Spectroscopy of the massive interacting binary UU Cassiopeiae

Context. The eclipsing close binary UU Cas is an interacting massive double-periodic system with a gainer star partly hidden in an accretion disk. Aims. In order to study the physics of the accretion process in greater detail, along with the structure and dynamics of the circumstellar matter in the system, we supplement our previous results obtained from photometry with an analysis of the spectra of UU Cas. Methods. We collected all available spectra used in previous publications on UU Cas and we acquired new ones. The method of disentangling was applied to this set of spectra spanning the years 2008 2021. The orbital parameters were disentangled and a fit of the separated component spectra by synthetic ones has been used to determine the physical parameters of the component stars. We compared the results to models of the evolution of interacting binaries. Results. We found that in addition to the dominant role of the donor star and a weak contribution of the gainer, the line profiles are strongly influenced by the circumstellar matter. The absorption lines reveal a presence of a disk wind emanating above the orbital plane. The variability of Hα emission yields evidence of changes in the structure of the circumstellar matter on a timescale of several orbital periods. © ESO 2022.Grantová Agentura České Republiky, GA ČR: 22-34467S; Fondo Nacional de Desarrollo Científico y Tecnológico, FONDECYT: 1190621, ANID PIA/BASAL FB210003, AP08856419, IN102120; Bulgarian National Science Fund, BNSF: DN 18/13-12.12.2017; Ministry of Education and Science of the Russian Federation, Minobrnauka: 075-15-2020-780, 780-10, FEUZ-2020-0030; Ministry of Education and Science of the Republic of Kazakhstan; Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja, MPNTR: 21202285, 451-03-68/2020-14/200002; Centro de Astrofísica y Tecnologías Afines, CATA: PFB–06/2007The authors highly appreciate valuable comments and suggestions by the referee Herman Hensberge, which helped to improve this paper. We acknowledge the allotment of observing time at San Pedro Mártir observatory, UNAM, Baja California, Mexico. We are also indebted to Drs. Gyula Szabó and his colleagues for obtaining the GAO spectra, Zlatan Zvetanov for the APO spectra, and Brankica Kubátová, Petr Kabáth and other colleagues from AI for the AIO spectra. P. Hadrava was supported by project RVO 67985815, M. Cabezas also by GAČR 22-34467S. G. Djurašević, J. Petrović and M. I. Jurkovic acknowledge the financial support from the Ministry of Education, Science and Technological Development of the Republic of Serbia through contract No. 451-03-68/2020-14/200002. J. Garcés acknowledges support by ANID project 21202285. S. Yu. Gorda was supported in part by the Ministry of Science and Higher Education of the Russian Federation (projects no. FEUZ-2020-0030 and no. 075-15-2020-780, contract 780-10). H. Markov acknowledges the support by Bulgarian National Science Fund under contract DN 18/13-12.12.2017. R. E. Mennickent acknowledges support by BASAL Centro de Astrofísica y Tecnologías Afines (CATA) PFB–06/2007, FONDECYT 1190621 and the grant ANID PIA/BASAL FB210003. S. Zharikov acknowledges PAPIIT grants IN102120 and grant no. AP08856419 of the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan.Acknowledgements. The authors highly appreciate valuable comments and suggestions by the referee Herman Hensberge, which helped to improve this paper. We acknowledge the allotment of observing time at San Pedro Mártir observatory, UNAM, Baja California, Mexico. We are also indebted to Drs. Gyula Szabó and his colleagues for obtaining the GAO spectra, Zlatan Zvetanov for the APO spectra, and Brankica Kubátová, Petr Kabáth and other colleagues from AI for the AIO spectra. P. Hadrava was supported by project RVO 67985815, M. Cabezas also by GACˇ R 22-34467S. G. Djurašević, J. Petrović and M. I. Jurkovic acknowledge the financial support from the Ministry of Education, Science and Technological Development of the Republic of Serbia through contract No. 451-03-68/2020-14/200002. J. Garcés acknowledges support by ANID project 21202285. S. Yu. Gorda was supported in part by the Ministry of Science and Higher Education of the Russian Federation (projects no. FEUZ-2020-0030 and no. 075-15-2020-780, contract 780-10). H. Markov acknowledges the support by Bulgarian National Science Fund under contract DN 18/13-12.12.2017. R. E. Mennickent acknowledges support by BASAL Centro de Astrofísica y Tecnologías Afines (CATA) PFB–06/2007, FONDECYT 1190621 and the grant ANID PIA/BASAL FB210003. S. Zharikov acknowledges PAPIIT grants IN102120 and grant no. AP08856419 of the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan.IRAF is distributed by the National Optical Astronomy Observatories, operated by the Association of Universities for Research in Astronomy, Inc., under contract to the National Science Foundation of the United States