X10: a magnetic cataclysmic variable with pole-switching accretion

  • Author / Creator
    Hattawi, Asma
  • Cataclysmic variables (CVs) are binary stellar systems with a white dwarf (WD) and a companion star that is losing mass to the WD. When the magnetic field of the WD is strong enough, the accreting matter follows its magnetic field lines then falls near a magnetic pole. This leads to emission of radiation including X-rays. I analyzed Chandra X-ray data of the magnetic CV X10 in the star cluster 47 Tucannae. Analysis of the system’s X-ray light curves shows a 4.185 ± 0.038 hour modulation, interpreted as the white dwarf (WD) spin period. The modulation also shows phase shifts around ∼ 165 degrees, which I interpret as a result of the accretion flow switching its trajectory between regions near two opposite WD magnetic poles. This implies a possible asynchronism between the WD spin and binary orbital periods. To investigate the two-accretion region scenario, I roughly constrained the system’s geometry by simulating theoretical X-ray light curves and comparing them to observations. To investigate the degree of asynchronism, I constrained the orbital period of the system by analyzing the envelope patterns in the X-ray light curves, resulting in a range of possible orbital periods from ≈ 4.26 to ≈ 4.37 hours, that correspond to degrees of asynchronism from ≈ 1.76% to ≈ 5.96%.

  • Subjects / Keywords
  • Graduation date
    Spring 2019
  • Type of Item
  • Degree
    Master of Science
  • DOI
  • License
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