Courtesy of EarthSky
A Clear Voice for Science
At early evening, look up high for the brilliant star Capella, the brightest in the constellation Auriga the Charioteer. Close to Capella is a prominent triangle of starlets called The Kids. Lighting up the apex of this triangle is the star Epsilon Aurigae (Almaaz), one of the most mysterious stars in all the heavens.
Although Capella looks much brighter than Epsilon, that is because Capella is so much closer. Capella resides about 42 light-years away, whereas Epsilon is probably over 2,000 light-years distant. If this supergiant star were as close as Capella, it would outshine Capella by some 150 times.
In cycles of 27 years, the light from Epsilon Aurigae dims for a period of two years. The star’s last dimming happened in 1982-1984. Epsilon was predicted to dim again, starting in August 2009 and to be totally eclipsed by December 21, 2009. Epsilon is an eclipsing binary star, whereby some “dark” star routinely eclipses the brighter star.
The dark body in this binary system might be a star that is surrounded by a large disk of dust. However, nobody knows for sure. No doubt, astronomers will be studying Epsilon Aurigae during its 2009-2011 dimming, to see if they can unlock the secret of this mystery star.
Tonight for binoculars:
Asteroid Vesta still lodges close to Leo’s star Algieba (Gamma Leonis). For a sky chart and more information, go back to our February 17 show: Asteroid Vesta at apposition in Leo the Lion.
Written by Bruce McClure
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