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HD 7449 is a binary star system about 126 light-years way. The primary star, HD 7449 A, is a main-sequence star belonging to the spectral class F9.5. It is younger than the Sun. The primary star is slightly depleted of heavy elements, having 80% of solar abundance.[7]

Companion

The stellar companion HD 7449 B, belonging to spectral class M4.5, was discovered in 2015.[9] A survey in 2017 has failed to find additional stars with masses above 0.35M☉ in the system.[10]

The most recent parameters for HD 7449 B as of 2022 come from a combination of data from radial velocity, astrometry, and imaging, showing that it is about 178 MJ (0.17 M☉), and orbiting with a semi-major axis of about 34.7 AU and an orbital period of about 175 years.[4]

Planetary system

In 2011 one super-Jupiter-mass planet, HD 7449 Ab [fr] on a very eccentric orbit around HD 7449 A was discovered utilising the radial velocity method.[7] A second, long-term radial velocity trend is present, and a second planet or brown dwarf has been proposed as the cause of this trend.[7][11] However, in 2015 a low-mass stellar companion (HD 7449 B) was found, which is likely the cause of the long-term trend. The large eccentricity of the inner planet is likely caused by this stellar companion.[3] In 2022, the inclination and true mass of HD 7449 Ab were measured via astrometry.[4]

The HD 7449 A planetary system[4]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination
(°) 		Radius
b 8.174+3.055
−2.699 MJ 		2.438+0.062
−0.063 		3.479+0.029
−0.020 		0.752+0.035
−0.032 		171.631+2.609
−3.740 		—

References

  1. ^ a b c d e f 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 source at VizieR.
  2. ^ a b c d Anderson, E.; Francis, Ch. (2012). “XHIP: An extended hipparcos compilation”. Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL…38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
  3. ^ a b Rodigas, Timothy J.; Arriagada, Pamela; Faherty, Jackie; Anglada-Escudé, Guillem; Kaib, Nathan; Butler, R. Paul; Shectman, Stephen; Weinberger, Alycia; Males, Jared R.; Morzinski, Katie M.; Close, Laird M.; Hinz, Philip M.; Crane, Jeffrey D.; Thompson, Ian; Teske, Johanna; Díaz, Matías; Minniti, Dante; Lopez-Morales, Mercedes; Adams, Fred C.; Boss, Alan P. (2016). “MagAO Imaging of Long-period Objects (MILO). I. A Benchmark M Dwarf Companion Exciting a Massive Planet around the Sun-like Star HD 7449”. The Astrophysical Journal. 818 (2): 106. arXiv:1512.04540. Bibcode:2016ApJ…818..106R. doi:10.3847/0004-637X/818/2/106. S2CID 51813840.
  4. ^ a b c d Feng, Fabo; Butler, R. Paul; et al. (August 2022). “3D Selection of 167 Substellar Companions to Nearby Stars”. The Astrophysical Journal Supplement Series. 262 (21): 21. arXiv:2208.12720. Bibcode:2022ApJS..262…21F. doi:10.3847/1538-4365/ac7e57. S2CID 251864022.
  5. ^ a b An, Qier; Brandt, Timothy D.; Brandt, G. Mirek; Venner, Alexander (2025-08-11). “Orbits and Masses for 156 Companions from Combined Astrometry and Radial Velocities, and A Validation of Gaia Non-Single Star Solutions”. The Astrophysical Journal Supplement Series. 280 (2): 61. arXiv:2508.08374. doi:10.3847/1538-4365/adfa99.
  6. ^ a b c d e f Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). “Age consistency between exoplanet hosts and field stars”. Astronomy & Astrophysics. 585: A5. arXiv:1511.01744. Bibcode:2016A&A…585A…5B. doi:10.1051/0004-6361/201527297. S2CID 53971692.
  7. ^ a b c d Dumusque, X.; Lovis, C.; Ségransan, D.; Mayor, M.; Udry, S.; Benz, W.; Bouchy, F.; Lo Curto, G.; Mordasini, C.; Pepe, F.; Queloz, D.; Santos, N. C.; Naef, D. (2011). “The HARPS search for southern extra-solar planets. XXX. Planetary systems around stars with solar-like magnetic cycles and short-term activity variation”. Astronomy & Astrophysics. 535: A55. arXiv:1107.1748. Bibcode:2011A&A…535A..55D. doi:10.1051/0004-6361/201117148. S2CID 119192207.
  8. ^ “HD 7449”. SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 10 October 2020.
  9. ^ Open Exoplanet Catalogue an open source database of all discovered extrasolar planets HD 7449
  10. ^ Wittrock, Justin M.; Kane, Stephen R.; Horch, Elliott P.; Howell, Steve B.; Ciardi, David R.; Everett, Mark E. (2017). “Exclusion of Stellar Companions to Exoplanet Host Stars”. The Astronomical Journal. 154 (5): 184. arXiv:1709.05315. Bibcode:2017AJ….154..184W. doi:10.3847/1538-3881/aa8d69. S2CID 55789971.
  11. ^ Wittenmyer, Robert A.; Clark, Jake T.; Zhao, Jinglin; Horner, Jonathan; Wang, Songhu; Johns, Daniel (2019). “Truly eccentric. I. Revisiting eight single-eccentric planetary systems”. Monthly Notices of the Royal Astronomical Society. 484 (4): 5859–5867. arXiv:1901.08471. Bibcode:2019MNRAS.484.5859W. doi:10.1093/mnras/stz290. S2CID 118915974.