Dust in Supernovae and Supernova Remnants I : Formation Scenarios

Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe

Moral spaces, and sexual transgression: understanding rape in war and post conflict

When it comes to rape in war, evocative language describing rape as a ‘weapon of war’ has become commonplace. Although politically important, overemphasis on strategic aspects of wartime sexual violence can be misleading. Alternative explanations tend to understand rape either as exceptional — a departure from ‘normal’ sexual relationships — or as part of a continuum of gendered violence. This article shows how, even in war, norms are not suspended; nor do they simply continue. War changes the moral landscape. Drawing on ethnographic research over 10 years in northern Uganda, this article argues for a re-sexualization of understandings of rape. It posits that sexual mores are central to explaining sexual violence, and that sexual norms — and hence transgressions — vary depending on the moral spaces in which they occur. In Acholi, moral spaces have temporal dimensions (‘olden times’, the ‘time of fighting’ and ‘these days’) and associated spatial dimensions (home, camp, bush, village, town). The dynamics of each help to explain the occurrence of some forms of sexual violence and the rarity of others. By reflecting on sexual norms and transgressions in these moral spaces, the article sheds light on the relationship between ‘event’ and ‘ordinary’, rape and war

The Role of Radioactivities in Astrophysics

I present both a history of radioactivity in astrophysics and an introduction to the major applications of radioactive abundances to astronomy

Collisional and Radiative Processes in Optically Thin Plasmas

Most of our knowledge of the physical processes in distant plasmas is obtained through measurement of the radiation they produce. Here we provide an overview of the main collisional and radiative processes and examples of diagnostics relevant to the microphysical processes in the plasma. Many analyses assume a time-steady plasma with ion populations in equilibrium with the local temperature and Maxwellian distributions of particle velocities, but these assumptions are easily violated in many cases. We consider these departures from equilibrium and possible diagnostics in detail

Dust in Supernovae and Supernova Remnants II: Processing and survival

Observations have recently shown that supernovae are efficient dust factories, as predicted for a long time by theoretical models. The rapid evolution of their stellar progenitors combined with their efficiency in precipitating refractory elements from the gas phase into dust grains make supernovae the major potential suppliers of dust in the early Universe, where more conventional sources like Asymptotic Giant Branch (AGB) stars did not have time to evolve. However, dust yields inferred from observations of young supernovae or derived from models do not reflect the net amount of supernova-condensed dust able to be expelled from the remnants and reach the interstellar medium. The cavity where the dust is formed and initially resides is crossed by the high velocity reverse shock which is generated by the pressure of the circumstellar material shocked by the expanding supernova blast wave. Depending on grain composition and initial size, processing by the reverse shock may lead to substantial dust erosion and even complete destruction. The goal of this review is to present the state of the art about processing and survival of dust inside supernova remnants, in terms of theoretical modelling and comparison to observations