SYRMA (Iota Virginis). Most of the brighter stars of Virgo spread to the northwest of the luminary Spica. The dimmer ones go to the northeast, including our current star Syrma, which from Greek refers to the train of a dress, appropriate to the celestial Maiden of the Zodiac. It's far better known not by its Greek proper name, but by its Bayer Greek letter name, Iota Virginis. Like the others in the neighborhood, Syrma is relatively dim, just fourth magnitude (4.09), but of interest in that it is not all that much different from the Sun, a class F (F6) giant, but just barely, really a subgiant that has just ceased its core hydrogen fusion and is just beginning to pass on to becoming a true giant. Rather nearby, only 72 light years away (just a bit closer than the stars of the Big Dipper), Iota Vir shines at us with the light of 9.4 Suns from its 6185 Kelvin surface, just a bit greater than the solar temperature (the metal content similar to that of the Sun as well). With a mass of between 1.5 and 1.55 solar, the dying star has swollen to a radius of 2.7 times that of the Sun, having begun life at roughly half that size as a white class F2 star some 2.7 billion years ago. A modest (and uncertain) rotation speed of at least 24 kilometers per second (and a rotation period under 5.5 days) helps produce magnetic activity and a hot outer corona estimated at two to eight million degrees Kelvin, not dissimilar to the one that surrounds our own Sun. Iota Vir is also surrounded by some mystery. First, it's slightly variable, shifting between magnitude 4.06 and 4.11. Though the period is unknown, it's probably in the neighborhood of a day or so in the mode of Gamma Doradus. Even the closest look shows the star to be decidedly single. Very subtle motions, however, allow the suspicion of a companion with a period of around 200 years, but about which nothing is known and probably never will be. If it exists at all. (Thanks to Paolo Colona, who suggested this star.)
Written by Jim Kaler 7/03/09. Return to STARS.