20 Ophiuchi is a class F6IV[3] (yellow-white subgiant)star in theconstellationOphiuchus. Its apparent magnitude is 4.64[2] and it is approximately 104 light years away based on parallax.[1] It lies near the star Zeta Ophiuchi.
20 Ophiuchi is anastrometric binary. The primary star is a lateF-typesubgiant star. It has a mass 1.72 times that of the Sun.[6] The companion star regularly perturbs the primary star, causing it to wobble around thebarycenter. From this, an orbital period of 35.5 years has been calculated. The secondary star is 0.8 times the mass of the Sun, and it may be awhite dwarf orred dwarf.[6]
^abGray, R. O.; Corbally, C. J.; Garrison, R. F.; McFadden, M. T.; Bubar, E. J.; McGahee, C. E.; O'Donoghue, A. A.; Knox, E. R. (2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc--The Southern Sample".The Astronomical Journal.132 (1):161–170.arXiv:astro-ph/0603770.Bibcode:2006AJ....132..161G.doi:10.1086/504637.S2CID119476992.
^abMallama, 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
^abAllende 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
