Delta Velorum

Delta Velorum (δ Velorum, abbreviated Delta Vel, δ Vel) is a triple star system in the southern constellation of Vela, near the border with Carina, and is part of the False Cross. Based on parallax measurements, it is approximately 80.6 light-years (24.7 parsecs) from the Sun. It is one of the stars that at times lies near the south celestial pole due to precession. δ Velorum consists of an eclipsing binary, designated Delta Velorum A, and a more distant third companion, Delta Velorum B. δ Velorum A's two components are themselves designated Aa (officially named Alsephina /ælsɪˈfaɪnə/, the traditional name for the entire system) and Ab. δ Velorum (Latinised to Delta Velorum) is the system's Bayer designation. The designations of the two constituents as Delta Velorum A and B, and those of A's components—Delta Velorum Aa and Ab—derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU). Delta Velorum bore the traditional name Alsafinah, which stems from the Arabic name al-safīnah meaning "the ship", referring to the ancient Greek constellation Argo Navis, the ship of the Argonauts. It was first used in a 10th-century Arabic translation of the Almagest, written by the Greek astronomer Ptolemy in the second century AD. Although the name originally referred to an entire constellation, it was assigned to this particular bright star at least as early as 1660, when it appeared in Andreas Cellarius's renowned Harmonia Macrocosmica, a magnificently illustrated 17th-century Dutch book about the cosmos. In 2016, the IAU organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems. It approved the name Alsephina for the component δ Velorum Aa on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.