Hot donors in cataclysmic variables: The case of EI Psc
Kára J. Zharikov S. Wolf M. Vaidman N. Agishev A. Khokhlov S. Chavez C.E.
1 July 2025EDP Sciences
Astronomy and Astrophysics
2025#699
Context. We present results of time-resolved optical spectroscopy and photometry of the short-orbital period dwarf nova EI Psc. Aims. This study aims to determine fundamental system parameters of EI Psc, study properties of accretion structures in the system, and investigate its origin and current evolution state. Methods. We analyse newly obtained time-resolved spectroscopic and photometric observations as well as archival data. We used light curve modelling, Doppler tomography, and MESA evolutionary models to study the characteristics of EI Psc. Results. The system contains a relatively low temperature (Teff = 6130 K) white dwarf with mass of MWD = 0.70(4) M⊙. The mass of the warm (T2 = 4440 K) secondary is M2 = 0.13 M⊙. The inclination of the system is i = 44°.5(7). The mass accretion rate is ≈4× 10-13 M⊙ year-1. The long-term light curve of the system shows outbursts and superoutbursts. The quiescence light curve is double-humped and is formed by the combination of radiation from the Roche lobe filling the hot secondary and the hot spot. The radius of the outer disc is about two times smaller than the tidal truncation radius. Most of the discs emission consists of emission lines and radiation from the hot spot at the stream-disc impact region. Conclusions. These types of systems are formed from progenitors with a low mass WD MWD≤ 0.6 M⊙ and relatively massive secondaries 1.1-1.5 M⊙ with initial orbital periods on a scale of days. The number of similar systems is expected to be significantly lower than the usual CVs due to a lower forming rate of their relatively massive progenitors.
Novae, cataclysmic variables , Stars: dwarf novae , Stars: fundamental parameters
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Astronomical Institute, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Praha 8, CZ-180 00, Czech Republic
Department of Physics and Astronomy, University of Texas Rio Grande Valley, Brownsville, 78520, TX, United States
Universidad Nacional Autónoma de México, Instituto de Astronomía, AP 106, BC, Ensenada, 22800, Mexico
Faculty of Physics and Technology, Al-Farabi Kazakh National University, Al-Farabi Ave., 71, Almaty, 050040, Kazakhstan
Fesenkov Astrophysical Institute, 23 Observatory Str., Almaty, 050020, Kazakhstan
Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Nuevo León, Monterrey, 66451, Mexico
Astronomical Institute
Department of Physics and Astronomy
Universidad Nacional Autónoma de México
Faculty of Physics and Technology
Fesenkov Astrophysical Institute
Facultad de Ingeniería Mecánica y Eléctrica
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