Star in the constellation Ophiuchus
74 Ophiuchi Location of 74 Ophiuchi (circled)
Observation dataEpoch J2000 Equinox J2000 Constellation Ophiuchus Right ascension 18h 20m 52.06435s [ 1] Declination 03° 22′ 37.7817″[ 1] Apparent magnitude (V)4.85[ 2] Characteristics Spectral type G8III[ 3] U−Bcolor index +0.61[ 4] B−Vcolor index +0.91[ 4] Astrometry Radial velocity (Rv )+4.35[ 5] km/s Proper motion (μ)RA: −7.646[ 1] mas /yr Dec.: +12.546[ 1] mas /yr Parallax (π)13.7320± 0.2060 mas [ 1] Distance 238 ± 4 ly pc ) Absolute magnitude (MV )0.34[ 2] Details Mass 2.38[ 6] M ☉ Radius +0.32 [ 1] R ☉ Luminosity ± 1.2[ 1] L ☉ Surface gravity (log g )2.70[ 6] cgs Temperature +271 [ 1] K Metallicity -0.21[ 6] dex Rotational velocity (v sin i )0.0[ 5] Age 1.73[ 7] Gyr Other designations 74 Oph ,BD +03°3680FK5 1476GC 25036GJ 9615 AHD 168656HIP 89918HR 6866SAO 123377CCDM J18209+0323AWDS J18209+0323A[ 8] Database references SIMBAD data
74 Ophiuchi is a suspectedbinary star [ 9] equatorial constellation ofOphiuchus , near the border withSerpens Cauda . It is visible to the naked eye as a faint, yellow-hued point of light with a combinedapparent visual magnitude of 4.85.[ 2] light years from the Sun based onparallax ,[ 1] radial velocity of +4.4 km/s.[ 5]
The primary member, designated component A, is an aginggiant star with astellar classification of G8III[ 3] [ 7] core , the star has expanded to 10.5[ 1] Sun's radius . It is ared clump giant,[ 10] horizontal branch and is generating energy throughhelium fusion at its core. The star has 2.4[ 6] mass of the Sun and is radiating 66[ 1] Sun's luminosity from its swollenphotosphere at aneffective temperature of around 5,073 K.[ 1]
The magnitude 11.5 secondary, component B, lies at anangular separation of[ 9] visual companion , component C, is magnitude 12.28 and has a separation of[ 11]
^a b c d e f g h i j k l 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 atVizieR .^a b c 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 ^a b Houk, N.; Swift, C. (1999). "Michigan catalogue of two-dimensional spectral types for the HD Stars".Michigan Spectral Survey .5 .Bibcode :1999MSS...C05....0H . ^a b 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 ^a b c Massarotti, Alessandro; Latham, David W.; Stefanik, Robert P.; Fogel, Jeffrey (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 ^a b c d Reffert, Sabine; et al. (2015). "Precise radial velocities of giant stars".Astronomy & Astrophysics .574 : A116.arXiv :1412.4634 Bibcode :2015A&A...574A.116R .doi :10.1051/0004-6361/201322360 .hdl :10722/215277 .S2CID 59334290 . Vizier catalog entry ^a b 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 . ^ "74 Oph" .SIMBAD Centre de données astronomiques de Strasbourg . Retrieved2019-06-26 .^a b 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 . ^ 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 . ^ 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
