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Short period, massive planets, known as hot Jupiters (HJs), have been discovered around $\sim 1$ percent of local field stars. The inward migration necessary to produce HJs may be `low eccentricity', due to torques in the primordial disc, or `high eccentricity' (HEM). The latter involves exciting high orbital eccentricity, allowing sufficiently close passages with the host star to raise circularising tides in the planet. We present an analytic framework for quantifying the role of dynamical encounters in high density environments during HEM. We show that encounters can enhance or suppress HEM, depending on the local stellar density and the initial semi-major axis $a_0$. For moderate densities, external perturbations can excite large eccentricities that allow a planet to circularise over the stellar lifetime. At extremely high densities, these perturbations can instead result in tidal disruption of the planet, thus yielding no HJ. This may explain the apparent excess of HJs in M67 compared with their local field star abundance versus their apparent deficit in 47 Tuc. Applying our analytic framework, we demonstrate that for an initial massive planet population similar to the field, the expected HJ occurrence rate in 47 Tuc is $f_\mathrm{HJ}=2.2\times 10^{-3}$, which remains consistent with present constraints. Future large (sample sizes $\gtrsim 10^5$) or sensitive transit surveys of stars in globular clusters are required to refute the hypothesis that the initial planet population is similar to the solar neighbourhood average. Non-detection in such surveys would have broad consequences for planet formation theory, implying planet formation rates in globular clusters must be suppressed across a wide range of $a_0$., Accepted for publication in MNRAS - 28 pages, 17 figures

We used the Atacama Pathfinder Experiment (APEX) telescope to search for CI 1-0 (492.16GHz) emission towards 8 proplyds in NGC 1977, which is an FUV radiation environment two orders of magnitude weaker than that irradiating the Orion Nebular Cluster (ONC) proplyds. CI is expected to enable us to probe the wind launching region of externally photoevaporating discs. Of the 8 targets observed, no 3$\sigma$ detections of the CI line were made despite reaching sensitivities deeper than the anticipated requirement for detection from prior APEX CI observations of nearby discs and models of external photoevaporation of quite massive discs. By comparing both the proplyd mass loss rates and CI flux constraints with a large grid of external photoevaporation simulations, we determine that the non-detections are in fact fully consistent with the models if the proplyd discs are very low mass. Deeper observations in CI and probes of the disc mass with other tracers (e.g. in the continuum and CO) can test this. If such a test finds higher masses, this would imply carbon depletion in the outer disc, as has been proposed for other discs with surprisingly low CI fluxes, though more massive discs would also be incompatible with models that can explain the observed mass loss rates and CI non-detections. The expected remaining lifetimes of the proplyds are estimated to be similar to those of proplyds in the ONC at 0.1Myr. Rapid destruction of discs is therefore also a feature of common, intermediate UV environments., Comment: 10 pages. Accepted for publication in MNRAS

INTRODUCTION: As gonococcal infections continue to increase, we wanted to review the number and clinical course of recent ocular gonococcal cases presenting to ophthalmology departments in NHS Greater Glasgow and Clyde. METHODS: A 5-year retrospective review of adult ocular gonococcal cases, where the diagnosis of Neisseria gonorrhoeae was made on microbiological culture, was undertaken. RESULTS: Fifteen cases were identified (80% male). Average age was 26 years (range 17–42; median 24). Most common presenting features included purulent discharge (14/15; 93%), haemorrhagic conjunctivitis (10/15; 67%) and pre-septal cellulitis (9/15; 60%). Corneal involvement was documented in 5 (33%), with marginal ulceration in 1 (7%) but none had corneal perforation. Most common systemic treatment was IV ceftriaxone, alone or in combination with another antibiotic (6/15; 40%), followed by IM ceftriaxone, alone or in combination with another antibiotic (5/15; 33%). Median time from presentation to treatment was 1 day (0–23). All patients were referred or recommended to attend sexual health services. Seven patients (47%) attended and received complete sexually transmitted infection (STI) testing and contact tracing: 3 patients had systemic treatment initiated or changed at this visit and 1 patient had concurrent syphilis identified. CONCLUSIONS: This series confirms purulent conjunctivitis and cellulitis as the main presenting features of ocular gonococcal infection requiring hospital review. Early identification with appropriate systemic antibiotic treatment avoided corneal melting in this cohort. As concurrent STIs were identified and/or treatments changed in 4/7 (57%) following sexual health review, we recommend a shared care approach between ophthalmology, microbiology and sexual health services to effectively address all management issues.

