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arXiv · 1701.07892

SDSS J105754.25+275947.5: a period-bounce eclipsing cataclysmic variable with the lowest-mass donor yet measured

M. J. McAllister·S. P. Littlefair·V. S. Dhillon·T. R. Marsh·B. T. Gänsicke·J. Bochinksi·M. C. P. Bours·E. Breedt·L. K. Hardy·J. J. Hermes·S. Kengkriangkrai·P. Kerry·S. G. Parsons·S. Rattanasoon
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Abstract

We present high-speed, multicolour photometry of the faint, eclipsing cataclysmic variable (CV) SDSS J105754.25+275947.5. The light from this system is dominated by the white dwarf. Nonetheless, averaging many eclipses reveals additional features from the eclipse of the bright spot. This enables the fitting of a parameterised eclipse model to these average light curves, allowing the precise measurement of system parameters. We find a mass ratio of q = 0.0546 $\pm$ 0.0020 and inclination i = 85.74 $\pm$ 0.21$^{\circ}$. The white dwarf and donor masses were found to be M$_{\mathrm{w}}$ = 0.800 $\pm$ 0.015 M$_{\odot}$ and M$_{\mathrm{d}}$ = 0.0436 $\pm$ 0.0020 M$_{\odot}$, respectively. A temperature T$_{\mathrm{w}}$ = 13300 $\pm$ 1100 K and distance d = 367 $\pm$ 26 pc of the white dwarf were estimated through fitting model atmosphere predictions to multicolour fluxes. The mass of the white dwarf in SDSS 105754.25+275947.5 is close to the average for CV white dwarfs, while the donor has the lowest mass yet measured in an eclipsing CV. A low-mass donor and an orbital period (90.44 min) significantly longer than the period minimum strongly suggest that this is a bona fide period-bounce system, although formation from a white dwarf/brown dwarf binary cannot be ruled out. Very few period-minimum/period-bounce systems with precise system parameters are currently known, and as a consequence the evolution of CVs in this regime is not yet fully understood.

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M. J. McAllister, S. P. Littlefair, V. S. Dhillon, T. R. Marsh, B. T. Gänsicke, J. Bochinksi, M. C. P. Bours, E. Breedt, L. K. Hardy, J. J. Hermes, S. Kengkriangkrai, P. Kerry, S. G. Parsons, S. Rattanasoon. 2017-01-26. SDSS J105754.25+275947.5: a period-bounce eclipsing cataclysmic variable with the lowest-mass donor yet measured. https://doi.org/10.1093/mnras%2Fstx253

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