Auriga

The constellation of Auriga is easy to find using the Plough as a signpost. From Megrez, the faintest of the Plough’s seven stars, draw a line through Dubhe, the top pointer and extend it until you get to a bright yellow star shining above the eastern horizon early on winter evenings. This is Capella, Auriga’s lead star (if you get to the Pleiades you have gone too far!). Capella, 46 light years from Earth, is the most northerly first magnitude star and is circumpolar from our latitude. It is the sixth brightest star in the sky and in fact is a multiple system consisting of at least four members. Since the earliest times Auriga has been identified with a charioteer carrying a she-goat & her kids and Capella is also known as the “Goat Star”.

Capella is also known as the “Goat Star”. Auriga is often overlooked amongst the fine winter constellations of Orion’s retinue, but it does contain a number of excellent objects for binoculars or small telescopes. Chief of these are the three open clusters from Charles Messier’s famous catalogue, M36, 37 & 38. Of these, M37 is a particularly fine object.

Finally before leaving Auriga, take a look at the three fainter stars close to Capella. These are known the “Kids”. Epsilon, the closest of the three to Capella is an extraordinary system. It has the longest known period of any eclipsing binary. The main star is an extremely luminous white supergiant. It is about 2,000 light years away and normally shines at magnitude 3.0. Every 27 years though, it gradually drops to magnitude 3.8 over a four month period, remaining at that magnitude for 14 months before returning to normal. The latest eclipse commenced in August 2009, so 2010 and early 2011 provide a rare opportunity to observe this highly unusual event. The nature of the object causing the eclipses remains something of a mystery but the favourite theory is that it is a huge, almost opaque cloud of dust surrounding a binary system.

POWERPOINT SLIDE SHOW  (218KB)