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Paper: New Candidate Supernova Remnants in Sagittarius
Volume: 424, Proceedings of the 9th International Conference of the Hellenic Astronomical Society
Page: 177
Authors: Alikakos, J.; Boumis, P.; Mavromatakis, F.; Xilouris, E.
Abstract: Deep optical CCD images of a large unknown area have been obtained in the through Hα+[N II], [O III] and [S II] filters. The resulting mosaic covers an area of 1.4 × 1.0 deg2 where filamentary and diffuse emission was discovered, suggesting the existence of more than one supernova remnants (SNRs) in the area. Deep long slit spectra were also taken at eight different regions. Both the flux calibrated images and the spectra show that the emission of the filamentary structures originates from shock-heated gas, while photo-ionization mechanism is responsible for the diffuse emission. In most cases, the optical emission is found to be well correlated with the radio at 1420 MHz and 4850 MHz, suggesting their association. The presence of the [O III] 5007 emission line in one of the candidate SNRs suggests shock velocities into the interstellar “clouds” of >100 km s-1 while the absence in the other indicates slower shock velocities. For all candidate remnants the [S II] λλ 6716/6731 ratio indicates electron densities below 270 cm-3, while the Hα emission has been measured to be between 0.6 to 41×10-17 erg s-1 cm-2 arcsec-2. The detected optical emission could be part of a number of supernovae explosions and the possibility that it is within an OB association can not be ruled out.
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