Abstract <p>The paper studies the characteristics of optical emissionformation and determines the fundamental parameters of the FL Pscdwarf nova for the epochs before and after its superoutburst in2023. Moderate-resolution spectral sets were obtained in 2021,2023 and 2024 with the BTA-6 telescope of the SAO RAS.Observations in all epochs are dominated by the continuousspectrum of the white dwarf (WD) with H I, He I, He II, C II,Mg I, Ca I, Ca II, Fe I emissions and Fe II from theaccretion disk and a bright spot at its outer radius. Changes inemission intensities and their Doppler half-widths showed thatduring the transition from the relaxation stage to quiescence,the zone of maximum radiation shifted to the periphery of thedisk, and the temperature in it decreased to <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(T_{e}<8000\)</EquationSource>  </InlineEquation> K. Ananalysis of the observed spectra for three epochs was performedusing model flux (i.e. in flux units) and normalized spectra ofthe WD and a modified method for determining the parameters oftheir atmospheres. As a result, the following estimates of theaccretor’s temperature were obtained for a single surface gravityvalue <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\log g=8.26\pm 0.13\)</EquationSource>  </InlineEquation>: <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(T_{\textrm{eff}}=17\,700\pm 1400\)</EquationSource>  </InlineEquation> K, <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(26\,700\pm 1900\)</EquationSource>  </InlineEquation> K and <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(19\,600\pm 1300\)</EquationSource>  </InlineEquation> K in 2021,2023 and 2024, respectively. It is shown that the observedsystematic variations in the brightness of FL Psc after the end ofthe outburst are correctly explained by changes in the WDtemperature, taking into account the additional contribution ofemission lines. Based on the parameters found for the accretor’satmosphere, the complete set of fundamental parameters of thesystem is refined. Its Doppler tomography showed that 1.3 yearsafter the outburst, the accretion disk remained optically thick inthe H I lines, but became optically thin in the lines of otherelements. Analysis of the FL Psc maps suggests that the H I,He I and He II emissions are formed predominantly underthermalization conditions, while the Ca II and Fe II  emissionsare formed under the influence of the fluorescence effects of softultraviolet radiation from the WD in the accretion disk and thesurrounding gaseous envelope.</p>

Optical and Physical Characteristics of the FL Psc Dwarf Nova before and after the 2023 Superoutburst

期刊论文
发表日期：

2025年9月1日

查看全文

V. V. Shimansky,
N. V. Borisov,
A. A. Dudnik,
A. I. Kolbin,
E. D. Motorina,
N. N. Shimanskaya,
A. S. Vinokurov

摘要

Abstract

The paper studies the characteristics of optical emissionformation and determines the fundamental parameters of the FL Pscdwarf nova for the epochs before and after its superoutburst in2023. Moderate-resolution spectral sets were obtained in 2021,2023 and 2024 with the BTA-6 telescope of the SAO RAS.Observations in all epochs are dominated by the continuousspectrum of the white dwarf (WD) with H I, He I, He II, C II,Mg I, Ca I, Ca II, Fe I emissions and Fe II from theaccretion disk and a bright spot at its outer radius. Changes inemission intensities and their Doppler half-widths showed thatduring the transition from the relaxation stage to quiescence,the zone of maximum radiation shifted to the periphery of thedisk, and the temperature in it decreased to \(T_{e}<8000\) K. Ananalysis of the observed spectra for three epochs was performedusing model flux (i.e. in flux units) and normalized spectra ofthe WD and a modified method for determining the parameters oftheir atmospheres. As a result, the following estimates of theaccretor’s temperature were obtained for a single surface gravityvalue \(\log g=8.26\pm 0.13\) : \(T_{\textrm{eff}}=17\,700\pm 1400\) K, \(26\,700\pm 1900\) K and \(19\,600\pm 1300\) K in 2021,2023 and 2024, respectively. It is shown that the observedsystematic variations in the brightness of FL Psc after the end ofthe outburst are correctly explained by changes in the WDtemperature, taking into account the additional contribution ofemission lines. Based on the parameters found for the accretor’satmosphere, the complete set of fundamental parameters of thesystem is refined. Its Doppler tomography showed that 1.3 yearsafter the outburst, the accretion disk remained optically thick inthe H I lines, but became optically thin in the lines of otherelements. Analysis of the FL Psc maps suggests that the H I,He I and He II emissions are formed predominantly underthermalization conditions, while the Ca II and Fe II emissionsare formed under the influence of the fluorescence effects of softultraviolet radiation from the WD in the accretion disk and thesurrounding gaseous envelope.