2001/06/26 by Randall K. Smith, Nancy S. Brickhouse, Duane A. Liedahl +1 · 31 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Atomic and Molecular Physics #astro-ph
paper · pdf · doi:10.1086/322992
published as Astrophys.J. 556 (2001) L91-L95 · 5 pages, 6 figures, accepted by ApJ Letters
arxiv created 2001/06/26 · openalex publication_date 2001/08/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
New X-ray observatories ( Chandra and XMM-Newton ) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code, the Astrophysical Plasma Emission Code (APEC), which uses atomic data in the companion Astrophysical Plasma Emission Database (APED) to calculate spectral models for hot plasmas. APED contains the requisite atomic data such as collisional and radiative rates, recombination cross sections, dielectronic recombination rates, and satellite line wavelengths. We compare the APEC results to other plasma codes for hydrogen- and helium-like diagnostics and test the sensitivity of our results to the number of levels included in the models. We find that dielectronic recombination with hydrogen-like ions into high ( n = 6-10) principal quantum numbers affects some helium-like line ratios from low-lying ( n = 2) transitions.