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Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Leo
Right ascension 10h 16m 44.8635s
Declination +19° 53′ 28.974″
Apparent magnitude (V) 9.75
Spectral type K2II
B−V color index 1.18
Variable type none
Proper motion (μ) RA: –35.20 mas/yr
Dec.: –31.70 mas/yr
Parallax (π)5.00 ± 3.33 mas
Distance650 ± 330 ly
(200 ± 100 pc)
Mass2.8 ± 1.5[1] M
Radius49[1] R
Luminosity624 L
Surface gravity (log g)2.5 cgs
Temperature4127 ± 17[1] K
Metallicity–1.00 ± 0.07
Other designations
PPM 127264
Database references
Exoplanet Archivedata
Extrasolar Planets

BD+20°2457 is a 10th magnitude K-type bright giant star located between 320 and 980 light years away in the constellation of Leo. This star is very metal-poor, containing only 10% as enriched with elements heavier than hydrogen and helium as our sun, almost classifying this as a population II star. On June 10, 2009, two planets were announced to be orbiting the star, with minimum masses 21.4 and 12.5 times the mass of Jupiter and orbital periods of 380 and 622 days for the inner and outer planets respectively.[1] A dynamical analysis reveals that the proposed system is unstable on astronomically-short timescales and so the suggested planetary configuration is unlikely to be correct: further data is needed to determine a physically-plausible explanation for the radial velocity variations.[2]


  1. ^ a b c d Niedzielski, A.; et al. (2009). "Substellar-mass Companions to the K-dwarf BD+14 4559 and the K-giants HD 240210 and BD+20 2457". The Astrophysical Journal. 707 (1): 768–777. arXiv:0906.1804Freely accessible. Bibcode:2009ApJ...707..768N. doi:10.1088/0004-637X/707/1/768. 
  2. ^ Horner, J.; Wittenmyer, R. A.; Hinse, T. C.; Marshall, J. P. (2014). "A dynamical investigation of the proposed BD +20 2457 system". Monthly Notices of the Royal Astronomical Society. 439 (1): 1176–1181. arXiv:1401.2793Freely accessible. Bibcode:2014MNRAS.439.1176H. doi:10.1093/mnras/stu081.