Thursday, August 4, 2016
Zubeneschamali: What Is It and Where Is It?
Pronounced, zoo-ben-es-sha-mali, rhymes with Obi-Wan-Kenobi of Star Wars fame, this tongue-twister name of a star and its discovery dates back to thousands of years B.C. The name originated from the Arabic and translates to The Northern Claw. When first discovered this emerald green star (yes, green) was located in the constellation Scorpio. The name makes perfect sense in liaison with its partner star called Zubenelgenubi, which means The Southern Claw. Later, the Romans came into play when they determined that the “claws” of Scorpio should belong to the constellation Libra. They not only redrew the boundaries of these two constellations but changed the name of Zubeneschamali. It is now better known as Beta Libra.
Zubeneschamali, as the star is still tagged, is the brightest star in the constellation Libra. It is just a bit brighter than its partner star. What makes this star so unique? Well I, for one, love the fact that it is the only naked-eye star that is green. Some scientists and star-gazers disagree. If it is truly green, then it is the only green star among the vast amount of stars in the sky. Why is this? Astronomers and sky-gazers can agree on one thing: people see colors differently.
To define the debate a little more, Zubeneschamali is classified as a Class B star, which typically is a blue-white star. So you can understand the confusion. Some of the explanation can be attributed to the fact that this star is 160 light years away, four times the size of our Sun, twice as hot, and spinning rapidly. On occasion, several star-gazers will get together to observe this star in the late southern summer sky with their naked eye. If you do not see green, then try binoculars. Some will see green and others only white. I say it is GREEN.
In addition, Zubeneschamali is at the center of a centuries-old debate. Over two thousand years ago it was listed as the brightest of all stars of the constellation Scorpio, even brighter than Antares. A few centuries later, however, the great astronomer Ptolemy described Antares’ brightness equal to Zubeneschamali. Today Antares appears five times brighter. Has Zubeneschamali dimmed over the years, or has Antares gotten much brighter? A new debate is waging that this infamous star may be a “variable” star. So now we have a green star (that scientists say is not green) but may be a “binary” star (one star eclipsing another) which causes the dimming effect. You can see why this star is one of my very favorites…it has history and mystery.
My sources: EarthSky.org, UniverseToday.com, jackstargazer.com, stars.astro.Illinois.edu, constellationsofwords.com, and Wikipedia