The Procyon AB binary system ( orbital period 40.838 years , a newly-refined determination ) , is near and bright enough that the component radii , effective temperatures and luminosities are very well determined , although more than one possible solution to the masses has limited the claimed accuracy .
Preliminary mass determinations for each component are available from HST imaging , supported by ground-based astrometry and an excellent Hipparcos parallax ; we use these for our preferred solution for the binary system .
Other values for the masses are also considered .
We have employed the TYCHO stellar evolution code to match the radius and luminosity of the F5 IV-V primary star to determine the system ’ s most likely age as 1.87 \pm 0.13 Gyr .
Since prior studies of Procyon A found its abundance indistinguishable from solar , the solar composition of Asplund , Grevesse & Sauval ( Z =0.014 ) is assumed for the HR Diagram fitting .
An unsuccessful attempt to fit using the older solar abundance scale of Grevesse & Sauval ( Z =0.019 ) is also reported .
For Procyon B , eleven new sequences for the cooling of non-DA white dwarfs have been calculated , to investigate the dependences of the cooling age on ( 1 ) the mass , ( 2 ) the core composition , ( 3 ) the helium layer mass , and ( 4 ) heavy-element opacities in the helium envelope .
Our calculations indicate a cooling age of 1.19 \pm 0.11 Gyr , which implies that the progenitor mass of Procyon B was 2.59 _ { -0.26 } ^ { +0.44 } M _ { \odot } .
In a plot of initial vs final mass of white dwarfs in astrometric binaries or star clusters ( all with age determinations ) , the Procyon B final mass lies several \sigma below a straight line fit .