M. Bryce

The Morphology and Kinematics of the Complex Polypolar Planetary Nebula NGC 2440

Spatially resolved profiles of the Hα, [N II] 6584 A, and [O III] 5007 A lines have been obtained with the Manchester echelle spectrometer combined with the 2.1 m San Pedro Martir telescope over the planetary nebula NGC 2440. The resulting position-velocity (PV) arrays are compared with ground-based and HST archival imagery, revealing the complex structure that prevails in this object. This work represents the first detailed kinematical study of NGC 2440. Several bipolar structures are shown to be emerging at different position angles from the core, as expected from bipolar, rotating, episodic outflows with different degrees of collimation. Line splitting reaches main peak to peak separations of 175 km s-1 and 145 km s-1 in the western and eastern main lobes, respectively. The FWZI values of the complex profiles span a range of 250 km s-1 near the core and 150 km s-1 in the outer regions. The nebular core is found to be a toroid expanding radially at ≥22 km s-1, and the systemic heliocentric radial velocity of NGC 2440 is found to be 65 km s-1. When combined with existing measurements of the upper limit to the angular expansion, and assuming a tilt for the axis of the central toroid of 40° in the plane of the sky, this lower limit for the expansion velocity implies a distance of ≥1.45 kpc to NGC 2440. Puzzling kinematical features are the faint velocity components receding with radial velocity differences of 150 km s-1 with respect to the systemic radial velocity from prominent knots at both ends of the brightest bipolar configuration. Scattering by dust in these knots of the line profiles from the bright nebular core is a likely explanation for this curious phenomenon.

The Hypersonic, Bipolar, Knotty Outflow from the Engraved Hourglass Planetary Nebula MyCn 18

The remarkable velocity structure of the different components of the young planetary nebula MyCn 18 have been revealed by obtaining imagery and spatially resolved spectrometry of the Hα and [N II] λλ6548, 6584 lines with the Manchester echelle spectrometer combined with the 3.9 m Anglo-Australian telescope. The bright, bipolar, nebular core is shown to be composed of two extended hemispherical cavities whose axes are tilted at 52° to the plane of the sky. Ionized flows, at ≤90 km s-1 and parallel to the walls of these cavities, are occurring. The full extent of the elongated bipolar assembly of high-speed knots which apparently lie along the same axis is now revealed in a continuum-subtracted image in the light of the Hα and [N II] λλ6548, 6584 nebular emission lines. Complete spatial coverage of line profiles from these knots is also presented for the first time. In their most likely configuration, these knots are shown to have a range of outflowing speeds of ≤630 km s-1 that are proportional to their distance from the central star. There is some degree of point/velocity symmetry, indicating that some pairs of knots have been ejected in opposing directions at the same speed. Curiously, the line profiles from the knots are very narrow, i.e., from 15 to 30 km s-1. Among several possible explanations of the origin of these hypersonic knots is a recurrent nova-like ejection from a central binary star.

The Formation of a Multiple Planetary Nebula:Hubble Space Telescope/WFPC2 Observations of KjPn 8

KjPn 8 is an extreme polypolar planetary nebula with a large-scale structure characterized by a giant biconical envelope. Spasmodic bipolar ejections in changing directions have occurred over thousands of years to create this peculiar nebula. Narrowband images of the core of KjPn 8 have now been obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST) and are reported here. The central star is finally revealed in these observations, and its compact nebular core is resolved into a remarkably young elliptical ring, currently expanding at only 16 km s-1. This ring is the ionized inner region of larger molecular CO and H2 counterparts, all sharing the same orientation. The highest speed and youngest outflows are perpendicular to this central ring, which is identified as the latest event in the creation of this nebula. It is shown that the formation history of KjPn 8 has involved two distinct and consecutive planetary nebulae-like events, probably originating from a binary core evolution with components of very similar mass. These characteristics indicate that KjPn 8 may be a rare object in our Galaxy and the first ever detected of this class.

