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arXiv · 1704.08690

Evidence from K2 for rapid rotation in the descendant of an intermediate-mass star

J. J. Hermes·Steven D. Kawaler·A. D. Romero·S. O. Kepler·P. -E. Tremblay·Keaton J. Bell·B. H. Dunlap·M. H. Montgomery·B. T. Gaensicke·J. C. Clemens·E. Dennihy·S. Redfield
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Abstract

Using patterns in the oscillation frequencies of a white dwarf observed by K2, we have measured the fastest rotation rate, 1.13(02) hr, of any isolated pulsating white dwarf known to date. Balmer-line fits to follow-up spectroscopy from the SOAR telescope show that the star (SDSSJ0837+1856, EPIC 211914185) is a 13,590(340) K, 0.87(03) solar-mass white dwarf. This is the highest mass measured for any pulsating white dwarf with known rotation, suggesting a possible link between high mass and fast rotation. If it is the product of single-star evolution, its progenitor was a roughly 4.0 solar-mass main-sequence B star; we know very little about the angular momentum evolution of such intermediate-mass stars. We explore the possibility that this rapidly rotating white dwarf is the byproduct of a binary merger, which we conclude is unlikely given the pulsation periods observed.

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J. J. Hermes, Steven D. Kawaler, A. D. Romero, S. O. Kepler, P. -E. Tremblay, Keaton J. Bell, B. H. Dunlap, M. H. Montgomery, B. T. Gaensicke, J. C. Clemens, E. Dennihy, S. Redfield. 2017-04-27. Evidence from K2 for rapid rotation in the descendant of an intermediate-mass star. https://doi.org/10.3847/2041-8213/aa6ffc

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