Fluorine in the solar neighborhood: Chemical evolution models

Abstract

Context. In the light of the new observational data related to fluorine abundances in the solar neighborhood stars, we present here chemical evolution models testing different fluorine nucleosynthesis prescriptions with the aim to best fit those new data. Aims. We consider chemical evolution models in the solar neighborhood testing different nucleosynthesis prescriptions for fluorine production with the aim of reproducing the observed abundance ratios [F/O] [Fe/H]. We study in detail the effects of different stellar yields on the fluorine production. Methods. The adopted chemical evolution models are: i) the classical "two-infall" model which follows the chemical evolution of halo-thick disk and thin disk phases, ii) and the " one-infall" model designed only for the thin disk evolution. We tested the effects on the predicted fluorine abundance ratios of different nucleosynthesis yield sources: AGB stars, Wolf-Rayet stars, Type II and Type Ia supernovae, and novae. Results. The fluorine production is dominated by AGB stars but the Wolf-Rayet stars are required to reproduce the trend of the observed data in the solar neighborhood by Jönsson et al. (2017a) 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 two of the Wolf-Rayet yields given by Meynet & Arnould (2000). We also show that the novae, even if their yields are still uncertain, could help to better reproduce the secondary behavior of

Fluorine in the Solar Neighborhood: The Need for Several Cosmic Sources

“…The yields needed to increase it instead, are larger than the current best description of the yields from Wolf-Rayet stars and Novea (Spitoni et al 2018), which are, most likely, even overestimated. In order to fit the increasing abundances at high metallicities, Spitoni et al (2018) tried to model the galactic chemical evolution of fluorine by artificially increasing the Wolf-Rayet yields as well as including a fluorine production from novae, which could better model the observed data. Thus, the super-solar fluorine trend can currently not be explained theoretically.…”

“…We find, in principle, a flat [F/Fe] versus [Fe/H] trend for sub-solar metallicities, but an increasing trend above solar metallicities. This increase in [F/Fe] is difficult to explain; even if possible novae and the less likely Wolf Rayet channels are at play for these metallicities, the predicted fluorine production is not enough (Spitoni et al 2018).…”

“…This part also shows a secondary behaviour. The large increasing trend is surprising, since according to galactic chemical evolution models, like the ones in Spitoni et al (2018), the Fe contribution from Supernovae Type Ia should nominally decrease the trend. The yields needed to increase it instead, are larger than the current best description of the yields from Wolf-Rayet stars and Novea (Spitoni et al 2018), which are, most likely, even overestimated.…”

“…From several papers on the galactic chemical evolution of fluorine, the AGB-star contribution in the approximate metallicity range of −0.6 < [Fe/H] < 0.0 is, indeed, claimed to be dominant (e.g. Renda et al 2004;Recio-Blanco et al 2012;Spitoni et al 2018;Olive & Vangioni 2019). It should, however, be noted that there are different theoretical predictions of the AGBstar contributions, mainly due to which nuclear reaction rates are adopted.…”

Fluorine Abundances in the Galactic Disk

“…The abundances of F and Fe illustrated in Figure 10 can be used to evaluate contributions from possible sources for the nucleosynthesis of 19 F based on chemical evolution model predictions by Timmes et al (1995), Alibés et al (2001), Renda et al (2004), Kobayashi et al (2011a;2011b), Spitoni et al (2018), and Prantzos et al (2018); shown in the bottom panel of Figure 10. Likely sources to consider are both neutrino nucleosynthesis (or the "ν-process"; Woosley et al 1990;Timmes et al 1995;Alibés et al 2001;Kobayashi et al 2011a;2011b) and AGB stars Forestini et al 1992;Abia et al 2009;Cristallo et al 2014;Spitoni et al2018).…”