Portrait of an archduchess (Archduchess Helena or Barbara?)

The museum's own title for this portrait ends with a question mark. The small panel, from about 1563, shows one of the younger daughters of Emperor Ferdinand I, and the Kunsthistorisches Museum names two candidates, Helena or Barbara. It gives the painter with a question mark too, as possibly Giuseppe Arcimboldo. The two sisters were four years apart, and within a few years of this portrait their lives went opposite ways. Barbara married Alfonso II d'Este, Duke of Ferrara, in 1565 and moved to his court in Italy, where she died in 1572. Helena stayed in Tyrol and entered the community for noblewomen that her elder sister Magdalena had founded in Hall, near Innsbruck. On the back of the panel is a red star, the same mark found on Magdalena's portrait from this group.