McGladdery, James II

James II. By Christine McGladdery. Pp. xxii, 306. ISBN: 9781904607892. Edinburgh: Birlinn, second revised edition, 2015. £25.00

The Early Stewart Kings, the Lordship of the Isles, and Ireland, c.1371-c.1433

This article explores the Stewart monarchy's relations with the lordship of the Isles within a broader Irish Sea World context, c.1370-c.1433

E. Purcell, P. MacCotter, J. Nyhan and J. Sheehan (eds), Kings, Clerics and Vikings: Essays in Honour of Donnchadh Ó Corráin (Four Courts Press; Dublin, 2015)

No abstract available

Richard II and the wider Gaelic world: a reassessment

Although Richard II's Irish expedition of 1394–95 has attracted considerable scholarly attention, the focus has largely been on Richard's relations with the colonial administration in Ireland, pointing mainly to the colonial government's plea for greater royal investment in the colony as the main factor underpinning Richard's decision to intervene in Ireland. Little attention, by comparison, has been devoted to exploring the king's relations with both the Gaelic Irish and Gaelic Scottish nobility. Using Richard's relations with the expanding Gaelic world as the main case study, this article reconsiders how developments in the Gaelic west influenced the king's decision to intervene in Ireland. Set against the backdrop of Anglo-Scottish relations and the Hundred Years’ War, the article draws on a broad range of Gaelic sources from Ireland and Scotland, English and Scottish governmental records, and material from the Avignon papacy. It uncovers and traces the development of the main Gaelic Irish and Gaelic Scottish dynasties during the late fourteenth century, their relationships with one another, and their unfolding connections with the English and Scottish crowns. By locating Richard's expeditions within the broader archipelagic context, this article argues that the wider Gaelic world, though on the geographic periphery of Ireland and Scotland, was capable of exerting a far greater degree of influence on the course of “British” politics than has previously been acknowledged

Distribution and characteristics of Infrared Dark Clouds using genetic forward modelling

Infrared Dark Clouds (IRDCs) are dark clouds seen in silhouette in mid-infrared surveys. They are thought to be the birthplace of massive stars, yet remarkably little information exists on the properties of the population as a whole (e.g. mass spectrum, spatial distribution). Genetic forward modelling is used along with the Two Micron All Sky Survey and the Besancon Galactic model to deduce the three dimensional distribution of interstellar extinction towards previously identified IRDC candidates. This derived dust distribution can then be used to determine the distance and mass of IRDCs, independently of kinematic models of the Milky Way. Along a line of sight that crosses an IRDC, the extinction is seen to rise sharply at the distance of the cloud. Assuming a dust to gas ratio, the total mass of the cloud can be estimated. The method has been successfully applied to 1259 IRDCs, including over 1000 for which no distance or mass estimate currently exists. The IRDCs are seen to lie preferentially along the spiral arms and in the molecular ring of the Milky Way, reinforcing the idea that they are the birthplace of massive stars. Also, their mass spectrum is seen to follow a power law with an index of -1.75 +/- 0.06, steeper than giant molecular clouds in the inner Galaxy, but comparable to clumps in GMCs. This slope suggests that the IRDCs detected using the present method are not gravitationally bound, but are rather the result of density fluctuations induced by turbulence.Comment: 15 pages, 9 figures, accepted for publication in Ap

IRDC G030.88+00.13: A Tale of Two Massive Clumps

Massive stars (M \gsim 10 \msun) form from collapse of parsec-scale molecular clumps. How molecular clumps fragment to give rise to massive stars in a cluster with a distribution of masses is unclear. We search for cold cores that may lead to future formation of massive stars in a massive ($> 10^3$ \msun), low luminosity ($4.6 \times 10^2$ \lsun) infrared dark cloud (IRDC) G030.88+00.13. The \nh3 data from VLA and GBT reveal that the extinction feature seen in the infrared consists of two distinctive clumps along the same line of sight: The C1 clump at 97 \kms-1 coincides with the extinction in the Spitzer 8 and 24 $\mu$m. Therefore, it is responsible for the majority of the IRDC. The C2 clump at 107 \kms-1 is more compact and has a peak temperature of 45 K. Compact dust cores and \h2O masers revealed in the SMA and VLA observations are mostly associated with C2, and none is within the IRDC in C1. The luminosity indicates that neither the C1 nor C2 clump has yet to form massive protostars. But C1 might be at a precluster forming stage. The simulated observations rule out 0.1pc cold cores with masses above 8 \msun\ within the IRDC. The core masses in C1 and C2, and those in high-mass protostellar objects suggest an evolutionary trend that the mass of cold cores increases over time. Based on our findings, we propose an empirical picture of massive star formation that protostellar cores and the embedded protostars undergo simultaneous mass growth during the protostellar evolution.Comment: 29 pages, 7 figures. Accepted to Astrophysical Journa

The "Nessie" Nebula: Cluster Formation in a Filamentary Infrared Dark Cloud

The "Nessie" Nebula is a filamentary infrared dark cloud (IRDC) with a large aspect ratio of over 150:1 (1.5 degrees x 0.01 degrees, or 80 pc x 0.5 pc at a kinematic distance of 3.1 kpc). Maps of HNC (1-0) emission, a tracer of dense molecular gas, made with the Australia Telescope National Facility Mopra telescope, show an excellent morphological match to the mid-IR extinction. Moreover, because the molecular line emission from the entire nebula has the same radial velocity to within +/- 3.4 km/s, the nebula is a single, coherent cloud and not the chance alignment of multiple unrelated clouds along the line of sight. The Nessie Nebula contains a number of compact, dense molecular cores which have a characteristic projected spacing of ~ 4.5 pc along the filament. The theory of gravitationally bound gaseous cylinders predicts the existence of such cores, which, due to the "sausage" or "varicose" fluid instability, fragment from the cylinder at a characteristic length scale. If turbulent pressure dominates over thermal pressure in Nessie, then the observed core spacing matches theoretical predictions. We speculate that the formation of high-mass stars and massive star clusters arises from the fragmentation of filamentary IRDCs caused by the "sausage" fluid instability that leads to the formation of massive, dense molecular cores. The filamentary molecular gas clouds often found near high-mass star-forming regions (e.g., Orion, NGC 6334, etc.) may represent a later stage of IRDC evolution.Comment: 5 pages, 2 figures, accepted for publication in The Astrophysical Journal Letter