Spurious Eccentricities of Distorted Binary Components

I discuss the effect of physical distortion on the velocities of close binary components and how we may use the resulting distortion of velocity curves to constrain some properties of binary systems, such as inclination and mass ratio. Precise new velocities for 5 Cet convincingly detect these distortions with their theoretically predicted phase dependence. We can even use such distortions of velocity curves to test Lucy's theory of convective gravity darkening. The observed distortions for TT Hya and 5 Cet require the contact components of those systems to be gravity darkened, probably somewhat more than predicted by Lucy's theory but clearly not as much as expected for a radiative star. These results imply there is no credible evidence for eccentric orbits in binaries with contact components. I also present some speculative analyses of the observed properties of a binary encased in a non-rotating common envelope, if such an object could actually exist, and discuss how the limb darkening of some recently calculated model atmospheres for giant stars may bias my resuts for velocity-curve distortions, as well as other results from a wide range of analyses of binary stars.Comment: 14 pp, 2 tables, 12 fig; under review by Ap

Artifacts and Their Functions

How do artifacts get their functions? It is typically thought that an artifact’s function depends on its maker’s intentions. This chapter argues that this common understanding is fatally flawed. Nor can artifact function be understood in terms of current uses or capacities. Instead, it proposes that we understand artifact function on the etiological model that Ruth Millikan and others have proposed for the biological realm. This model offers a robustly normative conception of function, but it does so naturalistically by employing our best scientific theories, in particular natural selection. To help make this case, it proposes “living artifacts” (organisms designed for human purposes through artificial selection) as a bridge between the artifactual and the biological realms

The Altitude Effect on Air Speed Indicators II

In an investigation described in NACA Technical Report 110, it was shown that under certain conditions, particularly for the relatively low-speed flight of airships, the data obtained were not sufficiently accurate. This report describes an investigation in which the data obtained were sufficiently accurate and complete to enable the viscosity correction to be deduced quantitatively for a number of the air-speed pressure nozzles in common use. The report opens with a discussion of the theory of the performance of air-speed nozzles and of the calibration of the indicators, from which the theory of the altitude correction is developed. Then follows the determination of the performance characteristics of the nozzles and calibration constants used for the indicators. In the latter half of the report, the viscosity correction is computed for the Zahm Pitot-venturi nozzles

New insights into the lithosphere beneath the Superior Province from Rayleigh wave dispersion and receiver function analysis

We study the azimuthally anisotropic upper-mantle structure of the Superior Craton and Grenville Province in Ontario, Canada, using Rayleigh wave phase-velocity data in the period range 40–160 s. 152 two-station dispersion measurements are combined in a tomographic inversion that solves simultaneously for isotropic and anisotropic terms using a least-squares technique. We perform a series of tests to derive optimal regularization (smoothing and damping) and to assess the resolution of, and trade-offs between, isotropic and anisotropic anomalies. The tomographic inversion is able to resolve isotropic phase-velocity anomalies on a scale of 200-300 km and to distinguish between different anisotropic regimes on a 500-km scale across the study region.\ud \ud Isotropic phase-velocity anomalies in the tomographic model span a range of up to ±2 per cent around a regional average which is similar to the Canadian Shield dispersion curve of Brune & Dorman (1963), with phase velocities up to 3 per cent above global reference models. The amplitude of azimuthal phase-velocity anisotropy reaches a maximum of ∼1.2 per cent. A clear east–west division of the study area, based on both isotropic phase-velocity anomalies and azimuthal anisotropy, is apparent.\ud \ud In the western Superior, isotropic phase velocities are generally higher than the regional average. Anisotropy is observed at all periods, with ENE–WSW to NE–SW fast-propagation directions. At periods ≤120 s, the anisotropy likely results from frozen lithospheric fabric aligned with tectonic boundaries, whereas the anisotropy at longer periods is interpreted to arise from present-day sublithospheric flow. The fast directions from published SKS measurements are close to the fast Rayleigh wave propagation directions throughout the period range sampled, and the large SKS splitting times may be accounted for by this near-coincidence of fast-propagation directions. Across most of eastern Ontario, phase velocities are lower than the regional average. Fast-propagation directions rotate from ∼NW–SE at 40–130 s period to WNW–ESE at periods 140–160 s. The results suggest a difference in fast-propagation directions between the anisotropic fabric frozen into the lithosphere and the fabric due to current and recent sublithospheric flow.\ud \ud The Superior Craton and Grenville Province are characterized by large-scale structural variations that reflect the complex tectonic history of the region. This study highlights differences between the characteristics of eastern and western Ontario and indicates the occurrence of multiple layers of anisotropy in the subcratonic upper mantle

