Leo Minor

by Tammy Plotner on November 18, 2008

Leo Minor

Leo Minor

Leo Minor is a very small and dim constellation which was created by Johannes Hevelius in 1687 and later recognized as one of the 88 modern constellations. While Leo Minor did not belong to any older star catalogs such as those drawn up by Ptolemy in the 2nd century AD, this set of stars became part of the Firmamentum Sobiescianum, a 56 sheet atlas created by master astronomer Hevelius in an attempt to update star catalogs using what (was then) considered modern equipment. Leo Minor was one of seven new constellations and endured to become officially recognized by the International Astronomical Union. It possesses no bright stars and has only 2 main stars in its asterism, yet there are 34 Bayer/Flamsteed designated stars within Leo Minor’s confines. It spans 232 square degrees of sky and is bordered by the constellations of Ursa Major, Lynx, Cancer and Leo. Leo Minor is visible to all observers at latitudes between +90° and ?45° and is best seen at culmination during the month of April.

Since Leo Minor, the “Little Lion” is consider a new constellation, it has no ancient mythology associated with it. As you may have noticed by looking at the chart, it curiously has no Alpha star. When it came to making charts, Hevelius was great – but he didn’t label stars. It wasn’t until the 19th-century when English astronomer Francis Baily had a go at Leo Minor that he assigned the stars with their Greek letters and he simply overlooked the Alpha designation! Leo Minor is just another example of how constellation names and figures can sometimes repeat themselves, like Ursa Major and Minor, Canis Major and Minor, Pegasus and Equuleus… Hydra and Hydrus. Half the challenge to this constellation is simply finding it!

Break out your binoculars and let’s have a look at Beta Leonis Minoris – the “B” shape on our map.. This is a very rapid binary star – not in terms of movement through space – but in orbit of its companion star. Believe it or not, the 6th magnitude companion completes a full orbit in less than 40 years. That’s just a little bit slower than Saturn takes to orbit our Sun and over twice as fast at it takes Neptune!

Now head east for 46 Beta Leonis Minoris. By all rights, this should have been the Alpha star and it’s the only Bayer/Flamsteed numbered stellar designation to have a proper name – Praecipua. As stars go? Well, Praecipua is actually pretty ordinary. Just another orange giant star hanging out in space around 98 light years from Earth. It is happily radiating away about 32 times brighter than our Sun and it is around 9 times bigger. One of the coolest things about this star is just how well we know it! According to Jim Kaler’s excellent information; “Recent accurate measures of angular diameter by the Navy Interferometer show it to be 0.00254 seconds of arc across (the separation of car headlights seen from a distance of 80,000 kilometers, 20 percent of the way to the Moon), which gives it a physical diameter 8.2 times that of the Sun, the agreement with the previously calculated diameter showing that we know the size, temperature, luminosity, and distance very well.”

Now, get out your telescope and let’s go on a galaxy hunt. Our first target is NGC 3486 (RA 11:00.4 Dec +28:58). At magnitude 10, this barred spiral galaxy discovered by Sir William Herschel is around 33 million light years away and it has attitude. Even in a small telescope, observers will note a bright, sharp nucleus and larger instruments will reveal a strong central bar and patchy structure that is the signature of a Seyfert galaxy.

Next up is a large telescope challenge – NGC 3344 (RA 10:43.31 Dec +24:55). Located much closer to the Milky Way Galaxy at 25 million light years in distance, this 13th magnitude grand design spiral galaxy is a face-on presentation, and only about half the size of our own galactic home. Like our preceding observation, it, too, has a central bar – but don’t be fooled by the foreground stars! According to studies done by Verdes-Montenegro (et al), the bar is exponential and dominates the central parts, while the bulge component is small. This makes this faint customer belong to the classification of a “ringed galaxy”.

Sources: SEDS, Wikipedia
Chart Courtesy of Your Sky.

About 

Tammy is a professional astronomy author, President Emeritus of Warren Rupp Observatory and retired Astronomical League Executive Secretary. She’s received a vast number of astronomy achievement and observing awards, including the Great Lakes Astronomy Achievement Award, RG Wright Service Award and the first woman astronomer to achieve Comet Hunter's Gold Status.

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