Stephen J. Meatheringham

The kinematics of the planetary nebulae in the Large Magellanic Cloud

The radial velocities of a total of 94 PN in the LMC have been determined. This kinematics of the population of PN is compared with the H I data in the context of a reanalysis of the survey by Rohlfs et al. (1984), taking into account the transverse velocity of the LMC. It is found that the best solution for this transverse velocity is 275 + or - 65 km/s and that the LMC is near perigalacticon. The rotation solution for the PN population is essentially identical with that of the H I, but the vertical velocity dispersion of 19.1 km/s is much greater than the value of 5.4 km/s found for the H I. This increase in velocity dispersion is consistent with it being the result of orbital heating and diffusion operating in the LMC in a manner essentially identical with that found for the solar neighborhood. 66 references.

Optical spectroscopy of Magellanic Cloud planetary nebulae. I

Optical spectroscopy in the range 3300-7400 A is presented for a total of 30 planetary nebulae in the LMC and 11 in the SMC, with measurements of line intensities down to about 1 percent of H-beta. Reddening estimates from Balmer line ratios have been determined, and the line intensities dereddened accordingly. Nebular forbidden O III electron temperatures and, where measurable, forbidden N II temperatures and forbidden S II densities are given. Forbidden O II electron densities are recalculated using appropriate electron temperatures. The forbidden S II and forbidden O II electron densities are found to correlate well. A number of spectra exhibit interesting spectral features, including symbiotic-type profiles, unidentified emission lines, and nonsimple Balmer decrements. These objects are discussed in some detail. Zanstra temperatures are derived for a total of 25 objects possessing detectable stellar continua. 57 refs.

The internal dynamics of the planetary nebulae in the Large Magellanic Cloud

The radial velocity and expansion velocity in the forbidden O III 5007 line have been determined for a sample of 94 PN in the LMC. In addition, densities and expansion velocities have been determined for a subset of 44 objects in both the LMC and SMC using the forbidden O II 3727, 3729 doublet. With a few notable exceptions, the forbidden O II expansion velocities are well correlated with, but are systematically higher than, the forbidden O III expansion velocities. For a given excitation class, there appears to be an upper limit to the density, in the sense that very high density objects are always of low excitation, but low-density objects can occur at any excitation. The population of PN in the Magellanic Clouds appears to form a sheet in dynamical age/excitation class/nebular density space, and therefore represents a two-parameter family. The implication of this is that the nebular parameters are entirely determined by the properties of the central star. This fact could represent the basis of a solution to the distance scale problem for Galactic PN. 44 references.

Hubble Space Telescope observations of planetary nebulae in the Magellanic Clouds. I: The extreme type I SMP 83/WS 35

We have obtained Hubble Space Telescope Planetary Camera images in both the Hα and the [O III] λ5007 emission lines of the planetary nebula SMP 83 alias WS35, alias N66 in the Large Magellanic Cloud. By combining these results with optical and UV spectrophotometry, absolute flux measurements, and dynamical and density information, we have been able to construct a fully self-consistent nebular model. This proves that SMP 83 is an extremely massive type I object having a central star having an effective temperature of 170,000 K and a luminosity of nearly 3×10 4 L ○. . The core mass is estimated in the range 1.0-1.2 M ○. , for which the main-sequence mass was greater than ∼6 M ○. . The nebular abundances are higher than the average for the LMC and show evidence for hot-bottom burning

Angular diameters and fluxes of Magellanic Cloud planetary nebulae. II. High-speed direct imaging

Line fluxes in H-beta and forbidden O III 5007 A have been obtained for 80 planetary nebulae in the Magellanic Clouds, and angular diameters larger than 0.7 arcsec have been derived for 20 of the nebulae. Ionized masses for the nebulae and luminosities for the central stars are derived. These quantities are shown to be in good agreement with the values expected from the properties of the immediate precursor stars, the long-period variables. 20 references.

Fluxes and ionized masses of Magellanic Cloud planetary nebulae

Absolute H-beta nebular fluxes are presented for a total of 97 planetary nebulae (PN) in the Magellanic Clouds. These new fluxes are compared with all previously published data. Nebular masses are derived for 54 objects and are found to lie mainly in the range 0.01-0.35 solar masses. A relationship between density and ionized mass for a subset of the nebulae is used to show that these objects are optically thick. Another relationship between H-beta flux and nebular density is examined. The point at which the nebulae become optically thin is seen as a change in the slope of this curve. From these relationships a nebular mass-radius relation is found to apply to optically thick nebulae. 37 references.

