IC 4406 is a large (about 100 × 30) southern bipolar planetary nebula, composed of two elongated lobes extending from a bright central region, where there is evidence for the presence of a large torus of gas and dust. We show new observations of this source performed with IRAC (Spitzer Space Telescope) and the Australia Telescope Compact Array. The radio maps show that the flux from the ionized...

With the VLBA, we have observed water masers associated with the OH/IR star, W43A, which trace a birth and growth of a molecular jet. The water masers exhibit the collimated distribution (1700 AU: 20 AU) and fast motions (±150 km s). The maser distribution was well fit by a precessing jet model. The jet length has extended by 800 AU within 8 years, indicating that the extension rate is roughly ...

This paper presents (Hα + [NII]) imaging and spectroscopy of a previously unknown, highly evolved planetary nebula of low excitation. It was discovered serendipitously from AAO/UKST Hα Survey images as part of a project to exploit the survey data and has evaded detection by previous surveys due to very low surface brightness. It is a remarkably annular planetary nebula, some 19 across, making i...

This paper continues our study of the behaviour of near infrared helium recombination lines in planetary nebula. We find that the 1.7007μm 4D–3P HeI line is a good measure of the HeI recombination rate, since it varies smoothly with the effective temperature of the central star. We were unable to reproduce the observed data using detailed photoionisation models at both low and high effective te...

Using the Planetary Camera on board the Hubble Space Telescope we have measured the projected separation of the binary components in the nucleus of the planetary nebula Abell 35 to be larger than 0.08 but less than 0.14. The system was imaged in three filters centered at 2950Å, 3350Å and 5785Å. The white dwarf primary star responsible for ionizing the nebula is half as bright as its companion i...

We study the motions of small solids, ranging from micron-sized dust grains to 100-m objects, in the vicinity of a local density enhancement of an isothermal gaseous solar nebula. Being interested in possible application of the results to the formation of clumps and spiral arms in a circumstellar disk, we numerically integrate the equations of motion of such solids and study their migration for...

Images of Hubble 12 were obtained with the HST/NICMOS instrument in the F110W, F164N, and F166N filters of NIC1, and the F160W, F187N, F190N, F212N, F215N filters of NIC2. The images show the structure of the inner “torus” and lobes much clearer than previous ground-based images. In particular, the [Fe II] lobes are clearly resolved and shown to be distinct from the H2 emission structures. Appa...

The planetary nebula known as the Cat's Eye Nebula (NGC 6543) has a complex, point-symmetric morphology that cannot be fully explained by current theory of formation, Interacting Stellar Winds Model. In order to reveal three dimensional (3D) structure Nebula, we created detailed 3D morpho-kinematic model this using [NII] image from Hubble Space Telescope and five different position-velocity dia...

V651 Mon is the binary central star of the bipolar planetary nebula NGC 2346. The star showed the secondever deep fading in 1996–1997, which was presumably caused by obscuration by a dust cloud in the planetary nebula, as was proposed to explain the 1981–1985 event. The entire duration of the 1996–1997 event was ∼400 d, remarkably shorter than the 1981–1985 event, suggesting that the obscuring ...

The mid-infrared spectrum of the rather circular planetary nebula NGC 2792 taken with the Spitzer Space Telescope is presented. This spectrum is combined with the ultraviolet IUE spectrum and with the spectrum in the visual wavelength region to obtain a complete, extinction corrected, spectrum. The chemical composition of the nebula is then calculated in two ways. First by directly calculating ...