41 Ophiuchi

41 Ophiuchi is a binary star[8] system in the zodiac constellation of Ophiuchus, and is positioned less than half a degree to the south of the celestial equator. It is visible to the naked eye as a faint, orange-hued point of light with a combined apparent visual magnitude of 4.72.[2] The distance to this system is approximately 202 light years based on parallax.[12]

41 Ophiuchi
Location of 41 Ophiuchi (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Ophiuchus
Right ascension 17h 16m 36.68653s[1]
Declination −00° 26′ 43.0915″[1]
Apparent magnitude (V) 4.72[2]
(4.92 + 7.51)[3]
Characteristics
Evolutionary stage horizontal branch[4]
Spectral type K2III[5]
U−B color index +1.11[6]
B−V color index +1.15[6]
Astrometry
Radial velocity (Rv)−0.16[7] km/s
Proper motion (μ) RA: −31.645[1] mas/yr
Dec.: −57.144[1] mas/yr
Parallax (π)16.1517 ± 0.2358[1] mas
Distance202 ± 3 ly
(61.9 ± 0.9 pc)
Absolute magnitude (MV)0.72[2]
Orbit[8]
Period (P)140.76±0.23 yr
Semi-major axis (a)0.959±0.008″
Eccentricity (e)0.866±0.003
Inclination (i)65.1±0.0°
Longitude of the node (Ω)220.5±0.0°
Periastron epoch (T)1890.53±0.36 B
Argument of periastron (ω)
(secondary)		287.5±0.0°
Details
41 Oph A
Mass1.46[9] M☉
Radius11.80+0.27
−0.39[1] R☉
Luminosity60.3±1.0[1] L☉
Surface gravity (log g)2.42[10] cgs
Temperature4,509±65[9] K
Metallicity [Fe/H]+0.06[2] dex
Rotational velocity (v sin i)2.6[7] km/s
Age3.73[9] Gyr
Other designations
41 Oph, BD−00°3255, GC 23320, HD 156266, HIP 84514, HR 6415, SAO 141586, CCDM J17166-0027AB, WDS J17166-0027[11]
Database references
SIMBADdata

This is a visual binary with an orbital period of 141 years and an eccentricity of 0.866.[8] The magnitude 4.92[3] primary, designated component A, is an aging K-type giant star with a stellar classification of K2III.[5] It is a red clump giant,[4] which indicates it is on the horizontal branch and is generating energy through helium fusion at its core. The star is 3.7[9] billion years old with 1.46[9] times the mass of the Sun and has expanded to nearly 12[1] times the Sun's radius. It is radiating 60[1] times the Sun's luminosity from its swollen photosphere at an effective temperature of 4,509 K.[9]

The secondary companion, component B, has a visual magnitude of 7.51 and an angular separation of 0.70″ from the primary along a position angle of 22°, as of 2017.[3]

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. 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. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (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
  4. Alves, David R. (August 2000). "K-Band Calibration of the Red Clump Luminosity". The Astrophysical Journal. 539 (2): 732–741. arXiv:astro-ph/0003329. Bibcode:2000ApJ...539..732A. doi:10.1086/309278. S2CID 16673121.
  5. 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.
  6. 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
  7. Massarotti, Alessandro; et al. (2008). "Rotational and Radial Velocities for a Sample of 761 Hipparcos Giants and the Role of Binarity". The Astronomical Journal. 135 (1): 209–231. Bibcode:2008AJ....135..209M. doi:10.1088/0004-6256/135/1/209.
  8. Tokovinin, Andrei; et al. (August 2015). "Speckle Interferometry at SOAR in 2014". The Astronomical Journal. 150 (2): 17. arXiv:1506.05718. Bibcode:2015AJ....150...50T. doi:10.1088/0004-6256/150/2/50. S2CID 30737411. 50.
  9. Luck, R. Earle (2015), "Abundances in the Local Region. I. G and K Giants", Astronomical Journal, 150 (3), 88, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114.
  10. 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
  11. "41 Oph". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-06-21.
  12. 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
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