Circular polarization shows the nature of pulsar magnetosphere composition

It has been argued in previous papers that an ion-proton plasma is formed at the polar caps of neutron stars with positive polar-cap corotational charge density. The present paper does not offer a theory of the development of turbulence from the unstable Langmuir modes that grow in the outward accelerated plasma, but attempts to describe in qualitative terms the factors relevant to the emission of polarized radiation at frequencies below 1 - 10 GHz. The work of Karastergiou and Johnston is of particular importance in this respect because it demonstrates in high-resolution measurements of the profiles of 17 pulsars that the relative phase retardation between the O- and E-modes of the plasma is no greater than of the order of pi. Provided the source of the radiation is at low altitudes, as favoured by recent observations, this order of retardation is possible only for a plasma of baryonic-mass particles.Comment: 7 page

Sigurd Lewerentz: Church of St Peter, Klippan, 1963–66

This modest building questions basic assumptions about processes and finishes, about the nature of brickwork and the detailing of window frames – and provides a powerful space for worship

Heteroatom-doped hydrogenated amorphous carbons, a-C:H:X 'Volatile' silicon, sulphur and nitrogen depletion, blue photoluminescence, diffuse interstellar bands and ferro-magnetic carbon grain connections (Research Note)

Context. Hydrogenated amorphous carbons, a-C:H, can incorporate a variety of heteroatoms, which can lead to interesting effects. Aims. To investigate the doping of interstellar a-C:H grains with, principally, Si, O, N and S atoms within the astrophysical context. Methods. A search of the literature on doped a-C:H reveals a number of interesting phenomena of relevance to astrophysics. Results. X dopants in a-C:H:X materials can affect the sp3/sp2 ratio (X = Si, O and N), lead to blue photoluminescence (undoped or X = N), induce ferromagnetic-like behaviour (X = N and S) or simply be incorporated (depleted) into the structure (X = Si, O, N and S). Si and N atoms could also incorporate into fullerenes, possibly forming colour-centres that could mimic diffuse interstellar bands. Conclusions. Doped a-C:H grains could explain several dust-related conundrums, such as: 'volatile' Si in photo-dissociation regions, S and N depletion in molecular clouds, blue luminescence, some diffuse interstellar bands and ferromagnetism in carbonaceous grains.Comment: 5 page