Members

Researchers

Michaela Kraus

Michaela is a senior researcher and a head of the Working group Physics of Hot Stars. Her research is dedicated to evolved massive stars with focus on B[e] supergiants, Yellow Hypergiants, Luminous Blue Variables, and classical blue supergiants. She is investigating their pulsation and mass-loss behavior, as well as the dynamics and chemistry of their circumstellar matter and the interaction of the ejected material with the local interstellar medium. For her research she developed several numerical codes that are continuously improved and used to analyze and interpret observational data from the optical up to the radio regime.

Contacts:

Pavel Koubský

Pavel is a emeritus researcher. His main research interests are early-type stars and their rapid variability, close binaries, and Be stars. In past he served as a head of the Stellar Physics department and a head of the Working Group Physics of Hot Stars, He also was the member of the Institute Council of the ASU. He was responsible for two upgrades of the Perek 2m telescope in the period 1982-1987 and 1996-1998.

Contacts:

  • email: pavel.koubsky @ asu.cas.cz

Jiří Kubát

Jiří is a senior researcher. His main research interests are radiative transfer and radiation-matter interactions (NLTE physics), modelling of stellar atmospheres and stellar winds. He is an author of a computer code for calculations of NLTE model stellar atmospheres and their emergent radiation. In past he served as a head of the Stellar Physics department, as a deputy director of the Astronomical Institute, and as a member of the Institute Council. Currently he represents the Czech Republic as a member of the Board of Directors of the international scientific journal Astronomy and Astrophysics.

Contacts:

Brankica Kubátová

Brankica is a senior researcher and a head of the Stellar Physics Department. Her main expertise lies in the area of hot, massive stars and their winds. , She is most known for work on the radiative transfer in inhomogennous (i.e., clumped) stellar winds. Her research aims to test how physical processes in the stellar winds influence mass-loss rates determination. She is also interested in quantitative spectroscopy, i.e., analysing spectroscopic data by means of detailed quantitative modelling in order to determined accurate values of the stellar and winds parameters.

Contacts:

Olga Maryeva

Olga is a researcher. Before coming to the Czech Republic, she worked at Russian 6-m telescope (Special Astrophysical observatory), where she defended my PhD in 2016. Her main field is an investigation of evolved massive stars on the stages when the hydrogen is already exhausted in their cores, and the stars are rapidly evolving towards supernova explosion. Her goal is to understand the physics of processes leading to the transition between various evolutionary stages, and the evolutionary links between such groups of objects as Blue Supergiants, Luminous Blue Variables, Red Supergiants and Wolf-Rayet stars.

Contacts:

  • email: olga.maryeva @ asu.cas.cz
  • phone: +420 323 620 217
  • ORCID

    Michalis Kourniotis

    Michalis is a researcher at Astronomical Institute of Czech Academy of Sciences. Observational study of advanced stages of massive stars; Luminous Blue Variables, Yellow Hypergiants, B[e] supergiants – Massive binaries – Winds from massive stellar clusters; simulations, population synthesis.

    Contacts:

    • email: kourniotis @ asu.cas.cz
    • phone: +420 323 620 136
    • ORCID

    Martin Jelínek

    Martin is a research scientists, his research areas are gamma-ray bursts, optical transients, and robotic telescopes.

    Contacts:

    René Hudec

    René is senior researcher and the former head of the High Energy Astrophysics group. His research interest is focused on high energy astrophysics, both galactic and extragalactic sources, analysing of blazars and gamma-ray bursts, searching for counterparts at optical wavelengths and multispectral analyses, analysing of optical transients of astrophysical origin. Hi is also designer of space and ground-based experiments with emphasis on X-ray optics and X-ray telescopes. He is involved in space projects such as ESA INTEGRAL, Gaia, SMILE and THESEUS. He has extended knowledge of extraction and scientific use of data from astronomical archival plate collections.

    Contacts:

    • email: rene.hudec @ asu.cas.cz
    • ORCID

    Vojtěch Šimon

    Vojtěch is a research scientist. His research field is astrophysical sources of the high-energy radiation.(a) X-ray sources: study of X-ray binaries (systems with the neutron star or the black hole accretor), cataclysmic variables, supersoft X-ray sources, analysis of their long-term activity in the X-ray and optical regions (transitions between the high and low states, outbursts,…); analysis of observations of X-ray monitors (ASM/RXTE, BAT/Swift, MAXI/ISS); study of activity on very long timescales using photographic archives; investigation of the dependence of the observed characteristics of these objects on their physical parameters. (b) Investigation of afterglows of gamma-ray bursts, study of their comprehensive properties, analysis of the observed relation of the afterglow and the underlying hypernova or supernova, implications for the environment in their host galaxies.

