Symbiotic database

The increasing number of symbiotic stars discovered in recent years has created a demand for a comprehensive catalog of these binaries that enables detailed population studies. To address this need, I have created the New Online Database of Symbiotic Variables, a modern and comprehensive catalog that serves as a one-stop source of data for all known symbiotic systems. The Database includes consistent references and a user-friendly web portal for easy access to the information. It is available online, allowing new objects to be added as soon as they are discovered and data to be updated as new information becomes available. As a result, the most up-to-date list of symbiotic variables, as well as the most comprehensive collection of orbital, stellar, and observational parameters for these interacting binaries available in the literature, are now accessible to the scientific community. The Database has already been cited tens of times in published papers according to ADS and Google Scholar, indicating its wide use and value to the symbiotic community.

The first release of the Database is described in Merc et al. (2019a, 2019b).

Analysis of the candidates

To provide a 'clean' and well-characterized sample of symbiotic stars for further research and to increase the number of confirmed systems, I have initiated an observational campaign aimed at gathering sufficient material to thoroughly characterize selected symbiotic candidates from the New Online Database of Symbiotic Variables. This ongoing project involves supplementing new, primarily spectroscopic data with long-term light curves, multi-frequency photometric data, astrometric measurements from the Gaia satellite, and information from the literature. By subjecting a substantial sample of symbiotic candidates to a thorough analysis, my goal is to reveal the nature of these objects and possibly add them to the population of known symbiotic stars. It's worth noting that this work is a collaborative effort between professional and amateur astronomers as I aim to build a strong link between these two communities.

The results of this ongoing project can be found in Merc et al. (2020a, 2021a, 2022a, 2023a, 2023b).

Search for new symbiotics

The comprehensive data collected in the New Online Database of Symbiotic Variables, combined with the tools and methods developed for the analysis of symbiotic candidates, have allowed me to systematically search for new objects in this group and to characterize some additional serendipitously discovered objects.

While many of the results are yet to be published, one of the most significant published outcomes of this work is the discovery of the first galactic and extragalactic symbiotic stars using the Gaia astrometric satellite (Merc et al., 2020b; Merc, 2022, PhD Thesis). These discoveries, among others, highlight the potential of utilizing new technology in the search for and characterization of symbiotic stars.

Also as part of this project, I have closely collaborated with amateur observers. Working together, we have achieved several notable results, including confirming the symbiotic nature of a photometrically detected transient (Merc et al., 2021b), identifying the first observed outburst of several symbiotic stars (Merc et al., 2021c, 2022b, 2023c), and discovering a new symbiotic star that was initially detected as an emission object and later confirmed as a symbiotic binary using amateur telescopes (Petit, Merc et al., 2023).

Cataclysmic variables

Cataclysmic variables are a type of binary star system that consists of a white dwarf and a companion star, typically a low-mass main-sequence star. The white dwarf is accreting material from its companion, which can lead to violent outbursts and variations in brightness. Cataclysmic variables are important objects for studying a variety of astrophysical processes, including accretion physics, binary evolution, and the production of novae and supernovae. They are also important for understanding the formation and evolution of compact objects such as white dwarfs and neutron stars.

I have been actively involved in the analysis of observations of cataclysmic variables, mostly novae (e.g., Merc et al., 2022c). Additionally, I have been regularly observing many eclipsing cataclysmic variables (e.g., Kára et al., 2023).

Other binaries

Studying binary stars is crucial for a deeper understanding of many astrophysical phenomena. Binary systems provide an opportunity to investigate a wide range of physical processes, such as mass transfer, accretion, and tidal interactions. Additionally, binary stars can serve as probes of stellar evolution and can help to determine the properties of stars, such as their masses and radii, that are difficult to measure directly.

In addition to my interest in interacting binary stars, I have also been involved in studying other binary systems. My observations have included binary systems such as central binaries of planetary nebulae, post-common envelope binaries, and low-mass and short-period eclipsing binaries in search of substellar companions (e.g., Wolf et al., 2021), or eccentric eclipsing binaries to study their apsidal motion (e.g., Zasche et al., 2020).

Asteroseismology of red giants

During one of the summer schools, I worked on the asteroseismic analysis of heartbeat stars to characterize their red giant component. This technique involves studying the internal oscillations of stars, making it a powerful tool for probing the properties and evolutionary history of evolved stars. By measuring the frequencies of acoustic waves that travel through the stellar interior, asteroseismology provides insights into a star's age, mass, radius, internal structure, chemical composition, and magnetic fields. Asteroseismic analysis can also study stellar evolution processes, including core and shell burning, mixing, and convective overshoot, all important for understanding the production and distribution of elements in the universe.

I aim to apply asteroseismic methods to investigate the structure and properties of red giant stars in symbiotic and related binary systems.

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