Photometric analysis of the eclipsing polar MN Hya  

作　　者：Qi-Shan Wang Sheng-Bang Qian Zhong-Tao Han Miloslav Zejda Eduardo Fernandez-Lajus Li-Ying Zhu 

机构地区：[1]Yunnan Observatories,Chinese Academy of Sciences,Kunming 650216,China [2]Key Laboratory of the Structure and Evolution of Celestial Objects,Chinese Academy of Sciences,Kunming650216,China [3]University of Chinese Academy of Sciences,Beijing 100049,China [4]Department of Theoretical Physics and Astrophysics,Masaryk University,Kotlfirgkfi 2,Bmo 611 37,Czech Republic [5]Facultad de Ciencias Astron6micas y Geoffsicas,Universidad Nacional de La Plata,Paseo del Bosque s/n,1900,La Plata,Pcia.Bs.As.,Argentina [6]Instituto de Astroffsica de La Plata(CCT La plata-CONICET/UNLP),Argentina

出　　处：《Research in Astronomy and Astrophysics》2018年第7期11-20,共10页天文和天体物理学研究（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.11325315,11611530685,11573063 and 11133007);the Strategic Priority Research Program the Emergence of Cosmological Structure of the Chinese Academy of Sciences(Grant No.XDB09010202);the Ministry of Education,Youth and Sports of the Czech Republic(Project LG15010)

摘　　要：As an eclipsing polar with a 3.39 h orbital period, MN Hya was going through a state change when we observed it during 2009-2016. Ten new mid-eclipse times, along with others obtained from literature, allow us to give a new ephemeris. The residuals of a linear fit show that period decreased during the phase of state change, which means angular momentum was lost during this phase. The associated X-ray observation indicates the mass accretion rate was about 3.6 x 10^-9 Mo yr^-1. The period decrease indicates that at least 60% of mass being transferred from the secondary was lost, maybe in the form of spherically symmetric stellar wind. In the high state, the data show the intensity of flickering reduced when the system had a higher accretion rate, and that flickering sticks out with a primary timescale of about 2 min, which implies the position of the threading point was about 30 white dwarf radii above its surface. The trend of light curves for the system in its high state follows that of the low state for a large fraction of the phase interval from phase 0 to phase 0.4 since, starting at phase 0.4, the cyclotron feature is visible, and the primary intensity hump of the light curves near phase 0.7 when the system is in the high state did not appear on the curve when it was in the low state. Those facts contradict predictions of the two-pole model.As an eclipsing polar with a 3.39 h orbital period, MN Hya was going through a state change when we observed it during 2009-2016. Ten new mid-eclipse times, along with others obtained from literature, allow us to give a new ephemeris. The residuals of a linear fit show that period decreased during the phase of state change, which means angular momentum was lost during this phase. The associated X-ray observation indicates the mass accretion rate was about 3.6 x 10^-9 Mo yr^-1. The period decrease indicates that at least 60% of mass being transferred from the secondary was lost, maybe in the form of spherically symmetric stellar wind. In the high state, the data show the intensity of flickering reduced when the system had a higher accretion rate, and that flickering sticks out with a primary timescale of about 2 min, which implies the position of the threading point was about 30 white dwarf radii above its surface. The trend of light curves for the system in its high state follows that of the low state for a large fraction of the phase interval from phase 0 to phase 0.4 since, starting at phase 0.4, the cyclotron feature is visible, and the primary intensity hump of the light curves near phase 0.7 when the system is in the high state did not appear on the curve when it was in the low state. Those facts contradict predictions of the two-pole model.

关 键 词：TECHNIQUES photometric-stars cataclysmic variables eclipsing polars-stars individ-ual （MN Hya） 

分 类 号：P152[天文地球—天文学]