41 Herculis
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Hercules |
| 41 Herculis | |
| Right ascension | 16h 44m 59.9853s |
| Declination | +06° 05′ 17.364″ |
| Apparent magnitude (V) | +6.55 |
| Ross 643 | |
| Right ascension | 16h 44m 59.9658s |
| Declination | +06° 02′ 37.111″ |
| Apparent magnitude (V) | 10.40 |
| Characteristics | |
| 41 Herculis | |
| Evolutionary stage | Red-giant branch |
| Spectral type | G8 |
| B−V color index | 0.89±0.01 |
| Ross 643 | |
| Evolutionary stage | main sequence |
| Spectral type | K3 |
| Astrometry | |
| 41 Herculis | |
| Radial velocity (Rv) | −6.47±0.02 km/s |
| Proper motion (μ) | RA: −213.497 mas/yr Dec.: −257.504 mas/yr |
| Parallax (π) | 22.7816±0.0216 mas |
| Distance | 143.2 ± 0.1 ly (43.90 ± 0.04 pc) |
| Absolute magnitude (MV) | +3.24 |
| Ross 643 | |
| Radial velocity (Rv) | −7.03±0.16 km/s |
| Proper motion (μ) | RA: −215.617 mas/yr Dec.: −258.546 mas/yr |
| Parallax (π) | 22.7631±0.0182 mas |
| Distance | 143.3 ± 0.1 ly (43.93 ± 0.04 pc) |
| Position (relative to 41 Herculis) | |
| Epoch of observation | 2016 |
| Angular distance | 163.1″ |
| Position angle | 191° |
| Projected separation | 7,150 AU |
| Details | |
| 41 Herculis | |
| Mass | 1.15±0.06 M☉ |
| Radius | 2.91±0.11 R☉ |
| Luminosity | 5.50+0.38 −0.37 L☉ |
| Surface gravity (log g) | 3.57±0.14 cgs |
| Temperature | 5,077±92 K |
| Metallicity [Fe/H] | −0.23±0.04 dex |
| Rotation | 9.3 days |
| Rotational velocity (v sin i) | 5.37 km/s |
| Age | 5.98±1.11 Gyr |
| Ross 643 | |
| Mass | 0.653±0.052 M☉ |
| Radius | 0.661±0.043 R☉ |
| Luminosity | 0.182±0.005 L☉ |
| Surface gravity (log g) | 4.59 cgs |
| Temperature | 4,641±155 K |
| Metallicity [Fe/H] | −0.16 dex |
| Other designations | |
| WDS J16450+0605 | |
| 41 Her: BD+06°3288, HD 151090, HIP 81991, G 17-35, 138-61, TIC 395-2558-1 | |
| Ross 643: HIP 81988, G 17-34, 138-60, LTT 19463, NLTT 43481, Ross 643, TYC 395-2352-1 | |
| Database references | |
| SIMBAD | 41 Herculis |
| Ross 643 | |
41 Herculis is a binary star in the constellation Hercules. At an apparent magnitude of +6.55, it is very close to the threshold for naked eye visibility, being visible only in locations far from light pollution. Parallax measurements give a distance of 143 light-years (43.9 parsecs).
Characteristics
The spectrum of 41 Herculis matches a spectral class of G8. Stellar evolution models suggest it is an evolved star that is in the base of the red-giant branch. The star is estimated to be six billion years old, has 1.15 times the mass of the Sun and 2.91 times the Sun's radius. It radiates 5.5 times the Sun's luminosity from its photosphere at an effective temperature of 5,077 K. This temperature give it the yellow hue typical of a G-type star.
41 Herculis has a common proper motion companion named Ross 643 which is separated by 163.1" from the primary, yielding a projected separation of 7,150 au at the system's distance. It has a spectral type K3, has 0.65 times the mass of the Sun and 61% of the Sun's radius. It irradiates 18.2% of the Sun's luminosity from its photosphere at an effective temperature of 4,641 K, giving it an orange hue typical of K-type stars.
Planetary system
In 2026, a likely planet was discovered around the primary, from the detection of its gravitational pull in the discrepancy between the Hipparcos and Gaia proper motion measurements, taken over a 25-year baseline. Direct imaging and radial velocity data were used to constrain the orbit and mass of the planet, although the use of radial velocity and astrometry alone was enough to rule out stellar companions as the cause of the proper motion changes. The planet has an orbital period between 14.4 and 17.7 years, a semi-major axis of 6.4+0.6
−0.3 au and a mass of 9.5+5.4
−2.2 MJ. The mass constraint yields a 35% chance that it may be a brown dwarf rather than a planet.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | 9.5+5.4 −2.2 MJ |
6.4+0.6 −0.3 |
14.4–17.7 | — | — | — |
References
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- 1 2 3 4 5 6 7 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.
