AE Aquarii

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Double star
AE Aquarii
Artist's impression of the AE Aquarii system
Artist's impression of the AE Aquarii system
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Aquarius
Right ascension 20 h 40 m 9.16 s
declination -00 ° 52 ′ 15.1 ″
Apparent brightness 10.18 - 12.12 mag
Typing
rel. Brightness
(G-band) 		(10.952 ± 0.005) mag
rel. Brightness
(J-band) 		(9.45) mag
B − V color index 2.06 
U − B color index 2.815 
R − I index 4.071 
Spectral class WD + K3Ve
Variable star type DQ + ELL 
Astrometry
Radial velocity −69.30 ± 4.8 km / s
parallax (10.966 ± 0.055)  mas
distance 258 to 470  ly
79 to 144  pc  
Proper movement 
Rec. Share: (9.0 ± 4.2)  mas / a
Dec. portion: (−14.6 ± 3.4)  mas / a
Physical Properties
Dimensions (0.63 / 0.37)  M ☉
radius (0.01 / 0.79)  R ☉
Rotation time 9.8797 h
Other names
and catalog entries
2MASS catalog 2MASS J20400915-0052151 [1]
Other names AE Aqr, AN 342.1931, ASAS J204009-0052.2, CSI-01-20376, 2E 4404, GSC 05177-00636, HIC 101991, HIP 101991, 1RXS J204009.4-005216, SDSS J204009.16-005215.0, TYC 5177-636- 1, Gaia DR1 4226332447299604352

Template: Infobox Star / Maintenance / MagGTemplate: Infobox Star / Maintenance / MagJ

AE Aquarii also AE Aqr is a cataclysmically variable binary star system of the DQ-Herculis type . It consists of a magnetic white dwarf , with a mass of about 0.63 M ☉ , and about 0.01 R ☉ . It is in close orbit with a low-mass main sequence star with about 0.76 M ☉ and 0.79 R ☉ of the spectral class K3-5 V, which fuses hydrogen to helium in its core butfillsits Roche volume . Both orbit around the common center of gravity with a period of 9.88 hours. The white dwarf has the shortest known period of rotation of all white dwarfs at 33.08 seconds per revolution, which increases at an unusually high rate of 1.78 n s per year.

AE Aquarii is assigned to the subclass of the DQ Herculis stars because the white dwarf has a medium-strength magnetic field of 2.4 × 10 6 Gauss , which is sufficient to significantly influence the movement of the plasma stream, but too weak around the white dwarf to force into a synchronous rotation with the companion star.

Astronomers believe that the extremely strong magnetic fields trap charged particles and accelerate them to near the speed of light . When the particles interact with the magnetic field, they emit X-rays . In addition, polarized cyclotron radiation is emitted through the plasma. Therefore, AE Aquarii's hard X-ray pulses are very similar to those of the pulsar in the center of the Crab Nebula .

This system shows bursts observed across multiple bands of the electromagnetic spectrum including the X-rays. The red dwarf star is constantly losing mass. Most of it is thrown out of the system by the rapidly rotating white dwarf. As already mentioned above, the X-ray brightness is caused by the accretion of the white dwarf, which prevents the formation of an accretion disk up to a radius of approx. 100,000 km due to its strong magnetic field . The matter, which hits with an estimated transfer rate of M ≈ 7.3 × 10 10 kg / s, is converted into thermal energy and emitted. The temperature of the accretion columns above the poles is approx. 10 7 to 10 8 K , so that the emission occurs predominantly in the ultraviolet and X-ray range .

It is now generally accepted that AE Aquarii was a super-soft X-ray source and is currently interpreted as a "propeller system". Observations with Hipparcos showed a parallax of 9.80 mas with an error of ± 2.84 mas. This corresponds to a distance of 102 pc from the earth. Due to the weak brightness of the object (11th order of magnitude), the error is relatively large, so that the actual value is probably between 79 and 144 pc (258 and 470 ly ). Because of its unique properties, this system has been subjected to a number of scientific studies.

See also

Individual evidence

  1. ↑ a b c d e f g h i V * AE Aqr. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed on March 29, 2019 .
  2. ↑ a b c d AE Aqr. In: VSX. AAVSO , accessed March 29, 2019 .
  3. ^ A b F. van Leeuwen: Validation of the new Hipparcos reduction . In: Astronomy and Astrophysics . 474, No. 2, November 2007, pp. 653-664. arxiv : 0708.1752 . bibcode : 2007A & A ... 474..653V . doi : 10.1051 / 0004-6361: 20078357 .
  4. ↑ a b c J. Echevarría, et al .: High-dispersion absorption-line spectroscopy of AE Aqr . In: Monthly Notices of the Royal Astronomical Society, Volume 387, Issue 4, 11 July 2008, Pages 1563-1574 . July 4, 2008. doi : 10.1111 / j.1365-2966.2008.13248.x .
  5. ^ The Characteristics of the Cool Component of the Cataclysmic Variable AE Aquarii From HIPPARCOS Observations. Michael Friedjung, 2006, accessed March 29, 2019 .
  6. ↑ a b c Christopher W. Mauche: Chandra High-Energy Transmission Grating Spectrum of AE Aquarii . In: The Astrophysical Journal . 706, No. 1, November 2009, pp. 130-141. arxiv : 0910.0084 . bibcode : 2009ApJ ... 706..130M . doi : 10.1088 / 0004-637X / 706/1/130 .
  7. ^ PJ Meintjes: On the evolution of the nova-like variable AE Aquarii . In: Monthly Notices of the Royal Astronomical Society, Volume 336, Issue 1, 11 October 2002, Pages 265-275 . October 11, 2002. doi : 10.1046 / j.1365-8711.2002.05731.x .
  8. ↑ a b Graham A. Wynn, et al .: A magnetic propeller in the cataclysmic variable AE Aquarii . In: Monthly Notices of the Royal Astronomical Society, Volume 286, Issue 2, April 1, 1997, Pages 436-446 . April 1, 1997. doi : 10.1093 / mnras / 286.2.436 .
  9. ↑ NASA - White Dwarf Pulses Like a Pulsar. Robert Naeye / Rob Gutro, February 1, 2008, accessed March 29, 2019 .
  10. ^ K. Beuermann: The Physics of Cataclysmic Variables and Related Objects . In: The Astronomical Society of the Pacific . 2002. doi : 10.1086 / 342494 .
  11. ↑ K. Schenker, et al .: AE Aquarii: how cataclysmic variables descend from supersoft binaries . In: Monthly Notices of the Royal Astronomical Society, Volume 337, Issue 3, 11 December 2002, Pages 1105-1112 . December 11, 2002. doi : 10.1046 / j.1365-8711.2002.05999.x .