RT Andromedae

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RT Andromedae
RT Andromedae system.png
RT Andromedae system.
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Andromeda
Right ascension 23h 11m 10.099s[1]
Declination +53° 01′ 33.04″[1]
Apparent magnitude (V) 9.043[2]
Spectral type G0V / K2V[3]
Variable type RS CVn
Proper motion (μ) RA: -7.01[1] mas/yr
Dec.: -20.80[1] mas/yr
Parallax (π) 10.05 ± 0.22 mas
Distance 270.7 ± 6.5 ly
(83 ± 2[3] pc)
Absolute bolometric
5.707 / 4.079[4]
Period (P) 0.62893095 ± 0.00000009 d
Semi-major axis (a) 0.01635 AU
Eccentricity (e) 0.31 ± 0.05
Inclination (i) 87.6 ± 0.1[3]°
Periastron epoch (T) JD 2435454.4554 ± 0.0009
Argument of periastron (ω)
306 ± 15°
RT And A
Mass 1.088 ± 0.030[4] M
Radius 1.286 ± 0.011[4] R
RT And B
Mass 0.837 ± 0.030[4] M
Radius 0.956 ± 0.012[4] R
Other designations
RT And, GSC 03998-02167, HIP 114484, TYC 3998-2167-1, BD+52° 3383a, GCRV 14555, 2MASS J23111009+5301330
Database references

RT Andromedae is a variable star in the constellation of Andromeda. The system is estimated to be 270.7 light-years (83 parsecs) away.[3]

RT Andromedae is classified as a RS Canum Venaticorum variable, a type of close eclipsing binary star. It varies from an apparent visual magnitude of 9.83 at minimum brightness to a magnitude of 8.97 at maximum brightness, with a period of 0.6289216 days.[6] The system consists of a G-type main-sequence star slightly more massive than the Sun, and a K-type main-sequence star.[3]

Presence of a third body[edit]

According to Pribulla et al. (2000), a third object could be present in the system. Its minimum mass is estimated to be 5 percent the mass of the Sun (roughly 50 times the mass of Jupiter), with an orbital period close to 75 years and an eccentricity that is thought to be fairly high (at 0.56).[3] Such an object could likely turn out to be a brown dwarf or even a massive jovian planet. However, a recent paper of Manzoori (2009) states that the minimum mass of the third body is likely to be close to 0.6 Solar masses, making the object stellar rather than substellar.[4] Also, the orbital period has turned out to be more than 85 years.

The RT Andromedae planetary system[3]
(in order from star)
Mass Semimajor axis
Orbital period
Eccentricity Inclination Radius
b (retracted) 27000 ± 3700 0.56 ± 0.13


  1. ^ a b c d van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. Bibcode:2007A&A...474..653V. arXiv:0708.1752Freely accessible. doi:10.1051/0004-6361:20078357.  Vizier catalog entry
  2. ^ Høg, E.; et al. (2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. 
  3. ^ a b c d e f g Pribulla; et al. (2000). "Active eclipsing binary RT Andromedae revisited". Astronomy & Astrophysics. 362: 169–188. Bibcode:2000A&A...362..169P. 
  4. ^ a b c d e f Manzoori, D. (2009). "Cyclic Variations of Orbital Period and Long-Term Luminosity in Close Binary RT Andromedae". The Astronomical Journal. 138 (6): 1917–1924. Bibcode:2009AJ....138.1917M. doi:10.1088/0004-6256/138/6/1917. 
  5. ^ Erdem, A.; Demircan, O.; Güre, M. (2001). "The light and period changes of RT Andromedae". Astronomy & Astrophysics. 379 (3): 878. Bibcode:2001A&A...379..878E. doi:10.1051/0004-6361:20011357. 
  6. ^ RT And, database entry, Combined General Catalog of Variable Stars (GCVS4.2, 2004 Ed.), N. N. Samus, O. V. Durlevich, et al., CDS ID II/250 Accessed on line 2009-06-22.