    Contacts:

    • email: vojtech.simon @ asu.cas.cz
    • phone: +420 323 620 347
    • ORCID

    Péter Németh

    In his research, Péter is focused on multi-wavelength spectroscopy, his research investigates the physical properties of single stars and binaries across the
    Hertzsprung–Russell diagram. Using observational constraints from different spectral regimes, he performs quantitative analyses of observed spectra. Combining state-of-the-art model atmosphere codes enables the determination of fundamental photospheric parameters. Key wind properties of massive stars are derived consistently with their photospheric solutions. Ultimately, this work contributes to a coherent understanding of stellar atmospheres, winds, and their role in stellar evolution.

    Contacts:

    • email: nemeth@asu.cas.cz
    • phone:
    • ORCID

    Postdocs

    Julieta Sanchez Arias

    Julieta is a postdoc. After obtaining her PhD at La Plata National University in Argentina, Julieta developed her research activities as a postdoc at the Astrophysics Institute of La Plata for one year. Currently, she is a postdoc at the ASU. Her main interest is the study of stellar oscillations through the development of stellar models and the analysis of light curves. At present, she is focused on pulsations of massive stars and its connection with the stellar winds, but she is also interested in pulsating A-F stars, low mass WDs and hot-Jup planets.

    Contacts:

    • email: julieta.sanchez @ asu.cas.cz
    • phone: +420 323 620 217
    • ORCID

    Alex Camilo Gormaz Matamala

    Alex got his PhD in Valparaíso, Chile, calculating self-consistent solutions between the hydrodynamics and the line-acceleration for the stellar wind of massive stars. These self-consistent solutions are important because the evolution of massive stars is heavily determined by the strength of their winds. Currently, Alex is dedicated to the application of the new wind prescription for the evolution of massive stars, thus finding new predictions concerning chemical abundances, spectroscopic phases and final masses prior to the core collapse. Such predictions are contrasted with observational diagnostics.

    Contacts:

    • email: alex.gormaz @ asu.cas.cz
    • phone: +420 323 620 140
    • ORCID

    Shilpa Sarkar

    Shilpa is a post-doc and did her PhD from ARIES, Nainital, India. Her work is mostly based on the theoretical modelling of flows around astrophysical objects. She has modeled two-temperature accretion flows black holes and neutron stars, which is important in obtaining an accurate spectra of these systems. Currently, she is working on high-mass X-ray binaries and specifically accretion onto the compact objects from the stellar companion. This complements the studies done by the group on star winds and binary systems.

    Contacts:

    • email: shilpa.sarkar@asu.cas.cz, shilpa.sarkar30@gmail.com
    • phone: +420 323 620 140
    • ORCID

    PhD students

    Suryani Guha

    Suryani is a PhD student of Charles University/ASU, Stellar Physics Department. She has accomplished her M.Sc degree from India. Her area of interests are physics, stellar astronomy, astroseismology. Her PhD project is based on ‘Study of pulsations in evolved massive stars’. At present she is working with TESS targets, blue supergiants and MESA code. She is also interested in spectroscopic data analysis, photometry and observational astronomy.

    Contacts:

    • email: suryani.guha @ asu.cas.cz
    • phone: +420 323 620 141

    Kateřina Pivoňková

    Kateřina is a PhD student at Masaryk University in Brno and at the Astronomical Institute of the Czech Academy of Sciences. In her current research, she focuses on structured winds of hot stars, specifically on studying the development of inhomogeneities in stellar winds and the instabilities responsible for the formation of individual structures within the wind. She employs three-dimensional radiative hydrodynamic models for this purpose. Additionally, she investigates spectroscopically variable stars and the observational consequences of the existence of structures in stellar winds.

    Contacts:

    • email: 500148 @ mail.muni.cz
    • phone: +420 323 620 140

    Nilesh Pandey

    Nilesh is a PhD student at Charles University / ASU (Stellar department), originally from Uttarakhand, India, and an alumnus of IISER Thiruvananthapuram, where he completed his Integrated BSc–MSc. His research focuses on the characterization of evolved massive stars using machine learning, employing variability-based classification informed by known stellar features and regression techniques to predict key physical and circumstellar parameters using grids of synthetic models. He also explores unsupervised clustering to identify noise and rare subclasses, integrating these results with spectral energy distribution analysis for a comprehensive multi-wavelength interpretation.

    Contacts:

    Former members

    Tiina Liimets (ORCID), Mauricio Cabezas, Joris Vos (ORCID), Jakub Fišák (ORCID).