HD 134687
# HD 134687

HD 134687 (e Lupi) is a binary star system in the southern constellation Lupus. It is visible to the naked eye with an apparent visual magnitude of 4.81. The distance to HD 134687 can be estimated from its annual parallax shift of 7.6 mas, yielding roughly 430 light years. It is a member of the ~11 million year old Upper Centaurus–Lupus subgroup of the Scorpius–Centaurus association, the closest OB association to the Sun.

This is a single-lined spectroscopic binary star system. The pair have a nearly circular orbit with an eccentricity of at or below 0.03 and a period of 0.901407 days (21.6338 h). The primary has an a sin i value of $2.735×10^5$ km, which only gives a lower bound for the semimajor axis a since the orbital inclination i to the line of sight is unknown. The system is a source for X-ray emission.

The visible component has a stellar classification of B3 IV/V, matching a B-type star showing a spectrum with mixed traits of a main sequence and a subgiant star. It is 20 million years old with a projected rotational velocity of 13 km/s. The star has 6.0 times the mass of the Sun and 7.1 times the Sun's radius. It is radiating 997 times the Sun's luminosity from its photosphere at an effective temperature of 17,100 K.

