Projects and Publications
Projects and Publications
There is a substantial gap between the percentage of observed binary Cepheids (<10% of all Cepheids) and the predicted percentage (>60%). This gap doesn't allow us to study binary Cepheids to the desired extent. Fortunately, various populations of synthetic binary Cepheids can be simulated and their physical or orbital characteristics studied. This project investigates the impact of Cepheids' companions on various characteristics of Cepheids, including the effect of excess companion light on period-luminosity relations.
Karczmarek et al. 2023, Synthetic Population of Binary Cepheids. II. The effect of companion light on the extragalactic distance scale, ApJ 950, 182
video-presentation of early results at the RR Lyrae and Cepheid Conference (La Palma, 26-30 September 2022) here
Karczmarek et al. 2022, Synthetic Population of Binary Cepheids. I. The Effect of Metallicity and Initial Parameter Distribution on Characteristics of Cepheids’ Companions, ApJ, 930, 65
Karczmarek et al. 2020, The impact of binary Cepheids on the distance determinations, Proceedings of the Polish Astronomical Society, 10, 40
RR Lyrae stars occupy the Horizontal Branch in the Hertzsprung-Russell diagram, and more specifically the instability strip. Regardless of their pulsation period, their intrinsic brightness stays constant in the visual domain. However, in the near-infrared they follow a period-luminosity relation, which can be used to determine more precise distances to RR Lyrae stars. This projects aims to determine distances to galaxies in the Local Group that host RR Lyrae stars, using the period-luminosity-metallicity relations.
Karczmarek et al. 2017, The Araucaria Project: The Distance to the Fornax Dwarf Galaxy from Near-infrared Photometry of RR Lyrae Stars, AJ, 154, 263
Karczmarek et al. 2015, The Araucaria Project: The Distance to the Carina Dwarf Galaxy from Infrared Photometry of RR Lyrae Stars, AJ, 150, 90
During 20+ years of the Araucaria Project, vast amounts of near-infrared data have been collected, mainly for purposes of distance determinations. Hoping that these data can be repurposed and used by broader scientific community, we offer them in a form of photometric maps, divided into a series of papers (more coming soon).
Karczmarek et al. 2021, The Araucaria Project: Deep Near-infrared Photometric Maps of Local and Sculptor Group Galaxies. I. Carina, Fornax, and Sculptor, ApJS, 253, 42
An unusually low-mass star (0.26 Msun) exhibiting RR Lyr-like pulsations has been discovered in a binary system. This star was called Binary Evolution Pulsators (BEP), owing its pulsations to the binary interaction in a form of mass transfer. Since only one BEP is known so far, I created a synthetic population of BEPs to investigate their characteristics.
Karczmarek et al. 2017, The occurrence of Binary Evolution Pulsators in the classical instability strip of RR Lyrae and Cepheid variables, MNRAS, 466, 2842
Karczmarek et al. 2016, Contamination of RR Lyrae stars from Binary Evolution Pulsators, Proceedings of the Polish Astronomical Society, 3, 45
Karczmarek 2012, Binary evolution pulsating star - new evolutionary channel to produce RR Lyr-like pulsations, Advances in Astronomy and Space Physics, 2, 135
As my very first scientific project I investigated LMC classical Cepheids with orbital periods >40 d from ASAS data, especially their rates of period change.
Karczmarek et al. 2011, Large Magellanic Cloud Cepheids in the ASAS Data, AcA, 61, 303
For all publications and nerdy statistics, click here.