Numerical simulations of mixed states quantum computation

We describe quantum-octave package of functions useful for simulations of quantum algorithms and protocols. Presented package allows to perform simulations with mixed states. We present numerical implementation of important quantum mechanical operations - partial trace and partial transpose. Those operations are used as building blocks of algorithms for analysis of entanglement and quantum error correction codes. Simulation of Shor's algorithm is presented as an example of package capabilities.Comment: 6 pages, 4 figures, presented at Foundations of Quantum Information, 16th-19th April 2004, Camerino, Ital

The Hudson Bay Lithospheric Experiment (HuBLE) : Insights into Precambrian Plate Tectonics and the Development of Mantle Keels

The UK component of HuBLE was supported by Natural Environment Research Council (NERC) grant NE/F007337/1, with financial and logistical support from the Geological Survey of Canada, Canada–Nunavut Geoscience Office, SEIS-UK (the seismic node of NERC), and First Nations communities of Nunavut. J. Beauchesne and J. Kendall provided invaluable assistance in the field. Discussions with M. St-Onge, T. Skulski, D. Corrigan and M. Sanborne-Barrie were helpful for interpretation of the data. D. Eaton and F. A. Darbyshire acknowledge the Natural Sciences and Engineering Research Council. Four stations on the Belcher Islands and northern Quebec were installed by the University of Western Ontario and funded through a grant to D. Eaton (UWO Academic Development Fund). I. Bastow is funded by the Leverhulme Trust. This is Natural Resources Canada Contribution 20130084 to its Geomapping for Energy and Minerals Program. This work has received funding from the European Research Council under the European Unions Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement no. 240473 ‘CoMITAC’.Peer reviewedPublisher PD

Orbits and Pulsations of the Classical ζ Aurigae Binaries

We have derived new orbits for ζ Aur, 32 Cyg, and 31 Cyg with observations from the Tennessee State University (TSU) Automatic Spectroscopic Telescope, and used them to identify nonorbital velocities of the cool supergiant components of these systems. We measure periods in those deviations, identify unexpected long-period changes in the radial velocities, and place upper limits on the rotation of these stars. These radial-velocity variations are not obviously consistent with radial pulsation theory, given what we know about the masses and sizes of the components. Our concurrent photometry detected the nonradial pulsations driven by tides (ellipsoidal variation) in both ζ Aur and 32 Cyg, at a level and phasing roughly consistent with simple theory to first order, although they seem to require moderately large gravity darkening. However, the K component of 32 Cyg must be considerably bigger than expected, or have larger gravity darkening than ζ Aur, to fit its amplitude. However, again there is precious little evidence for the normal radial pulsation of cool stars in our photometry. Hα shows some evidence for chromospheric heating by the B component in both ζ Aur and 32 Cyg, and the three stars show among them a meager ~2-3 outbursts in their winds of the sort seen occasionally in cool supergiants. We point out two fundamental questions in the interpretation of these stars: (1) whether it is appropriate to model the surface brightness as gravity darkening and (2) whether much of the nonorbital velocity structure may actually represent changes in the convective flows in the stars\u27 atmospheres

Random Spots on Chromospherically Active Stars

We have investigated the effect of large numbers of moderately sized spots placed randomly on a differentially rotating star as the explanation of the rotational light curves of magnetically active cool stars. This hypothesis produces light variation very similar to observed light curves of RS CVn binaries, provided there are of order 10-40 spots at any time and provided individual spots have a finite lifetime

The Rotation Period of the Planet-Hosting Star HD 189733

We present synoptic optical photometry of HD 189733, the chromospherically active parent star of one of the most intensively studied exoplanets. We have significantly extended the timespan of our previously reported observations and refined the estimate of the stellar rotation period by more than an order of magnitude: $P = 11.953\pm 0.009$ days. We derive a lower limit on the inclination of the stellar rotation axis of 56\arcdeg (with 95% confidence), corroborating earlier evidence that the stellar spin axis and planetary orbital axis are well aligned.Comment: To appear in A