Yields from massive stars in binaries

Chemical evolution of the Milky Way disk

¹ Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, Via G.B. Tiepolo 11, 34143 Trieste, Italy
² Dipartimento di Fisica e Astronomia “Augusto Righi”, Alma Mater Studiorum, Università di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
³ INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, 40129 Bologna, Italy
⁴ INAF – Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, 34131, Trieste, Italy
⁵ INFN – Sezione di Trieste, via Valerio 2, 34134 Trieste, Italy
⁶ IFPU Institute for Fundamental Physics of the Universe, Via Beirut 2, 34151 Trieste, Italy

^★ Corresponding authors; EMANUELE.PEPE@studenti.units.it; marco.palla@inaf.it; francesca.matteucci@inaf.it

Received: 22 October 2024
Accepted: 6 December 2024

Abstract

A large fraction of massive stars in the Galaxy reside in binary systems and their evolution is different from that of single stars. The yields of massive stars, which produce the majority of the metals in the Universe, could therefore be affected by the binary nature of the systems. However, very few studies have explored the effects of massive interacting binaries on the chemical evolution of the Milky Way. Recently, new grids of yields have been computed for single and binary-stripped massive stars with solar chemical composition. The main purpose of the present study is to test whether the results from these yields agree with models of the chemical evolution of Galactic stars. To this end, we adopted well-tested chemical evolution models for the Milky Way disk, implementing these yields for both single and binary-stripped massive stars. In particular, we assume different percentages of massive binary systems within the initial mass function. We computed the evolution of 22 chemical species starting from ⁴He to ⁶⁴Zn, including CNO, α-elements, and Fe-peak elements. Our main results can be summarized as follows: (i) When adopting the new computed yields, large differences are found relative to the solar abundances predicted by chemical evolution models that adopt “standard” massive star yields from the literature for ¹²C, ¹⁴N, ²⁴Mg, ³⁹K, ⁴⁰Ca, ⁵⁵Mn, and ⁵⁹Co. Generally, the yields for single stars reproduce the observed solar abundances slightly better, although for several elements a large fraction of binaries helps to reproduce the observations. (ii) Using different fractions of massive binaries (from 50% to 100%) leads to negligible differences in the predicted solar abundances, whereas these differences are more marked between models with and without binary-stripped stellar yields. (iii) Regarding [X/Fe] versus [Fe/H] relations, the yields including massive stars in binaries produce the best agreement with observational data for ⁵²Cr, while for ¹²C, ³⁹K, ⁴⁰Ca, and ²⁴Mg the best agreement with observational data are obtained with Farmer’s yields with no binaries.