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Rotational period of WD1953-011 - a magnetic white dwarf with a star spot

C. S. Brinkworth·T. R. Marsh·L. Morales-Rueda·P. F. L. Maxted·M. R. Burleigh·S. A. Good
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Abstract

WD1953-011 is an isolated, cool (7920 +/- 200K, Bergeron, Legget & Ruiz, 2001) magnetic white dwarf (MWD) with a low average field strength (~70kG, Maxted et al. 2000) and a higher than average mass (~0.74 M_sun, Bergeron et al. 2001). Spectroscopic observations taken by Maxted et al. (2000) showed variations of equivalent width in the Balmer lines, unusual in a low field white dwarf. Here we present V band photometry of WD1953-011 taken at 7 epochs over a total of 22 months. All of the datasets show a sinusoidal variation of approximately 2% peak-to-peak amplitude. We propose that these variations are due to a star spot on the MWD, analogous to a sunspot, which is affecting the temperature at the surface, and therefore its photometric magnitude. The variations have a best-fit period over the entire 22 months of 1.4418 days, which we interpret as the rotational period of the WD.

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C. S. Brinkworth, T. R. Marsh, L. Morales-Rueda, P. F. L. Maxted, M. R. Burleigh, S. A. Good. 2004-11-19. Rotational period of WD1953-011 - a magnetic white dwarf with a star spot. https://doi.org/10.1111/j.1365-2966.2005.08649.x

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