Cas A: The bright x-ray knots and oxygen emission

D. Dewey, T. DeLaney, J. S. Lazendic

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review

5 Citations (Scopus)


Chandra High-Energy Transmission Grating (HETG) X-ray spectra are extracted from 17 bright, narrow regions of Cas A and provide unique measurements of their kinematic and plasma states. From the dominant emission lines, e.g. He-like Si, we derive accurate Doppler shifts in the range -2500 to +4000 kms-1; these agree well with transverse-velocity measurements and allow the features to be located in 3D. Plasma diagnostics of these regions indicate temperatures largely around 1 keV with some above 3 keV. Using as well the non-dispersed zeroth-order data, we determine NEI model parameters for the regions which lead to density estimates. Values of ne ≈ 100 cm-3 are likely the maximum of a range of densities in this X-ray emitting material. The common "oxygen-rich" assumption is coarsely tested by comparing the integrated O VIII line flux and continuum levels. It appears that most of the continuum is due to another source, e.g.. from He.

Original languageEnglish
Title of host publicationCircumstellar media and latetsages of massive stellar evolution
Number of pages6
Publication statusPublished - 2007
Externally publishedYes
EventCircumstellar media and late stages of massive stellar evolution - Ensenada, B.C., Mexico
Duration: 4 Sep 20068 Sep 2006

Publication series

NameRevista Mexicana de Astronomia y Astrofisica: Serie de Conferencias
ISSN (Print)1405-2059


ConferenceCircumstellar media and late stages of massive stellar evolution
CityEnsenada, B.C.


  • Radiation mechanisms: Thermal
  • Supernova remnants: Individual(Cas A, G111.7-2.1)
  • Techniques: Spectroscopic
  • X-Rays: ISM


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