We herein determine the average integrated mass loss from stars belonging to the dominant metal-poor population ( [ Fe/H ] \sim –1.7 ) of the Galactic globular cluster \omega Centauri ( NGC 5139 ) during their red giant and horizontal branch evolution .
Masses are empirically calculated from spectroscopic measurements of surface gravity and photometric measurements of temperature and luminosity .
Systematic uncertainties prevent an absolute measurement of masses at a phase of evolution .
However , the relative masses of early asymptotic giant branch stars and central red giant branch stars can be measured , and used to derive the mass loss between these two phases .
This can then be used as a physical check of models of horizontal branch ( HB ) stars .
For \omega Cen , the average difference is found to be 26 \pm 4 % .
Assuming initial and final masses of 0.83 and 0.53 M _ { \odot } , we determine that 0.21 \pm 0.03 M _ { \odot } is lost on the RGB and 0.09 \pm \sim 0.05 M _ { \odot } is lost on the AGB .
The implied HB stellar mass of 0.62 \pm 0.04 M _ { \odot } is commensurate with literature determinations of the masses of the cluster ’ s HB stars .
The accuracy of this measurement can be improved through better selection of stars and spectral coverage , and applied to other clusters where horizontal branch models do not currently agree .