68 Ophiuchi

68 Ophiuchi is a binary star system in the equatorial constellation of Ophiuchus. It is visible to the naked eye as a faint star with an apparent visual magnitude of 4.42.[2] The system is located around 89.69 parsecs (292.5 ly) distant from the Sun, based on parallax,[1] and is drifting further away with a radial velocity of +6 km/s.[6]

68 Ophiuchi
Location of 68 Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 18h 01m 45.19884s[1]
Declination 1° 18′ 18.2775″[1]
Apparent magnitude (V) 4.42[2] + 7.48[3]
Characteristics
Spectral type A2Vn[4]
U−B color index +0.02[5]
B−V color index +0.04[5]
Astrometry
Radial velocity (Rv)+6.00[6] km/s
Proper motion (μ) RA: +15.93[1] mas/yr
Dec.: -13.29[1] mas/yr
Parallax (π)11.15 ± 0.60[1] mas
Distance290 ± 20 ly
(90 ± 5 pc)
Absolute magnitude (MV)-0.34[2]
Orbit[7]
Period (P)175.74±4.65 yr
Semi-major axis (a)1.090±0.027″
Eccentricity (e)0.831±0.035
Inclination (i)69.5±3.0°
Longitude of the node (Ω)160.2±1.6°
Periastron epoch (T)2019.87±1.48
Argument of periastron (ω)
(secondary)		78.9±4.7°
Details
68 Oph A
Mass3.07[8] M☉
Radius4.5[9] R☉
Luminosity160[8] L☉
Surface gravity (log g)3.76[10] cgs
Temperature9,594[8] K
Metallicity [Fe/H]-0.14[11] dex
Rotational velocity (v sin i)201[8] km/s
Other designations
BD+01°3560, CCDM J18018+0118AB, GC 24534, HIP 88290, HR 6723, HD 164577, NSV 10009, SAO 123035, WDS J18018+0118AB
Database references
SIMBADdata

This is a spectroscopic binary with an orbital period of 177 years and an eccentricity of 0.83.[7] The brighter member, component A, is an A-type main-sequence star of spectral type A2Vn,[4] a star that is currently fusing its core hydrogen. The 'n' suffix indicates "nebulous" lines due to rapid rotation. The star is suspected of varying between magnitudes 4.42 and 4.48.[12] It displays an infrared excess that matches a circumstellar disk of dust orbiting 32.5 AU from the star with a mean temperature of 160 K.[13] The secondary companion, component B, is of magnitude 7.48.[3][14]

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. 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
  3. Malkov, O. Yu.; Tamazian, V. S.; Docobo, J. A.; Chulkov, D. A. (2012). "Dynamical masses of a selected sample of orbital binaries". Astronomy & Astrophysics. 546: A69. Bibcode:2012A&A...546A..69M. doi:10.1051/0004-6361/201219774. Vizier catalog entry
  4. Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  5. Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
  6. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. S2CID 119231169.
  7. Hartkopf, William I.; Mason, Brian D. (2009). "Speckle Interferometry at Mount Wilson Observatory: Observations Obtained in 2006-2007 and 35 New Orbits". The Astronomical Journal. 138 (3): 813–826. Bibcode:2009AJ....138..813H. doi:10.1088/0004-6256/138/3/813.
  8. 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
  9. 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
  10. 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
  11. Wu, Yue; Singh, H. P.; Prugniel, P.; Gupta, R.; Koleva, M. (2010). "Coudé-feed stellar spectral library – atmospheric parameters". Astronomy & Astrophysics. 525: A71. arXiv:1009.1491. Bibcode:2011A&A...525A..71W. doi:10.1051/0004-6361/201015014. S2CID 53480665.
  12. VSX (17 December 2005). "NSV 10009". AAVSO Website. American Association of Variable Star Observers. Retrieved 28 July 2014.
  13. Cotten, Tara H.; Song, Inseok (July 2016), "A Comprehensive Census of Nearby Infrared Excess Stars", The Astrophysical Journal Supplement Series, 225 (1): 24, arXiv:1606.01134, Bibcode:2016ApJS..225...15C, doi:10.3847/0067-0049/225/1/15, S2CID 118438871, 15.
  14. Cvetkovic, Z.; Ninkovic, S. (2010). "On the Component Masses of Visual Binaries". Serbian Astronomical Journal. 180 (180): 71. Bibcode:2010SerAJ.180...71C. doi:10.2298/SAJ1080071C.
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