Looking Up: This Star Is Linkedin

Supernova remnant Simeis 147 (S147). It covers nearly 3 degrees or 6 full moons on the sky. Anchoring the frame at the right, bright star Elnath (Beta Tauri) is seen towards the boundary of the constellations Taurus and Auriga, almost exactly opposite the galactic center in planet Earth's sky. The supernova remnant has an estimated age of about 40,000 years. The cosmic catastrophe also left behind a spinning neutron star or pulsar, all that remains of the original star's core.

On this week's episode of Looking Up we hear about two familiar constellations and what they have in common.

We’ve talked before about most everyone’s favorite winter constellation, Orion the Hunter. We’ve also talked about Taurus the Bull, who is the target of Orion’s hunt. And today, I want to talk with you about a cool star in Taurus that is visible in the Colorado night sky right now.

The star Elnath is the top, or north-most star in the horns of Taurus the bull. Elnath is a nasty place, far hotter than our own Sun. Lying about 130 LY from Earth, Elnath is 700 times brighter than the Sun and is about 5 times bigger. It’s the 25th brightest star in the night sky.

But what makes Elnath especially interesting, at least to nerds like me, is that it is one of only two stars in the entire sky that belong to not one, but two constellations. Known as a “linking star,” Elnath is part of Taurus’s horns, but is also a part of the pentagon of stars in the constellation of Auriga. So, which is correct? Both of course! So impress your friends and family by dropping that cool factoid into your next conversation, and you’ll really impress all the cool kids.

If you’d like to take a closer look at Elnath, or any of the other 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.