2006/11/02 by A. E. Glassgold, Alfred E. Glassgold, Joan Najita +3 · 4 citations
Physics and Astronomy · #Argon #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Atomic physics #Emission spectrum #Ion #Line (geometry) #Neon #Physics #Spectral line #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/510013
published as Astrophys.J.656:515-523,2007 · 24 pages, 5 figures
arxiv created 2006/11/02 · openalex publication_date 2007/02/03 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Using a thermal-chemical model for the generic T-Tauri disk of D'Alessio et al. (1999), we estimate the strength of the fine-structure emission lines of NeII and NeIII at 12.81 and 15.55 microns that arise from the warm atmosphere of the disk exposed to hard stellar X-rays. The Ne ions are produced by the absorption of keV X-rays from the K shell of neutral Ne, followed by the Auger ejection of several additional electrons. The recombination cascade of the Ne ions is slow because of weak charge transfer with atomic hydrogen in the case of Ne2+ and by essentially no charge transfer for Ne+. For a distance of 140pc, the 12.81 micron line of Ne II has a flux of 1e-14 erg/cm2s, which should be observable with the Spitzer Infrared Spectrometer and suitable ground based instrumentation. The detection of these fine-structure lines would clearly demonstrate the effects of X-rays on the physical and chemical properties of the disks of young stellar objects and provide a diagnostic of the warm gas in protoplanetary disk atmospheres. They would complement the observed H2 and CO emission by probing vertical heights above the molecular transition layer and larger radial distances that include the location of terrestrial and giant planets.