Markeb

A blue star lying near the southern edge of Vela the Sail, where that constellation runs along the Milky Way on the borders of Carina the Keel. In combination with another star in Vela, Alsephina, and two from neighbouring Carina, Aspidiske and Avior, Markeb forms part of the False Cross formation. This is a combination of stars remarkably reminiscent of the true Southern Cross, Crux, lying somewhat to the east across the sky.

The names Markeb and Markab derive from words for 'conveyance' or 'vehicle', here referring to the large star-group of the Ship Argo, of which Vela represents the Sail. The names are also used for other stars elsewhere in the sky: most notably Markab is the common name of Alpha Pegasi, where it represents the saddle of the Flying Horse. In Vela's neighbouring constellation of Puppis, the star k Puppis is also given the name Markeb, apparently due to some confusion with the Markeb in Vela, whose Greek designation on the Bayer system is κ (Kappa) Velorum.

Markeb is known to be a binary system, with two component stars orbiting one other in a period of 117 days. The stars appear to be relatively close to one another, separated by a distance of approximately half an Astronomical Unit, but little else is known about the details of the system. In combination, the two stars present a B-type blue spectral classification that describes a subgiant, implying that one of the components has burned its supplies of hydrogen and is approaching the giant phase of its existence. The Markeb system is a source of high levels of X-rays, implying intense magnetic activity in one of the component stars, or possibly arising from interactions between the two.