Gamma Canis Majoris is a star of magnitude 4.12 in the constellation Canis Major. It also has the traditional name Muliphein, not to be confused with Muhlifain, which is Gamma Centauri; both names derive from the same Arabic root.
It unclear why Bayer gave this relatively faint star the constellation's γ designation - possibly because it is in the same part of Canis Major as Sirius (α CMa) and Murzim (β CMa). Muliphein may have faded since Bayer's time (around 1600). There is a reference which states that in 1670 the star disappeared, and was not seen again until 1693. However, since there is no known mechanism that could cause such an event, this has to be taken with suspicion.
Properties
The star itself, 400 light years away, is a class B8 II blue-white bright giant with a surface temperature of 13,600 K. It radiates 685 times more energy than the Sun and is 5 solar diameters across. If the star were as close as Sirius, it would shine almost as brightly as Venus.
Muliphein's luminosity and temperature indicate a 4.3 solar-mass star that has recently ended its hydrogen-fusing stage and is now starting to evolve into a red giant. It rotates slowly for a class B star, at only 15 times the Sun's rotation speed. Like many class B and A stars, it is chemically peculiar. Muliphein is a "mercury-manganese star" with a level of mercury more than 2000 times the sun's, and is 40% richer in iron and chromium than the Sun. These abundances result from radiation forces physically lofting certain elements.
[Adapted from STARS by Jim Kaler, Professor Emeritus of Astronomy, University of Illinois]