PhD study

•   
• Study  
PhD study

1. Extrasolar planets
2. Numerical simulation of jets in the solar atmosphere
3. Distribution of the orbits of sporadic meteoroids
4. The early stage of classical nova explosions
5. Analysis and modelling of asteroid activity in terms of rotation, 3D shape and tail morphology changes
6. The anomalous spectral dependence of polarization in selected comets
7. The origin and formation of the inner Oort cloud
8. Outburst of the symbiotic star BF Cyg with flares and collimated mass ejections
9. Cycle of solar activity – empirical implications for the solar dynamo modelling
10. Solar activity and the cosmic rays – magnetic fields in the solar atmosphere and their effect on the cosmic rays level
11. High-contrast SB2 spectroscopic systems with peculiar early-type component(s)

The Astronomical Institute SAS organizes PhD study in astronomy and astrophysics.

Conditions for the interview:

1. Graduation of the University study at the Master level (the 2nd education degree). Applicants from the outside of EU are required to submit “Recognizing certificates on the 1st and 2nd education  degree acquired at universities abroad” at the registration of his/her study (around the beginning of September). See: Recognizing certificates on study abroad

2. Filled in application with its attachments sent to the address of the Astronomical Institute SAS within the given deadline.

For the PhD program of Astronomy and Astrophysics, Astronomical Institute SAS advertises the following themes:

