Oliveira, R. Lopes deBruch, A.Rodrigues, C. V.Oliveira, A. S.Mukai, K.2020-08-192020-08-192020-07-30R. Lopes de Oliveira et al., CTCV J2056-3014: An X-Ray-faint Intermediate Polar Harboring an Extremely Fast-spinning White Dwarf, ApJL 898 L40 (2020), https://doi.org/10.3847/2041-8213/aba618https://doi.org/10.3847/2041-8213/aba618http://hdl.handle.net/11603/19468We report on XMM-Newton X-ray observations that reveal CTCV J2056-3014 to be an unusual accretion-powered, intermediate polar (IP) system. It is a member of the class of X-ray-faint IPs whose space density remains unconstrained but potentially very high, with L x,0.3–12 keV of 1.8 × 10³¹ erg s⁻¹. We discovered a coherent 29.6 s pulsation in X-rays that was also revealed in our reanalysis of published optical data, showing that the system harbors the fastest-spinning, securely known white dwarf (WD) so far. There is no substantial X-ray absorption in the system. Accretion occurs at a modest rate (~6 × 10⁻¹² M ⊙ yr⁻¹) in a tall shock above the WD, while the star seems to be spinning in equilibrium and to have low magnetic fields. Further studies of CTCV J2056-3014 potentially have broad implications on the origin of magnetic fields in WDs, on the population and evolution of magnetic cataclysmic variables, and also on the physics of matter around rapidly rotating magnetic WDs.5 pagesen-USThis item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author.© 2020. The American Astronomical Society. All rights reserved.Text