AA Tauri

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AA Tauri
AA Tauri star and planet.png

Artist's impresion of AA Tauri and possible substellar companion
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Taurus
Right ascension  04h 34m 55.42s
Declination +24° 28′ 53.2″
Apparent magnitude (V) 12.82
Spectral type K7V
Variable type T Tauri-type?
Distance≈456.4 ly
(≈140 pc)
Mass0.76[1] M
Radius1.81[1] R
Luminosity0.8[1] L
Temperature4060[1] K
Age2.4[1] million years
Other designations
AA Tau, GCRV 55202, XEST 25-026, AN 196.1930, GSC 01833-00851, 2MASS J04345542+2428531, CSI+24-04319, MHA 259-17, 2E 0431.8+2422, IRAS 04318+2422, UBV 4396, 2E 1098, IRAS F04318+2422, XEST 25-OM-003
Database references

AA Tauri is a young star in the constellation of Taurus, located in the young Taurus-Auriga Star Forming Region, roughly at 460 light years away from the Sun.

A possible planetary system[edit]

In their paper of 2003, Grinin et al. invoke the possible presence of a substellar object to explain peculiar and periodic eclipses occurring to the young star every 8.3 days.[2] They infer a mass of 20 times that of Jupiter for the perturbing object and an orbital separation of 0.08 Astronomical Units.

In 2011, AA Tauri suddenly faded from its original brightness of V = 12.5 mag to 10.5 mag and has not changed since. Bouvier's research on this strange occurrence concluded that AA Tauri's sudden dimming was caused by an increase in dust in our line of sight to the star. They theorised that the root cause of this dimness is a warp in the accretion disk, located at a distance of 7.7 AU or more from the centre, that was brought into the line of sight by its elliptical motion around the central star.[3]

The AA Tauri planetary system
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b (unconfirmed) ≤20 MJ 0.08 8.5 0


  1. ^ a b c d e Güdel; et al. (2007). "The XMM-Newton Extended Survey of the Taurus Molecular Cloud (XEST)". Astronomy and Astrophysics. 468 (2): 353–377. arXiv:astro-ph/0609160. Bibcode:2007A&A...468..353G. doi:10.1051/0004-6361:20065724.
  2. ^ Bouvier; et al. (2003). "Eclipses by circumstellar material in the T Tauri star AA Tau. II. Evidence for non-stationary magnetospheric accretion". Astronomy and Astrophysics. 409: 169–192. arXiv:astro-ph/0306551. Bibcode:2003A&A...409..169B. doi:10.1051/0004-6361:20030938.
  3. ^ Bouvier, J., K. Grankin, L. E. Ellerbroek, H. Bouy, and D. Barrado. (2013). "AA Tauri’s Sudden and Long-lasting Deepening: Enhanced Extinction by Its Circumstellar Disk." Astronomy & Astrophysics. 557:A77. doi:10.1051/0004-6361/201321389.