1. Extrasolar planets
   Language of Thesis: English
   Secondary language: Slovak
   Supervisor: Dr. Jan Budaj (budaj@ta3.sk)
   Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Tatranska Lomnica, 059 60 Vysoké Tatry, Slovakia
   Syllabus:
   Focus of the research:
   Today, we know of more than 5000 extrasolar planets (exoplanets). Smaller objects such as exoasteroids and exoplanets have been discovered too. Most of them are transiting their host stars and their transits have nice symmetric shape and are stable. This is similar to eclipses in eclipsing binaries. However, there are objects with anomalous, asymmetric, and variable transits or eclipses. These will be of our main interest. This field of research is evolving quickly opening new possibilities, surprises and challenges. That is why objectives of the thesis may shift according the current situation, availability of data, as well as interests and activity of the student.
   Objectives:
   -disintegrating exoplanets or “exo”bodies on close orbits around their parent stars (photometry, simulations)
   -eclipsing stellar systems with dark dusty disks – a cradle for planets (photometry and modelling of spectra and lightcurves),
   -reflection effect and albedo in interacting binaries and exoplanets (photometry and modelling)
   Requirements:
   knowledge of English language, basics of Astronomy and Astrophysics.
   Welcomed experience: programming (Fortran, Python,…), Linux operating system,
   Research field:
   Extrasolar planets, brown dwarfs, and low mass stars, Binary and multiple stellar systems
   Literature:
   Heng, K. 2017, Exoplanetary Atmospheres, Princeton Univ. Press
   Perryman, M. 2018, The exoplanet handbook 2nd Edition
   Cassen, P., Guillot, T., Quirrenbach, A., 2006, Extrasolar Planets
   Seager, S., 2010, Exoplanets (Univ. of Arizona Press, hard cover, 626p) and mostly recent papers from arXiv
2. Numerical simulation of jets in the solar atmosphere
   Language of Thesis: English
   Secondary language: Slovak
   Supervisor: Mgr. Peter Gömöry, PhD. (gomory@astro.sk)
   Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, 059 60 Vysoké Tatry, Slovakia
   Consultant: Prof. Teimuraz Zaqarashvili, PhD. (temury.zaqarashvili@iliauni.edu.ge)
   Affiliation: Ilia State University, Tbilisi, Georgia
   Sylabus
   Focus of Thesis: Solar plasma jets are highly dynamic and complex phenomena occurring in the Sun’s atmosphere. They play a critical role in energy and mass transfer within the solar atmosphere and contribute to space weather effects that impact Earth. Despite substantial progress in solar physics, many mysteries remain, such as the rapid heating of plasma to coronal temperatures and the short lifetimes of jets like type II spicules. These processes are believed to be driven by various instabilities, including Kelvin-Helmholtz (KH), kink, and Rayleigh-Taylor instabilities, within magnetised plasma flows.
   This thesis aims to investigate the dynamics, stability, and heating mechanisams of solar plasma jets through advanced numerical simulations. By integrating theoretical models, high-resolution numerical simulations, and observational data, the research seeks to provide a deeper understanding of how instabilities and other processes contribute to the behaviour of solar plasma jets and their role in the coronal heating problem. The outcomes are expected to enhance our understanding of solar atmospheric dynamics and inform space weather prediction models.
   Objectives: The overarching goal of this thesis is to deepen our understanding of the dynamics of solar plasma jets and the associated coronal heating problem. By employing advanced numerical simulations, the project aims to unravel the physical processes driving these phenomena, which are critical for advancing solar physics and improving space weather prediction.
   Requirements: good background in physics, basic knowledge in programing (e. g., IDL).
   Research field: Research of physical properties and processes in the atmosphere of the Sun.
   Literature:
   [1] Beckers, J. M. (1968). Solar Phys., 3, 367.
   [2] De Pontieu, B., McIntosh, S., Hansteen, V. H., et al. (2007). PASJ, 59, S655.
   [3] Rouppe van der Voort, L., Leenaarts, J., de Pontieu, B., et al. (2009). ApJ, 705, 272.
   [4] Tsiropoula, G., Tziotziou, K., Kontogiannis, I., et al. (2012). Space Sci. Rev., 169, 181.
   [5] Shibata, K., Ishido, Y., Acton, L. W., et al. (1992). PASJ, 44, L173.
   [6] Moore, R. L., Sterling, A. C., Falconer, D. A., & Robe, D. (2013). ApJ, 769, 134.
   [7] Nishizuka, N., et al. (2011). ApJ, 731, 43.
   [8] Sterling, A. C., Moore, R. L., Falconer, D. A., & Adams, M. (2015). Nature, 523, 437.
   [9] Murawski, K. & Zaqarashvili, T. V. (2010). A&A, 519, A8.
   [10] Zaqarashvili, T. V., Vörös, Z., Narita, Y., & Bruno, R. (2014a). ApJL, 783, L19.
   [11] Zaqarashvili, T. V., Vörös, Z., & Zhelyazkov, I. (2014b). A&A, 561, A62.
   [12] Zaqarashvili, T. V. (2020). ApJL, 893, L46.
   [13] Zaqarashvili, T. V., Lomineishvili, S., Leitner, P., et al. (2021). A&A, 649, A179.
   [14] Hollweg, J. V. (1982). ApJ, 257, 345.
   [15] Chandrasekhar, S. (1961). Hydrodynamic and Hydromagnetic Stability. Oxford Univ. Press.
3. Distribution of the orbits of sporadic meteoroids
   Language of Thesis: English
   Secondary language: Slovak
   Supervisor: RNDr. Mária Hajduková Jr., PhD. (Maria.Hajdukova@savba.sk)
   Affiliation: Astronomical Institute of the Slovak Academy of Sciences, The Department of Interplanetary Matter, Bratislava, Slovakia
   Syllabus
