Fluorine in the solar neighborhood: Chemical evolution models

¹ Dipartimento di Fisica, Sezione di Astronomia, Università di Trieste, Via G.B. Tiepolo 11, 34131 Trieste, Italy
e-mail: spitoni@oats.inaf.it
² INAF – Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, 34131 Trieste, Italy
³ INFN – Sezione di Trieste, Via Valerio 2, 34100 Trieste, Italy
⁴ Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 22100 Lund, Sweden
⁵ INAF – Osservatorio Astronomico di Bologna, Via Gobetti 93/3, 40129 Bologna, Italy

Received: 12 October 2017
Accepted: 25 November 2017

Abstract

Context. In light of new observational data related to fluorine abundances in solar neighborhood stars, we present chemical evolution models testing various fluorine nucleosynthesis prescriptions with the aim to best fit those new data.

Aim. We consider chemical evolution models in the solar neighborhood testing various nucleosynthesis prescriptions for fluorine production with the aim of reproducing the observed abundance ratios [F/O] versus [O/H] and [F/Fe] versus [Fe/H]. We study in detail the effects of various stellar yields on fluorine production.

Methods. We adopted two chemical evolution models: the classical two-infall model, which follows the chemical evolution of halo-thick disk and thin disk phases; and the one-infall model, which is designed only for thin disk evolution. We tested the effects on the predicted fluorine abundance ratios of various nucleosynthesis yield sources, that is, asymptotic giant branch (AGB) stars, Wolf–Rayet (W-R) stars, Type II and Type Ia supernovae, and novae.

Results. The fluorine production is dominated by AGB stars but the W-R stars are required to reproduce the trend of the observed data in the solar neighborhood with our chemical evolution models. In particular, the best model both for the two-infall and one-infall cases requires an increase by a factor of 2 of the W-R yields. We also show that the novae, even if their yields are still uncertain, could help to better reproduce the secondary behavior of F in the [F/O] versus [O/H] relation.

Conclusions. The inclusion of the fluorine production by W-R stars seems to be essential to reproduce the new observed ratio [F/O] versus [O/H] in the solar neighborhood. Moreover, the inclusion of novae helps to reproduce the observed fluorine secondary behavior substantially.