Heavy element contributions of rotating massive stars to interstellar medium

Abstract

Employing the stellar evolution code Modules for Experiments in Stellar Astrophysics (MESA), we calculate yields of heavy elements from massive stars via stellar wind and core−collapse supernova (CCSN) ejecta to the interstellar medium (ISM). In our models, the initial masses (M ini) of massive stars are taken from 13 to 80 M ⊙, their initial rotational velocities (V) are 0, 300 and 500 km s−1, and their metallicities are [Fe/H] = –3, –2, –1 and 0. The yields of heavy elements coming from stellar winds are mainly affected by stellar rotation which changes the chemical abundances of stellar surfaces via chemically homogeneous evolution, and enhances mass-loss rate. We estimate that the stellar wind can produce heavy element yields of about 10−2 (for low metallicity models) to a mass of several M ⊙ (for low metallicity and rapid rotation models). The yields of heavy elements produced by CCSN ejecta also depend on the large amount of remnant mass which is mainly determined by the mass of the CO-core. Our models calculate that the yields of heavy elements produced by CCSN ejecta can get up to several M ⊙. Compared with stellar wind, CCSN ejecta has a greater contribution to the heavy elements in ISM. We also compare the 56Ni yields calculated in this work with the observational estimate. Our models only explain the 56Ni masses produced by faint SNe or normal SNe with progenitor mass lower than about 25 M ⊙, and greatly underestimate the 56Ni masses produced by stars with masses higher than about 30 M ⊙.