   Focus of the thesis: On its orbit around the Sun, the Earth crosses the orbits of a number of meteoroids, and, together with the whole solar system, passes through the interstellar medium. Thus, it collides with nearby particles which can be registered as meteors in the Earth’s atmosphere. Observations of the atmospheric trajectories of meteors lead us to their heliocentric orbits, on which meteoroids moved before their collision with the Earth. These indicate the origin of the meteoroids. We can identify specific parent bodies of meteoroid streams in the Solar system; we can classify sporadic meteoroids (whether they are cometary or asteroidal particles); and we may indicate the origin of meteoroids outside the Solar system. This thesis will focus on the origin of the largest population – sporadic meteoroids, which have lost their identity during their evolution (i.e. no similarity between their orbits and the orbit of their parent body or that of other meteoroids can be found).
   Aim of the work: The aim of this work is to map the sporadic background, based on models and the synthesis of observations obtained by different techniques. Observations from Earth of the sporadic background (and its representation in a coordinate system centered at the Earth’s apex) have revealed six apparent sources in which enhanced meteor densities are observed: the so-called helion and antihelion sources, the northern and southern apex sources, and the northern and southern toroidal sources. The distribution of radiants is geometrically determined, but different types of comets or asteroids can be found associated with different regions of enhanced density.
   However, the origin of the sporadic background has not been fully explained. Generally, the entire population of comets, as well as various types of asteroids, is considered to be the source. But there are a few specific comets that distribute significantly more particles to the near-Earth region than others. We will investigate these sources on the basis of statistical distributions of the orbital elements and compare them with the results of different models.
   Moreover, in the search for a dominant source for given radiant densities, the result turns out to depend on the observation technique. Different techniques are differently sensitive to different particle masses; however, their synthesis will allow a more comprehensive view of the distribution of the sporadic background, including the study of its evolution. In this work, we use meteoroid orbits from various available meteor databases.
   Requirements: programming, English
   Research field: Dynamical evolution of small solar system bodies
   Literature:
   [1] Ryabova, Galina O.; Asher, David J.; Campbell-Brown, Margaret J. (Eds.), Meteoroids: Sources of Meteors on Earth and Beyond, ISBN 9781108426718, Cambridge University Press, 2019 (vybrané kapitoly).
   [2] Murray, C. D., Dermott, S. F. Solar system dynamics, Cambridge, UK: Cambridge University Press, ISBN 0-521-57295-9 (hc.), ISBN 0-521-57297-4, 1999 (vybrané kapitoly).
   [3] Wiegert, Paul, Vaubaillon, Jeremie, Campbell-Brown, Margaret, A dynamical model of the sporadic meteoroid complexc, Icarus, Volume 201, Issue 1, p. 295-310, 2009.
   [4] Li, Y., Zhou, Q., Urbina, J., Huang, T.Y., Sporadic micro/meteoroid source radiant distribution inferred from the Arecibo 430 MHz radar obsertvations, MNRAS 515, 2088-2098, 2022.
4. The early stage of classical nova explosions
   Language of Thesis: English
   Secondary language: Slovak
   Supervisor: Mgr. Ľubomír Hambálek, PhD. (lhambalek@astro.sk)
   Consultant: RNDr. Augustin Skopal, DrSc.
   Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, 059 60 Vysoké Tatry, Slovakia
   Syllabus:
   Focus of the research: The nova phenomenon is the result of the sudden thermonuclear fusion of hydrogen into helium in the surface layer of a white dwarf (WD). The fuel for this process is hydrogen material that is deposited on the surface of the WD from its companion in the binary. When the pressure at the base of the accumulated layer reaches a critical value, thermonuclear fusion takes place on a time scale of minutes (so-called fast novae) with an energy output of about 1031 W, which ejects the remaining accumulated mass into the surrounding space at a speed of several thousand km/s. High-energy gamma-photons produced by thermonuclear fusion are transmitted through this material and thereby redistribute their energy throughout the electromagnetic spectrum depending on the optical and geometric properties of the ejected matter, which are dependent on the time since the eruption. In the case of fast novae (the case of massive WDs), the maximum brightness in the optical usually occurs within a few days of the explosion and reaches an amplitude of around 9 to 15 magnitudes. For low-mass WDs, the ignition of thermonuclear fusion is not explosive, the optical maximum usually occurs on a scale of weeks to months, and is often accompanied by other less energetic flares before a gradual decrease in brightness (so-called slow novae). The development of classical novae, especially from their first hours to a few days (tens of days) of their life, is still poorly understood. Determining the basic physical parameters and geometric structure of a nova in its early stages will therefore allow us to better understand the nature of nova explosions and their development, and thus also their integration into the evolution of other stars and stellar systems.
