HAT-P-20 is a K-type main-sequence star about 233 light-years away. The star has a strong starspot activity,^[3] and its equatorial plane is misaligned by 36⁺¹⁰
₋₁₂° with the planetary orbit.^[4] Although star with a giant planet on close orbit is expected to be spun-up by tidal forces, only weak indications of tidal spin-up were detected.^[5]

Planetary system[edit]

In 2010 a transiting hot super-Jovian planet was detected.^[6] Its equilibrium temperature is 996±19K.

Size comparison of HAT-P-20 b and Jupiter

The HAT-P-20 planetary system^[6]^[3]^[4]

Companion
(in order from star)

Mass

Semimajor axis
(AU)

Orbital period
(days)

Eccentricity

Inclination

Radius

7.59±0.12 $M$ _J

0.03671±0.00027

2.8753172±0.0000003

0.0172±0.0016

86.3±0.1°

0.952±0.017 $R$ _J

References[edit]

^ ^a ^b ^c ^d Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this sourceatVizieR.

^ ^a ^b HAT-P-20 -- High proper-motion Star

^ ^a ^b ^c Leilei Sun, Shenghong Gu, Xiaobin Wang at al., "REFINED SYSTEM PARAMETERS AND TTV STUDY OF TRANSITING EXOPLANETARY SYSTEM HAT-P-20", 2017

^ ^a ^b ^c Esposito, M.; Covino, E.; Desidera, S.; Mancini, L.; Nascimbeni, V.; Zanmar Sanchez, R.; Biazzo, K.; Lanza, A. F.; Leto, G.; Southworth, J.; Bonomo, A. S.; Suárez Mascareño, A.; Boccato, C.; Cosentino, R.; Claudi, R. U.; Gratton, R.; Maggio, A.; Micela, G.; Molinari, E.; Pagano, I.; Piotto, G.; Poretti, E.; Smareglia, R.; Sozzetti, A.; Affer, L.; Anderson, D. R.; Andreuzzi, G.; Benatti, S.; Bignamini, A.; et al. (2017), "The GAPS Programme with HARPS-N at TNG. XIII. The orbital obliquity of three close-in massive planets hosted by dwarf K-type stars: WASP-43, HAT-P-20 and Qatar-2.", Astronomy & Astrophysics, 601: A53, arXiv:1702.03136, Bibcode:2017A&A...601A..53E, doi:10.1051/0004-6361/201629720, S2CID 119341241

^ Salz, M.; Schneider, P. C.; Czesla, S.; Schmitt, J. H. M. M. (2015), "High-energy irradiation and mass loss rates of hot Jupiters in the solar neighborhood", Astronomy & Astrophysics, 576: A42, arXiv:1502.00576, Bibcode:2015A&A...576A..42S, doi:10.1051/0004-6361/201425243, S2CID 55139248

^ ^a ^b Bakos, G. Á.; Hartman, J.; Torres, G.; Latham, D. W.; Kovács, Géza; Noyes, R. W.; Fischer, D. A.; Johnson, J. A.; Marcy, G. W.; Howard, A. W.; Kipping, D.; Esquerdo, G. A.; Shporer, A.; Béky, B.; Buchhave, L. A.; Perumpilly, G.; Everett, M.; Sasselov, D. D.; Stefanik, R. P.; Lázár, J.; Papp, I.; Sári, P. (2010), "HAT-P-20b–HAT-P-23b: FOUR MASSIVE TRANSITING EXTRASOLAR PLANETS", The Astrophysical Journal, 742 (2): 116, arXiv:1008.3388, Bibcode:2011ApJ...742..116B, doi:10.1088/0004-637X/742/2/116, S2CID 119182075