AE Aquarii is a cataclysmic variablebinary star of the DQ Herculis type. Based upon parallax measurements, the system is located at a distance of about 280 light-years (86 parsecs) from the Earth.[1] Because of its unique properties, this system has been subject to a number of scientific studies.[3] The white dwarf in the AE Aquarii system is the first star of its type known to give off pulsar-like pulsations that are powered by its rotation and particle acceleration.[9][10][11]
A visual bandlight curve for AE Aquarii. The main plot shows the long term variability, and the inset plot shows the short term variability over one orbital period. Adapted from Šimon (2020).[12]
Arno Arthur Wachmann discovered that the star was variable after examining four photographic plates taken from 1923 through 1930. He classified the star as a mira variable based on that sparse data set. Wachmann published the discovery in 1931, naming the star 342.1931 Aquarii.[13] In 1938, Ernst Zinner classified the star, which by then had received the variable star designation AE Aquarii, as a cataclysmic variable, based upon a much larger data set.[14]
The AE Aquarii system consists of an ordinary star in a close orbit around a magnetic white dwarf; the pair orbit each other with a period of 9.88 hours. The white dwarf primary has 63% of the Sun's mass but a radius of only about 1% of the Sun. As of 2009, it has the shortest known spin period of any white dwarf, completing a full revolution every 33.08 seconds. This spin is decreasing at a rate of 1.78 ns per year, which is unusually high.[3] The secondary star has a stellar classification of K4-5 V, making it a main sequence star that is generating energy at its core through the thermonuclear fusion of hydrogen. It has about 37% of the Sun's mass but 79% of the Sun's radius.
This system displays flare activity that has been observed across multiple bands of the electromagnetic spectrum, including X-rays. Mass is being lost from the secondary star, most of which is being flung out of the system by the rapidly spinning magnetic primary. The X-ray luminosity is likely being caused by the accretion of mass onto the white dwarf, which is occurring at an estimated rate of about 7.3 × 1010 kg per second.[3]
^Evans, D. S. (June 20–24, 1966). Batten, Alan Henry; Heard, John Frederick (eds.). "The Revision of the General Catalogue of Radial Velocities". Determination of Radial Velocities and Their Applications, Proceedings from IAU Symposium. 30. University of Toronto: International Astronomical Union: 57. Bibcode:1967IAUS...30...57E.
^Patterson, Joseph (December 15, 1979). "Rapid oscillations in cataclysmic variables. III. An oblique rotator in AE Aquarii". Astrophysical Journal. 234: 978. Bibcode:1979ApJ...234..978P. doi:10.1086/157582.
^Ikhsanov, Nazar R. (1998). "The pulsar-like white dwarf in AE Aquarii". Astronomy and Astrophysics. 338: 521–526. Bibcode:1998A&A...338..521I.
^Šimon, Vojtěch (April 2020). "The long-term optical activity of the propellers AE Aquarii and AR Scorpii". Publications of the Astronomical Society of Japan. 72 (2). doi:10.1093/pasj/psaa012.
