W Canis Majoris -- Carbon Star in Canis Major
I was just starting my observing session. Tonight’s targets were a half dozen Open Clusters in
Monoceros (constellation of the Unicorn). From my suburban backyard, I started my star hop
from Sirius. I was not even out of the constellation of the Greater Dog, when a dark reddish
star passed through my field-of-view in the eyepiece. It was distinctive enough to catch my
attention. I made a quick drawing of the star and noted its location before continuing to my
targeted Open Clusters. As I suspected it was a Carbon Star and was identified as W Canis
Carbon Stars are unique in that their atmospheres contain more carbon than oxygen – not so
in other stars. The carbon combines with the oxygen, forming carbon monoxide, which
consumes all the available oxygen in the star’s upper atmosphere. The leftover carbon atoms
bond with other elements causing the star to shine ruby-red in color. No stars are darker-red
than Carbon Stars.
I have many times "discovered" interesting objects and stars while star-hoping to a completely
different object. It is one of the reasons that I usually prefer to take the time to find an object
the old fashion way instead of using an electronic GoTo system. Not only do I find, on occasion,
new interesting objects, but it helps me remain familiar with the night sky.