74 Ophiuchi

74 Ophiuchi
Location of 74 Ophiuchi (circled)
Observation data
Epoch 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−B color index +0.61[4]
B−V color 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]
Distance238 ± 4 ly
(73 ± 1 pc)
Absolute magnitude (MV)0.34[2]
Details
Mass2.38[6] M☉
Radius10.52+0.32
−1.04[1] R☉
Luminosity66.0±1.2[1] L☉
Surface gravity (log g)2.70[6] cgs
Temperature5,073+271
−76[1] K
Metallicity [Fe/H]-0.21[6] dex
Rotational velocity (v sin i)0.0[5] km/s
Age1.73[7] Gyr
Other designations
74 Oph, BD+03°3680, FK5 1476, GC 25036, GJ 9615 A, HD 168656, HIP 89918, HR 6866, SAO 123377, CCDM J18209+0323A, WDS J18209+0323A[8]
Database references
SIMBADdata

74 Ophiuchi is a suspected binary star[9] in the equatorial constellation of Ophiuchus, near the border with Serpens Cauda. It is visible to the naked eye as a faint, yellow-hued point of light with a combined apparent visual magnitude of 4.85.[2] The system is located at a distance of 238 light years from the Sun based on parallax,[1] and is drifting further away with a radial velocity of +4.4 km/s.[5]

The primary member, designated component A, is an aging giant star with a stellar classification of G8III[3] and an estimated age of 1.73[7] billion years. Having exhausted the hydrogen supply at its core, the star has expanded to 10.5[1] times the Sun's radius. It is a red clump giant,[10] which means it is on the horizontal branch and is generating energy through helium fusion at its core. The star has 2.4[6] times the mass of the Sun and is radiating 66[1] times the Sun's luminosity from its swollen photosphere at an effective temperature of around 5,073 K.[1]

The magnitude 11.5 secondary, component B, lies at an angular separation of 28.1″ from the primary, as of 2008.[9] A visual companion, component C, is magnitude 12.28 and has a separation of 57.9″.[11]

  1. ^ a b c d e f g h i j k l Cite error: The named reference GaiaDR2 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference XHIP was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Houk1999 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Mallama2014 was invoked but never defined (see the help page).
  5. ^ a b c Cite error: The named reference Massarotti2008 was invoked but never defined (see the help page).
  6. ^ a b c d Cite error: The named reference Reffert2015 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Luck2015 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Alves2000 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference WDS was invoked but never defined (see the help page).