On the cosmic origin of fluorine
- PDF / 216,877 Bytes
- 3 Pages / 595.276 x 790.866 pts Page_size
- 25 Downloads / 219 Views
J. Astrophys. Astr. (2020)41:34 https://doi.org/10.1007/s12036-020-09657-4
Sadhana(0123456789().,-volV)FT3](012345 6789().,-volV)
On the cosmic origin of fluorine NILS RYDE Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University, Box 43, 221 00 Lund, Sweden. E-mail: [email protected] MS received 7 September 2020; accepted 25 September 2020 Abstract. The cosmic origin of fluorine, the ninth element of the periodic table, is still under debate. The reason for this fact is the large difficulties in observing stellar diagnostic lines, which can be used for the determination of the fluorine abundance in stars. Here we discuss some recent work on the chemical evolution of fluorine in the Milky Way and discuss the main contributors to the cosmic budget of fluorine. Keywords. Abundances—fluorine—red giants.
1. Introduction Since 2019 was the 150th anniversary of the Periodic Table of Chemical Elements, UNESCO proclaimed it as the ‘International Year of the Periodic Table of Chemical Elements’. However, it was not until 2016, that the periodic table was completed up to period 7, with the identification of the element Oganesson with atomic number 118. Much astrophysical work has been devoted to understanding the cosmic origin of the elements, with large success for a range of elements. However, one element that has escaped a full understanding of its origin is fluorine, which has an atomic number of 9. The reason for this lack of understanding is the very few measurements done of the abundance evolution of fluorine in the Universe. Fluorine is interesting since it is the most electronegative element, extremely chemically reactive, as well as very nuclear reactive with p (H) and a (He) nuclei. On Earth, fluorine can be found in many minerals (such as the colourful calcium fluorite, a.k.a. fluorspar) and chemical compounds (such as the hazardous liquid hydrogen fluoride (HF)). Fluorine was first isolated in 1888 by Henri Moissan, which earned him the Nobel Prize in Chemistry in 1906. This article is part of the Topical Collection: Chemical Elements in the Universe: Origin and Evolution.
The cosmic abundance of fluorine is several orders of magnitude lower than that of the neighbouring elements in the periodic table. It is only the 24th most common element in the Universe. It is thus clear that stellar nucleosynthesis processes must by-pass it. Indeed, the nuclear reaction cross sections F(p), and F(a), in these processes are very high, which leads to the destruction of much of the newly formed fluorine. The main cosmic formation processes and sites for the production of fluorine is reviewed in detail in Ryde et al. (2020), and are as follows: (1) In massive stars: The contribution from nonrotating stars, from conventional Type II supernovae explosions (SNIIe), is negligible. However, rapidly rotating massive stars can produce primary fluorine from 14 N, via proton and alpha captures (Prantzos et al. 2018). Also, other processes have been suggested, such as the m-process in SNIIe. In this process, n
Data Loading...
