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PhD. Topics

Astronomical Institute

Exoplanets transiting early-type stars
PhD. program
Astonomy and Astrophysics
Name of the supervisor
RNDr. Theodor Pribulla, CSc.
Receiving school
Faculty of Mathematics, Physics and Informatics
Affiliation: Astronomical Institute of the Slovak Academy of Sciences, Stellar Department, Tatranská Lomnica
Focus of the research:
Majority of the known exoplanets was found orbiting solar-type stars of late spectral types. Detection of exoplanets around early-type stars is complicated mainly by the large ratio of the parent star’s and planet’s radii which results in a small transit depth. The spectroscopic detection is complicated by the high rotational velocity of the parent star and small number of available spectral lines, which significantly decreases the precision of the radial-velocity measurements. Another complication are sometimes pulsations of the parent star. Hence, it is often necessary to prove the existence of the planet by the Doppler tomography of its transits. The transit progress across the spectral line profiles, however, enables us to determine the projected misalignment of the stellar rotation axis with respect to the exoplanet orbital plane normal. If we have high-precision satellite photometry of the transit, we can determine the true (not projected) misalignment. This is holds clues to the evolutionary history of the object. Some objects (e.g. Kepler-13Ab) were found to show precession of the exoplanet orbit caused by the tides due to the rotationally-deformed parent star. These cause changes of the transit duration (TDV) due to the shift of the the transit cord across the stellar surface. Exoplanet orbit precession and the connected precession of the parent’s star rotational axis brings us information on the internal structure of the star.
Objectives: Detection of transiting exoplanets showing transit duration changes (TDV). Realistic modeling of exoplanet transits in rapidly rotating stars including fine light-curve effects (exact stellar and planetary shapes, Doppler beaming, gravity darkening). Finding the wavelength effects on the transit light curves relevant for the upcoming mission ARIEL.
Requirements: good knowledge of English, good knowledge of programming, ability to work independently with literature.
Research field: Extrasolar planets, brown dwarfs and low-mass stars.

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