Abstract:
Elemental abundance patterns of globular cluster stars can provide important clues for understanding cluster formation and early chemical evolution. The origin of the abundance patterns, however, still remains poorly understood. We have studied the impact of p-capture reaction cycles on the
abundances of oxygen, sodium and aluminium considering nuclear reaction cycles of carbon-nitrogenoxygen-fluorine, neon-sodium and magnesium-aluminium in massive stars in stellar conditions of temperature range 2×107
to 10×107 K and typical density of 102 gm cc−1
. We have estimated abundances
of oxygen, sodium and aluminium with respect to Fe, which are then assumed to be ejected from those
stars because of rotation reaching a critical limit. These ejected abundances of elements are then compared with their counterparts that have been observed in some metal-poor evolved stars, mainly giants
and red giants, of globular clusters M3, M4, M13 and NGC 6752. We observe an excellent agreement
with [O/Fe] between the estimated and observed abundance values for globular clusters M3 and M4 with
a correlation coefficient above 0.9 and a strong linear correlation for the remaining two clusters with a
correlation coefficient above 0.7. The estimated [Na/Fe] is found to have a correlation coefficient above
0.7, thus implying a strong correlation for all four globular clusters. As far as [Al/Fe] is concerned,
it also shows a strong correlation between the estimated abundance and the observed abundance for
globular clusters M13 and NGC 6752, since here also the correlation coefficient is above 0.7 whereas
for globular cluster M4 there is a moderate correlation found with a correlation coefficient above 0.6.
Possible sources of these discrepancies are discussed.
