Looking Up: Is It Better To Burn Out Or Fade Away?

Jan 14, 2019

In this 20-image digitally-composed mosaic, cool red giant Betelgeuse takes on a strong orange tint as the brightest star at the upper left. Orion's hot blue stars are numerous, with supergiant Rigel balancing Betelgeuse at the lower right, and Bellatrix at the upper right. Lined up in Orion's belt are three stars all about 1,500 light-years away, born from the constellation's well-studied interstellar clouds.
Credit Derrick Lim / nasa.gov

This week on Looking Up Hal spotlights Bellatrix, one of his favorite stars in the constellation Orion.

The mighty constellation of Orion dominates Colorado’s winter sky, and it’s a wonderful area of the sky to observe with a telescope, binoculars, or just naked eye.

You likely know the constellation as a warrior, drawing his bow, with his faithful dog following along behind. And, you like know about the most famous of all the Orion stars, Betelgeuse, which gets much more attention. After all, Betelgeuse is a giant star getting ready to explode into a super nova any day now (or century, or millennium, so don’t spend lots of time watching for the boom, we’ll let you know if it happens).

But the opposite shoulder of Orion is the very special star Bellatrix, one of my favorites. Bellatrix is about 240 ly from Earth, and is very hot, with a temperature of 38,000 F, far hotter than our Sun’s measly 10,000 F or so. And as you might expect, burning that hot has helped Bellatrix burn through most of its hydrogen fuel. But unlike its neighbor Betelgeuse, Bellatrix will not explode, but rather will puff up, then slowly fade into a massive white dwarf star in eons to come. And it may be a bit lonely, as it’s not actually part of the same group of stars that makes up most of Orion. Bellatrix is actually much closer to us, and just happens to line up with the other stars in the great hunter.

If you’d like to take a closer look Bellatrix, 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.