Radio emission from the massive stars in the Galactic Super Star Cluster Westerlund 1

Current mass-loss rate estimates imply that main sequence winds are not sufficient to strip away the H-rich envelope to yield Wolf-Rayet (WR) stars. The rich transitional population of Westerlund 1 (Wd 1) provides an ideal laboratory to observe mass-loss processes throughout the transitional phase of stellar evolution. An analysis of deep radio continuum observations of Wd 1 is presented. We detect 18 cluster members. The radio properties of the sample are diverse, with thermal, non-thermal and composite thermal/non-thermal sources present. Mass-loss rates are ~10^{-5} solar mass/year across all spectral types, insufficient to form WRs during a massive star lifetime, and the stars must undergo a period of enhanced mass loss. The sgB[e] star W9 may provide an example, with a mass-loss rate an order of magnitude higher than the other cluster members, and an extended nebula of density ~3 times the current wind. This structure is reminiscent of luminous blue variables, and one with evidence of two eras of high, possibly eruptive, mass loss. Three OB supergiants are detected, implying unusually dense winds. They also may have composite spectra, suggesting binarity. Spatially resolved nebulae are associated with three of the four RSGs and three of the six YHGs in the cluster, which are due to quiescent mass loss rather than outbursts. For some of the cool star winds, the ionizing source may be a companion star though the cluster radiation density is sufficiently high to provide the necessary ionizing radiation. Five WR stars are detected with composite spectra, interpreted as arising in colliding-wind binaries.Comment: 15 pages, 6 figures. Accepted for publication in Astronomy and Astrophysic

Radio emission from the massive stars in Westerlund 1

The diverse massive stellar population in the young massive clusterWesterlund 1 (Wd 1) provides an ideal laboratory to observe and constrain mass-loss processes throughout the transitional phase of massive star evolution. A set of high sensitivity radio observations of Wd 1 leads to the detection of 18 cluster members, a sample dominated by cool hypergiants, but with detections among hotter OB supergiants and WR stars. Here the diverse radio properties of the detected sample are briefly described. The mass-loss rates of the detected objects are surprisingly similar across the whole transitional phase of massive star evolution, at ~ 10-5 Mo yr−1. Such a rate is insufficient to strip away the H-rich mantle in a massive star lifetime, unless the stars go through a period of enhanced mass-loss. The radio luminous star W9 provides an example of such an object, with evidence for two eras of mass-loss with rates of ~ 10−4 Mo yr−1

TAIR: A transonic airfoil analysis computer code

The operation of the TAIR (Transonic AIRfoil) computer code, which uses a fast, fully implicit algorithm to solve the conservative full-potential equation for transonic flow fields about arbitrary airfoils, is described on two levels of sophistication: simplified operation and detailed operation. The program organization and theory are elaborated to simplify modification of TAIR for new applications. Examples with input and output are given for a wide range of cases, including incompressible, subcritical compressible, and transonic calculations

On Z2Z4-additive complementary dual codes and related LCD codes

Linear complementary dual codes were defined by Massey in 1992, and were used to give an optimum linear coding solution for the two user binary adder channel. In this paper, we define the analog of LCD codes over fields in the ambient space with mixed binary and quaternary alphabets. These codes are additive, in the sense that they are additive subgroups, rather than linear as they are not vector spaces over some finite field. We study the structure of these codes and we use the canonical Gray map from this space to the Hamming space to construct binary LCD codes in certain cases. We give examples of such binary LCD codes which are distance-optimal, i.e., they have the largest minimum distance among all binary LCD codes with the same length and dimension

BIOMECHANICS OF RUNNING - Electromyographic Analysis of the Hip during Jogging, Running and Sprinting

The patterns of muscle action during human locomotion have been investigated for several decades. Lower extremity electromyographic activity in walking was investigated by Bartholomew and the Prosthetic Research Group at Berkeley in 1953. (1) Others investigated the actions of specific muscles during various leg movements. Basmajian and LeBan et al. (6) examined the electromyographic action of the iliopsoas muscle. These studies have led to the investigation of running. Saito et aI., (10) presented temporal data on the gait cycle of running. James and Brubaker (5) presented a descriptive analysis of running. Other researchers have directed their work toward sprinting: Fenn (4) investigated frictional and kinetic factors in 1930, and Dillman (3) and Ralph Mann (7) used kinetic analysis. Mann and Hagy (9) and Mann et aI. (8) investigated temporal and electromyographic patterns of walking, running and sprinting. This study investigates and describes the electromyographic activity ofthe lower extrJmities and trunk musculature duringjogging, running, and sprinting

