March 4, 2001
You are a way for the cosmos to know itself, Carl Sagan once said. On your birthday, the cosmos got to know itself a little better.
TT Cygni: Carbon Star
Birthday · March 4, 2001
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APOD published March 4, 2001. Full image credits are on the original APOD entry below. A publication-date match, not a photo taken on your date. Independent of NASA.
TT Cygni is a cool red giant star with a wind. This false-color picture of TT Cyg was made using a coordinated array of millimeter wavelength radio telescopes and shows radio emission from carbon monoxide (CO) molecules in the surrounding gas. The central emission is from material blown off the red giant over a few hundred years while the thin ring, with a radius of about 1/4 light-year, actually represents a shell of gas expanding outward for 6,000 years. Carbon stars like TT Cyg are so named for their apparent abundance of carbon containing molecules. The carbon is likely the dredged-up ashes of nuclear helium burning in the stellar interior. Carbon stars lose a significant fraction of their total mass in the form of a stellar wind which ultimately enriches the interstellar gas - the source of material for future generations of stars. TT Cyg is about 1,500 light-years away in the constellation Cygnus.