Carbon stars are red in virtue of their lower temperatures, reaching just around 3,500 degrees Celsius. In comparison, our sun shines at about 6,000° C. The hottest stars shine at higher than 30,000° C. They are termed as carbon stars because of their carbon dust particles in their atmosphere. This carbon comes from the fact that these kind of stars have used up most of their Hydrogen fuel via fusion. The subsequent fusion of Helium results in the formation of Carbon, Silicon and Oxygen. Internal currents in the star's structure bring these elements and related molecules to the star's outer layers enhancing therefore their intense reddish colour.
We continued observing this variable star for a total of 348 observations, carried out over a 118-day period. On the basis of these observations it was deduced that this star shifts its brightness from one extreme to the other every 135 days, more or less.
For those who would like to look at the scientific analysis of our data:
Carbon Star CGCS 673 identified as a Semi-regular variable star
Stephen M. Brincat, C. Galdies and K. Hills