Binary planetary nebulae nuclei towards the Galactic bulge. II. A penchant for bipolarity and low-ionisation structures

Considerable effort has been applied towards understanding the precise shaping mechanisms responsible for the diverse range of morphologies exhibited by planetary nebulae (PNe). A binary companion is increasingly gaining support as a dominant shaping mechanism, however morphological studies of the few PNe that we know for certain were shaped by binary evolution are scarce or biased. Newly discovered binary central stars (CSPN) from the OGLE-III photometric variability survey have significantly increased the sample of post common-envelope (CE) nebulae available for morphological analysis. We present Gemini South narrow-band images for most of the new sample to complement existing data in a qualitative morphological study of 30 post-CE nebulae. Nearly 30% of nebulae have canonical bipolar morphologies, however this rises to 60% once inclination effects are incorporated with the aid of geometric models. This is the strongest observational evidence yet linking CE evolution to bipolar morphologies. A higher than average proportion of the sample shows low-ionisation knots, filaments or jets suggestive of a binary origin. These features are also common around emission-line nuclei which may be explained by speculative binary formation scenarios for H-deficient CSPN.Comment: Accepted for publication in A&

War as exit from exclusion?: the formation of Mayi-Mayi militias in Eastern Congo

In eastern Congo scores of young and marginalized people have been increasingly attracted to the mobilising efforts of new local actors. The inquiry into this phenomenon traces the emergence of the first militias to the end of the eighties. These first generation militias were a result of the growing willingness of marginalized youngsters and school drop-outs to form groups of under-aged combatants acting against eveiy representative of modern political authority and against their desperate feelings of exclusion, for which both their political and social environment were held responsible. As they had nothing more to lose than their marginalisation, rebellion became an option, both as a survival strategy and as a strategy of self-defence against a predatory political and social order. The shiftiness of their ideological basis and allies only further proved what these first militias were about: a search for alternatives to a situation of acute deprivation. This article reveals that the present RCD rebellion that rages through the eastern parts of the Democratic Republic of Congo has had an escalating effect on the proliferation of new militias. Before, the Kabila-led AFDL rebellion had already offered the already existing militias a new cause: that of an anti-Tutsi force fighting against foreign occupation. In resistance to the effects of state collapse and armed foreign interventions, rural and urban youth today have combined former traditions and newly developed patterns of mobility in an interpretation of customary and national defence. This has not meant that they link up with the traditional emanations of authority. Rather, a crisis in the social fabric has meant a shift in authority towards these combatants and the use of violence. In addition, shared feelings of antipathy towards the 'Tutsi-aggressors ' have facilitated the creation of links between these diverse local groupings and other, foreign, factions of armed militia roaming the local countryside. Consolidation, however, remains unlikely as this shared ideology does not run very deep and alliances continuously change. The question remains what the future impact of these militias might be on the local social order. On the one hand, for several years now in some remote areas these armed groupings have become the only representatives of any authority structure, even if this structure is based on violence. Contrary to other cases, these militias in South Kivu are still closely linked to the rural population and have not turned against them. On the other hand, the dynamic of the Inter-Congolese Dialogue has forced their leaders to present their grievances to the outside world

Spectral analysis of the background in ground-based, long-slit spectroscopy

This paper examines the variations, because of atmospheric extinction, of broad-band visible spectra, obtained from long-slit spectroscopy, in the vicinity of some stars, nebulae, and one faint galaxy.Comment: 12 figure

Spectral variability of planetary nebulae and related objects

The results of long-term spectral observations were used to search for changes in planetary nebulae and emission-line stars. Significant increase of excitation degree is found in two objects: M1-6 and M1-11