7 Vulpeculae
7 Vulpeculae is a binary star system approximately 940 light years away in the northern constellation of Vulpecula. It is a challenge to view with the naked eye, having an apparent visual magnitude of 6.33. The system is moving closer to the Earth with a heliocentric radial velocity of −38 km/s.
This is a single-lined spectroscopic binary star system with an orbital period of 69.3 days and an eccentricity of 0.16. The visible component is a Be star with a stellar classification of B4–5 III–IVe that appears to be nearing the end of its main sequence lifetime. It shows a rapid rotation rate with a projected rotational velocity of 300 km/s, which is just below the estimated critical velocity of 367 km/s.
The nature of the companion is unknown, but based upon its mass it may be a K- or M-type star. However, it could be a white dwarf that has previously undergone a mass transfer event with the now visible component. Because of the lack of X-ray emission from the system, a third possibility is that the companion is a naked He star that has been stripped of its hydrogen envelope.
