A lion far less famous

¡SkyCaramba! Weekly astronomy blog for the week ending March 23, 2013

It’s very easy to think Leo is the only lion on our constellation maps. It’s simply named Leo and not Leo Major. And we never hear about any lion in the sky except Leo. This week’s story is about Leo Minor, how to find it, and why it has so little fame.

Astronomer Johannes Hevelius gave the name Leo Minor to an area of stars between Leo and Ursa Major about the year 1687. He and other astronomers wanted to name previously unnamed parts of the sky so they could better communicate with each other about where to find stars, comets, and other objects they were studying up there.

There are no ancient Greek legends associated with Leo Minor, because to the ancient Greeks, these stars weren’t a little lion or anything else. They were among the star groups called the amorphotoi. That word means unformed. The ancient Arabs may have thought of the stars as a gazelle. In some ancient Chinese depictions, they and the stars of Leo were a dragon.

All the stars of Leo Minor are fourth magnitude and dimmer. So you may not even see them from light polluted cities. If you look at a lot of star maps, you know that the brightest star in a constellation is usually given the Greek letter alpha. However, there’s no Alpha Leonis Minoris. An astronomer working on a British star catalog in the 1800s somehow overlooked it. Rather than correct the mistake, today’s astronomers refer to the brightest star in the constellation as 46 Leonis Minoris. It’s 75 light years away. If you want to know the star by a less scientific sounding name, it’s sometimes called Praecipua. The name is Latin for chief.

The second brightest, Beta Leonis Minoris, is 100 light years away. It’s a binary star.

A mysterious mass called Hanny’s Voorwerp is in Leo Minor, about 700 million light years from us. A Dutch school teacher, Hanny van Arkel, discovered it during an astronomy event in 2007. The name means Hanny’s object. It appears somewhat like a nebula, but there is no identifiable light or radiation source to illuminate the gas. Some scientists think the voorwerp is what’s left over from a galaxy shredded apart by a black hole. What little light has reflected off of it or was made to glow from it may have come from a quasar that no longer shines.

Leo Minor is visible in the evening this time of year in the northern hemisphere and into the middle southern latitudes. It’s two thirds of the way from the bowl of the Big Dipper to the sickle or hook of Leo.