HD 11343 (HIP 8541) is a wide binary system between HD 11343 A, a K-type borderline giant star, and HD 11343 B, a red dwarf companion, located in the southern constellation of Eridanus about 500 light-years (150 pc) distant. Two gas giant exoplanets are known to orbit the primary star.
Stellar characteristics
The HD 11343 system has an apparent magnitude of 7.88,[2] making it too faint to be visible by the naked eye from Earth under most circumstances, but can be observed using binoculars[8] as an orangish dot near Achernar.
The primary component, HD 11343 A, is a red-giant branch star slightly more massive than the Sun (albeit one estimate places its mass at a significantly higher 2.0 M☉[5]), but approximately eight times as large in radius and 25 times as luminous. It has an effective temperature of 4,670 K (4,400 °C; 7,950 °F), corresponding to its spectral type of K2, and is slightly metal-poor, with an iron content 71% that of the Sun.[6]
During a 2021 survey[9] searching for binaries within data from Gaia EDR3, the star was found to be orbited by a 13th-magnitude[10] M-dwarf, designated HD 11343 B. It is about 70% as large as the Sun both in mass and radius, is slightly cooler than the primary red giant at 4,351 K (4,078 °C; 7,372 °F), and is situated at a separation of roughly 2,600 astronomical units (0.041 ly) from its brighter companion.[4][7]
Planetary system
In 2016, a super-Jupiter planet orbiting HD 11343 A was discovered from radial-velocity observations, alongside three other substellar companions to giant stars, namely HIP 74890 b, HIP 84056 b, and HIP 95124 b.[6] This planet, HD 11343 b, is estimated to be slightly larger than Jupiter and has a mass of 5.7 MJ,[4] close to the initially estimated minimum of 5.5 MJ.[6] It revolves around its host star at a semi-major axis of 2.8 AU (420,000,000 km), around where the asteroid belt would lie in the Solar System, every 1,585 days (4.34 years) in a mildly eccentric orbit.[6]
Another planet, HD 11343 c, was discovered in 2022 closer to HD 11343 A, also using the radial-velocity method. The planet is reportedly a Jupiter analog, larger than the previous planet but likely considerably less massive, with a minimum mass of 0.804 MJ. It orbits its star at a distance of 0.923 AU (138,100,000 km) every 228.5 days (0.626 years). Due to the faintness of the astrometric signals it produces, its orbital inclination cannot be well-constrained. The discovery paper for HD 11343 c notably presents a higher mass (7.71+0.73 −1.19MJ), semi-major axis (3.729 AU), orbital period (5.07 years), and eccentricity (0.360) for HD 11343 b.[5]
^ abcdFeng, Fabo; Butler, R. Paul; Vogt, Steven S.; Clement, Matthew S.; Tinney, C. G.; Cui, Kaiming; Aizawa, Masataka; Jones, Hugh R. A.; Bailey, J.; Burt, Jennifer; Carter, B. D.; Crane, Jeffrey D.; Dotti, Francesco Flammini; Holden, Bradford; Ma, Bo; Ogihara, Masahiro; Oppenheimer, Rebecca; O’Toole, S. J.; Shectman, Stephen A.; Wittenmyer, Robert A.; Wang, Sharon X.; Wright, D. J.; Xuan, Yifan (1 September 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series. 262 (1): 21. arXiv:2208.12720. Bibcode:2022ApJS..262...21F. doi:10.3847/1538-4365/ac7e57. ISSN0067-0049. This article incorporates text from this source, which is available under the CC BY 4.0 license.