   Objectives: For selected fast and slow novae, determine the basic physical parameters of the radiation regions of the nova (temperatures, radii, luminosities, emission volume, mass-loss rate) and their geometric structure in the early stages after the explosion. This goal is achieved by modeling the energy distribution in the spectrum of the nova (software available), which will distinguish its individual radiation components. The doctoral student will work with existing observations (UBVRI photometry, spectroscopy). For new objects, it will also be possible to obtain own observations with AI SAS telescopes. He/she will be included in the research team of the VEGA project, which will enable him/her to present the obtained results at international conferences.
   Requirements: knowledge of English, basics of programming
   Research field: Symbiotic stars and novae
   Bibliography:
   Appenzeller I., 2012: Introduction to Astronomical Spectroscopy, Cambridge: Cambridge University Press
   Bode, M.F., Evans. A. (eds.), 2008: Classical novae, 2nd ed., Cambridge Astrophysics no. 43, Cambridge: CUP
   Howell, S.B., 2006: Handbook of CCD Astronomy, Cambridge: Cambridge University Press
   Warner, B., 1995: Cataclysmic Variable Stars, Cambridge Astrophysics no. 28, Cambridge: CUP
5. Analysis and modelling of asteroid activity in terms of rotation, 3D shape and tail morphology changes
   Language of Thesis: English
   Secondary language: Slovak
   Supervisor: Mgr. Marek Husárik, PhD. (mhusarik@astro.sk)
   Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, 059 60 Vysoké Tatry, Slovakia
   Syllabus
   Focus of the research: The activity of small objects in the Solar System is usually expected (in the case of comets), but in recent decades we have also encountered cases where mostly objects classified orbitally as asteroids show some unexpected activity. The reasons of the activity may be different: an impact of a small body, a rotational splitting, a thermal defragmentation, etc. (the cause is not always clear). Also, the duration of the active phase can vary considerably from a few days to several months. Sometimes the activity is recurrent, but it may not be related to, for example, the arrival of a body in perihelion. Among other things, these bodies leave behind rather unusually shaped tails than those seen in comets.
   Objectives: Analysis of the activity of a normally inactive body with respect to the orientation of the rotation axis in space, with respect to its shape, possible precession or surface albedo variegation. Computational modelling of tail formation and morphology based also on own observations.
   Requirements:
   (i) knowledge of programming in a commonly used language (Java, C++, preferably Python with astropy, scipy, matplotlib…) and the basics of the LaTeX environment, (ii) good knowledge of the English language, (iii) experience in observations and the ability to reduce the observed material and obtain the values needed for further analysis are welcome.
   Research field: Dynamic evolution of small Solar System bodies
   Literature:
   [1] Binzel, R. P., Gehrels, T., and Matthews, M. S., Asteroids II, 1989
   [2] Bottke, W.F. at al., Asteroids III, 2002
   [3] Michel P., DeMeo, F., Bottke, W.F., Asteroids IV, 2015
   [4] Warner, B.D., A Practical Guide to Lightcurve Photometry and Analysis 2nd ed., 2016
   [5] Chandler, C. O., et al., SAFARI: Searching Asteroids for Activity Revealing Indicators, Publications of the Astronomical Society of the Pacific, vol. 130, no. 993, p. 114502, 2018. doi:10.1088/1538-3873/aad03d.
6. The anomalous spectral dependence of polarization in selected comets
   Language of Thesis: English
   Secondary language: Slovak
   Supervisor: Mgr. Oleksandra Ivanova, PhD. (oivanova@ta3.sk)
   Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, 059 60 Vysoké Tatry, Slovakia
   Focus of the Research: Comets are relic formations that are closest in composition to the primordial protoplanetary cloud. They contain both solar nebula particles and pre-solar (interstellar) particles, offering an opportunity to study the chemical and physical processes of the early Solar System. Radial temperature and compositional gradients of the protosolar nebula, as well as the degree of material mixing during comet formation, are reflected in the properties of cometary dust. Comets may have played a significant role in transporting water and organic molecules to the inner planets, including Earth, making their study essential not only for understanding of their evolution, but also of the formation of Earth and emergence of life on it.
   Objectives: The research focuses on the search and study of comets with anomalous spectral polarization dependence, potentially linked to the chemical composition, structure, and other properties of dust, particularly an increased content of organic materials. The primary objective is to determine the physical characteristics of such comets to establish a connection between their properties, formation regions in the Solar System, and evolutionary processes. The study will compare the properties of comets with normal and anomalous spectral polarization dependence, enabling a deeper understanding of how composition, porosity, and structure of dust particles influence observed polarimetric effects. Photometric and polarimetric methods will be jointly applied to determine all key physical characteristics of the dust component in the coma of selected comets. Analysis of phase functions of brightness and polarization, along with their wavelength-dependent parameters, will provide insights into the composition, sizes, structures, and shapes of dust particles. Comparing observational data with theoretical modelling and laboratory experiments will allow for the identification of the most probable physical properties of cometary dust.
