A BRIGHT EMISSION REGION IN THE NEW NEARBY DWARF IRREGULAR GALAXY CASSIOPEIA-1

In recent years several dwarf galaxies belonging to the highly obscure d Maffei-IC 342 group have been discovered. Due to its shape, colour a nd the presence of a few possible H II regions, one of these objects ( l = 129 degrees.6, b = +7 degrees.1) was suspected to be a dwarf irreg ular galaxy, named Cas 1. We have obtained optical spectra of the brig htest H II candidate in Cas 1. By using the H-alpha/H-beta emission li ne ratio we could, for the first time, determine a rather reliable for eground extinction of A(v) 2.5 mag and thus cannot support Tikhonov's (1996) view that Cas 1 is a member of the Local Group. For [OIII](5007 Angstrom)/H-beta we obtained a ratio of 2.6, much higher than typical ratios for (galactic) H It regions. The nature of the emitting nebula is unclear: a supernova remnant seems to be implausible (there is an IRAS counterpart), but we might deal with an HII region, possibly exci ted by a WR star.