HX Velorum

HX Velorum, also known as HR 3462 and HD 74455, is a star in the constellation Vela. It is a 5th magnitude star, so it will be faintly visible to the naked eye of an observer far from city lights. It is a variable star, whose brightness varies slightly from magnitude 5.48 to 5.53 over a period of 1.12 days.

In 1981, Robert Shobbrook announced that HR 3462 is a variable star based on observations made in 1976. He correctly classified it as an ellipsoidal variable, but the period he derived, $42$ days, was a factor of two too short because his data did not allow him to distinguish between primary and secondary minima in the light curve. It was given the variable star designation HX Velorum in 1980. In 1983, Christoffel Waelkens and Frédy Rufener published the correct period of variability, 1.124 days.

HX Velorum is a triple star, consisting of a pair (components A, magnitude 5.5, and B, magnitude 8.28) separated by 0.5 arc seconds. Component A is itself a close binary pair (components Aa and Ab). The system's brightness variation is caused by the ellipsoidal Aa and Ab components orbiting each other.

HX Velorum is only about 2 arc minutes from the center of IC 2395, so it appears to be within that cluster. However the Gaia DR3 dataset lists the parallax of HX Velorum as $-3.714$, yielding a distance of $4.758$ light years, while the distance to IC 2395 has been estimated to be $8.5$ light years, so HX Velorum might be a foreground object rather than a true cluster member. Mark Blackford et al. concluded HX Velorum is a member of the cluster, but that conclusion was based in part on earlier, significantly different distance estimates for both the star and the cluster.