Canada and the Korean War: Fifty Years On

In September 1998, the Canadian War Museum initiated a visiting speaker series to make available to the general public the latest research, debate and opinion on Canadian and international military history. Like the Museum’s highly popular film series, the talks were usually held on week nights and carried no admission fee. They have proven highly successful, both with Museum visitors and invited speakers. The latter have included eminent Canadian historians like Terry Copp, David Bercuson and Bill McAndrew, and international scholars like John Keegan, Paul Gough, and Christopher Pugsley. In the autumn of 2000, the Museum will welcome world-renowned First World War scholar Jay Winter and Pulitzer Prize winner James McPherson. The Museum staged one of these events to coincide with the 50th anniversary of the outbreak of the Korean War. In addition to hosting several hundred Korean War veterans during the anniversary weekend of June 24–25, updating its Korean War permanent gallery, and mounting a travelling exhibit of contemporary war photographs, the Museum invited Dalhousie University professor Denis Stairs to comment on Canada’s diplomatic role in the crisis from the perspective of 50 years. This, in effect, amounted to a reconsideration of the arguments first presented in Professor Stairs’ seminal work, The Diplomacy of Constraint, which, twenty five years after its publication, remains the standard work in the field. Speaking on Sunday, 25 June 2000, fifty years to the day after North Korean forces first crossed the 38th parallel to invade the American-supported Republic of Korea in the south, the text of his address follows. Like the monograph on which it comments, the article constitutes a critical component of Canada’s Korean War literature, a tour de force by one of Canada’s most gifted scholars

The Formation of the Double Pulsar PSR J0737-3039A/B

Recent timing observations of the double pulsar J0737-3039A/B have shown that its transverse velocity is extremely low, only 10 km/s, and nearly in the Plane of the Galaxy. With this new information, we rigorously re-examine the history and formation of this system, determining estimates of the pre-supernova companion mass, supernova kick and misalignment angle between the pre- and post-supernova orbital planes. We find that the progenitor to the recently formed `B' pulsar was probably less than 2 MSun, lending credence to suggestions that this object may not have formed in a normal supernova involving the collapse of an iron core. At the same time, the supernova kick was likely non-zero. A comparison to the history of the double-neutron-star binary B1534+12 suggests a range of possible parameters for the progenitors of these systems, which should be taken into account in future binary population syntheses and in predictions of the rate and spatial distribution of short gamma-ray burst events.Comment: To appear in MNRAS Letters. Title typo fix only; no change to pape

Radiation pattern of the isolated pulsar PSR B1828-11

Based on the free precession model of the isolated pulsar PSR B1828-11, Link & Epstein 2001) showed that the observed pulse durations require the radio beam to have a non-standard shape: the beam duration is larger for beam sweeps farthest from the dipole axis. In their analysis they assumed that the actual precession period is ~ 500 d. Recent theoretical studies suggested that the actual precession period might be ~ 1000 d as seen in observations (Rezania 2002, Wasserman 2002). In this paper, in a good agreement with the observed data (Stairs et al. 2000), we model the changes of the pulse shape in a precession cycle with period ~ 1000 d and find that the variation of the pulse duration follows from a {\it standard} beam pattern in each cycle.Comment: 9 pages, 3 figures, Accepted for publication in A&

Testing Lorentz violation with binary pulsars: constraints on standard model extension

Under the standard model extension (SME) framework, Lorentz invariance is tested in five binary pulsars: PSR J0737-3039, PSR B1534+12, PSR J1756-2251, PSR B1913+16 and PSR B2127+11C. By analyzing the advance of periastron, we obtain the constraints on a dimensionless combination of SME parameters that is sensitive to timing observations. The results imply no evidence for the break of Lorentz invariance at $10^{-10}$ level, one order of magnitude larger than previous estimation.Comment: 4 pages, no figure, accepted for publication in RA

Neutron Stars in Globular Clusters

Dynamical interactions that occur between objects in dense stellar systems are particularly important for the question of formation of X-ray binaries. We present results of numerical simulations of 70 globular clusters with different dynamical properties and a total stellar mass of 2*10^7 Msun. We find that in order to retain enough neutron stars to match observations we must assume that NSs can be formed via electron-capture supernovae. Our simulations explain the observed dependence of the number of LMXBs on ``collision number'' as well as the large scatter observed between different globular clusters. For millisecond pulsars, we obtain good agreement between our models and the numbers and characteristics of observed pulsars in the clusters Terzan 5 and 47 TucComment: 5 pages, 3 figures, to appear in "Dynamical Evolution of Dense Stellar Systems", IAUS 246, ed. E. Vesperin