Narrow-band interference filter photographs in the light of Hα, [S II] (λ = 6717 and 6731 A). [N II] (λ = 6584 A) and [O III] (λ = 4363 A) of four extended PNs are shown. These photographs were obtained with a focal reducer and a single-stage image tube attached to the 2.1 m Cassegrain focus telescope of the Observatorio Astronómico Nacional at San Pedro Mártir, B.C.N. The exposure times were of one hour. For each photograph we have obtained a calibration by means of a step density wedge.

Direct interference filter CCD frames of a number of northern planetary nebulae were obtained at the Cassegrain focus of the 182-cm telescope of Asiago Astrophysical Observatory (Italy).

A large, long-term survey of southern hemisphere planetary nebulae is being undertaken with several narrow-band filters (primarily [N II], H-alpha, [O III] and He II) on the 0.9-m telescope at CTIO using a TI CCD chip. The purposes of this survey are to get sizes and morphological classifications for nebulae that are little-known (indeed, some do not have size measurements at all) and to search for multiple shells and other structures that are of interest for studies of nebular formation and evolution.

The pointed observations made by the IRAS satellite have been analysed. In total 67 nebulae have been observed of which 10 proved to be resolved. The majority of the observations were carried out with the CPC and with the DSD macro of the survey array (Leene & Pottasch, 1987b). Further special deep maps were made of six nebulae (Leene & Pottasch, 1987a; Leene, 1987). Typical noise levels of the deep images are 0.03–0.1 MJy ster−1.

The distribution of emission around the central star confirms that the 12 and 25 μm emission are due to ionic line emission. This is very clear in the nebula NGC 7293 (Leene & Pottasch, 1987a) and in NGC 6853 (Zhang et al., 1987). The other nebulae (A7, A21, A31, A35 and NGC 1360) confirm these findings. The 12 μm emission is most likely due to the NeII (12.81 μm) or due to the SIV (10.52 μm) line. The 25 μm band shows a strong central contribution due to the OIV (25.87 μm) line and a halo of the SIII (18.68 μm) line.

The symmetry of planetary nebulae demands an explanation. Underlying previous attempts to explain these objects is the inferred density distribution based on spatio-kinematic models such as those of Weedman (1968), Reay et al. (1983) and others. Although some observations suggest a linear velocity-radius relationship for planetaries, plausible hypothetical examples may be constructed which greatly violate a linear relationship, and hydrodynamic theory (Schmalz 1986) suggests it may not hold even when observations may be most easily interpreted as supporting a linear relationship. Therefore, an independent assessment of the nebular density distribution is needed.

Radio maps of the free-free radio continuum flux (angular resolution ≅ 1.3 arcseconds) from NGC 7027 were made with the VLA operating at 20-cm, 6-cm, and 2-cm wavelengths which are near and straddle unit optical depth. Mean line-of-sight electron temperature and emission measure distributions were calculated by pairing the 2-cm and 6-cm maps, and the electron temperature distribution on the near side of the nebula was then obtained from the 20-cm map. The results suggest that the energy balance is complex in this planetary. For example, mean line-of-sight temperatures are higher than average in the direction of one of the bright lobes but not in the direction of the other. Especially noteworthy is an apparent “hot spot” on the near side of the nebula which has no apparent relation to either of the bright lobes, but it is approximately coincident with the brightest portion of the optical image.

This paper describes PC_IMega, a menu driven program that allows digital images to be displayed and manipulated on an IBM PC or compatible microcomputer, running under PC-DOS versions 2 or 3 with 128k of RAM. A sixteen colour Enhanced Graphics Adaptor card gives a screen resolution of 640 × 350 pixels.

