G247.8+4.9: A Newly Discovered Optical Supernova Remnant in Puppis

As a first step to investigate a newly detected possible supernova remnant in Puppis, a few optical spectra have been obtained. The spectra of this extremely faint nebula, although of poor quality, show strong (N ii) 6583/6548 A u emission. Radial velocities derived from the (N ii) 6583 A u line amount to 50 km s 1 , for both the easternmost and westernmost optical borders of the nebula, and a distinctly blueshifted velocity relative to this value for an emission region close to the eastern rim. In order to check whether the remnant might be akin to the nebula W50 associated with the compact source SS 433, a spectrum of four stars near the center of the image of the nebula was taken; it showed them to be of quite ordinary type and exhibits some traces of (nebular) (N ii) 6583 A u emission. No IRAS source is located at or within the boundaries of the nebula, which coincides with an extended radio source of about 78 mJy at 4850 MHz. The star that gave rise to the remnant may have been a remote member of the Pup OB2 association, at a distance of about 5 kpc.