EDP Sciences
Free access
Volume 385, Number 3, April III 2002
Page(s) 1042 - 1048
Section Diffuse matter in space
DOI http://dx.doi.org/10.1051/0004-6361:20020185

A&A 385, 1042-1048 (2002)
DOI: 10.1051/0004-6361:20020185

First optical light from the supernova remnant G 17.4-2.3

P. Boumis1, F. Mavromatakis1 and E. V. Paleologou2

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

(Received 19 November 2001 / Accepted 29 January 2002)

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 $\alpha+[$ $\ion{N}{ii}$ ], [S II] and [ $\ion{O}{iii}$ ], 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 $\ion{H}{ii}$ region ([S II]/H $\alpha$ < 0.3). Furthermore, deep long-slit spectra were taken at the bright [ $\ion{O}{iii}$ ] filament and clearly show that the emission originates from shock heated gas. The [ $\ion{O}{iii}$ ] flux suggests shock velocities into the interstellar ``clouds" greater than 100 km s -1, while the [ $\ion{S}{ii}$ $]\lambda\ 6716/6731$ ratio indicates electron densities ~240 cm -3. Finally, the H $\alpha$ emission has been measured to be between 7 to 20 $\times$ 10-17 erg s -1 cm -2 arcsec -2.

Key words: ISM: general -- ISM: supernova remnants -- ISM: individual objects: G 17.4-2.3

Offprint request: P. Boumis, ptb@physics.uoc.gr

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