First optical light from the supernova remnant G 17.4-2.3

¹ University of Crete, Physics Department, PO Box 2208, 710 03 Heraklion, Crete, Greece
² Foundation for Research and Technology-Hellas, PO Box 1527, 711 10 Heraklion, Crete, Greece

Corresponding author: P. Boumis, ptb@physics.uoc.gr

Received: 19 November 2001
Accepted: 29 January 2002

Abstract

Deep optical CCD images of the supernova remnant G 17.4–2.3 were obtained and faint emission has been discovered therein. The images, taken in the emission lines of H ], [S ii] and [ ], reveal filamentary structures in the east, south–east area, while diffuse emission in the south and central regions of the remnant is also present. The radio emission in the same area is found to be well correlated with the brightest optical filament. The flux calibrated images suggest that the optical filamentary emission originates from shock-heated gas, while the diffuse emission seems to originate from an  region ([S ii]/Hα  < 0.3). Furthermore, deep long–slit spectra were taken at the bright [ ] filament and clearly show that the emission originates from shock heated gas. The [ ] flux suggests shock velocities into the interstellar clouds” greater than 100 km s^-1, while the [  ratio indicates electron densities ~240 cm^-3. Finally, the Hα emission has been measured to be between 7 to 20 10^-17 erg s^-1 cm^-2 arcsec^-2.