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We present first results from a coordinated multiwavelength study of the neutron star low-mass X-ray binary EXO 0748 676. Fast UV, X-ray, and optical data were obtained including both spectral and timing information. We discuss how this study allows us to probe the temperature distribution within the binary and hence the geometry and efficiency of X-ray irradiation.
The scientific advances that underpin economic growth and human health would not be possible without research investments. Yet demonstrating the impact of research programs is a challenge, especially in areas that span disciplines, industrial sectors, and encompass both public and private sector activity. All areas of research are under pressure to demonstrate benefits from federal funding of research. This exciting and innovative study demonstrates new methods and tools to trace the impact of federal research funding on the structure of research, and the subsequent economic activities of funded researchers. The case study is food safety research, which is critical to avoiding outbreaks of disease. The authors make use of an extraordinary new data infrastructure and apply new techniques in text analysis. Focusing on the impact of US federal food safety research, this book develops vital data-intensive methodologies that have a real world application to many other scientific fields.
We report the preliminary results of a CCD surface photometry survey of a large fraction of all known Galactic globular clusters. About 1/5 of all surveyed clusters show a characteristic post-core-collapse (PCC) morphology. The PCC clusters are on average closer to the Galactic center than the King-model-like clusters.
Radio-interferometric tracking of the Global Positioning System (GPS) satellites offers a new technique for regular monitoring of variations in the earth's rotation. The observations are sensitive to pole position and length-of-day, at a level of precision which may make this technique competitive with satellite and lunar laser ranging and very long baseline interferometry (VLBI). The present limitations are the number of satellites and tracking stations available and inadequate modeling of non-gravitational forces on the satellites. The potential advantages are rapid turn-around and minimal incremental cost. We have performed a preliminary analysis using six days of observations from a four-station network. Comparison of earth rotation values from our GPS analysis with values obtained by VLBI and laser ranging reveals differences after five days of 0.9 ms in UT1, 0.04″ in x and 0.07″ in y. These differences reflect errors in the GPS determinations due primarily to inadequate modeling of non-gravitational forces.
We report the discovery of a new double image gravitational lens system B1030+074 which was found during the Jodrell Bank - VLA Astrometric Survey (JVAS). We have collected extensive radio data on the system using the VLA, MERLIN, the EVN and the VLBA as well as HST WFPC2 and NICMOS observations. The lensed images are separated by 1.56 arcseconds and their flux density ratio at centimetric wavelengths is approximately 14:1 although the ratio is slightly frequency dependent and the images appear to be time variable. The HST pictures show both the lensed images and the lensing galaxy close to the weaker image. The lensing galaxy has substructure which could be either part of the galaxy or a companion object. We have modeled B1030+074 using a Singular Isothermal Ellipsoid that yielded a time delay of 156/h50 days. This lens is likely to be suitable for the measurement of the Hubble constant.
This triennium has been quiet but industrious. Information and understanding about star clusters and associations have advanced in a quantitative way, on a broad front that encompasses all their aspects. The tabulations given below refer to many of the well-known objects, for which improved data are now available, plus an impressive number of objects that heretofore have been little more than catalogue entries. Clusters and associations have always been the source, the stage, and the touchstone for the investigation of star birth, stellar evolution, populations, and galactic structure, and the data of the 1976 report of Commission 37 will figure in the scientific advances reported in 1979 by several other IAU Commissions.
The data contained in this report have been taken from two sources: (1) Information received from astronomers active in the field of Commission 37 in response to a circular letter mailed July 1969; (2) Surveys of special fields, prepared by W. Becker on “Open star clusters and spiral structure”, by G. Larsson-Leander on “Clusters and stellar evolution”, by M. Walker on “Young clusters’, and by P. -B. Bouvier on “Dynamical models and numerical computations’. It is a pleasure to thank them and all of those who have contributed to the preparation of this report.
G. Alter reports that after a long delay the second edition of the Catalogue of Star Clusters and Associations. (G. Alter, J. Ruprecht, V. Vanýsek), which was discussed at a meeting of our commission at the Congress in Hamburg (1964) (Trans, IAU, 12B, 1966, 336), will now be published by Publishing House of the Hungarian Academy of Sciences. It is considerably enlarged, since it includes the contents of the annual Supplements published in B.A.C. between 1959 and 1967.
The Thumbprint Nebula (TPN) in Chamaeleon (first described by Fitzgerald (1974), and shown in Figure 1) is a good example of the class of dense, dark nebulae that exhibit dark cores and bright rims, and have been referred to (Lynds 1967) as ‘bright dark nebulae’. Early observations of these nebulae established that the dust grains within them were strongly forward-scattering (Struve and Elvey 1936, Struve 1937). However, the treatment of the radiative transfer problem was too inadequate to permit more than tentative conclusions regarding the nebulae. In more recent years, with the advent of modern computers, the transfer of radiation through a dust cloud has been treated more rigorously, using Monte Carlo techniques (Mattila 1970, Witt and Stephens 1974). Witt and Stephens (1974) have demonstrated that for a dense nebula the surface brightness profile is sensitive to the dust grain density distribution within the cloud and to the scattering properties of the grains. The scattering model approach can be valuable in the investigation of very opaque dark nebulae that cannot be studied by conventional star counting techniques. This has been demonstrated in the case of the TPN by Fitzgerald et al (1976), who used the Witt and Stephens model.