V429 Geminorum

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BD+20° 1790
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Gemini
Right ascension  07h 23m 43.592s
Declination +20° 24′ 58.66″
Apparent magnitude (V) 9.93
Spectral type K5Ve[1]
Apparent magnitude (B) 11.08
Apparent magnitude (R) 9.43
Apparent magnitude (I) 8.9
Apparent magnitude (J) 7.643
Apparent magnitude (H) 7.032
Apparent magnitude (K) 6.879
B−V color index 1.15
V−R color index 0.50
R−I color index 0.5
Variable type BY Dra[2]
Radial velocity (Rv)+9.3 km/s
Proper motion (μ) RA: −65.8 mas/yr
Dec.: −228.1 mas/yr
Distance84.76 ly
(26[1] pc)
Absolute magnitude (MV)7.86
Mass0.63[3] M
Radius0.71[3] R
Luminosity0.17[3] L
Surface gravity (log g)4.53[3] cgs
Temperature4410[3] K
Rotation3.59 days
Rotational velocity (v sin i)10.03[3] km/s
Age35-80[3][4]million years
Other designations
V429 Gem, BD+20°1790, TYC 1355-214-1, USNO-B1.0 1104-00142035, 2MASS J07234358+2024588, 1SWASP J072343.59+202458.6
Database references
Exoplanet Archivedata
Extrasolar Planets

V429 Geminorum (BD+20°1790) is a young orange dwarf star in the constellation Gemini, located nearly 85 light years away from the Sun. It is a BY Draconis variable, a cool dwarf which varies rapidly in brightness as it rotates.


The star is young and very active and is a member of the AB Doradus Moving Group.[5] The star has also been studied and monitored by SuperWASP group and found to coincide with the ROSAT source 1RXS J072343.6+202500.[6] The planet candidate was announced in December 2009.[3]

Disproven planet[edit]

The Keplerian fit of the RV data suggested an orbital solution for a close-in massive planet with an orbital period of 7.7834 days. Moreover, the presence of a close-in massive jovian planet could explain the high level of stellar activity detected.[3] However, further study suggests that this planet may not exist because the radial velocity variations are strongly correlated to stellar activity, suggesting this activity is the cause of the variations.[7] This echoes the similar case of the disproven planet detection around TW Hydrae, which was also found to be due to stellar activity rather than orbital motion.[8]


  1. ^ a b Torres & Quast; Quast, G. R.; Melo, C. H. F.; Sterzik, M. F. (2008). "Young Nearby Loose Associations". Handbook of Star Forming Regions, Volume II: the Southern Sky ASP Monograph Publications. 5: 1–757. arXiv:0808.3362. Bibcode:2008hsf2.book..757T.
  2. ^ Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/gcvs. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. ^ a b c d e f g h i j Hernán-Obispo; Gálvez-Ortiz, M. C.; Anglada-Escudé, G.; Kane, S. R.; Barnes, J. R.; de Castro, E.; Cornide, M.; et al. (2009). "Evidence of a massive planet candidate orbiting the young active K5V star BD+20 1790". Astronomy and Astrophysics. 0912: A45. arXiv:0912.2773. Bibcode:2010A&A...512A..45H. doi:10.1051/0004-6361/200811000.
  4. ^ Carpenter; Bouwman, Jeroen; Mamajek, Eric E.; Meyer, Michael R.; Hillenbrand, Lynne A.; Backman, Dana E.; Henning, Thomas; Hines, Dean C.; et al. (2009). "Formation and Evolution of Planetary Systems: Properties of Debris Dust Around Solar-Type Stars". The Astrophysical Journal Supplement. 181 (1): 197–226. arXiv:0810.1003. Bibcode:2009ApJS..181..197C. doi:10.1088/0067-0049/181/1/197.
  5. ^ Lopez-Santiago; Montes, D.; Crespo-Chacón, I.; Fernández-Figueroa, M. J.; et al. (2006). "The Nearest Young Moving Groups". The Astrophysical Journal. 643 (2): 1160–1165. arXiv:astro-ph/0601573. Bibcode:2006ApJ...643.1160L. doi:10.1086/503183.
  6. ^ Norton; Wheatley, P. J.; West, R. G.; Haswell, C. A.; Street, R. A.; Collier Cameron, A.; Christian, D. J.; Clarkson, W. I.; et al. (2007). "New periodic variable stars coincident with ROSAT sources discovered using SuperWASP". Astronomy and Astrophysics. 467 (2): 785–905. arXiv:astro-ph/0702631. Bibcode:2007A&A...467..785N. doi:10.1051/0004-6361:20077084.
  7. ^ Figueira; Marmier; Bonfils; di Folco; Udry; Santos; Lovis; Megevand; Melo; Pepe, F.; Queloz, D.; Segransan, D.; Triaud, A. H. M. J.; Viana Almeida, P.; et al. (2010). "Evidence against the young hot-Jupiter around BD +20 1790". Astronomy and Astrophysics. 513: L8. arXiv:1003.3678. Bibcode:2010A&A...513L...8F. doi:10.1051/0004-6361/201014323.
  8. ^ Huelamo, N.; Figueira, P.; Bonfils, X.; Santos, N. C.; Pepe, F.; Gillon, M.; Azevedo, R.; Barman, T.; Fernández, M.; Di Folco, E.; Guenther, E. W.; Lovis, C.; Melo, C. H. F.; Queloz, D.; Udry, S.; et al. (2008). "TW Hydrae: evidence of stellar spots instead of a Hot Jupiter". Astronomy and Astrophysics. 489 (2): L9–L13. arXiv:0808.2386. Bibcode:2008A&A...489L...9H. doi:10.1051/0004-6361:200810596. Retrieved 2008-10-02.

See also[edit]

Coordinates: Sky map 07h 23m 44s, +20° 24′ 51″