Multi-wavelength study of the G 82.2+5.3 supernova remnant

¹ University of Crete, Physics Department, PO Box 2208, 710 03 Heraklion, Crete, Greece
² Max-Planck-Institut für extraterrestrische Physik, Postfach 1312, 85741 Garching, Germany
³ Foundation for Research and Technology-Hellas, PO Box 1527, 711 10 Heraklion, Crete, Greece

Corresponding author: F. Mavromatakis, fotis@physics.uoc.gr

Received: 8 August 2003
Accepted: 6 November 2003

Abstract

We present the first CCD flux–calibrated images of the supernova remnant G 82.2+5.3  in major optical emission lines. The medium ionization line of []5007 Å provides the first direct evidence of optical emission originating from G 82.2+5.3. Filamentary emission is detected in the west and east areas of the remnant, roughly defining an ellipsoidal shell. The [] emission is rather well correlated with the radio emission suggesting their association, while typical fluxes are found in the range of 20–30 10^-17 erg s^-1 cm^-2 arcsec^-2. Deep long–slit spectra taken at specific positions of the remnant verify that the detected filamentary emission originates from shock heated gas, while the diffuse [] emission in the south results from photoionization processes. The spectra further suggest shock velocities around 100 km s^-1 and low electron densities. The X-ray surface brightness is quite patchy, missing obvious limb brightening and is dominated by a bright bar–like emission region which is off-set from the geometric center by ~9´. The X-ray emission is thermal and requires two temperatures of 0.2 keV and 0.63 keV. The bright bar region shows overabundant Mg, Si and Fe, which might indicate still radiating ejecta matter. The azimuthally averaged radial surface profile is consistent with the matter density changing with distance r from the center e^-r/r_0 with a characteristic angular length of 36´, or, alternatively, with an r density profile. The matter inside the remnant is quite likely structured like a porous cloudy medium. The average matter density is ~0.04   with the distance in units of 1.6 kpc. Because of the low density and the long cooling times involved the remnant is more likely to be in the adiabatic phase, which is consistent with the densities derived for the X-ray plasma and the optical line emission, but it is not excluded that is has reached the radiating phase. This, however, would imply a lower density, greater age and much larger distance, at the edge of the upper limits obtained from N and .