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HD 154345

Coordinates: Sky map 17h 02m 36.40s, +47° 04′ 54.77″
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HD 154345
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Hercules[1]
Right ascension 17h 02m 36.40381s[2]
Declination +47° 04′ 54.7642″[2]
Apparent magnitude (V) +6.76[1]
Characteristics
Evolutionary stage main sequence[2]
Spectral type G8V[3]
U−B color index 0.27
B−V color index 0.728±0.005[1]
Astrometry
Radial velocity (Rv)−47.08±0.12[2] km/s
Proper motion (μ) RA: 123.274 mas/yr[2]
Dec.: 853.639 mas/yr[2]
Parallax (π)54.7359±0.0176 mas[2]
Distance59.59 ± 0.02 ly
(18.270 ± 0.006 pc)
Absolute magnitude (MV)+5.41[1]
Details[4]
Mass0.89±0.04[5] M☉
Radius0.85±0.01 R☉
Luminosity0.620±0.002 L☉
Surface gravity (log g)4.53±0.01 cgs
Temperature5,557±15 K
Metallicity [Fe/H]−0.14±0.04[6] dex
Rotation27.8±1.7 d[7]
Age4.10±1.20 Gyr
Other designations
BD+47°2420, GC 23011, GJ 651, HD 154345, HIP 83389, SAO 46452, GCRV 9834[8]
Database references
SIMBADdata

HD 154345 is a star in the northern constellation of Hercules. With an apparent visual magnitude of +6.76[1] it is a challenge to view with the naked eye, but using binoculars it is an easy target.[9] The distance to this star is 59.6 light years based on parallax, but it is drifting closer with a radial velocity of −47 km/s.[2] At least one exoplanet is orbiting this star.[10]

The stellar classification of HD 154345 is G8V,[3] matching an ordinary G-type main-sequence star that is generating energy by core hydrogen fusion. The magnetic activity cycle of this star is correlated with the radial velocity variations induced by its putative planetary companion.[11][12] It is around four[4] billion years old and is spinning with a rotation period of 28 days.[7] The star is smaller and less massive than the Sun. It is radiating 62% of the luminosity of the Sun from its photosphere at an effective temperature of 5,557 K.[4]

Planetary system

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In 2006, a long-period, wide-orbiting planet was observed by radial velocity, and published in May 2007, gaining the designation HD 154345 b.[10] It has been called a "Jupiter twin".[13] While the existence of HD 154345 b has been unclear due to the correlation of its orbital period with the star's activity cycle,[11] a study in 2021 confirmed its planetary nature.[14]

The complete observation of its nine-year orbit rules out any interior planets of minimum mass (m sini) greater than 0.3 Jupiter.[13] The star rotates at an inclination of 50+40
−26 degrees relative to Earth.[7] It is probable that the planet shares that inclination.[15][16] In 2023, the inclination and true mass of HD 154345 b were determined via astrometry, consistent within the margin of error with the stellar rotational inclination.[17] More precise measurements found a nearly edge-on inclination.[5]

The system's habitable zone stretches from 0.64 AU out to 1.26 AU, and is narrower than the Sun's. It forms a stable region where an Earth-mass exoplanet could orbit.[18]

The HD 154345 planetary system[5]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(years) 		Eccentricity Inclination Radius
b 1.186+0.095
−0.059 MJ 		4.158+0.066
−0.067 		8.981+0.079
−0.076 		0.058±0.019 88±20° —

