Fe II fluorescence in main-sequence K-dwarfs
2024 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 527, no 3, p. 9522-9528Article in journal (Refereed) Published
Abstract [en]
Main-sequence K-dwarfs possess strong emission in the form of the H I Ly α line. There is a close coincidence between the energy corresponding to the transitions H I 1s-2p and Fe II (5D)5s 4D5/2–(5D)5p 4D5/2. Singly ionized iron has been confirmed being pumped by photo-excitation by accidental resonance (PAR) in planetary nebulae, symbiotic stars, K-giants, and active galactic nebulae. I investigate in this work whether PAR can occur in the atmospheres of main-sequence K-dwarfs, which do not possess the large extended atmospheres of the late-type K-giants. Specifically a search for possible Fe II fluorescence lines is conducted. For the case when I can confirm PAR, I estimate the total flux leaving the stars in the form of Fe II fluorescence. I search for emission lines from the Fe II (5D)5p 4D5/2 level. Since those of these lines with the largest branching fractions correspond to lines at wavelengths covered by the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite, a search for archival FUSE spectra from K-dwarfs within 20 ly from the sun is conducted. I retrieve and analyse FUSE spectra for four of these K-dwarfs. In each case I can confirm PAR, I fit the H I Ly α line in Hubble Space Telescope spectra recorded with the Space Telescope Imaging Spectrograph, in order to estimate the efficiency of the PAR mechanism. I can now confirm Fe II fluorescence in the two closest K-dwarfs, Alpha Centauri B, and Epsilon Eridani. The total power leaving as Fe II fluorescence are 4.9 × 1017 and 1.30 × 1018 W respectively. © The Author(s) 2023 Published by Oxford University Press on behalf of Royal Astronomical Society.
Place, publisher, year, edition, pages
Oxford University Press, 2024. Vol. 527, no 3, p. 9522-9528
Keywords [en]
atomic processes, formation line, identification line, low-mass stars, Galaxies, Iron compounds, Space telescopes, Stars, Ultraviolet spectroscopy, Atomic process, Energy, Far Ultraviolet Spectroscopic Explorer, Ionized iron, Line formations, Identification line, Ly-α, Photo-excitations, Spectra's, Low mass stars, Fluorescence
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
URN: urn:nbn:se:bth-25928DOI: 10.1093/mnras/stad3852ISI: 001159068100015Scopus ID: 2-s2.0-85181845282OAI: oai:DiVA.org:bth-25928DiVA, id: diva2:1832396
2024-01-292024-01-292024-03-28Bibliographically approved