2007AJ....133..147P


C.D.S. - SIMBAD4 rel 1.7 - 2019.10.15CEST19:56:22

2007AJ....133..147P - Astron. J., 133, 147-153 (2007/January-0)

Small-scale X-ray variability in the Cassiopeia A supernova remnant.

PATNAUDE D.J. and FESEN R.A.

Abstract (from CDS):

A comparison of X-ray observations of the Cassiopeia A supernova remnant taken in 2000, 2002, and 2004 with the Chandra ACIS-S3 reveals the presence of several small-scale features (≤10") that exhibit significant intensity changes over a 4 yr time frame. Here we report on the variability of six features, four of which show count rate increases from ∼10% to over 90%, and two of which show decreases of ∼30%-40%. While extracted 1-4.5 keV X-ray spectra do not reveal gross changes in emission-line strengths, spectral fits using nonequilibrium-ionization, metal-rich plasma models indicate increased or decreased electron temperatures for features showing increasing or decreasing count rates, respectively. Based on the observed count rate changes and the assumption that the freely expanding ejecta has a velocity of ∼5000 km/s at the reverse shock front, we estimate the unshocked ejecta to have spatial scale variations of 0.02-0.03 pc, which is consistent with the X-ray-emitting ejecta belonging to a more diffuse component of the supernova ejecta than that seen in the optically emitting ejecta, which have spatial scales of ∼10–3 pc.

Abstract Copyright:

Journal keyword(s): ISM: Individual: Name: Cassiopeia A - ISM: Kinematics and Dynamics - ISM: Supernova Remnants

Nomenclature: Figs 1,2, Table 1: [PF2007] RN (Nos R1-R6).

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2019
#notes
1 SN 1987A SN* 05 35 28.020 -69 16 11.07   4.75 4.81     SN.IIPec 4381 2
2 [PF2007] R4 reg 23 23 11.20 +58 48 53.2           ~ 1 0
3 [PF2007] R3 reg 23 23 13.40 +58 48 10.0           ~ 1 0
4 [PF2007] R6 reg 23 23 18.00 +58 48 37.0           ~ 1 0
5 NAME Cas A SNR 23 23 24.000 +58 48 54.00           ~ 2336 1
6 [PF2007] R2 reg 23 23 24.40 +58 47 13.2           ~ 1 0
7 [PF2007] R5 reg 23 23 26.90 +58 48 19.0           ~ 1 0
8 [PF2007] R1 reg 23 23 34.00 +58 49 56.2           ~ 1 0

    Equat.    Gal    SGal    Ecl

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2019.10.15-19:56:22

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