   Requirements: Programming skills in a commonly used language (IDL or Python) and basic knowledge of LaTeX environment, good knowledge of the English language, experience in observations and the ability to reduce the observed material and obtain the values needed for further analysis are welcome.
   Research field: Dust properties in active small bodies of the Solar System
   Literature:
   [1] Bagnulo, S., Belskaya, I., Cellino, A., Kwon, Y. G., Muñoz, O., & Stam, D. M. (2024). Polarimetry of Solar System minor bodies and planets. The Astronomy and Astrophysics Review, 32(1), 1-103.
   [2] Ivanova, O., Rosenbush, V., Afanasiev, V., & Kiselev, N. (2017). Polarimetry, photometry, and spectroscopy of comet C/2009 P1 (Garradd). Icarus, 284, 167-182.
   [3] Kolokolova, L. (2015). Polarimetry of stars and planetary systems.
   [4] Kiselev N., Rosenbush V. 2004. Polarimetry of comets: Progress and problems. In: Photopolarimetry in Remote Sensing, Eds. G. Videen, Y. Yatskiv, M. Mishchenko. – Dordrecht: Kluwer Academic Publishers, 411–430.
   [5] Kiselev N., Jockers K., Rosenbush V. 2002. Comparative study of the dust polarimetric properties in split and normal comets. Earth, Moon, Planets 90, 167-176..
   [6] Kiselev N. N., Jockers K., Rosenbush V. K. et al. 2000. Anomalous wavelength dependence of polarization of comet 21P/Giacobini-Zinner. Planet. Space Sci. 48, 1005-1009.
7. The origin and formation of the inner Oort cloud
   Language of Thesis: English
   Secondary language: Slovak
   Supervisor: Mgr. Marián Jakubík, PhD. (mjakubik@astro.sk)
   Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, 059 60 Vysoké Tatry, Slovakia
   Syllabus
   Focus of the research: The origin and formation of the Oort cloud, spherically symmetric cloud of comets orbiting the Sun in orbits with semi-major axis from 2000 au to 200000 au, are the focus of our research. The Oort cloud can be divided into 2 parts – inner and outer Oort cloud. There are models, which describe scenarios of the origin and formation of Oort cloud resulting from very recent observations. So far, the most suitable are models from time-period when the Sun was located in its birth star cluster. These models of the formation of Oort cloud (both parts) can realistically describe many details, which we can obtain from observations of comets and trans-neptunian objects.
   Objectives: The main aim of this work is detailed description of the origin and formation of inner Oort cloud with main emphasis on models describing the formation of the Oort cloud in its birth star cluster. In more detail, we will solve open questions of this process using numerical simulations with respect of recent observations. Among answers on various open questions, we will find the solution of particular problem related to high number of objects (in the inner Oort cloud) revolving around Sun on retrograde orbits resulting from previous numerical simulations. However, this fact does not result from the analysis of recent available observations of inner Oort cloud objects.
   Requirements:
   programming skills (python, fortran), English language
   Research field:
   The dynamical evolution of the small bodies of the Solar system
8. Outburst of the symbiotic star BF Cyg with flares and collimated mass ejections
   Language of Thesis: English
   Secondary language: Slovak
   Supervisor: Mgr. Emil Kundra, PhD. (ekundra@astro.sk)
   Consultant: RNDr. Augustin Skopal, DrSc.
   Affiliation: Astronomical Insititute of Slovak Academy of Sciences, Tatranská Lomnica, 059 60 Vysoké Tatry, Slovakia
   Syllabus:
   Focus of the research: Symbiotic stars are interacting binaries with very long orbital periods (on the order of years). They consist of a red giant that is losing some of its mass and a white dwarf that is accreting it. Occasionally, on a time scale of tens of years, outbursts occur, during which we observe an increase in the brightness of the system by 2 to 7 magnitudes and significant changes in the spectrum. An outburst is often characterized by a single brightening followed by a decrease to the original brightness. In some cases, the main maximum is accompanied by a secondary flare. In the case of the symbiotic star BF Cyg, the primary outburst occurred in 2006, but the slow decline was interrupted by further flares in 2015 and 2017, after which collimated mass ejections were indicated. The high level of BF Cyg activity continues to the present. The fundamental problem is to clarify the source of energy and the mechanism that maintains such a long-lasting outburst. The essence of symbiotic star outbursts is one of the key problems of their research.
   Objectives: The aim of the PhD thesis is to determine the basic physical parameters of the BF Cyg radiation regions (temperatures, radii, luminosities, emission volume, mass-loss rate from the system) during outburst that occurred in 2006, especially during flares in 2015 and 2017. This goal will be achieved by modeling the energy distribution in the BF Cyg spectrum (software available), which will distinguish its individual radiation components. Furthermore, it is the determination of the basic physical parameters of collimated mass ejections and their evolution in different stages of the outburst. Both tasks should contribute to a better understanding of the process of mass accretion onto a white dwarf as well as the mechanism that maintains the high energy output of BF Cyg for a long time (17 years so far). The doctoral student will work with existing observations (UBVRI photometry, spectroscopy) with the possibility of obtaining new observations with the AISAS telescopes.
