模擬短片 Video http://www.youtube.com:80/watch?v=hhMeumI36BM
See how the star pulsated (changed in brightness and radius) in 408-day period between 2003-2009. This star is one of the variables with largest brightness changes ever known.
Anyway, red giant stars don’t live long before they turn into planetary nebulae.
BTW, the recent news on Chi Cygni has stirred up some discussions in the astronomy community. This astronomer’s blog said that the mass of Chi Cygni might be twice the solar mass.