Looking Up: Zeta O' Brother Where Art Thou?

Jul 3, 2017

Have you seen me? The blue star near the center of this image is Zeta Ophiuchi. When seen in visible light it appears as a relatively dim red star surrounded by other dim stars and no dust. However, in this infrared image taken with NASA's Wide-field Infrared Survey Explorer, or WISE, a completely different view emerges. Zeta Ophiuchi is actually a very massive, hot, bright blue star plowing its way through a large cloud of interstellar dust and gas.
Credit NASA/JPL-Caltech/UCLA

This week on Looking Up Hal  reveals an 'inconvenient truth'. 

Can I tell you the dirty little secret of the nonsense known as astrology? Turns out, there are not actually 12 signs of the Zodiac, but rather 13. Yup, the Sun moves through 13 constellations each year, not 12, so astrologers just pretend that the constellation of Ophiuchus doesn’t exist. 

But today, let’s talk about a very interesting star in Ophiuchus the Serpent Bearer, known as Zeta Ophiuchi.

Zeta doesn’t have a common name, just Zeta. But Zeta O is not common at all. First, it burns at a surface temperature of nearly 60,000 degrees, far hotter than our Sun’s measly 10,000 degrees. It puts out massive amounts of ultraviolet light – if your eyes could see that wavelength, Zeta Ophiuchi would be one of the most brilliant stars in the sky.

But Zeta is also interesting for what happened to its neighbor. You see, Zeta Ophiuchi is what’s known as a “runaway star,” in that it appears to have been expelled from a double star system, when the other, larger star blew up! Zeta got pushed out into space, while its former companion collapsed into an unbelievably dense neutron star, only about the size of downtown Colorado Springs! Talk about a bad neighbor!

If you’d like to take a closer look at Zeta Ophiuchi or any of the wonderful and amazing things in the sky, please visit csastro.org for a link to information on our monthly meetings and our free public star parties!