The faint supernova remnant G 34.7-0.4 (W44)

Abstract

Flux calibrated images of the known supernova remnant G 34.7-0.4 in basic optical emission lines are presented. The low ionization images show a relatively flat flux distribution. The diffuse and patchy morphology of the detected optical emission may indicate the presence of turbulent magnetic fields. Typical observed Halpha+[N II] fluxes are ~8 x 10^{-17} erg s^{-1} cm^{-2} arcsec^{-2}, while the [S II] fluxes are lower around 4 x 10^{-17} erg s^{-1} cm^{-2} arcsec^{-2}. Emission in the medium ionization line of [O III] 5007 A is not detected within our sensitivity limits, probably due to the heavy extinction towards the remnant. The long-slit spectra reveal strong [S II] and [N II] emission relative to Halpha and moderate [O I] 6300 A emission. Shock velocities in the range of 110-150 km/s and low electron densities are estimated. Archival MSX infrared data show emission in the south and west areas of the remnant matching rather well the optical and radio emission.