IGR J19552+0044: A new asynchronous short period polar: Filling the gap between intermediate and ordinary polars

G. Tovmassian, D. González-Buitrago, J. Thorstensen, E. Kotze, H. Breytenbach, A. Schwope, F. Bernardini, S. V. Zharikov, M. S. Hernandez, D. A.H. Buckley, E. De Miguel, F. J. Hambsch, G. Myers, W. Goff, D. Cejudo, D. Starkey, T. Campbell, J. Ulowetz, W. Stein, P. NelsonD. E. Reichart, J. B. Haislip, K. M. Ivarsen, A. P. Lacluyze, J. P. Moore, A. S. Miroshnichenko

    Research output: Contribution to journalArticlepeer-review


    Context. Based on XMM-Newton X-ray observations IGR J19552+0044 appears to be either a pre-polar or an asynchronous polar. Aims. We conducted follow-up optical observations to identify the sources and periods of variability precisely and to classify this X-ray source correctly. Methods. Extensive multicolor photometric and medium- to high-resolution spectroscopy observations were performed and period search codes were applied to sort out the complex variability of the object. Results. We found firm evidence of discording spectroscopic (81.29 ± 0.01 m) and photometric (83.599 ± 0.002 m) periods that we ascribe to the white dwarf (WD) spin period and binary orbital period, respectively. This confirms that IGR J19552+0044 is an asynchronous polar. Wavelength dependent variability and its continuously changing shape point at a cyclotron emission from a magnetic WD with a relatively low magnetic field below 20 MG. Conclusions. The difference between the WD spin period and the binary orbital period proves that IGR J19552+0044 is a polar with the largest known degree of asynchronism (0.97 or 3%).

    Original languageEnglish (US)
    Article numberA36
    JournalAstronomy and Astrophysics
    StatePublished - Dec 1 2017


    • Accretion, accretion disks
    • Binaries: close
    • Stars: magnetic field

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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