HD 93129A at different radio scales

Recent observations toward the O2 If* star HD 93129A have revealed important non-thermal radio emission, and that it has an early O companion 140 AU away if at 2.5 kpc (FGS-HST data). These facts strongly support the possibility of a massive stars wind-collision region as the acceleration site of the synchrotron-emitting relativistic electrons. We have carried out LBA VLBI observations at 2.37 GHz to resolve the non-thermal source, and search for a bow-shock shape, typical of a wind-collision region. Preliminary results are presented here.Fil: Benaglia, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto Argentino de Radioastronomia (i); ArgentinaFil: Dougherty, S. M.. National Research Council of Canada, Herzberg Institute for Astrophysics, Dominion Radio Astrophysical Observatory; CanadáFil: Phillips, C.. Australia Telescope National Facility, CSIRO; AustraliaFil: Koribalski, B.. Australia Telescope National Facility, CSIRO; AustraliaFil: Tzioumis, T.. Australia Telescope National Facility, CSIRO; Australi

Cassini observations of ion and electron beams at Saturn and their relationship to infrared auroral arcs

We present Cassini Visual and Infrared Mapping Spectrometer observations of infrared auroral emissions from the noon sector of Saturn's ionosphere revealing multiple intense auroral arcs separated by dark regions poleward of the main oval. The arcs are interpreted as the ionospheric signatures of bursts of reconnection occurring at the dayside magnetopause. The auroral arcs were associated with upward field-aligned currents, the magnetic signatures of which were detected by Cassini at high planetary latitudes. Magnetic field and particle observations in the adjacent downward current regions showed upward bursts of 100–360 keV light ions in addition to energetic (hundreds of keV) electrons, which may have been scattered from upward accelerated beams carrying the downward currents. Broadband, upward propagating whistler waves were detected simultaneously with the ion beams. The acceleration of the light ions from low altitudes is attributed to wave-particle interactions in the downward current regions. Energetic (600 keV) oxygen ions were also detected, suggesting the presence of ambient oxygen at altitudes within the acceleration region. These simultaneous in situ and remote observations reveal the highly energetic magnetospheric dynamics driving some of Saturn's unusual auroral features. This is the first in situ identification of transient reconnection events at regions magnetically conjugate to Saturn's magnetopause

Distinguishing step relaxation mechanisms via pair correlation functions

Theoretical predictions of coupled step motion are tested by direct STM measurement of the fluctuations of near-neighbor pairs of steps on Si(111)-root3 x root3 R30 - Al at 970K. The average magnitude of the pair-correlation function is within one standard deviation of zero, consistent with uncorrelated near-neighbor step fluctuations. The time dependence of the pair-correlation function shows no statistically significant agreement with the predicted t^1/2 growth of pair correlations via rate-limiting atomic diffusion between adjacent steps. The physical considerations governing uncorrelated step fluctuations occurring via random attachment/detachment events at the step edge are discussed.Comment: 17 pages, 4 figure

The parent analogy: a reassessment

According to the parent analogy, as a caretaker’s goodness, ability and intelligence increase, the likelihood that the caretaker will make arrangements for the attainment of future goods that are unnoticed or underappreciated by their dependents also increases. Consequently, if this analogy accurately represents our relationship to God, then we should expect to find many instances of inscrutable evil in the world. This argument in support of skeptical theism has recently been criticized by Dougherty. I argue that Dougherty’s argument is incomplete, for there are two plausible ways of construing the parent analogy’s conclusion. I supplement Dougherty’s case by offering a new argument against the parent analogy based on failed expectations concerning the amount of inscrutable evils encountered in the world. Consequently, there remains a significant empirical hurdle for skeptical theism to overcome if it is to maintain its status as a defeater for our reliability when tracking gratuitous evils.Publisher PDFPeer reviewe