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arXiv · 2304.08524

Dynamical mass of the white dwarf in XY Ari: a test for intermediate polar X-ray spectral models

A. Álvarez-Hernández·M. A. P. Torres·P. Rodríguez-Gil·T. Shahbaz·J. Sánchez-Sierras·J. A. Acosta-Pulido·P. G. Jonker·K. D. Gazeas·P. Hakala·J. M. Corral-Santana
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Abstract

We present a dynamical study of the eclipsing intermediate polar XY Ari based on time-resolved near-infrared spectroscopy obtained with the EMIR spectrograph on the 10.4-m Gran Telescopio Canarias. Using main sequence template spectra taken with the same instrument setup as the target spectra, we measure a radial velocity amplitude of the late K-type donor star $K_2=256 \pm 2$ km s$^{-1}$. We also obtain the rotational broadening of its photospheric lines $v_\mathrm{rot} \sin i = 141 \pm 3$ km s$^{-1}$. From these and the eclipse geometry, we derive a donor-to-white-dwarf mass ratio $q = M_2/M_1 = 0.62 \pm 0.02$, an orbital inclination $i = 80.8^{\circ} \pm 0.5^{\circ}$ and dynamical masses $M_{1} = 1.21 \pm 0.04 \, \mathrm{M}_{\odot}$ and $M_2 = 0.75 \pm 0.04 \, \mathrm{M}_{\odot}$ ($1 \sigma$). This result places the white dwarf in XY Ari as one of the three most massive known in a cataclysmic variable. Comparison with white dwarf mass estimates from X-ray spectral studies could indicate the necessity of an improvement of the X-ray models and/or analysis techniques, as a number of X-ray white dwarf masses are in disagreement with the dynamical mass value.

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A. Álvarez-Hernández, M. A. P. Torres, P. Rodríguez-Gil, T. Shahbaz, J. Sánchez-Sierras, J. A. Acosta-Pulido, P. G. Jonker, K. D. Gazeas, P. Hakala, J. M. Corral-Santana. 2023-04-17. Dynamical mass of the white dwarf in XY Ari: a test for intermediate polar X-ray spectral models. https://doi.org/10.1093/mnras%2Fstad2010

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