TY - GEN
T1 - Cas A
T2 - Circumstellar media and late stages of massive stellar evolution
AU - Dewey, D.
AU - DeLaney, T.
AU - Lazendic, J. S.
PY - 2007
Y1 - 2007
N2 - 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.
AB - 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.
KW - Radiation mechanisms: Thermal
KW - Supernova remnants: Individual(Cas A, G111.7-2.1)
KW - Techniques: Spectroscopic
KW - X-Rays: ISM
UR - http://www.scopus.com/inward/record.url?scp=38349097836&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:38349097836
SN - 9789703232758
T3 - Revista Mexicana de Astronomia y Astrofisica: Serie de Conferencias
SP - 84
EP - 89
BT - Circumstellar media and latetsages of massive stellar evolution
Y2 - 4 September 2006 through 8 September 2006
ER -