Recent work has proposed that a merger event between a red-giant and a He white dwarf may be responsible for the production of R stars (Izzard, Jeffery & Lattanzio 2007). We investigate the proposed evolution and nucleosynthesis of such a model. We simulate the hypothesized late ignition of the core flash by increasing neutrino losses until ignition occurs sufficiently far from the centre that the subsequent evolution produces carbon dredge-up to the extent that the post-flash object is a carbon star. Detailed nucleosynthesis is performed within this approximation and we show that the overall properties are broadly consistent with the observations. Details will depend on the dynamics of the merger event.

We report radio continuum observations with the Australia Telescope Compact Array of two molecular clouds. The impetus for these observations is a search for synchrotron radiation by cosmic-ray secondary electrons/positrons in a region of enhanced density and possibly high magnetic field. We present modelling which shows that there should be an appreciable flux of synchrotron above the more diffuse, galactic synchrotron background.

The starless core G333.125–0.562 and infrared source IRAS15596–5301 were observed at 1384 and 2368 MHz. For G333.125–0.562, we find no significant levels of radio emission from this source at either frequency, nor any appreciable polarisation: we place an upper limit on the radio continuum flux from this source of 0.5 mJy beam−1 at both 1384 and 2368 MHz. Due to the higher than expected flux density limits, we also obtained archival ATCA data at 8640 MHz for this cloud and place an upper limit on the flux density of 50 μJy beam−1. Assuming the cosmic ray spectrum is similar to that near the Sun and given the cloud's molecular density and mass, we place an upper limit on the magnetic field of 500 μG.

IRAS 15596–5301, with an RMS of 50 μJy beam−1 at 1384 MHz, shows an HII region consistent with optically thin free–free emission already detected at 4800 MHz. We use the same prescription as G333 to constrain the magnetic field from this cloud to be less than 500 μG. We find that these values are not inconsistent with the view that magnetic field values scale with the average density of the molecular cloud.

An updated catalogue of 76 galaxies, with direct measurements of supermassive black-hole mass (Mbh) plus, when available, the central velocity dispersion (σ0) of their host bulge is provided. Fifty of these mass measurements are considered reliable, while the others remain somewhat uncertain at this time. An additional nine stellar systems, including one stellar cluster and three globular clusters, are listed as hosting potential intermediate mass black holes <106M⊙.

With this larger data set, the demographics within the Mbh–σ0 diagram are briefly explored. Many barred galaxies are shown to be offset from the Mbh–σ0 relation defined by the non-barred galaxies, in the sense that their velocity dispersions are too high. Furthermore, including 88 AGN with black-hole mass estimates from reverberation mapping studies, we speculate that barred AGN may follow this same general trend. We also show that some AGN with σ0 < 100 km s−1 tend to reside up to (∼0.6 dex) ∼1.0 dex above the (barless) Mbh–σ0 relation. Finally, it is shown that ‘core galaxies’ appear not to define an additional subdivision of the Mbh–σ0 diagram, although improved methods for measuring σ0 values may be valuable.

We assemble a sample of galaxy clusters whose brightest members are dumbbell galaxies and compare them with a control sample in order to investigate if they are the result of recent mergers. We show that the dumbbell sample is no more likely than other clusters to exhibit subclustering. However, they are much more likely to have at least one dumbbell component possessing a significant peculiar velocity with respect to the parent cluster than a non-dumbbell brightest cluster member. We interpret this in the context of seeing the clusters at various stages of post-merger relaxation.

We present a new joint analysis of pulsar dispersion measures and diffuse Hα emission in the Milky Way, which we use to derive the density, pressure and filling factor of the thick disk component of the warm ionised medium (WIM) as a function of height above the Galactic disk. By excluding sightlines at low Galactic latitude that are contaminated by Hii regions and spiral arms, we find that the exponential scale-height of free electrons in the diffuse WIM is 1830–250+120 pc, a factor of two larger than has been derived in previous studies. The corresponding inconsistent scale heights for dispersion measure and emission measure imply that the vertical profiles of mass and pressure in the WIM are decoupled, and that the filling factor of WIM clouds is a geometric response to the competing environmental influences of thermal and non-thermal processes. Extrapolating the properties of the thick-disk WIM to mid-plane, we infer a volume-averaged electron density 0.014 ± 0.001 cm−3, produced by clouds of typical electron density 0.34 ± 0.06 cm−3 with a volume filling factor 0.04 ± 0.01. As one moves off the plane, the filling factor increases to a maximum of ∼30% at a height of ≈1–1.5 kpc, before then declining to accommodate the increasing presence of hot, coronal gas. Since models for the WIM with a ≈1 kpc scale-height have been widely used to estimate distances to radio pulsars, our revised parameters suggest that the distances to many high-latitude pulsars have been substantially underestimated.