Issue |
A&A
Volume 372, Number 2, June III 2001
|
|
---|---|---|
Page(s) | 627 - 635 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20010407 | |
Published online | 15 June 2001 |
A high frequency radio study of G11.2-0.3, a historical supernova remnant with a flat spectrum core
1
National Research Council, Herzberg Institute of Astrophysics, Dominion Radio Astrophysical Observatory, PO Box 248, Penticton, British Columbia, V2A 6K3, Canada
2
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: wreich@mpifr-bonn.mpg.de
Corresponding author: R. Kothes, roland.kothes@hia.nrc.ca
Received:
30
January
2001
Accepted:
19
March
2001
We present radio maps of the historical supernova remnant
G11.2-0.3 in the frequency range from 4.85 GHz to 32 GHz. The
integrated spectrum with (
) is
dominated by its steep spectrum shell emission (
),
although a flat spectrum core structure classifies G11.2-0.3 as a
composite supernova remnant. A radial magnetic field structure is
observed. An analysis of the multi-frequency polarization data results
in highly varying rotation measures along the shell. The percentage
polarization is rather low (~2% ) and we conclude that
G11.2-0.3 is in the transient phase from free to adiabatic expansion.
The central flat spectrum component is partly resolved. A compact radio
source with an inverted spectrum likely coincides with the previously
detected X-ray pulsar (Torii et al. [CITE]). Two symmetric
structures with flat radio spectra possibly indicate a bipolar
outflow. Combining available X-ray and radio data we conclude that G11.2-0.3
is likely the remnant of a type II supernova explosion with an early
type B progenitor star.
Key words: supernova remnant / magnetic field / radio continuum: ISM
© ESO, 2001
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