J0359 light curves showing pairs of eclipses. Credit: Kozhevnikov et al., 2024.
Russian astronomer Valerij Kozhevnikov has made photometric observations of a candidate cataclysmic variable known as LAMOST J035913.61+405035.0. It detected 14 eclipses of this system. The discovery was reported in a paper published October 9 on the preprint server. arXiv.
Cataclysmic variables (CVs) are binary star systems consisting of a primary white dwarf that accumulates material from a normal companion star. Their brightness increases irregularly and considerably, then falls back to a resting state. Polars are a subclass of cataclysmic variables that are distinguished from other CVs by the presence of a very strong magnetic field in their white dwarfs.
These binaries have been found in many environments, such as the center of the Milky Way, the solar neighborhood, and within open and globular clusters. Polars are a subclass of cataclysmic variables that are distinguished from other CVs by the presence of a very strong magnetic field in their white dwarfs.
LAMOST J035913.61+405035.0, or J0359 for short, was discovered in 2020 as a cataclysmic candidate variable. Previous observations of this system have detected helium emission lines, suggesting a possible magnetic nature.
Recently, to establish the true nature of J0359, Valerij Kozhevnikov of the Ural Federal University in Yekaterinburg, Russia, carried out photometric observations of this source in search of short-period oscillations, similar to those observed in the intermediate polars.
As a result of these observations, conducted using the Kurovka Observatory at the Ural State University, Kozhevnikov identified 14 eclipses of J0359 on two groups of nights separated by 13 months. The orbital period of the system was determined to be approximately 0.228 days.
According to the study, the detected eclipses showed changes in their depth and width, linked to variations in the brightness of J0359. It was found that as brightness decreased, eclipses became deeper and narrower.
“The depth of the eclipse varied between 0.75 (± 0.01) and 1.86 (± 0.08) mag, and the width of the eclipse at mid-depth varied between 13.1 (± 1, 3) and 22.1 (± 0.8) min,” Kozhevnikov wrote.
Additionally, observations revealed that J0359’s brightness outside of eclipses varied between 15.32 and 17.25 mag and did not show significant changes typical of dwarf novae (DNe). In general, DNe are cataclysmic variables that experience recurrent explosions of 2 to 10 mag caused by instabilities of the accretion disk.
Analyzing the light curve of J0359, no significant explosions over the past 1.6 years have been detected. During this time, the system remained on average 0.3 mag brighter than during periods when explosions were visible.
Summarizing the results, the author of the article concludes that the discovered eclipses, as well as other photometric characteristics of J0359, confirm that this object is indeed a cataclysmic variable system.
More information:
VP Kozhevnikov, Discovery of eclipses in the cataclysmic variable LAMOST J035913.61+405035.0, arXiv (2024). DOI: 10.48550/arxiv.2410.06873
Journal information:
arXiv
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