light curves for Mu Geminorum, adapted from Percy
et al. (2001). The 27 day periodicity is visible in the lower plot. Mu Geminorum has an average
apparent visual magnitude of about 2.9, which makes it the
fourth-brightest member of Gemini. It is 0.8 degrees south of the
ecliptic, so it is subject to
occultations by the
Moon and, rarely, by planets. Seen from Earth, its brightness is reduced by 0.07 magnitudes by
extinction from intervening gas and dust. It is a
slow irregular variable of type LB. Its brightness varies between
magnitude +2.75 and +3.02 over a 72-day period, along with a 2,000-day period of long term variation. It is a
red giant at a
stellar classification of M3 III, with a surface temperature of , meaning it is considerably cooler than the Sun. Despite being cooler than the Sun, it is over 1,500 times
as luminous as it has expanded to more than 100 times
the size of the Sun. Mu Geminorum is currently on the
asymptotic giant branch and is generating energy through the nuclear fusion of hydrogen and helium along concentric shells surrounding an inert core of carbon and oxygen. ==References==