Patterson, JosephMiguel Agustino, Enrique deKemp, JonathanDvorak, Shawn2020-10-152020-10-152020-07Patterson, J., de Miguel Agustino, E., Kemp, J. ... Dvorak, S. (2020). The Spin-period History of Intermediate Polars. The Astrophysical Journal, 897(1), 70. DOI: https://doi.org/10.3847/1538-4357/ab863d0004-637Xhttp://hdl.handle.net/10272/18908We report the detailed history of spin-period changes in five intermediate polars (DQ Herculis, AO Piscium, FO Aquarii, V1223 Sagittarii, and BG Canis Minoris) during the 30–60 yr since their original discovery. Most are slowly spinning up, although there are sometimes years-long episodes of spin-down. This is supportive of the idea that the underlying magnetic white dwarfs are near spin equilibrium. In addition to the 40 stars sharing many properties and defined by their strong, pulsed X-ray emission, there are a few rotating much faster (P<80 s), whose membership in the class is still in doubt—and who are overdue for closer study.engAtribución-NoComercial-SinDerivadas 3.0 Españahttp://creativecommons.org/licenses/by-nc-nd/3.0/es/Cataclysmic variable starsClassical novaeClose binary starsDQ Herculis starsInteracting binary starsNovaeStellar accretionStellar accretion disksjournal article10.3847/1538-4357/ab863dopen access