar mass, optical color, morphology, size, etc. While there are historical methods developed for this purpose, they are based on limited amount and quality of data. The data sets from modern wide-field surveys provide detailed data for tens of thousands of galaxies which is an opportunity to develop more precise recipe for calculating this important parameter. A reliably assigned “normal” gas content can help us find galaxies in the process of transformation.

This project aims to combine existing data from large surveys, namely SDSS for optical data and ALFALFA for cold gas measurements, and to find a recipe for calculating the “normal” gas content of galaxies. Ideally this will be done with a machine learning classifier (e.g. Random forest). The work will require a modest knowledge of SQL to query the data bases and (Python) programming to set up the classifier. The ideal outcome will be a stand alone software tool that can accept table with galaxy parameters and return the expected gas content. This open source tool will be made available for the wider astronomical community.

While doing the analysis the student will have an opportunity to further explore the field of evolution of galaxies while immersed in the friendly atmosphere of the GPS department of the Institute of Astronomy in Prague. The named above methods and programming tools are only a suggestion, the student is encouraged, and will be provided with support, to develop their own ideas for achieving the said goal.

Research Project 32

Title: Multiwavelength analysis of the Changing Look Active Galactic Nuclei

Mentor: Dr. Abhijeet Borkar

Institution: Astronomical Institute of the Czech Academy of Sciences, Prague, Czech Republic

Abstract: Supermassive black holes reside in the centres of galaxies, and accrete matter that falls in their gravitational potential. These active galactic nuclei are classified by their optical spectra, which show either broad and narrow atomic ionization emission lines (type 1) or only narrow emission lines (type 2). The difference between these two types of AGN are attributed to the viewing angle towards the SMBH, which may be obscured by absorbing material. But several AGN are found to be changing in their AGN type over the timescales of few months to years. These are called the Changing-look AGN (CLAGN) and are often considered to be candidates for studying accretion state change analogous to that observed in stellar mass black holes in X-ray binaries. The aim of this project will be to collate a sample of CLAGN and examine their multiwavelength properties, in particular, by creating a hardness-intensity diagram. Additionally, we will explore what properties of the AGN and their host galaxies are associated with the CL phenomenon. The prospective student will get a hand-on experience of working with large astronomy catalogues and familiarize with data from several space and ground based observatories. They will also learn data compilation, reduction and data analysis techniques using modern astronomy software and tools.

Research Project 33

Title: Exploring the star formation in dwarf galaxies with radio, X-ray and other multiwavelengh data

Mentor: Dr. Jiri Svoboda

Institution: Astronomical Institute of the Czech Academy of Sciences, Prague, Czech Republic

Abstract: Dwarf galaxies are a subclass of galaxies which have at most a few billion stars. Dwarf galaxies play a cruicial role in our understanding of galaxy evolution. In the hierarchical galaxy evolution scenario, it is thought that the smaller dwarf galaxies form the building blocks which merge together to create the large galaxies we see in the local Universe. Studying these galaxies can allow us to explore star formation and ISM properties in conditions that may be representative of early Universe environments, which are being explored by JWST. Many dwarf galaxies are also expected to harbour intermediate mass black holes (IMBH), which are the progenitors of the supermassive black holes and active galactic nuclei (AGN).

One of the most important property of galaxies is their star formation rate (SFR), which is usually derived using empirical relations. These relations are often constructed for the large galaxies and it is not clear whether the relations hold for the lower mass end. It is important to accurately estimate the SFR luminosity to identify the presence of IMBHs in the dwarf galaxies. The aim of this project would be to examine the SFR-luminosity relations for a large sample of nearby dwarf galaxies and establish whether the luminosity relations hold towards the low-mass end. The student will learn to analyse multiwavelength data of galaxies and perform data reduction and processing. They will also have an opportunity to work with the international group of experts in star formation and AGN astrophysics using optical, radio and X-ray data.

Research Project 34

Mentor: Dr. Michalis Kourniotis

Institution: Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic

Abstract: Variable massive stars in the era of TESS Stars with mass over eight times the mass of Sun, outshine the vast majority of stars in the Universe. These rare and high-luminous objects live a very short but active life, impacting both their local environment and the evolution of galaxies. The evolution of massive stars, however, is still not well understood. One of the biggest challenges that astronomers address is their variability. This is expressed in different forms such as, the pulsations, the remarkable ejections of material, and the encounters with companion stars. In the recent years, the launch of TESS spacecraft has opened a new road in the exploration of stellar variability. The mission provides astronomers with high-accuracy photometry that is obtained at short time intervals of several to even couple of minutes. On the other hand, the main drawback of TESS is the low spatial resolution, which makes difficult to extract information from stars that are located in crowded fields of the sky. With the current project, we invite a student who will work in exploring the variability of massive stars that are observed in late phase of their evolution, using data from TESS. The student will work under the guidance of Dr. Michalis Kourniotis at the department of Stellar Physics of the Astronomical Institute, in Ondrejov. During the project, the researcher will introduce to the student the basic tools for downloading, extracting, correcting, analyzing, and visualizing the TESS light curves of the stars. Furthermore, the student will be motivated to develop strategies that could minimize contamination of the data from nearby stars and due to systematic effects. At the end of the project, the results will be discussed/presented to the scientists of the department, offering the student the opportunity to develop communicative skills on top of the research ones that are needed for sharing knowledge and for a future involvement in astronomy.

Research Project 35

Title: Solar flares at FICUS

Mentor: Dr. Jana Kasparova (jana.kasparova@asu.cas.cz)

Institution: Astronomical Institute of the Czech Academy of Sciences, Ondrejov, Czech Republic

Abstract: Solar flare is energetic process which affects all layers of solar atmosphere and is the cause of flare emission in almost whole electromagnetic spectrum. A substantial part of the emission is in the form of so-called continua, however nature of the emission origin is still not understood well. Flare Intensity Continuum Ultrawide Spectrograph (FICUS) is an instrument based at the Astronomical Institute of the CAS, Ondrejov, and is dedicated to observations of solar flares in full width of the optical range. The aim of the project is to learn how to operate the instrument and to analyse the FICUS imaging and spectral data. It is expected that the student will actively observe with the instrument, co-operate on the analysis of the FICUS data, and use and extend data analysis software written in Python. FICUS flare data can be also combined with data at other wavelengths, such as EUV, X-ray, or radio observations from space-born and ground-based instruments. BSc like level of astronomy and astrophysics is an advantage, serious interest to learn new things is expected. Data analysis experience is welcome. Basic knowledge of Python or a keen interest to learn it is essential.