New Fe I Level Energies and Line Identifications from Stellar Spectra. III. Initial Results from UV, Optical, and Infrared Spectra
| Autor: | Peterson, Ruth C., Kurucz, Robert L. |
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| Rok vydání: | 2021 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.3847/1538-4365/ac596b |
| Popis: | The spectrum of neutral iron is critical to astrophysics, yet furnace laboratory experiments cannot reach many high-lying Fe I levels. Instead, Peterson & Kurucz (2015) and Peterson, Kurucz & Ayres (2017) turned to UV and optical spectra of warm stars to identify and assign energies for 124 Fe I levels with 1900 detectable Fe I lines, and to derive astrophysical gf values for over a thousand of these. An energy value was assumed for each unknown Fe I level, and confirmed if it shifted the predicted positions in updated Kurucz (2011) Fe I calculations to match exactly in wavelength the positions of four or more unidentified lines in the observed spectra. Nearly all these identifications were for LS levels characterized by spin-orbit coupling, whose lines fall primarily at UV and optical wavelengths. This extension of these searches provides nearly a hundred new Fe I level identifications. Thirty-nine LS levels are identified largely by incorporating published positions of unidentified laboratory Fe I lines with wavelengths < 2000A. Adding infrared spectra provided sixty Fe I jK levels, where a single isolated outer electron orbits a compact core. Their weak, blended lines fall mostly in the infrared, but are searchable because their mutual energies obey tight relationships. For each new Fe I level, this work again provides and makes publicly available its identification, its energy, and a list of over 16,000 of its potentially detectable lines with theoretical gf values. For over 2,000 of these, this work also includes astrophysical gf values, ones adjusted semi-empirically to fit the stellar spectra. The potential impact of this work on modeling UV and IR stellar spectra is noted. Comment: 23 pages, 1 figure. Near-final ApJS version. Section 9 characterizes and quantifies uncertainties in deduced level energies and astrophysical dgf values. Table 3 includes >16,000 Fe I lines potentially detectable in solar-metallicity dwarfs and giants, and dgf values for >2,000 of these. It is currently available from the website of R. Kurucz at http://kurucz.harvard.edu/atoms/2600/PK21/table3.txt |
| Databáze: | arXiv |
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