VINDEMIATRIX (Epsilon Virginis). Just over the line into third magnitude (2.83) and third brightest in the constellation Virgo following first magnitude Spica (the Alpha star) and Porrima (Gamma), Vindemiatrix still wound up with Bayer's Epsilon designation. The Beta star, (Zavijava) shines only at fourth. The name is a somewhat corrupted feminized Latin form for the original Greek name that meant "the Grape Gatherer," as the first visibility of the star in morning light after the Sun cleared out of the way (the "heliacal rising") told that it was time to pick the grapes. An alternative name derived from Arabic, Almuredin, means the same thing, the term also translated from the original Greek. Vindemiatrix is a somewhat unusual star, a middling temperature (4990 Kelvin) yellow class G (G8) giant only a bit cooler than the Sun. As a giant, however, it is considerably brighter than the Sun. From its temperature and distance of 102 light years, its luminosity is 83 times solar, these combining to give a radius 12 times that of the Sun, all similar to the brighter, cooler component of Capella. The star seems to be a about 15% richer than the Sun in metals, and is somewhat distinguished by having most of its motion in the direction perpendicular to the line of sight, making it appear to move rather rapidly against the background stars, a second of arc in five years. Much more significantly, Vindemiatrix is a rather powerful X-ray source, implying considerable magnetic surface activity. Its total X-ray radiation is almost 300 times that of the Sun, ranking it third among nearby cool single giants and beat out only by Deneb Kaitos and a star called 24 Ursae Majoris, which lies northeast of the bowl of the Big Dipper. (The double star Capella far exceeds it, the X-radiating component unknown.) Though Vindemiatrix has surely ceased fusing hydrogen to helium in its core, its exact internal structure is uncertain. At three solar masses, it probably began life as a blue-white class B star, and is now either in transition to beginning to fire up its internal helium or has already begun to do so.
Written by Jim Kaler. Return to STARS.