The Distance and Age of the SNR Kes 73 and AXP 1E 1841-045

We provide a new distance estimate to the supernova remnant (SNR) Kes 73 and its associated anomalous X-ray pulsar (AXP) 1E 1841-045. 21 cm HI images and HI absorption/ emission spectra from new VLA observations, and 13CO emission spectra of Kes 73 and two adjacent compact HII regions (G27.276+0.148 and G27.491+0.189) are analyzed. The HI images show prominent absorption features associated with Kes 73 and the HII regions. The absorption appears up to the tangent point velocity giving a lower distance limit to Kes 73 of 7.5 kpc, which has previously been given as the upper limit. Also, G27.276+0.148 and G27.491+0.189 are at the far kinematic distances of their radio recombination line velocities. There is prominent HI emission in the range 80--90 km/s for all three objects. The two HII regions show HI absorption at ~ 84 km/s, but there is no absorption in the Kes 73 absorption spectrum. This implies an upper distance limit of ~ 9.8 kpc to Kes 73. This corrected larger distance to Kes 73/ AXP 1E 1841-045 system leads to a refined age of the SNR of 500 to 1000 yr, and a ~ 50% larger AXP X-ray luminosity.Comment: 10 pages, 2 figures, ApJ, dol:10.1086/"529120

Shocked H2 and Fe+ Dynamics in the Orion Bullets

Observations of H2 velocity profiles in the two most clearly defined Orion bullets are extremely difficult to reconcile with existing steady-state shock models. We have observed [FeII] 1.644um velocity profiles of selected bullets and H2 1-0 S(1) 2.122um velocity profiles for a series of positions along and across the corresponding bow-shaped shock fronts driven into the surrounding molecular cloud. Integrated [FeII] velocity profiles of the brightest bullets are consistent with theoretical bow shock predictions. However, observations of broad, singly-peaked H2 1-0 S(1) profiles at a range of positions within the most clearly resolved bullet wakes are not consistent with molecular shock modelling. A uniform, collisionally broadened background component which pervades the region in both tracers is inconsistent with fluorescence due to the ionizing radiation of the Trapezium stars alone.Comment: 20 pages including 18 figures, published in MNRA

Unified powered flight guidance

A complete revision of the orbiter powered flight guidance scheme is presented. A unified approach to powered flight guidance was taken to accommodate all phases of exo-atmospheric orbiter powered flight, from ascent through deorbit. The guidance scheme was changed from the previous modified version of the Lambert Aim Point Maneuver Mode used in Apollo to one that employs linear tangent guidance concepts. This document replaces the previous ascent phase equation document

Constraints on the distance to SGR 1806-20 from HI absorption

The giant flare detected from the magnetar SGR 1806-20 on 2004 December 27 had a fluence more than 100 times higher than the only two other SGR flares ever recorded. Whereas the fluence is independent of distance, an estimate for the luminosity of the burst depends on the source's distance, which has previously been argued to be ~15 kpc. The burst produced a bright radio afterglow, against which Cameron et al. (2005) have measured an HI absorption spectrum. This has been used to propose a revised distance to SGR 1806-20 of between 6.4 and 9.8 kpc. Here we analyze this absorption spectrum, and compare it both to HI emission data from the Southern Galactic Plane Survey and to archival 12-CO survey data. We confirm ~6 kpc, as a likely lower limit on the distance to SGR 1806-20, but argue that it is difficult to place an upper limit on the distance to SGR 1806-20 from the HI data currently available. The previous value of ~15 kpc thus remains the best estimate of the distance to the source.Comment: 3 pages, 1 embedded EPS figure. Added sentences to end of Abstract and Conclusion, clarifying that most likely distance is 15 kpc. ApJ Letters, in pres

Proper Motion of Pulsar B1800-21

We report high angular resolution, multi-epoch radio observations of the young pulsar PSR B1800-21. Using two pairs of data sets, each pair spanning approximately a ten year period, we calculate the proper motion of the pulsar. We obtain a proper motion of mu_alpha=11.6 +- 1.8 mas/yr, mu_delta=14.8 +- 2.3 mas/yr, which clearly indicates a birth position at the extreme edge of the W30 supernova remnant. Although this does not definitively rule out an association of W30 and PSR B1800-21, it does not support an association.Comment: 13 pages, 1 color figure. Replaced with version accepted for publication in Astrophysical Journa

The Enquirer Club

Title Onlyhttps://scholarsjunction.msstate.edu/cht-sheet-music/11427/thumbnail.jp

Experimental demonstration of painting arbitrary and dynamic potentials for Bose-Einstein condensates

There is a pressing need for robust and straightforward methods to create potentials for trapping Bose-Einstein condensates which are simultaneously dynamic, fully arbitrary, and sufficiently stable to not heat the ultracold gas. We show here how to accomplish these goals, using a rapidly-moving laser beam that "paints" a time-averaged optical dipole potential in which we create BECs in a variety of geometries, including toroids, ring lattices, and square lattices. Matter wave interference patterns confirm that the trapped gas is a condensate. As a simple illustration of dynamics, we show that the technique can transform a toroidal condensate into a ring lattice and back into a toroid. The technique is general and should work with any sufficiently polarizable low-energy particles.Comment: Minor text changes and three references added. This is the final version published in New Journal of Physic