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A Photometry Campaign for IR Geminorum in Quiescence

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Chinese Journal of Astronomy and Astrophysics 2004年第1期4卷 88-96页

作者： HaiFu Zong-YunLi Kam-ChinaLeung Zhou-ShengZhang Zi-LiLi C.MartinGaskell DepartmentofAstronomy NanjingUniversityNanjing210093 DepartmentofPhysicsandAstronomy UniversityofNebraskaLincolnNE68588-0111USA YunnanObservatory Kunming650011

We report a V band photometry of the SU UMa star IR Gem at quiescence in January 2002. The observations were made with two telescopes spaced ~ 160° apart in longitude. Several photometric modulations have been found. One gives a period of 98.50(13) min, exactly equal to the orbital period determined spectroscopically. Two others occasionally strengthen and seem to be positive and negative superhumps with periods of 103.6(4) and 95.4(4) min, 5.2 % longer and 3.1 % shorter than the orbital period, respectively. A signal at ~ 0.6 c/d in the power spectrum is roughly consistent with the expected period of nodal precession of the disk. There is a puzzling peak at 0.21(3) c/d corresponding to the ~ 4.3 d sine wave seen in the raw light curve. We suspect it to be a beat frequency between the frequencies of apsidal and nodal precessions of the disk. Quasi-periodic cycles with amplitudes 0.15–0.6 mag can be seen in the light curve. The mechanism underlying this modulation is not clear.

关键词： accretion accretion disks binaries: close novae cataclysmic variables stars: dwarf nova stars: individual (IR geminorum)

Photometric analysis of the eclipsing polar MN Hya

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Research in Astronomy and Astrophysics 2018年第7期18卷 11-20页

作者： Qi-Shan Wang Sheng-Bang Qian Zhong-Tao Han Miloslav Zejda Eduardo Fernandez-Lajus Li-Ying Zhu Yunnan Observatories Chinese Academy of SciencesKunming 650216China Key Laboratory of the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming650216China University of Chinese Academy of Sciences Beijing 100049China Department of Theoretical Physics and Astrophysics Masaryk UniversityKotlfirgkfi 2Bmo 611 37Czech Republic Facultad de Ciencias Astron6micas y Geoffsicas Universidad Nacional de La PlataPaseo del Bosque s/n1900La PlataPcia.Bs.As.Argentina Instituto de Astroffsica de La Plata(CCT La plata-CONICET/UNLP) Argentina

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)

The Impact of Nova Outbursts on the Chemical Abundance of the Interstellar Medium

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Research in Astronomy and Astrophysics 2024年第10期24卷 116-129页

作者： Guoli He Chunhua Zhu Guoliang Lü Lin Li Sufen Guo Helei Liu Jun Gao School of Physical Science and Technology Xinjiang UniversityUrumqi 830017China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China

Nova outbursts are the results of thermonuclear runaways,which occur when sufficient material accretes on the surfaces of white dwarfs(WDs).Using the MESA code,we construct a detailed grid for carbon-oxygen and oxygen-neon-magnesium *** employing population synthesis methods,we conduct a statistical analysis of the distribution of novae in the Milky *** our models,on average,a typical nova system may undergo about8000 eruptions and the Galactic nova rate is~130 yr^(-1).The C,N,and O elements in nova ejecta are strongly affected by the mixing degree between WD core and accreted *** results show that the average value of^(12)C/^(13)C in nova ejecta is about an order of magnitude lower than that on the surface of a red giant,that for^(16)O/^(17)O is about 5 times lower,and that for^(14)N/^(15)N is about 1.5 times *** annual yields of^(13)C,^(15)N,and^(17)O from nova ejection are larger than those from AGB *** indicates that compared to a red giant,nova eruptions are a more important source of the odd-numbered nuclear elements of^(13)C,^(15)N,and^(17)O in the Galactic interstellar medium.

关键词： ISM:abundances (stars:)novae cataclysmic variables (stars:)white dwarfs

The Energy Sources and the Explosion Mechanism of Ca-rich Supernova PTF 10iuv

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Research in Astronomy and Astrophysics 2024年第9期24卷 106-118页

作者： Qiu-Ping Huang Shan-Qin Wang Tao Wang Wen-Pei Gan Deng-Wang Shi Liu-Yi Wang En-Wei Liang Guangxi Key Laboratory for Relativistic Astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China Department of Astronomy Beijing Normal UniversityBeijing 100875China Nanjing Hopes Technology Co. Ltd.Nanjing 210000China

In this paper,we perform the detailed modeling for the light curves(LCs)of PTF 10iuv which is a calcium-rich(Ca-rich)supernova(SN)to constrain the physical properties of its ejecta and the energy sources,as well as the explosion *** find that the^(56)Ni model and the56Ni plus circumstellar interaction model fail to explain the LCs,while the four-element(^(56)Ni,^(48)Cr,^(52)Fe,and^(44)Ti)model can account for the *** ejecta mass of PTF10iuv derived by the model(1.52_(-0.25)^(+0.34)M_(⊙))is consistent with that of the merger of a sub-Chandrasekhar mass white *** early-time LCs were mainly powered by^(56)Ni whose mass is~0.03 M_(⊙),while the contributions of^(48)Cr and^(52)Fe can be *** derived^(44)Ti mass(~0.25 M_(⊙))is~1.8 times the upper limit of the derived^(44)Ti mass of Ca-rich SN *** suggest that subtracting the contributions of the host-galaxy,which are unknown,and including the flux from other long-lived elements(e.g.,^(57)Co,^(55)Fe,^(60)Co)can reduce the amount of^(44)Ti,and that this value can be regarded as an upper limit.

关键词： (stars:)supernovae:general (stars:)supernovae:individual(PTF 10iuv) (stars:)novae cataclysmic variables