We present high spatial resolution infrared images of the planetary nebulae NGC 7027, M2-9, BD +30 3639, NGC 7099 and NGC 7662. These were taken through a selection of broad and narrow-band line and continuum filters (including a Fabry-Pérot interferometer) using the 2D infrared array “IRCAM” on the United Kingdom Infrared Telescope, UKIRT, in July 1987. Comparison is made with recently published high-resolution VLA radio maps (Basart and Daub 1987, Ap. J., 317, 412) and mid-IR Wyoming Infrared Telescope raster-scanning maps (Bentley et al.1984, Ap. J., 278, 665).

NGC 2899 (PK 277-3°l, He 2-30, RCW 43) is a southern planetary nebula of fairly large angular size (∼2!6 × 1!4) and moderate high surface brightness. Its morphology strongly resembles a loose bipolar structure with conspicuous bright condensations of toroidal geometry placed along the minor axis, on each side of the central object.

We have obtained high-dispersion, long-slit echelle spectra at closely spaced intervals across the face of the bipolar planetary nebulae NGC 2440, NGC 6302 and Mz-3. Deep monochromatic images of these objects in lines from high (HeII, [OIII]), intermediate (HI, [OII]) and low ([NII], [SII]) excitation species have also been acquired. Taken together, these data permit us to construct self-consistent spatio-kinematic models of these nebulae and to investigate the spatial variations of excitation conditions within them.

The kinematics of the gas motions in several e-m E planetary nebulae (PNs) have been mapped with ∼ 1 - 2″ resolution. All of the eE PNs (e.g., NGC 2392, 3242, 6543, 6826, 7009, and 7662) show evidence of highly focused linear flows at projected velocities of 20 - 170 km s−1. The flows generally appear as linear, almost jet-like features in emission lines of low ionization. mE PNs show expanding protuberances along their polar axes.

We present newly determined expansion velocities for a number of Planetary Nebulae (PNe) which have been observed with the ESO 1.4m CAT and the Coude' Echelle Spectrograph (CES), operated at a r.p. of 105, corresponding to a resolution of about 3km/s at Hα. Two detector systems have been used: the standard ESO Reticon and a two-dimensional photon-counting imaging detector developed at the A.I.T. (AIT-MCP-Camera).

Abell 30 is a remarkable PN with a H-depleted core. Four bright knots have been identified in the [O III] line (Jacoby 1979). The previous kinematic study has shown that J1 and J3 form a pair expanding at radial velocities of ±25 km/s with respect to the central star, and J4 has a radial velocity of −22 km/s (Reay, Atherton, and Taylor 1983).

High spectral resolution bidimensional spectroscopy of A78 in the He II λ4686 A, H λ4861 A, [O III] λ4959 A and [O III] λ5007 A lines is reported, confirming the different morphology of the nebula in these lines. The resulting velocity maps suggest different episodes in the history of the nebula, with an external hydrogen-rich layer expanding at low velocity (35±10 km/s), showing little structure and extending from approximately 35 to 55 arcsec. The [O III] and the He II maps show, however, an inner shell with at least two different expansion velocities; 73 km/s and 41 km/s.

We present a velocity field of the planetary nebula A78 based on three Fabry Pérot Hα (10A) interferograms taken with a focal reducer attached to the 2.1 m reflector of the Observatorio Astronómico Nacional at San Pedro Mártir, Mexico. We have used a single-stage Varo image intensifier and two different étalons with interorder separations of 283 km s−1 (2 interf.) and 100 km s−1 (1 interf.). The scale of the original photographs is 49 arcsec mm−1. Our data have yielded radial velocities in the Hα line at 110 points on the face of A78; the velocity field is far from being smooth. The rings are wide around the central hole, and a few show definite splittings; from these splittings we have estimated an overall expansion velocity of 27 km s−1. The average systemic velocity is found to be around −3 km s−1.

