TU Geminorum -- Carbon Star in Gemini
Red Star North of Open Cluster M35
It was a treat to start my star hop from the magnificent Open Cluster in Gemini (M35). My
eventual goal was a dark-red carbon star (TU Geminorum) only 1.5 degrees to the north of
the cluster. Even with the nearby moon, I paused for a while at the spectacle of the glittering
starlight of M35, before moving on to TU Geminorum. Finally forcing myself away from the
famous Open Cluster and pushing the telescope north, the blood-red star was an easy spot
since it stood out among the less colorful stars surrounding it.
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.