Astron. Astrophys. 331, 661-668 (1998)

Astron. Astrophys. 331, 661-668 (1998)

A multifrequency study of G182.4+4.3:
a new supernova remnant in the Galactic anti-centre

R. Kothes , E. Fürst and W. Reich

Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany

Received 30 April 1997 / Accepted 16 October 1997

Abstract

A new supernova remnant (G182.4+4.3) in the Galactic anti-centre region has been detected at radio frequencies. Observations at 1400 MHz, 2675 MHz, 4850 MHz, and at 10450 MHz with the Effelsberg 100-m telescope reveal a shell structure of about 50' across. The flux density radio spectral index is [FORMULA] , (). The polarization percentage of the brighter part of the shell is about 40%. At 4850 MHz the polarization percentage near the peak of the shell exceeds 60%. The Faraday rotation measure varies between 0 rad m^-2 and 70 rad m^-2. The total flux density extrapolated to 1 GHz is Jy leading to a radio surface brightness of [FORMULA] Watt m^-2 Hz^-1 sr^-1. HI line observations of neutral hydrogen show that the column density towards G182.4+4.3 must be cm^-2. No X-ray emission is visible in the ROSAT all-sky survey at the position of the new supernova remnant. This corresponds to an upper limit of counts s^-1. Some information on the nature of G182.4+4.3 is obtained from a discussion of these observations: G182.4+4.3 is at a distance of [FORMULA] kpc and probably expanding according to the classical Sedov equations. Assuming an initial explosion energy of erg the following parameters are obtained: cm^-3, a radius of pc, a swept-up mass of M , keV, years, and km s^-1.