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adial-velocity scanner (RVS). In addition, over 100 new velocities fromphotographic plates have been added to those published ten years ago.The standard deviation of the RVS velocities is about three times largerthan that of the photographic data. The RVS velocities were obtainedwith a variety of masks, but zero-point adjustments have been madeempirically between them and between the RVS and the plates. Anabsolute zero-point has been provided by observations of brightasteroids. Comparison between the DAO data and large compilationspublished recently, by groups at the Center for Astrophysics and at theGeneva Observatory, reveals excellent agreement. In particular, apreviously troublesome colour-dependent discrepancy between theGeneva observations and others has been eliminated, by adjustmentsmade recently by the Geneva group, to an extent greater than eventhey had anticipated. The long task of revising the IAU standard systemand providing a list of objects with radial velocities known absolutelyto better than 100 m s –1 , and constant at the same level, now seems tobe nearly complete.Interstellar Clumps: Physical Relations, Magnetism, and Energy, JacquesP. Vallée, National Research Council of Canada’s Herzberg Institute ofAstrophysicsUniversal scaling relations exist in interstellar molecular clouds andclumps, governing the mean physical parameters such as the gas densityn, diameter D, magnetic field B, and gas linewidth W (for recent reviews,see Vallée 1997, Fun. Cos. Phys., 19, 1; Vallée 1998, Fun. Cos. Phys., 19,319). The relations follow the form: ~ D c , ~ k , ~ p ,~ q . In molecular clouds, with D > 1 pc but < 100 pc, theexponents are: c = –1.0; k = +0.5; p = –0.5; and q = +0.5 (e.g., Larson1981, MNRAS, 194, 809). There is a natural separation between cloudsand clumps, occurring near 0.5 pc. One does not expect the physicalbehaviours of clumps (< 0.5 pc) to be the same as for clouds (> 1 pc).In cold clumps, with D > 0.01 pc but < 0.50 pc, the gas density is higherthan in clouds. Clumps are beginning to reveal their secrets, usingobserved findings at high angular resolution. Here I report on a statisticalstudy of the exponent values c, k, p, q for clumps, and on the energycomponents for clumps. The exponent values for clumps are found todiffer from those found by Larson (1981, MNRAS, 194, 809) for molecularclouds. The differences could be indicative of ongoing accretion processesin shocked media. The energy distribution in clumps reveals that thesupport against gravitational collapse in clumps with sizes > 0.1 pccomes mainly from turbulent energy, while clumps with sizes < 0.1 pcare supported by both magnetic and turbulent energies. The clumpsize of 0.1 pc is critical in many other aspects.Pulsation of the Scuti star V369 Scuti, V. A. Volk, E. F. Milone, K. M.Volk and W. J. F. Wilson, University of CalgaryV369 Scuti is a low amplitude, short period Scuti star. These areknown to pulsate in multi-frequency radial and non-radial modes.Photoelectric and CCD differential photometry in BVRI from theRothney Astrophysical Observatory, University of Calgary, and radialvelocity measurements from spectra taken at the Dominion AstrophysicalObservatory, Victoria, were obtained over the summers of 1997 through1999. Fourier analyses of the resulting magnitude, colour and velocitycurves reveal periods consistent with the published principal periodof 0.223 day and its frequency 1 cpd aliases. Multiple frequencies areclearly evident, some of which correspond to p-mode oscillationsexpected by stellar pulsation models. Using Baade-Wesselink precepts,attempts are being made to describe the change in shape and luminosityof the star.Variable Analysis of Compact Sources in the Canadian Galactic PlaneSurvey, S. Wilder, and A. R. Taylor, University of Calgary, and L. A. Higgs,Herzberg Institute of AstrophysicsThe 1420 MHz radio continuum images from Canadian Galactic PlaneSurvey contain tens of thousands of compact radio sources in the planeof the Galaxy down to a flux density limit of about 1 mJy. Some fractionof these sources will be exotic Galactic radio emitters such as energeticbinary star systems, pulsars, and flare stars that can be identified byvariable radio flux. We are carrying out a sensitive search for variableradio sources by combined analysis of the CGPS radio images and theNorthern VLA Sky Survey, which has a similar radio continuum sensitivityand resolution to the CGPS. This variability search is an order ofmagnitude deeper than any previous survey for variable radio sourcesin the Galaxy. We present initial results of an analysis of about 5000sources in an 80 square degree sub-region of the CGPS. The nature ofthe population of radio continuum sources is further investigated bymeasurement of spectral indices by comparison with the WesterborkNorthern Sky Survey images at 327 MHz.Simulations of Planetary Transits of Stars in the Globular Cluster 47Tucanae, M.D. Williams, E.F. Milone, M. McClure, J. Kallrath and C.Stagg, University of CalgaryIn an attempt to answer some of the questions about planets withshort orbital periods, Gilliland et al. conducted an eight-day photometricsearch for planetary transits in the globular cluster 47 Tucanae. Forthe purposes of predicting lightcurves that may be observed, a databaseof lightcurves was constructed. The database spans systems withplanetary radii from half a Jupiter radius up to those of brown dwarfs.Since the problem of modelling the lightcurves of planetary transitsis similar to modelling the lightcurves of eclipsing binary stars, programsthat were originally designed for binary stars were used to model thethese systems. Two programs were used, the Wilson-Devinney (wd98k93)(Milone et al. 2000; Kallrath & Milone 1999) program and as an aid toconstructing an archive, the visualization package Binary Maker 2(Bradstreet 1993). In addition to predicting possible lightcurves, thedatabase will also be used to speed up the modelling of observed systemsby permitting the comparison of lightcurve properties such as thedepth and the width of observed transits with those already modeledto estimate the system parameters. The parameters of the planetarysystem can then be refined using the Wilson-Devinney code and themethod of differential corrections. The first observation of a planetarytransit was made for the star HD209458. Photometric data fromCharbonneau et al., and Henry et al., were used to determine theparameters, like planetary mass and radius, of the HD209458 system.This work was supported by grants to EFM from the U of C ResearchGrants Committee and NSERC.December / décembre 2000 JRASC251