Re: what stage of the life cycle is achernar in

Achernar is in the "main sequence" phase of its life. This means that deep
down in the center of the star, hydrogen fusion is going on. In a hydrogen
fusion reaction, atoms of hydrogen are slammed together with amazing force
to create helium. 

It takes four atoms of hydrogen make one atom of helium. However, one atom
of helium weighs less than four atoms of hydrogen. So, where does the extra
mass go?

The answer is that the extra mass is released as energy (heat and light).
Einstein's famous equations E=mc^2 means that mass and energy can be
transformed into each other. That's what happens at the center of Achernar,
or the Sun, or any other star. 

Just like Achernar, the Sun is also on the main sequence. Being a main
sequence star just means that hydrogen fusion is the energy source. When a
star uses up the hydrogen at its core, it leaves the main sequence and goes
through a number of changes. For a light star like the Sun, that means
becoming a red giant star and then a white dwarf. But for a heavy star like
Achernar, it means several red giant stages. Eventually, Achernar will wind
up as either a white dwarf or a neutron star.