- 1 2 3 4 5 6 7 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.
- 1 2 3 4 5 Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (December 2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.
- 1 2 3 4 Bidelman, W. P. (October 1985). "G. P. Kuiper's spectral classifications of proper-motion stars". The Astrophysical Journal Supplement Series. 59: 197. Bibcode:1985ApJS...59..197B. doi:10.1086/191069. ISSN 0067-0049.
- 1 2 Jönsson, Henrik; Holtzman, Jon A.; Prieto, Carlos Allende; Cunha, Katia; García-Hernández, D. A.; Hasselquist, Sten; Masseron, Thomas; Osorio, Yeisson; Shetrone, Matthew; Smith, Verne; Stringfellow, Guy S.; Bizyaev, Dmitry; Edvardsson, Bengt; Majewski, Steven R.; Mészáros, Szabolcs (2020-08-17). "APOGEE Data and Spectral Analysis from SDSS Data Release 16: Seven Years of Observations Including First Results from APOGEE-South". The Astronomical Journal. 160 (3): 120. arXiv:2007.05537. Bibcode:2020AJ....160..120J. doi:10.3847/1538-3881/aba592. ISSN 0004-6256.
- 1 2 3 4 5 Zandt, Judah Van; Bowler, Brendan; Petigura, Erik; Franson, Kyle; Xuan, Jerry; Morgan, Marvin; Biddle, Lauren; Kiman, Rocio; Zhang, Jingwen (2026-05-21). "Gaia Exoplanet Orbits, Demographics, and Evolution Survey (GEODES): Characteristics of Three Long-Period Companions Accelerating their Host Stars". arXiv:2605.23018 [astro-ph.EP].
- 1 2 3 4 5 Maldonado, J.; Villaver, E.; Eiroa, C. (June 2013). "The metallicity signature of evolved stars with planets". Astronomy & Astrophysics. 554: A84. arXiv:1303.3418. Bibcode:2013A&A...554A..84M. doi:10.1051/0004-6361/201321082. ISSN 0004-6361.
- 1 2 3 4 Chanamé, Julio; Ramírez, Iván (2012-01-27). "Towards precise ages for single stars in the field. Gyrochronology constraints at several Gyr using wide binaries. I. Ages for initial sample". The Astrophysical Journal. 746 (1): 102. arXiv:1109.0013. Bibcode:2012ApJ...746..102C. doi:10.1088/0004-637X/746/1/102. ISSN 0004-637X.
- ↑ Oelkers, Ryan J.; Rodriguez, Joseph E.; Stassun, Keivan G.; Pepper, Joshua; Somers, Garrett; Kafka, Stella; Stevens, Daniel J.; Beatty, Thomas G.; Siverd, Robert J.; Lund, Michael B.; Kuhn, Rudolf B.; James, David; Gaudi, B. Scott (2018). "Variability Properties of Four Million Sources in the TESS Input Catalog Observed with the Kilodegree Extremely Little Telescope Survey". The Astronomical Journal. 155 (1): 39. arXiv:1711.03608. Bibcode:2018AJ....155...39O. doi:10.3847/1538-3881/aa9bf4.
- 1 2 3 4 5 Hardegree-Ullman, Kevin K.; Apai, Dániel; Bergsten, Galen J.; Pascucci, Ilaria; López-Morales, Mercedes (2023-06-01). "Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O 2 Levels in Nearby Transiting Habitable-zone Exoplanets". The Astronomical Journal. 165 (6): 267. arXiv:2304.12490. Bibcode:2023AJ....165..267H. doi:10.3847/1538-3881/acd1ec. ISSN 0004-6256.
- ↑ Stassun, Keivan G.; et al. (2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467.
- ↑ Ammons, S. Mark; Robinson, Sarah E.; Strader, Jay; Laughlin, Gregory; Fischer, Debra; Wolf, Aaron (2006). "The N2K Consortium. IV. New Temperatures and Metallicities for More than 100,000 FGK Dwarfs". The Astrophysical Journal. 638 (2): 1004. arXiv:astro-ph/0510237. Bibcode:2006ApJ...638.1004A. doi:10.1086/498490.
- 1 2 "41 Her". SIMBAD. Centre de données astronomiques de Strasbourg.
- ↑ "Ross 643". SIMBAD. Centre de données astronomiques de Strasbourg.
- ↑ "20.2.1 astrophysical_parameters‣ 20.2 Astrophysical parameter tables ‣ Chapter 20 Datamodel description ‣ Part V Gaia archive ‣ Gaia Data Release 3 Documentation release 1.3". gea.esac.esa.int. Retrieved 2025-06-01.
- 1 2 "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Archived from the original on 2013-12-03. Retrieved 2012-01-16.
