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HIP 72217
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| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Libra[1] |
| AB | |
| Right ascension | 14h 46m 10.811s[2] |
| Declination | −21° 10′ 35.05″[2] |
| Apparent magnitude (V) | 6.43±0.01[3] (7.06 + 7.33)[1] |
| C | |
| Right ascension | 14h 46m 11.349s[4] |
| Declination | −21° 10′ 36.04″[4] |
| Apparent magnitude (V) | 16.82[1] |
| Characteristics | |
| Evolutionary stage | subgiant + subgiant + main sequence[1] |
| Spectral type | G1V[5] |
| B−V color index | 0.603[1] |
| Astrometry | |
| AB | |
| Radial velocity (Rv) | −1.9±0.4[6] km/s |
| Proper motion (μ) | RA: −57.28 mas/yr[7] Dec.: −101.60 mas/yr[7] |
| Parallax (π) | 24.24±0.63 mas[7] |
| Distance | 135 ± 3 ly (41 ± 1 pc) |
| Absolute magnitude (MV) | +3.35[8] |
| C | |
| Proper motion (μ) | RA: −71.95 mas/yr[4] Dec.: −108.23 mas/yr[4] |
| Parallax (π) | 24.8360±0.1337 mas[4] |
| Distance | 131.3 ± 0.7 ly (40.3 ± 0.2 pc) |
| Orbit[1] | |
| Primary | A |
| Companion | B |
| Period (P) | 12.9170±0.0012 years |
| Semi-major axis (a) | 0.1854±0.0003" (7.65 au[a]) |
| Eccentricity (e) | 0.6319±0.0012 |
| Inclination (i) | 25.29±0.31° |
| Longitude of the node (Ω) | 277.42±0.96° |
| Periastron epoch (T) | 1995.2607±0.0022 |
| Argument of periastron (ω) (secondary) | 44.42±0.91° |
| Semi-amplitude (K1) (primary) | 7.06±0.00 km/s |
| Semi-amplitude (K2) (secondary) | 7.32±0.00 km/s |
| Details[1] | |
| A | |
| Mass | 1.14±0.15 M☉ |
| Radius | 1.47±0.04 R☉ |
| Luminosity | 2.73±0.19 L☉ |
| Habitable zone inner limit | 1.223 au |
| Habitable zone outer limit | 2.847 au |
| Surface gravity (log g) | 4.14±0.11 cgs |
| Temperature | 6,125±50 K |
| Age | 3.55±0.30 Gyr |
| B | |
| Mass | 1.12±0.14 M☉ |
| Radius | 1.39±0.03 R☉ |
| Luminosity | 2.21±0.14 L☉ |
| Habitable zone inner limit | 1.108 au |
| Habitable zone outer limit | 2.599 au |
| Surface gravity (log g) | 4.20±0.12 cgs |
| Temperature | 5,950±50 K |
| Age | 3.55±0.30 Gyr |
| C | |
| Mass | 0.17±0.01 M☉ |
| Radius | 0.28±0.01 R☉ |
| Luminosity | 0.0070±0.0002 L☉ |
| Surface gravity (log g) | 4.76±0.17 cgs |
| Temperature | 3,250±50 K |
| Age | 3.55±0.30 Gyr |
| Other designations | |
| BD−20°4087, HD 129980, HIP 72217, HR 5504, TYC 6166-454-1[9] | |
| Database references | |
| SIMBAD | data |
| C | |
HIP 72217 is a triple star system in the constellation Libra. With an apparent visual magnitude of 6.43, it is very close to the limit for naked eye vision, and thus can only be seen in dark skies. Based on parallax measurements, it lies at a distance of roughly 130 light-years (40 parsecs).
Characteristics
[edit]This system is in a hierarchical configuration, with an inner pair of stars and an outer circumbinary component.
The two inner components A and B are G-type stars that have reached the subgiant stage of evolution and are larger, hotter and more luminous than the Sun. The stars take 12.917 years (4,718 days) to fully orbit each other, have a semi-major axis of 7.65 astronomical units (au) and are in an eccentric orbit with e = 0.6319.[1]
Any planet orbiting either of the two inner stars would need to have an orbit between 0.003 and 0.067 au, since a longer orbit would be unstable due to the gravitational perturbations of the binary system, while a shorter orbit would reach the Roche lobe. A circumbinary planet would need to be orbiting between 2.734 and 2.966 au. Meanwhile, the habitable zone spans from roughly 1.2 to 2.8 au for the star A, and 1.1 to 2.6 au for the star B.[1]
The outer component C is a red dwarf separated by 290 au from the inner pair.[b] It has around 28% of the Sun's size, shining with less than 1% of the Sun's luminosity and having an effective temperature of 3,250 K.[1]
Notes
[edit]- ^ Calculated using the parallax of 0.02424 arcseconds and the separation of 0.1854 arcseconds. 0.1854" / 0.02424" = 7.65 au.
- ^ Calculated using the parallax of 0.02424 arcseconds and the separation of 6.923 arcseconds. 6.923" / 0.02424" = 286 au.
References
[edit]- ^ a b c d e f g h i j Nazar, Naufa; Al-Wardat, Mashhoor A.; Abushattal, Ahmad; Haboubi, Hassan B. (30 October 2025). "Stellar Parameters and Evolutionary Pathways of the Subgiant system HIP 72217". arXiv:2510.26224 [astro-PH].
- ^ a b 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.
- ^ Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (2002). "The Tycho double star catalogue". Astronomy and Astrophysics. 384: 180. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822.
- ^ 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 source at VizieR.
- ^ Abt, H. A. (1981). "Visual multiples. VII. MK classifications". The Astrophysical Journal Supplement Series. 45: 437. Bibcode:1981ApJS...45..437A. doi:10.1086/190719.
- ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
- ^ a b Van Leeuwen, F.; Al-Wardat, Mashhoor A.; Abushattal, Ahmad; Haboubi, Hassan B. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
- ^ 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. XHIP record for this object at VizieR.
- ^ "HD 129980". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 28 November 2025.
