HD 158614 is a visual binary star system in the equatorial constellation of Ophiuchus. The system is visible to the naked eye with a combined apparent visual magnitude of +5.31.^[2] It is located at a distance of 53.3 light years from the Sun based on parallax, but is drifting closer with a radial velocity of −77 km/s^[5] and is predicted to come to within 11.0 light-years in around 196,000 years.^[9] The system has been included as a candidate member of the Zeta Herculis moving group.^[10] However, chemical abundances appear to rule that out.^[11]

The pair were found to be a double star by F. G. W. Struve in 1827 and given the catalogue identifier Σ 2173 (now STF 2173). Since then it has completed multiple orbits,^[12] yielding orbital elements showing a period of 46.3 years and an eccentricity of 0.17.^[3] The two components have similar spectra that match a stellar classification of G9IV-V.^[3] They show almost no luminosity variation; one of the pair appears to vary by 0.002 in magnitude.^[4] Both components have a slightly lower mass than the Sun: 96% and 95%, respectively.^[6] The system is estimated to be 12.3 billion years old.^[7]

This binary was included in a search for brown dwarfs that turned up no large companions.^{[citation needed]}

• Zeta Herculis