References

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  1. ^ a b c d e 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.
  2. ^ a b c d e f g 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.
  3. ^ a b Cowley, A. P.; et al. (1967). "Spectral classification and photometry of high proper motion stars". The Astronomical Journal. 72: 1334. Bibcode:1967AJ.....72.1334C. doi:10.1086/110413.
  4. ^ a b c Bonfanti, A.; Ortolani, S.; Nascimbeni, V. (2016). "Age consistency between exoplanet hosts and field stars". Astronomy & Astrophysics. 585: 14. arXiv:1511.01744. Bibcode:2016A&A...585A...5B. doi:10.1051/0004-6361/201527297. S2CID 53971692. A5.
  5. ^ a b c Giovinazzi, Mark R.; et al. (2025-07-01). "The NEID Earth Twin Survey. II. Dynamical Masses in Seven High-acceleration Star Systems". The Astronomical Journal. 170 (1): 52. arXiv:2505.12563. Bibcode:2025AJ....170...52G. doi:10.3847/1538-3881/add922. ISSN 0004-6256.
  6. ^ Aguilera-Gómez, Claudia; et al. (June 2018). "Lithium abundance patterns of late-F stars: an in-depth analysis of the lithium desert". Astronomy & Astrophysics. 614: 15. arXiv:1803.05922. Bibcode:2018A&A...614A..55A. doi:10.1051/0004-6361/201732209. S2CID 62799777. A55.
  7. ^ a b c Simpson, E. K.; et al. (November 2010). "Rotation periods of exoplanet host stars". Monthly Notices of the Royal Astronomical Society. 408 (3): 1666–1679. arXiv:1006.4121. Bibcode:2010MNRAS.408.1666S. doi:10.1111/j.1365-2966.2010.17230.x. S2CID 6708869.
  8. ^ "HD 154345". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-01-19.
  9. ^ "The astronomical magnitude scale". International Comet Quarterly. Retrieved 2021-01-19.
  10. ^ a b Wright, J. T.; et al. (2007). "Four New Exoplanets and Hints of Additional Substellar Companions to Exoplanet Host Stars". The Astrophysical Journal. 657 (1): 533–545. arXiv:astro-ph/0611658. Bibcode:2007ApJ...657..533W. doi:10.1086/510553. S2CID 35682784.
  11. ^ a b Wright, J. T. (October 2015). Boisse, I.; Demangeon, O.; Bouchy, F.; Arnold, L. (eds.). Twenty Years of Precise Radial Velocities at Keck and Lick Observatories. Proceedings of colloquium 'Twenty years of giant exoplanets' held at Observatoire de Haute Provence, France, October 5-9, 2015. Observatoire de Haute-Provence, Institut Pythéas. pp. 8–17. arXiv:1603.08384. Bibcode:2015tyge.conf....8W.
  12. ^ Wright, Jason Thomas; Miller, Brendan (August 2015). Magnetism and Activity of Planet-Hosting Stars. IAU General Assembly, Meeting #29. arXiv:1706.07102. Bibcode:2015IAUGA..2258453W. 2258453.
  13. ^ a b Wright, J. T.; et al. (2008). "The Jupiter Twin HD 154345b". The Astrophysical Journal Letters. 683 (1): L63 – L66. arXiv:0802.1731. Bibcode:2008ApJ...683L..63W. doi:10.1086/587461. S2CID 16808434.
  14. ^ Rosenthal, Lee J.; Fulton, Benjamin J.; Hirsch, Lea A.; Isaacson, Howard T.; Howard, Andrew W.; Dedrick, Cayla M.; Sherstyuk, Ilya A.; Blunt, Sarah C.; Petigura, Erik A.; Knutson, Heather A.; Behmard, Aida; Chontos, Ashley; Crepp, Justin R.; Crossfield, Ian J. M.; Dalba, Paul A.; Fischer, Debra A.; Henry, Gregory W.; Kane, Stephen R.; Kosiarek, Molly; Marcy, Geoffrey W.; Rubenzahl, Ryan A.; Weiss, Lauren M.; Wright, Jason T. (2021). "The California Legacy Survey. I. A Catalog of 178 Planets from Precision Radial Velocity Monitoring of 719 Nearby Stars over Three Decades". The Astrophysical Journal Supplement Series. 255 (1): 8. arXiv:2105.11583. Bibcode:2021ApJS..255....8R. doi:10.3847/1538-4365/abe23c. S2CID 235186973.
  15. ^ "hd_154345_b". Extrasolar Planets Encyclopaedia. 1995. Retrieved November 12, 2012.
  16. ^ Sanchis-Ojeda, Roberto; Winn, Josh N.; Fabrycky, Daniel C. (2012). "Starspots and spin-orbit alignment for Kepler cool host stars". Astronomische Nachrichten. 334 (1–2): 180–183. arXiv:1211.2002. Bibcode:2013AN....334..180S. doi:10.1002/asna.201211765. S2CID 38743202.
  17. ^ Xiao, Guang-Yao; Liu, Yu-Juan; et al. (March 2023). "The Masses of a Sample of Radial-Velocity Exoplanets with Astrometric Measurements". Research in Astronomy and Astrophysics. 23 (5). arXiv:2303.12409. Bibcode:2023RAA....23e5022X. doi:10.1088/1674-4527/accb7e. S2CID 257663647.
  18. ^ Funk, B.; Libert, A. -S.; Süli, Á.; Pilat-Lohinger, E. (February 2011). "On the influence of the Kozai mechanism in habitable zones of extrasolar planetary systems". Astronomy and Astrophysics. 526: 7. Bibcode:2011A&A...526A..98F. doi:10.1051/0004-6361/201015218. A98.
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