   Requirements: knowledge of English, basics of programming
   Research field: Symbiotic stars and novae
   Literature:
   Bode, M.F., Evans. A. (eds.), 2008: Classical novae, 2nd ed., Cambridge Astrophysics no. 43, Cambridge: CUP
   Skopal, A., 2005, Astronomy & Astrophysics, 440, 995-1031
   Warner, B., 1995: Cataclysmic Variable Stars, Cambridge Astrophysics no. 28, Cambridge: CUP
9. Cycle of solar activity – empirical implications for the solar dynamo modelling
   Language of Thesis: English
   Secondary language: Slovak
   Supervisor: RNDr. Ján Rybák, CSc. (rybak@astro.sk)
   Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, 059 60 Vysoké Tatry, Slovakia
   Syllabus
   Focus of the research: An analysis of the long-term observations of the solar activity – sunspots, photospheric magnetic fields as well as measurements of prominences and green corona, developed at the AISAS – for determination of behaviour and importance of manifestations of activity separately on individual hemispheres of the Sun. Searching for empirical implications for modeling of the solar activity by numerical methods describing the solar dynamo.
   Objectives: An expected output of the research is determination of the temporal evolution of the time-latitude asymmetry of the solar activity for time period of several solar activity cycles and an analysis of its importance for different periods together with searching for probable periodicities of the activity.
   Requirements:
   English language, programming skills, physical background
   Research field:
   Research of physical properties and processes in the atmosphere of the Sun
10. Solar activity and the cosmic rays – magnetic fields in the solar atmosphere and their effect on the cosmic rays level
    Language of Thesis: English
    Secondary language: Slovak
    Supervisor: RNDr. Ján Rybák, CSc. (rybak@astro.sk)
    Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, 059 60 Vysoké Tatry, Slovakia
    Syllabus
    Focus of the research: An analysis of effects of the large-scale structures of the magnetic fields in the solar atmosphere on the cosmic rays level in course of six solar cycles.
    Objectives: An expected output of the research is finding of reasons of variable cosmic rays level on spatial distribution, structure and duration of the large-scale structures of the magnetic fields in the solar atmosphere.
    Requirements:
    English language, programming skills, physical background
    Research field:
    Research of physical properties and processes in the atmosphere of the Sun
11. High-contrast SB2 spectroscopic systems with peculiar early-type component(s)
    Language of Thesis: English
    Secondary language: Slovak
    Supervisor: Mgr. Martin Vaňko, PhD. (vanko@astro.sk)
    Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Tatranská Lomnica, 059 60 Vysoké Tatry, Slovakia
    Syllabus
    Focus of the research: The easiest proof that a system is a binary star is the presence of eclipses. The second most useful technique is radial-velocity (RV) variations. Such variations are typically detected within spectroscopic surveys, which result in a list of objects catalogued according to their specific stellar attributes. Once such a variation has been detected, targeted and systematic observations must be obtained to characterize the system. In the simplest case, the binary comprises two components of relatively close luminosity which results in two systems of spectral lines in the composed spectrum. When the components differ significantly in luminosity, spectral lines of the fainter secondary component become less evident. The situation gets especially difficult when the secondary is a fast rotator (> 100 km/s). Although the spectral lines of the fast-rotating secondary component are shallow and hard both to identify and model, its light boosts the continuum level, which uniformly reduces the depths of the dominant component’s spectral lines. More rarely, a star might be revealed to be double when discrepancies in the projected rotational velocity, v sin i, determined using spectral lines that have a different sensitivity to the atmospheric effective temperature are detected, e.g., the lines of Mg II at λ 4481 Å and Ca II H and K.
    Objectives: Modelling the spectroscopic data of several peculiar, high-contrast, early-type systems on the main sequence with a combination of photometric measurements from the archive of the TESS satellite. The main goal is to determine the RVs and rotational velocities of the studied objects and the possible presence of other components. Our analysis will also be focused on characteristic of possible short-term (tens of minutes) or medium-term (several hours) pulsations of individual components, determination of their atmospheric parameters (surface temperature, metallicity, surface gravity) and absolute parameters (radius, mass, luminosity). Based on the obtained results, the evolutionary status of studied systems will be discussed.
    Requirements: good knowledge of English, good knowledge of programming, ability to work independently with literature.
    Research field: Binary and multiple stellar systems

For further information, please contact supervisors via email…

In Tatranska Lomnica, January 31st, 2025

Mgr. Peter Gömöry, PhD.
Director of the AISAS

Requirements

Programme: ASTRONOMY AND ASTROPHYSICS

• Programme: ASTRONOMY
  • Interview (PDF)
  • Dissertation exam: ASTRONOMY (PDF)
• Programme: ASTROPHYSICS
  • Interview – solar physics (PDF)
  • Interview – stellar astronomy (PDF)
  • Dissertation exam: ASTROPHYSICS (PDF)