Letter to the Editor

Is the Cygnus Loop two supernova remnants?

¹ National Research Council, Herzberg Institute of Astrophysics, Dominion Radio Astrophysical Observatory, PO Box 248, Penticton, British Columbia, V2A 6K3, Canada e-mail: aylin.yar@.nrc.ca, roland.kothes@nrc.ca
² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: wreich@mpifr-bonn.mpg.de, efuerst@mpifr-bonn.mpg.de
³ Department of Physics and Astronomy, The University of Calgary, 2500 University Dr. NW, Calgary, AB, T2N 1N4 Canada

Corresponding author: B. Uyanıker, bulent.uyaniker@.nrc.ca

Received: 26 March 2002
Accepted: 26 May 2002

Abstract

The Cygnus Loop is classified as a middle-aged supernova remnant (SNR) located below the Galactic equator () and 770 pc away from us. Its large size and little confusion with Galactic emission makes it an ideal test ground for evolutionary and structural theories of SNRs. New radio continuum mapping of the Cygnus Loop at 2695 MHz with the Effelsberg 100-m telescope provides indications that the Cygnus Loop consists of two separate SNRs. Combining this result with data from the literature we argue that a secondary SNR exists in the south with a recently detected neutron star close to its center. Two interacting SNRs seem to be the best explanation to account for the Cygnus Loop observations at all wavelengths.