The sizes of fifty planetaries at the four IRAS wavelengths are presented as a result of performing spatial deconvolution of survey mode data. We obtain an increase in resolving of a factor of about 2 or 3 from the normal IRAS detector sizes of 45″, 45″, 90″, and 180″ at wavelengths 12, 25, 60 and 100 microns. Most of the planetaries deconvolve at 12 and 25 microns to sizes equal to or smaller than the optical size. Some of the nebulae such as NGC 6720 and NGC 6543 show full width at half maximum at all IRAS wavelengths that are about equal to the optical size, while others give an increasing size with wavelength. The profiles of a few interesting cases are shown. The method and results should allow comparison with models for infrared emission from dust from planetary nebulae.

We present observations of the bipolar planetary nebula NGC 2346 carried out with the 1-m telescope at the Vainu Bappu Observatory in Kavalur, India using (1) a high resolution piezo-electric scanned Fabry-Pérot Spectrometer (with a velocity resolution of 10 km s−1) for line studies in the 6000 A - 7000 A spectral range and (2) a pressure scanned Fabry-Pérot spectrometer (with a velocity-resolution of 5 km s−1) in the green region. The nebula was observed in the H I 6563 A and [N II] 6583 A emission lines using a 15″ aperture and in the [O III] 5007 A line using an 8″ aperture centered on the bright central spot. A number of scans in each of these lines were co-added to improve the signal-to-noise ratio. The [O III] profile shows a well defined split between the blue and the red component, typical of an expanding shell. The [N II] profile does not show a well resolved split, although a pronounced suggestion of a split was observed in all the scans. The Hα profile was broad and asymmetric. The composite [O III] and [N II] profiles were decomposed into two individual Gaussians for obtaining the expansion velocity.

In order to seek out intrinsically compact PN, we have observed high-excitation and angularly small PN, M1-1, with the intensified Reticon system (one-dimensional 1024 pixel-array) at the Coude focus of the 188 cm telescope. We have obtained highly resolved emission line profiles of [NII]λ6583, Hα, [OIII]λ5007, and HeIIλ4686 at several slit position angles. These lines were analyzed with the aid of Multiple Gaussian Method. From the analysis of their radial velocities and decomposed profiles, we can summarize our observational results as follows, (a) HeII were fitted by three Gaussians, those are main blue and red-components and an extremely red-shifted sub-component. Hα and [OIII] were decomposed into blue and red components. [NII] were fitted by single Gaussian.

The Planetary Nebulae IC 4593 and NGC 6153 are two rather compact objects not well studied. The nebula IC 4593 is about 12 arcsec in diameter and has a central star of Type 07 f; while the southern nebula NGC 6153 is about 22 arcsec in diameter and its central star is faint and of unknown spectral type. Using a high-resolution scanning Fabry-Pérot spectrometer we have made profile measurements of emission lines Hα λ6563 A, [O III] λ5007 A, and [N II] λ6584 A in the central regions of these two nebulae. We have found expansion velocities for IC 4593 of 40 km s−1 in [N II] and 16 km s−1 in [O III]. In the case of NGC 6153, we have obtained expansion velocities of 15 km s−1 in [N II] and 13 km s−1 in [O III] line. The profiles in Hα in both the nebulae dis not show a double peaked feature due to the larger thermal broadening. In the case of IC 4593, both [O III] and [N II] profiles showed complex structures. These results and their interpretation will be discussed.

Expansion velocities ([O III], [O II], and He II) have been measured for a sample of 64 Southern Planetary Nebulae (PN). The ratio of [O III] to [O II] expansion velocities is used to derive a typical ionized shell thickness of order ΔR/Rneb ≍ 0.12. Nebular electronic densities have been determined from the [O II]λλ3727, 3729 A doublet for 23 of these objects. These data are compared with previously published values. The Dopita et al. (1987) distance scale for Magellanic Cloud PN based on a correlation between observable nebular parameters is used to derive distances to 32 Galactic nebulae. These distances are compared with published values, and lead to the conclusion that the Dopita et al., Daub (1982) and Maciel (1984) distance scales agree well, but that the Shklovsky (1956) method yields distances that are too large. Nebular ionized masses are also calculated for a subset of 30 objects.