2002/06/26 by Yaron Sheffer, David L. Lambert, S. R. Federman · 1 citation
Physics and Astronomy · #Absorption spectroscopy #Astrophysics and Star Formation Studies #Fractionation #Interstellar medium #Isotope #Photodissociation #Solar and Space Plasma Dynamics #Spectral line #Spectroscopy #Stellar, planetary, and galactic studies #Ultraviolet #Ultraviolet astronomy #astro-ph
paper · pdf · doi:10.1086/342501
published as Astrophys.J. 574 (2002) L171 · 11 pages, incl. 1 figure. Accepted by ApJL
arxiv created 2002/06/26 · openalex publication_date 2002/08/01 · arxiv updated 2009/12/01 · openalex created_date 2019/06/27 · openalex updated_date 2026/08/05
We report the detection of fully resolved absorption lines of A-X bands from interstellar 12 C 17 O and 12 C 18 O, through high-resolution spectroscopy of X Persei with the Space Telescope Imaging SpectrographBased on observations obtained with the NASA/ESA Hubble Space Telescope through the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.. The first ultraviolet measurement of an interstellar 12 C 17 O column density shows that its isotopomeric ratio is 12 C 16 O/ 12 C 17 O = 8700 ± 3600. Simultaneously, the second ultraviolet detection of interstellar 12 C 18 O establishes its isotopomeric ratio at 3000 ± 600. These ratios are about five times higher than local ambient oxygen isotopic ratios in the ISM. Such severe fractionation of rare species shows that both 12 C 17 O and 12 C 18 O are destroyed by photodissociation, whereas 12 C 16 O avoids destruction through self-shielding. This is to be contrasted with our ratio of 12 C 16 O/ 13 C 16 O = 73 ± 12 toward X Per, which is indistinguishable from 12 C/ 13 C, the result of a balance between the photodissociation of 13 C 16 O and its preferential formation via the isotope exchange reaction between CO and C + .