Hubble Space Telescope observations of planetary nebulae in the magellanic clouds. 2: SMP 85, a young planetary

We have obtained Hubble Space Telescope Planetary Camera images in the (O III) lambda 5007 A emission line, and Faint Object Spectrograph (FOS) UV spectrophotometry of the low-excitation planetary nebula SMP 85 in the Large Magellanic Cloud. By combining these results with existing optical spectrophotometry, absolute flux measurements, and dynamical and density information, we have been able to construct a fully self-consistent nebular model. This proves that SMP 85 is a dense, young, carbon-rich object which started to be ionized about 500-1000 years ago, and which contains a substantial inner reservoir of atomic or molecular gas, probably in the form of many small cloudlets. These cloudlets have been ejected at a velocity not exceeding 6 km/s, a result which, together with the morphology is an important clue to mass loss during late asymptotic giant branch (AGB) evolution. We have directly detected the central star through its UV continuum emission, and from both Zanstra techniques and nebular modeling derive a stellar temperature of 46000 +/- 2000 K, a stellar luminosity of 7300 +/- 700 solar luminosity, and a core mass of 0.63-0.67 solar mass. The nebular analysis also demonstrates that there is severe depletion of the nebular gases onto dust grains, most likely of the calcium magnesium silicate variety; a surprising result in view of the carbon-rich nature of the ionized nebula.

Hubble Space Telescope Observations of Planetary Nebulae in the Magellanic Clouds. VI. Cycles 4 and 5 Ultraviolet Spectroscopy Using the Faint Object Spectrograph

The Faint Object Spectrograph on board the Hubble Space Telescope (HST) is used to obtain spectra in the wavelength range λλ1150-4800 of three planetary nebulae in the Small Magellanic Cloud and 10 planetary nebulae in the Large Magellanic Cloud. This sample extends the sample of 12 objects previously observed with HST and reported in the third paper of this series. Observed and dereddened emission-line fluxes are presented. Reddening estimates from the He II λ1640/λ4686 flux ratio are generally up to 0.2 dex lower than the reddening derived from the Balmer decrement. Nebular temperatures are estimated from the N+ λλ2138, 2142/λλ6548, 6583 flux ratio. Nebular densities are calculated from the O IV] complex at λ1400, the N IV] λλ1483, 1487 doublet, and the Si III] λλ1883, 1892 doublet. Densities calculated using the oxygen lines are comparable to those determined from the optical lines. Densities calculated from the nitrogen lines show a scatter of over 3 dex, which is relatively large compared to the optically derived densities. Three of the five densities derived from the silicon lines are greater than 10,000 cm-3. The C+2/O+2, Si+2/C+2, and N+2/O+2 ionic abundance ratios are calculated using the available ultraviolet emission features. The C/O and N/O ratios are anticorrelated, which supports the premise that third dredge-up has taken place during the asymptotic giant branch phase. In contrast to the third paper in this series, type I classification does not imply the presence of Si III] emission. Three objects show P Cygni-like line profiles at C IV λλ1548, 1551, indicative of stellar winds.

New evolutionary relationships for Magellanic Cloud planetary nebulae

Two new evolutionary correlations have been discovered to apply to the population of planetary nebulae (PN) in the Magellanic Clouds. First, the age of the nebular shell is found to follow a relationship, which is shown to be consistent with a model in which the total energy of the ionized and swept-up gas drives the expansion down the density gradient in the precursor AGB wind. Second, a tight correlation is found between the expansion velocity and a combination of the excitation class and the H-beta flux. This appears to be determined by the mass of the planetary nebula nuclear star. These correlations provide strong observational support for the idea that the PN shells are ejected at low velocity during the asymptotic giant branch phase of evolution, and that they are continually accelerated during their nebular lifetimes. 30 references.

The kinematics of planetary nebulae in the outer fields of the Large Magellanic Cloud

We present echelle observations of 16 planetary nebulae (PNs) in the [O III] λ5007 emission line, originally detected in a UK-Schmidt objective prism survey of the outer fields of the Large Magellanic Cloud (LMC). Of these 16 objects, 11 have had no velocity information published previously. Expansion and radial velocities have been derived by a simple Gaussian fitting technique