Inside number 9: the evolution of a sociology textbook

In this feature essay, Phil Sutton takes readers inside the writing of the ninth edition of Polity’s flagship sociology textbook, Sociology, co-authored with Anthony Giddens. He discusses the evolution of the textbook to reflect the way sociology is practised and taught in 2021, the selection of new subjects and research methods to cover in the book and the process of revising and reviewing the content. Sociology (9th edition). Anthony Giddens and Philip W. Sutton. Polity. 2021

Saturn's turbulent F ring

As our abilities to utilise high performance computing to theoretically probe many astrophysical systems increases, a genuine need to relate to real systems becomes ever more important. Here, Saturn s rings can be used as a nearby laboratory to investigate in real time many astrophysical processes. One such system is the narrow F ring and its interaction with its inner shepherd moon Prometheus. Through numerical modelling and direct observations of the in-situ spacecraft Cassini we find new and exciting dynamics. These might help explain some of the asymmetries witnessed in the distribution of embedded moonlets and azimuthal ring brightness known to exist within the F ring. Spatially we find asymmetry in the Prometheus induced channel edges with regards to density, velocity and acceleration variations of ring particles. Channel edges that show fans (embedded moonlets) are also the locations of highly localised increases in densities, velocity and acceleration changes where opposing edges are considerably less localised in their distribution. As a result of the highly localised nature of the velocity and acceleration changes chaotic fluctuations in density were witnessed. However, this could seek to work in favour of creating coherent objects at this channel edge as density increases were significantly large. Thus, density here had a greater chance of being enhanced beyond the local Roche density. Accompanied with these dynamics was the discovery of a non-zero component to vorticity in the perturbed area of the F ring post encounter. By removal of the background Keplerian flow we find that encounters typically created a large scale rotation of ~10,000 km^2. Within this area a much more rich distribution of local rotations is also seen located in and around the channel edges. Although the real F ring and our models are non-hydrodynamical in nature the existence of a curl in the velocity vector field in the perturbed region could offer some interesting implications for those systems that are gas rich

A Detailed Numerical Analysis of Asymmetrical Density Distribution in Saturn's F ring During an Encounter with Prometheus

Saturn's rings, reminiscent of an early Solar System present a unique opportunity to investigate experimentally some mechanisms thought to be responsible for planet and planetesimal formation in protoplanetary discs. Here we extended the comparison of our numerical models of Prometheus encountering the F ring employing non-interacting and interacting particles. Higher resolution analysis revealed that the density increases known to exist at channel edges is more complex and localised than previously thought. Asymmetry between density increases on channel edges revealed that the channel edge facing way from Prometheus to be the most stable but with lowest maximum increases. However, on the channel edge facing Prometheus the interacting model showed large chaotic fluctuations in the maximum density of some clumps, much larger than those of the other channel. The likely cause of this asymmetry is a variance in localised turbulence introduced into the F ring by Prometheus. High resolution velocity dispersion maps showed that there was a spatial link between the highest densities and the highest velocity dispersions in the interacting model. Thus suggesting that the high velocity dispersion we see is the reason for the observed inhomogeneous distribution of fans (evidence of embedded moonlets) on some of the channel edges facing Prometheus

Gravitational vortices and clump formation In Saturn's F ring during an encounter with Prometheus

Saturn rings are most beautiful and dynamic places in the solar system, consisting of ice particles in a constant battle between the gravitational forces of Saturn and its many moons. Fan, spiral, propellers, moonlets and streamer-channels observed by CASSINI in the F-ring have been attributed to encounters by Prometheus on the F ring, with investigations of optical thickness revealing large populations of transient moonlets. Taking into account gravitational interaction between particles and a multi-stranded F-ring structure we show that Prometheus' encounters create rotational flows, like atmospheric vortices and the self-gravity enhances the accelerated growth and size of moonlets. Vortex patches form caustics, which is a primary cause of the transient particle density clumps of 20 km width and 100 km length, and they are elongated to cover an area of 1600 km by 150 km, which may eventually combine into a vortex sheet

Prometheus induced vorticity in Saturn’s F ring

Saturn’s rings are known to show remarkable real time variability in their structure. Many of which can be associated to interactions with nearby moons and moonlets. Possibly the most interesting and dynamic place in the rings, probably in the whole Solar System, is the F ring. A highly disrupted ring with large asymmetries both radially and azimuthally. Numerically non-zero components to the curl of the velocity vector field (vorticity) in the perturbed area of the F ring post encounter are witnessed, significantly above the background vorticity. Within the perturbed area rich distributions of local rotations is seen located in and around the channel edges. The gravitational scattering of ring particles during the encounter causes a significant elevated curl of the vector field above the background F ring vorticity for the first 1–3 orbital periods post encounter. After 3 orbital periods vorticity reverts quite quickly to near background levels. This new found dynamical vortex life of the ring will be of great interest to planet and planetesimals in proto-planetary disks where vortices and turbulence are suspected of having a significant role in their formation and migrations. Additionally, it is found that the immediate channel edges created by the close passage of Prometheus actually show high radial dispersions in the order ~20–50 cm/s, up to a maximum of 1 m/s. This is much greater than the value required by Toomre for a disk to be unstable to the growth of axisymmetric oscillations. However, an area a few hundred km away from the edge shows a more promising location for the growth of coherent objects

