Analysis of information sources in references of the Wikipedia article "Twin Spica" in English language version.
What's really fascinating is that the two big, bright, massive components of Spica are so close together. Their center-to-center separation averages just 0.12 AU—that's about 11 million miles, with the larger star having an average diameter of nearly 3½ million miles. [...] Could there be more stars in the Spica system? Apparently there is evidence from lunar occultations that there are three other, fainter components.