Looking Up: You've Tried The Rest, Now Triangulum

Sep 12, 2016

Triangulum as viewed from Kenosha Pass, Colorado
Credit Photo by Linda Spadero / earthsky.org

This week on Looking Up Hal gives us the very latest hypote-news on a  constellation by the name of Triangulum.

We talked before about the interesting shapes of constellations in the night sky. Some look like their name, like Scorpio the scorpion. Others, like Ophiuchus, looked nothing like their namesake. But there is one small constellation in southern Colorado skies right now that you might recognize from both its shape and its name – Triangulum.

Yes, there’s actually a constellation named after triangle. Can you guess how many stars it contains? If you guessed three, you win. Triangulum looks very much like an upside down right triangle. But each of the three stars is interesting in their own right.

Metallah, the star at the far end of the hypotenuse, is a sub giant star, about 10% hotter than our sun. It’s only 64 light years away, and it appears to be about 13 times brighter and about three times bigger than our sun. It’s an old star, getting ready to shut down the hydrogen fusion in its core. As big as it is, there is some evidence that there is a small companion star that orbits Metallah in an orbit not measured in months or years, but in hours.  This dim companion seems to whip around Metallah in only about 30 hours.

At the base of the right triangle, Beta Tranguli has a companion that orbits it every 30 days. But in between the two there appears to be a disc of dust. We can’t be sure, but it’s possible there are planets there, and can you imagine the Star Wars-like double sun sunsets anyone on those planets would see? Amazing.

Lastly, Gamma Trianguli is not a double star, but rather a triple. It also appears that the main star is a baby, perhaps only 200 million years old. And it’s one of the fastest spinning stars out there, rotating at almost 465,000 mph.

That’s a lot of cool things packed into a small triangle. And you thought geometry was never useful.

If you’d like to take a closer look at Triangulum, 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! 

This is Hal Bidlack for the Colorado Springs Astronomical Society, telling you to keep looking up, Southern Colorado!