Tags: Star.
TT Cygni is a carbon star. It is 561 parsecs (1830 ly) away in Cygnus. It has an apparent magnitude of 7.44. It is called a carbon star because it has a high ratio of carbon to oxygen in its surface layers. The carbon was produced by helium fusion dredged up from inside the star. A shell of carbon monoxide about half a light year across was emitted 6000 years before the star was as it appears to us now.