A deep, continuum-subtracted, image of NGC 7293 has been obtained in the light of the Halpha+[N II] emission lines. New images of two filamentary halo stuctures have been obtained and the possible detection of a collimated outflow made. Spatially resolved, longslit profiles of the Halpha+[N II] lines have been observed across several of these features with the MES combined with the SPM 2.1m telescope; these are compared with the [N II]6584, [O III]5007, HeII 6560 and Halpha profiles obtained over the nebular core. The central HeII emission is originating in a ~0.34pc diameter spherical volume expanding at <=12km/s which is surrounded, and partially coincident with an [O III] emitting inner shell expanding at 12km/s. The bright helical structure surrounding this inner region is modelled as a bi-polar nebula with lobe expansions of 25km/s whose axis is tilted at 37deg to the sight line but with a toroidal waist itself expanding at 14 km/s. These observations are compared with the expectations of the interacting two winds model for the formation of PNe. Only after the fast wind has switched off could this global velocity structure be generated. Ablated flows must complicate any interpretation. It is suggested that the clumpy nature of much of the material could play a part in creating the radial `spokes' shown here to be apparently present close to the central star. These `spokes' could in fact be the persistant tails of cometary globules whose heads have now photo-evaporated completely. A halo arc projecting from the north-east of the bright core has a conterpart to the south-east. Anomolies in the position-velocity arrays of line profiles could suggest that these are part of an expanding disc not aligned with the central helical structure though expanding bi-polar lobes along a tilted axis are not ruled out.Comment: 17 pages, 11 figures, accepted for publication in MNRA

Abstract. We report optical and infrared photometric and spectroscopic observations that identify the counterpart to the 358.6-s X-ray transient pulsar SAX J2103.5+4545 with a moderately reddened V = 14.2 B0Ve star. This identification makes SAX J2103.5+4545 the Be/X-ray binary with the shortest orbital period known, P orb = 12.7 days. The amount of absorption to the system has been estimated to be A V = 4.2 ± 0.3, which for such an early-type star implies a distance of about 6.5 kpc. The optical spectra reveal major and rapid changes in the strength and shape of the Hα line. The Hα line was initially observed as a double peak profile with the ratio of the intensities of the blue over the red peak greater than one (V/R > 1). Two weeks later this ratio reversed (V/R < 1). Subsequently, in less than a month, the emission ceased and Hα appeared in absorption. This fast spectral variability is interpreted within the viscous decretion disc model and demonstrates the significant role of the neutron star on the evolution of the circumstellar disc around the Be star. The implications of the small orbit and moderate eccentricity on the spin period of the neutron star are discussed.

Abstract. The planetary nebula NGC 6781 was imaged in major optical emission lines. These lines allow us to construct maps of the projected, two dimensional Balmer decrement, electron density, electron temperature, ionization and abundance structure. The average electron density, determined from the [S ii] lines, is ∼500 cm −3 , while the electron temperature distribution, determined from the [N ii] lines, is flat at ∼10 000 K. The Balmer decrement map shows that there are variations in extinction between the north and south areas of the planetary nebula. The higher extinction observed to the north of the central star is probably caused by dust spatially associated with CO emission at blue-shifted velocities. The [N ii] image reveals the known optical halo, at a flux level of ∼0.2% of the strong shell emission in the east, but now the angular extent of 216 ×190 is much larger than previous measurements. The halo is also present in [O iii], where we measure an extent of 190 ×162 . The ionization maps indicate substantial ionization along the caps of the ellipsoid as well as in the halo. The maps also show a sharp decrease in ionization along the outer edge of the shell in the west and the east, south-east. The typical log abundances measured for He, N, O and S are 10.97, 8.14, 8.72 and 6.90, respectively.

Deep CCD exposures of the peculiar supernova remnant CTB 80 in the light of the Hα + [NII], [SII], [OII], and [OIII] filters have been obtained. These images reveal significant shock heated emission in the area of the remnant. An extended bright diffuse nebula in the south-east part of CTB 80 overlaps soft X-ray emission from ROSAT but it does not appear to be related to the remnant under study. New diffuse and filamentary structures are detected to the south, southeast, and north of PSR 1951+32 most likely associated with CTB 80. Especially, the sulfur line image shows emission in the north along the outer boundary of the IRAS and HI shells.

We present the first results of an [O iii] 5007 Å interference filter survey for planetary nebulae (PNe) in the Galactic bulge. Covering (at first) the 66 per cent of the survey area, we detected a total of 90 objects, including 25 new PNe, 57 known PNe and eight known PNe candidates. Deep Hα+[N ii] CCD images have been obtained as well as low‐resolution spectra for the newly discovered PNe. Their spectral signature suggests that the detected emission originates from a photoionized nebula. In addition, absolute line fluxes have been measured and the electron densities are given. Accurate optical positions and optical diameters have also been determined.