72 Ophiuchi

72 Ophiuchi

Location of 72 Ophiuchi (circled)
Observation data Epoch J2000      Equinox J2000
Constellation	Ophiuchus
Right ascension	18^h 07^m 20.98393^s[1]
Declination	9° 33′ 49.8501″[1]
Apparent magnitude (V)	3.73[2] + 14.0[3]
Characteristics
Spectral type	A5 V[4]
U−B color index	+0.10[2]
B−V color index	+0.12[2]
Astrometry
Radial velocity (Rv)	-23.90[5] km/s
Proper motion (μ)	RA: -62.17[1] mas/yr Dec.: +79.66[1] mas/yr
Parallax (π)	37.55 ± 0.21 mas[1]
Distance	86.9 ± 0.5 ly (26.6 ± 0.1 pc)
Absolute magnitude (MV)	1.58[6]
Details
Mass	1.99[7] M☉
Radius	1.9[8] R☉
Luminosity	20[7] L☉
Surface gravity (log g)	4.04[9] cgs
Temperature	8,718[9] K
Metallicity [Fe/H]	+0.09[6] dex
Rotational velocity (v sin i)	65[7] km/s
Age	250[9] Myr
Other designations
72 Oph, BD+09°3564, FK5 680, GC 24695, GJ 9615 A, HD 165777, HIP 88771, HR 6771, SAO 123142, CCDM J18073+0934A, WDS J18073+0934A[10]
Database references
SIMBAD	data

72 Ophiuchi is a binary star^[3] system in the equatorial constellation of Ophiuchus. It is visible to the naked eye as a faint, white-hued point of light with a combined apparent visual magnitude of 3.73.^[2] It is located approximately 86.9 light years away from the Sun based on parallax,^[1] but is moving closer with a heliocentric radial velocity of -23.9 km/s.^[5]

As of 2008, the pair had an angular separation of 25″.^[3] According to Gray et al. (2003), the primary component has a stellar classification of A5 V,^[4] matching an A-type main-sequence star. Cowley et al. (1969) had assigned it to a class of A4 IVs,^[11] suggesting it is a sharp-lined (s) subgiant star. The latter class is still in use by some sources.^[7][3][12]

The primary is 250^[9] million years old with double^[7] the mass of the Sun and is spinning with a moderate projected rotational velocity of 65 km/s.^[7] It is radiating 20^[7] times the luminosity of the Sun from its photosphere at an effective temperature of 8,718 K.^[9] It displays an infrared excess, suggesting a debris disk is orbiting the star with a mean separation of 82.96 AU and temperature of 60 K.^[13] The system is a source of X-ray emission,^[12] which is most likely coming from the 14th^[3] magnitude companion.^[12]

There are additional visual companions: component C with magnitude 11.5 lies at an angular separation of 64″ from the primary,^[14] while component D, has magnitude 14.8 and separation 24".^[15]

This star was once considered part of the obsolete constellation Taurus Poniatovii, the brightest star in it. After the International Astronomical Union officially recognised constellations, it was placed in Ophiuchus.^[16]

References

1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Vizier catalog entry
2. Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". CDS/ADC Collection of Electronic Catalogues. 2237. Bibcode:2002yCat.2237....0D.
3. Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. S2CID 14878976.
4. Gray, R. O.; et al. (2003). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I". The Astronomical Journal. 126 (4): 2048. arXiv:astro-ph/0308182. Bibcode:2003AJ....126.2048G. doi:10.1086/378365. S2CID 119417105.
5. Kharchenko, N. V.; Scholz, R.-D.; Piskunov, A. E.; Röser, S.; Schilbach, E. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. S2CID 119323941.
6. 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. Vizier catalog entry
7. Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars". Astronomy & Astrophysics. 537: A120. arXiv:1201.2052. Bibcode:2012A&A...537A.120Z. doi:10.1051/0004-6361/201117691. S2CID 55586789. Vizier catalog entry
8. Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics. 352: 555–562. arXiv:astro-ph/9911002. Bibcode:1999A&A...352..555A. Vizier catalog entry
9. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146. S2CID 33401607. Vizier catalog entry
10. "72 Oph". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-26.
11. Cowley, A.; et al. (April 1969). "A study of the bright A stars. I. A catalogue of spectral classifications". Astronomical Journal. 74: 375–406. Bibcode:1969AJ.....74..375C. doi:10.1086/110819.
12. De Rosa, R. J.; et al. (July 2011). "The Volume-limited A-Star (VAST) survey - I. Companions and the unexpected X-ray detection of B6-A7 stars". Monthly Notices of the Royal Astronomical Society. 415 (1): 854–866. arXiv:1103.4363. Bibcode:2011MNRAS.415..854D. doi:10.1111/j.1365-2966.2011.18765.x. S2CID 84181878.
13. Gáspár, András; et al. (2016). "The Correlation between Metallicity and Debris Disk Mass". The Astrophysical Journal. 826 (2): 171. arXiv:1604.07403. Bibcode:2016ApJ...826..171G. doi:10.3847/0004-637X/826/2/171. S2CID 119241004.
14. Renson, P.; Manfroid, J. (2009). "Catalogue of Ap, HgMn and Am stars". Astronomy and Astrophysics. 498 (3): 961. Bibcode:2009A&A...498..961R. doi:10.1051/0004-6361/200810788.
15. Mason, Brian D.; et al. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. Vizier catalog entry
16. Ian Ridpath. "Taurus Poniatovii". Star Tales. Retrieved 2023-11-01.