TT Cygni: Carbon Star
Credit:
H. Olofsson
(Stockholm Observatory) et al.
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.