Followup ground-based observations of the dwarf nova KZ Gem

• 作者： Zhibin Dai ^1,2,3,4,5 Paula Szkody ⁶ John R. Thorstensen ⁷ N. Indika Medagangoda ⁸
• 作者单位：
  1.  Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, 650216, China.
  2.  Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, 650216, China.
  3.  Center for Astronomical Mega-Science, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing, 100012, China.
  4.  University of Chinese Academy of Sciences, No.19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China
  5.  Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100101, China
  6.  Department of Astronomy, University of Washington, Seattle, WA, 98195, USA.
  7.  Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory Hanover, NH 03755, USA.
  8.  Astronomy Division, Arthur C. Clarke Institute for Modern Technologies, Sri Lanka.
• 通讯作者： Zhibin Dai  Email:zhibin_dai@ynao.ac.cn
• 提交时间：2020-03-09

摘要: We present spectroscopy of stars in the immediate vicinity of the dwarf nova (DN) KZ Gem to confirm its identification, which had been ambiguous in the literature. Analysis of 73 radial velocities spanning from 2014 to 2019 provides a high-precision orbital period of 0.2224628(2) d (~5.34 hr) and shows KZ Gem to be a double-lined DN. Time series photometry taken from 2016 to 2018 shows a variable double-hump modulation with a full amplitude of ~0.3 mag, along with five Gaussian-like transient events lasting ~30 min or more. Using the light curve code XRBinary and nonlinear fitting code NMfit, we obtain an optimized binary model of the dwarf nova (DN) KZ Gem, from time series photometry, consisting of a Roche-lobe-filling K type dwarf with a mass transfer rate of 2.7 - 7.9 x 10^{-10} solar mass per yr to a large, cool and thick disk surrounding a white dwarf, in an orbit with an inclination of 51.6(+/-1.4) degree. Two hotspots on the disk are demonstrated to cause the observed variations in the ellipsoidal modulations from the secondary star. This physical model is compatible with the Gaia distance of KZ Gem.

Abstract: We present spectroscopy of stars in the immediate vicinity of the dwarf nova (DN) KZ Gem to confirm its identification, which had been ambiguous in the literature. Analysis of 73 radial velocities spanning from 2014 to 2019 provides a high-precision orbital period of 0.2224628(2) d (~5.34 hr) and shows KZ Gem to be a double-lined DN. Time series photometry taken from 2016 to 2018 shows a variable double-hump modulation with a full amplitude of ~0.3 mag, along with five Gaussian-like transient events lasting ~30 min or more. Using the light curve code XRBinary and nonlinear fitting code NMfit, we obtain an optimized binary model of the dwarf nova (DN) KZ Gem, from time series photometry, consisting of a Roche-lobe-filling K type dwarf with a mass transfer rate of 2.7 - 7.9 x 10^{-10} solar mass per yr to a large, cool and thick disk surrounding a white dwarf, in an orbit with an inclination of 51.6(+/-1.4) degree. Two hotspots on the disk are demonstrated to cause the observed variations in the ellipsoidal modulations from the secondary star. This physical model is compatible with the Gaia distance of KZ Gem.

• 来自： Zhibin Dai
• 期刊： Accepted in The Astrophysical Journal
• 分类： 天文学 >> 天体物理学
• 引用： ChinaXiv:202003.00051 (或此版本 ChinaXiv:202003.00051V1)
  doi:10.12074/202003.00051
  CSTR:32003.36.ChinaXiv.202003.00051.V1
• 推荐引用方式： Zhibin Dai,Paula Szkody,John R. Thorstensen,N. Indika Medagangoda.(2020).Followup ground-based observations of the dwarf nova KZ Gem.Accepted in The Astrophysical Journal.[ChinaXiv:202003.00051] (点此复制)