High-speed outflows driven by the 30 Doradus starburst

ABSTRACT Echelle spectroscopy has been carried out towards a sample region of the halo of thegiantHiiregion30Doradusin the LargeMagellanicCloud.This newkinematicaldatais the amongst the most sensitive yet obtained for this nebula and reveals a wealth offaint, complex high speed features. These are interpreted in terms of localised shellsdue to individual stellar winds and supernova explosions, and collections of discreteknots of emission that still retain the velocity pattern of the giant shells from whichthey fragmented. The high speed velocity featuresmay tracethe baseof the superwindthatemanatesfromthe30Doradusstarburst,distributedaroundthesuperstarclusterR136.Key words: galaxies:starburst – galaxies:Magellanic Clouds – H ii regions – ISM:kinematics and dynamics – ISM:supernova remnants – ISM:individual (30 Doradus) 1 INTRODUCTIONThe 30 Doradus nebula in the Large Magellanic Cloud(LMC) is the closest example of a giant extragalactic Hiiregion and the largest in the local group of galaxies. It isregarded as undergoing intense enough star formation to bereferred to as a ‘mini-starburst’ by Leitherer (1998) and assuch is an important nearby laboratory of both massive starformation and starburst phenomena. The highly dynamicnebulosity (e.g. Meaburn 1981; Meaburn 1987) is poweredby a super star cluster of ∼ 100 massive stars. RemarkableHST imagery of the environment of the central cluster ofmassive stars has recently been presented by Walborn et al.(2002). The combined winds, UV radiation and supernovaexplosions from so many massive stars at a similar evolu-tionary epoch enables the generation of the nested giant (20– 300 pc diameter) shells that comprise the giant Hii re-gion (Meaburn 1980; Meaburn 1990; Leitherer 1998). Onthe largest scales, surrounding 30 Dor are supergiant (600 –1400 pc diameter) interstellar shells such as LMC3.The term ’shell’ will be used in this paper rather thanthe commonly used term ‘bubble’ since it is preferable touse a term that is dynamically neutral and constrained tono specific geometry (e.g. spherical). The term ‘bubble’, of-ten erroneously presupposes a roughly spherical, pressure–driven, energy-conserving shell. This is certainly not thecase for the supergiant shells which are unlikely to be eitherspherical or energy-conserving. The division between ’giant’and ’supergiant’ when applied to the LMC shells will be forthe diameter ranges above and recently confirmed by the H iobservations of Kim et al. (1999). Different, though related,mechanisms must be involved in the formation of LMC shellsin these distinctly separate diameter ranges. The most im-portant difference is that supergiant shells have diametersin excess of the neutral gas scale-height of the LMC.The overlapping giant shells comprising the halo of30 Doradus have been shown to be expanding at around50 km s

An Optical Nebula Associated with a Young X-Ray Supernova Remnant in Vela

A remarkable filamentary nebula (RCW 37) in the close vicinity of the newly discovered X-ray-emitting supernova remnant in Vela (RX J0852.0-4622) is investigated. This supernova explosion is arguably the nearest in recent history. A comparison is made between deep United Kingdom Schmidt Telescope optical images of the region and the ROSAT X-ray data in which the remnant was discovered. This reveals that RCW 37 is most likely directly associated with an X-ray projection from RX J0852.0-4622. This interpretation is strengthened by new long-slit echelle spectrometry of the edge of RCW 37 in the light of [S II] λ6716. A systematic increase in the velocity splitting of the line profiles, from the nebular edge toward its center, of 100 km s-1 is found. The structure bears morphological and kinematical similarities to the famous Crab Nebula funnel.

Smoke Rings Around Supernova 1987A

Detailed observations of the [Oiii]5007 Å emission from the elliptical rings around SN 1987A suggest a model wherein the two faint, outer rings are due to emission from two circular toroids moving outwards (at ≤ 25 km s−1) along a bipolar cone centred on the site of the supernova. The brighter, central ring is expanding radially outward at 8.3 km s−1. The rings must have been created ∼ 2-3 × 104 years before the supernova explosion and are thought to be a consequence of the interaction of stellar winds emanating from the progenitor system during the final stages of its evolution to a supernova.

The real-time evolution of sakurai's star (V4334 Sgr) and other (V)LTP objects

We report on the progress of our on-going campaign to monitor the evolution of the VLTP objects V4334 Sgr and V605 Aql, as well as the suspected (V)LTP object CK Vul. V4334 Sgr does not show signs of increased ionization compared to our previous observations in 2004. We obtained the first radio detection of V605 Aql, indicating a strong increase in radio flux since 1987. We also present the first radio detection of CK Vul and discuss the expansion of the material ejected during the 1670 event.

The SPM Kinematic Catalogue of Planetary Nebulae

The San Pedro Mártir Kinematic Catalogue of Planetary Nebulae aims at providing detailed kinematic information for galactic planetary nebulae (PNe) and bright PNe in the Local Group. The database provides long-slit, Echelle spectra and images where the location of the slits on the nebula are indicated. As a tool to help interpret the 2D line profiles or position-velocity data, an atlas of synthetic emission line spectra accompanies the Catalogue. The atlas has been produced with the code SHAPE and contains synthetic spectra for all the main morphological groups for a wide range of spatial orientations and slit locations over the nebula.

The structures and kinematics of planetary nebulae with close-binary central stars

A programme is currently underway to study the structures and kinematics of planetary nebulae known to contain close-binary central stars. Images and high-resolution spectroscopy are presented of the collimated nebula Abell 63 and the ring-like nebula Sp 1. A spatio-kinematical model shows that Abell 63 has a tube-like structure, which has the same inclination as the orbital plane of the central binary system. Kinematic data reveal that Sp 1 is not a hollow sphere, but a tube-like nebula viewed pole-on.

Morphological and Kinematical Modelling of PNe and Nova Shells Using XSHAPE

XSHAPE has been developed to aid the better understanding of the 3D morphologies and kinematics of PNe and novae, by producing models which closely predict the observed 2D images and long-slit spectra of these objects. Early successes include plausible simulations for the elliptical PN Sa 2-21 and the nova HR Del.