The exotic range of known planetary systems has provoked an equally exotic range of physical explanations for their diverse architectures. However, constraining formation processes requires mapping the observed exoplanet population to that which initially formed in the protoplanetary disc. Numerous results suggest that (internal or external) dynamical perturbation alters the architectures of some exoplanetary systems. Isolating planets that have evolved without any perturbation can help constrain formation processes. We consider the Kepler multiples, which have low mutual inclinations and are unlikely to have been dynamically perturbed. We apply a modelling approach similar to that of Mulders et al. (2018), additionally accounting for the two-dimensionality of the radius ($R =0.3-20\,R_\oplus$) and period ($P= 0.5-730$ days) distribution. We find that an upper limit in planet mass of the form $M_{\rm{lim}} \propto a^\beta \exp(-a_{\rm{in}}/a)$, for semi-major axis $a$ and a broad range of $a_{\rm{in}}$ and $\beta$, can reproduce a distribution of $P$, $R$ that is indistinguishable from the observed distribution by our comparison metric. The index is consistent with $\beta= 1.5$, expected if growth is limited by accretion within the Hill radius. This model is favoured over models assuming a separable PDF in $P$, $R$. The limit, extrapolated to longer periods, is coincident with the orbits of RV-discovered planets ($a>0.2$ au, $M>1\,M_{\rm{J}}$) around recently identified low density host stars, hinting at isolation mass limited growth. We discuss the necessary circumstances for a coincidental age-related bias as the origin of this result, concluding that such a bias is possible but unlikely. We conclude that, in light of the evidence that some planetary systems have been dynamically perturbed, simple models for planet growth during the formation stage are worth revisiting., Comment: 21 pages, 16 figures, accepted for publication in MNRAS

Most stars form and spend their early life in regions of enhanced stellar density. Therefore the evolution of protoplanetary discs (PPDs) hosted by such stars are subject to the influence of other members of the cluster. Physically, PPDs might be truncated either by photoevaporation due to ultraviolet flux from massive stars, or tidal truncation due to close stellar encounters. Here we aim to compare the two effects in real cluster environments. In this vein we first review the properties of well studied stellar clusters with a focus on stellar number density, which largely dictates the degree of tidal truncation, and far ultraviolet (FUV) flux, which is indicative of the rate of external photoevaporation. We then review the theoretical PPD truncation radius due to an arbitrary encounter, additionally taking into account the role of eccentric encounters that play a role in hot clusters with a 1D velocity dispersion $\sigma_v > 2$ km/s. Our treatment is then applied statistically to varying local environments to establish a canonical threshold for the local stellar density ($n_{c} > 10^4$ pc$^{-3}$) for which encounters can play a significant role in shaping the distribution of PPD radii over a timescale $\sim 3$ Myr. By combining theoretical mass loss rates due to FUV flux with viscous spreading in a PPD we establish a similar threshold for which a massive disc is completely destroyed by external photoevaporation. Comparing these thresholds in local clusters we find that if either mechanism has a significant impact on the PPD population then photoevaporation is always the dominating influence., ERC Advanced Grant grant agreement 341137

Protoplanetary disk surveys by the Atacama Large Millimeter/sub-millimeter Array (ALMA) are now probing a range of environmental conditions, from low-mass star-forming regions like Lupus to massive OB clusters like $\sigma$ Orionis. Here we conduct an ALMA survey of protoplanetary disks in $\lambda$ Orionis, a ~5 Myr old OB cluster in Orion, with dust mass sensitivities comparable to the surveys of nearby regions (~0.4 $M_\oplus$). We assess how massive OB stars impact planet formation, in particular from the supernova that may have occurred ~1 Myr ago in the core of $\lambda$ Orionis; studying these effects is important as most planetary systems, including our Solar System, are likely born in cluster environments. We find that the effects of massive stars, in the form of pre-supernova feedback and/or a supernova itself, do not appear to significantly reduce the available planet-forming material otherwise expected at the evolved age of $\lambda$ Orionis. We also compare a lingering massive "outlier" disk in $\lambda$ Orionis to similar systems in other evolved regions, hypothesizing that these outliers host companions in their inner disks that suppress disk dispersal to extend the lifetimes of their outer primordial disks. We conclude with numerous avenues for future work, highlighting how $\lambda$ Orionis still has much to teach us about perhaps one of the most common types of planet-forming environments in the Galaxy., Comment: 21 pages, 8 figures, 3 tables. Accepted to AAS Journals