The Night Sky: Canis Major

Attached is a wide angle picture of the constellation Canis Major. It is a four minute exposure taken with a Canon T1i camera, and a 28mm lens at f/5.

The constellation Canis Major represents Orion’s hunting dog. It can be found low in the southwest this time of year just below and left of the constellation Orion.

Sirius is the brightest star in Canis Major and also the brightest in our sky. Some stars appear bright to us because they are close; some are distant but look bright because, well, they are very bright! Sirius is both; it is relatively close to us (about 8 light years away) and is very bright (25 times brighter that our Sun).

Like half of all stars, Sirius has a companion star. Its companion, Sirius B, is a white dwarf star that orbits around Sirius every 50 years. A white dwarf is the remaining hot core of what used to be a giant star. With a mass almost that of our Sun packed into a volume the size of the Earth, the white hot core of Sirius B no longer produces heat through fusion, and will slowly cool over billions of years.

In this wide angle picture of Canis Major two star clusters (labeled 41 and 93) look like blue patches of light. Near the center of the picture is M41, a star cluster 2,300 light years away that contains about one hundred stars. In the upper left corner is M93, even farther away at 3,600 light years distant, and containing about 80 stars. Viewed through the telescope at the observatory, M41 and M93 are magnified and resolved into true Star Clusters.

Starry nights!