Gravitational vortices and clump formation in Saturn's F ring during an encounter with Prometheus

Saturn rings are most beautiful and dynamic places in the solar system, consisting of ice particles in a constant battle between the gravitational forces of Saturn and its many moons. Fan, spiral, propellers, moonlets and streamer-channels observed by CASSINI in the F-ring have been attributed to encounters by Prometheus on the F ring, with investigations of optical thickness revealing large populations of transient moonlets. Taking into account gravitational interaction between particles and a multi-stranded F-ring structure we show that Prometheus' encounters create rotational flows, like atmospheric vortices and the self-gravity enhances the accelerated growth and size of moonlets. Vortex patches form caustics, which is a primary cause of the transient particle density clumps of 20 km width and 100 km length, and they are elongated to cover an area of 1600 km by 150 km, which may eventually combine into a vortex sheet

Meridional Oceanic Heat Transport Influences Marine Heatwaves in the Tasman Sea on Interannual to Decadal Timescales

Marine heatwaves (MHWs) pose an increasing threat to the ocean’s wellbeing as global warming progresses. Forecasting MHWs is challenging due to the various factors that affect their occurrence, including large variability in the atmospheric state. In this study we demonstrate a causal link between ocean heat content and the area and intensity of MHWs in the Tasman Sea on interannual to decadal time scales. Ocean heat content variations are more persistent than ‘weather-related’ atmospheric drivers (e.g., blocking high pressure systems) for MHWs and thus provide better predictive skill on timescales longer than weeks. Using data from a forced global ocean sea-ice model, we show that ocean heat content fluctuations in the Tasman Sea are predominantly controlled by oceanic meridional heat transport from the subtropics, which in turn is mainly characterized by the interplay of the East Australian Current and the Tasman Front. Variability in these currents is impacted by wind stress curl anomalies north of this region, following Sverdrup’s and Godfrey’s ‘Island Rule’ theories. Data from models and observations show that periods with positive upper (2000 m) ocean heat content anomalies or rapid increases in ocean heat content are characterized by more frequent, larger, longer and more intense MHWs on interannual to decadal timescales. Thus, the oceanic heat content in the Tasman Sea acts as a preconditioner and has a prolonged predictive skill compared to the atmospheric state (e.g., surface heat fluxes), making ocean heat content a useful indicator and measure of the likelihood of MHWs

Mean Motion Resonances With Nearby Moons: An Unlikely Origin For The Gaps Observed In The Ring Around The Exoplanet J1407b

With the use of numerical models, we investigate whether Mean Motion Resonances (MMR) with nearby moons to the J1407b ring system were the cause of the observed 0.0267AU wide gap located at 0.4AU. Only one location of a moon at 0.63AU (corresponding to a 2:1 MMR) was found to form a gap at 0.4AU over short time periods of <100yr. However, the proximity of a low mass moon (0.08M_⊕) caused significant scattering of the outer ring edge at 0.6AU, along with the formation of an additional gap at the 3:2 MMR (0.485 AU), which is not consistent with observations. Further models with moons located at MMR’s 3:1, 4:1, 7:3 and 5:3 failed to form gaps at 0.4AU for time periods <100yr. Instead, gaps were formed in the ring at 3:2 and 2:1 MMR’s which resulted in gaps at radial locations between 0.44-0.56AU. Additionally, gaps also take longer than one orbital period of J1407b about the primary to form. Given that J1407b is on a highly eccentric orbit and is thought to strongly perturb the ring at apocentre it appears unlikely that gaps form due to MMR’s with nearby moons as opposed to embedded moons. Including an appropriate total mass of the ring equal to Earth a dampening effect was witnessed on the gap formation process, causing an increase in the time required to open a gap due to MMR’s. Therefore, we conclude the observed gap at 0.4 AU is unlikely to be caused by MMR’s with nearby moons

Chronicles of Oklahoma

Notes and Documents section from Volume 97, Number 2, Summer 2019. It includes Phil Sutton's 'That Man Stone Photography: "Anything, Any time, Anywhere,'" a short document describing the history of That Man Stone Company, one of the most prolific photography studios before, and after, Oklahoma became a state