Research

Professional experiences:

• asteroseismology of pulsating white dwarf stars
• pulsation studies of A-F-type variables (gamma Doradus, delta Scuti stars)
• CCD photometry of variable stars
• photometric data reduction
• light curve analysis
• analysis of space-based data (CoRoT, Kepler, MOST, TESS)
• spectroscopic observations and data analysis
• participation in international observing campaigns

White dwarf pulsation:

White dwarfs represent the final evolutionary stage of about 97% of the stars. By the investigation of their interiors, we can find the clue to the previous steps of stellar evolution, use them as cosmic laboratories, and measure the age of the stellar population they are belonging to. Some of them show pulsational light variations on time scales of minutes.

We aim local, long time-base, single-site monitoring of selected white dwarf stars to examine the short-term variability of pulsation modes in amplitude/frequency/phase, and to get precise period values for asteroseismic investigations. The research program perfectly fits to our observational possibilities, regarding the size and the limiting magnitude of the 1m RCC telescope at Piszkéstető mountain station of Konkoly Observatory.

Part of my research work is to join the world-wide efforts (WET/DARC) to empirically determine the physical properties of convection by coordinated, international campaigns. The good coverage and high precision needed can be obtained only in these efforts.

I also participate occasionally in smaller size international campaigns (2-3 sites) on both white dwarfs and sdBV stars, carried out to obtain better estimate of the total mass, hydrogen mass fraction and rotational rate.

Considering the TESS-related activities, see the webpage of my NKFIH PD-123910 project.

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A-F-type 'classical' pulsators:

These targets are main-sequence, pre- and post-main-sequence objects with masses between 1.2 and 2.5 solar mass. They form the groups of delta Scuti and gamma Doradus pulsating stars. Their theoretical instability strips overlap, so the presence of hybrid variables was expected. The first such hybrid star was discovered in 2005, but finding these hybrids is difficult with ground-based observations.

The measurements of space telescopes completely revolutionized the study of A-F variables. We now have data on hundreds of stars of this type. This allows both statistical analyses on this large sample as well as detailed investigations of particular stars. With our project, running in collaboration with colleagues at the Royal Observatory of Belgium, one of the principal aims is to learn more about the nature of A-F-type hybrid stars, in particular which mechanisms cause the observed low-frequency variations in these objects.