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  • 21 Aug, 2019

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AE Aquarii
AE Aquarii is a cataclysmic variable binary 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. Because of its unique properties, this system has been subject to a number of scientific studies. 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.

A visual band light 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).

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. 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.

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. 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 × 10 kg per second.

See also

References

  1. ^ van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  2. ^ "V* AE Aqr". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved July 22, 2008.
  3. ^ Mauche, Christopher W. (November 2009), "Chandra High-Energy Transmission Grating Spectrum of AE Aquarii", The Astrophysical Journal, 706 (1): 130–141, arXiv:0910.0084, Bibcode:2009ApJ...706..130M, doi:10.1088/0004-637X/706/1/130, S2CID 16457151
  4. ^ 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.
  5. ^ From apparent magnitude and parallax.
  6. ^ Echevarría, J.; et al. (July 2008). "High-dispersion absorption-line spectroscopy of AE Aqr". Monthly Notices of the Royal Astronomical Society. 387 (4): 1563–1574. arXiv:0804.0291. Bibcode:2008MNRAS.387.1563E. doi:10.1111/j.1365-2966.2008.13248.x. S2CID 11324791.
  7. ^ Itoh, Kei; et al. (2005). "Density diagnostics of the hot plasma in AE Aquarii with XMM-NEWTON" (PDF). The Astrophysical Journal. 639 (1): 397–404. arXiv:astro-ph/0412559. Bibcode:2006ApJ...639..397I. doi:10.1086/499152. S2CID 14578720. Archived from the original (PDF) on 2011-07-19. Retrieved 2009-11-15.
  8. ^ 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.
  9. ^ Ikhsanov, Nazar R. (1998). "The pulsar-like white dwarf in AE Aquarii". Astronomy and Astrophysics. 338: 521–526. Bibcode:1998A&A...338..521I.
  10. ^ Terada, Yukikatsu; Hayashi, Takayuki; Ishida, Manabu; Mukai, Koji; Dotani, Tadayasu; Okada, Shunsaku; Nakamura, Ryoko; Naik, Sachindra; Bamba, Aya; Makishima, Kazuo (2008-04-25). "Suzaku Discovery of Hard X-Ray Pulsations from a Rotating Magnetized White Dwarf, AEAquarii". Publications of the Astronomical Society of Japan. 60 (2): 387–397. arXiv:0711.2716. Bibcode:2008HEAD...10.1003T. doi:10.1093/pasj/60.2.387. ISSN 0004-6264.
  11. ^ "NASA - White Dwarf Pulses Like a Pulsar". www.nasa.gov. Archived from the original on 2021-11-18. Retrieved 2021-12-13.
  12. ^ 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.
  13. ^ Wachmann, A. A. (July 1931). "Neue Veränderliche". Astronomische Nachrichten. 242 (21): 381. Bibcode:1931AN....242..381W. doi:10.1002/asna.19312422105. Retrieved 15 November 2024.
  14. ^ Zinner, E. (May 1938). "Mitteilungen über veränderliche und verdächtige Sterne". Astronomische Nachrichten. 265 (22): 345. Bibcode:1938AN....265..345Z. doi:10.1002/asna.19382652204. Retrieved 15 November 2024.


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