72 Herculis

72 Herculis is a single^[10] star in the northern constellation of Hercules. The Flamsteed designation for this star comes from the publication Historia Coelestis Britannica by John Flamsteed. It is the 72nd star in Flamsteed's list of stars in Hercules. This star is faintly visible to the naked eye with an apparent visual magnitude of 5.4.^[2] Parallax measurements show this star to be located at a distance of about 47 light years from the Sun.^[1] It is drifting closer with a radial velocity of −78.6 km/s,^[5] and is predicted to come to within 32.1 light-years in around 98,000 years.^[6]

72 Herculis

Observation data Epoch J2000      Equinox J2000
Constellation	Hercules
Right ascension	17h 20m 39.56754s[1]
Declination	+32° 28′ 03.8773″[1]
Apparent magnitude (V)	5.377±0.005[2]
Characteristics
Evolutionary stage	Main sequence
Spectral type	G0 V[3]
U−B color index	+0.06[4]
B−V color index	+0.62[4]
Variable type	Suspected
Astrometry
Radial velocity (Rv)	−78.608±0.0065[5] km/s
Proper motion (μ)	RA: +135.731[1] mas/yr Dec.: −1040.913[1] mas/yr
Parallax (π)	68.7539 ± 0.0904 mas
Distance	47.44 ± 0.06 ly (14.54 ± 0.02 pc)
Absolute magnitude (MV)	4.43±0.05[2]
Details
Mass	0.91 M☉[2] or 1.18[6] M☉
Radius	1.13+0.004 −0.007[1] R☉
Luminosity	1.331±0.003[1] L☉
Surface gravity (log g)	4.26±0.10[2] cgs
Temperature	5,745±35[7] K
Metallicity [Fe/H]	−0.31±0.11[7] dex
Rotational velocity (v sin i)	1.0±1.0[2] km/s
Age	4.1–6.6[8] Gyr
Other designations
w Her, 72 Her, NSV 8553, BD+32°2896, FK5 1456, GJ 672, HD 157214, HIP 84862, HR 6458, SAO 65963, LHS 441, LTT 15148[9]
Database references
SIMBAD	data

This is an ordinary G-type main-sequence star with a stellar classification of G0 V. It is similar in mass to the Sun,^[2] with a 13% larger radius.^[1] The star is radiating 1.3^[1] times the luminosity of the Sun from its photosphere at an effective temperature of 5,745 K.^[7] The metallicity is much lower than in the Sun, with an [Fe/H] equal to −0.31±0.11.^[7] The star is an estimated 4–7^[8] billion years old with a projected rotational velocity of 1 km/s.^[2] The level of chromospheric activity appears to be at or below that in the Sun.^[11]

As of 2010, no planetary companion had been detected orbiting this star.^[12] The Washington Visual Double Star Catalog for 1996 showed two visual companions of this star. The first is a visual magnitude 9.7 star located 289.1 arc seconds away. The second is only separated by 8.7 arc seconds, and is magnitude 12.9.^[13] It is unknown whether these visual companions are gravitationally-bound to 72 Her.

References

1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
2. Fuhrmann, Klaus (February 2008). "Nearby stars of the Galactic disc and halo - IV". Monthly Notices of the Royal Astronomical Society. 384 (1): 173–224. Bibcode:2008MNRAS.384..173F. doi:10.1111/j.1365-2966.2007.12671.x.
3. Cenarro, A. J.; et al. (July 2009). "Mg and TiO spectral features at the near-IR: spectrophotometric index definitions and empirical calibrations". Monthly Notices of the Royal Astronomical Society. 396 (4): 1895–1914. arXiv:0903.4835. Bibcode:2009MNRAS.396.1895C. doi:10.1111/j.1365-2966.2009.14839.x. S2CID 15729759.
4. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. SIMBAD. Bibcode:1986EgUBV........0M.
5. Soubiran, C.; et al. (2018). "Gaia Data Release 2. The catalogue of radial velocity standard stars". Astronomy and Astrophysics. 616: A7. arXiv:1804.09370. Bibcode:2018A&A...616A...7S. doi:10.1051/0004-6361/201832795. S2CID 52952408.
6. Bailer-Jones, C.A.L.; et al. (2018). "New stellar encounters discovered in the second Gaia data release". Astronomy & Astrophysics. 616: A37. arXiv:1805.07581. Bibcode:2018A&A...616A..37B. doi:10.1051/0004-6361/201833456. S2CID 56269929.
7. Stonkutė, E.; et al. (2020). "High-resolution Spectroscopic Study of Dwarf Stars in the Northern Sky: Lithium, Carbon, and Oxygen Abundances". The Astronomical Journal. 159 (3): 90. arXiv:2002.05555. Bibcode:2020AJ....159...90S. doi:10.3847/1538-3881/ab6a19. S2CID 211096705.
8. Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008). "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics". The Astrophysical Journal. 687 (2): 1264–1293. arXiv:0807.1686. Bibcode:2008ApJ...687.1264M. doi:10.1086/591785. S2CID 27151456.
9. "72 Her". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 31 January 2018.
10. Fuhrmann, K.; et al. (February 2017). "Multiplicity among Solar-type Stars". The Astrophysical Journal. 836 (1): 23. Bibcode:2017ApJ...836..139F. doi:10.3847/1538-4357/836/1/139. 139.
11. Hall, Jeffrey C.; et al. (July 2009). "The Activity and Variability of the Sun and Sun-Like Stars. II. Contemporaneous Photometry and Spectroscopy of Bright Solar Analogs". The Astronomical Journal. 138 (1): 312–322. Bibcode:2009AJ....138..312H. doi:10.1088/0004-6256/138/1/312. S2CID 12332945.
12. Lubin, Dan; et al. (June 2010). "Lithium Abundance in Solar-type Stars with Low Chromospheric Activity: Application to the Search for Maunder Minimum Analogs". The Astrophysical Journal. 716 (1): 766–775. Bibcode:2010ApJ...716..766L. doi:10.1088/0004-637X/716/1/766.
13. Mason, B. D.; et al. (2014). "The Washington Visual Double Star Catalog". The Astronomical Journal. 122 (6): 3466–3471. Bibcode:2001AJ....122.3466M. doi:10.1086/323920.