A search for starlight reflected from HD 75289b     

Christopher Leigh  rew Collier Cameron  Stephane Udry  Jean-François Donati  Keith Horne  David James  Alan Penny 《Monthly notices of the Royal Astronomical Society》2003,346(2):L16-L20

We have used a Doppler tomographic analysis to conduct a deep search for the starlight reflected from the planetary companion to HD 75289. In four nights on VLT(UT2)/UVES in 2003 January, we obtained 684 high-resolution echelle spectra with a total integration time of 26 h. We establish an upper limit on the geometric albedo of the planet   p < 0.12  (to the 99.9 per cent significance level) at the most probable orbital inclination   i ≃ 60°  , assuming a grey albedo, a Venus-like phase function and a planetary radius   R _p= 1.6 R_Jup  . We are able to rule out some combinations of the predicted planetary radius and atmospheric albedo models with high, reflective cloud decks.  相似文献   

Constraints on Jupiters from observations of Galactic bulge microlensing events during 2000     

Yiannis Tsapras †  Keith Horne  Richard Carson  Javier Méndez Alvarez  Dan Batcheldor  Alister W. Graham  Philip A. James  Johan Knapen  Hannah Quaintrell  Ignacio Gonzalez Serrano  Peter Sorensen  Nick Wooder 《Monthly notices of the Royal Astronomical Society》2002,337(1):41-48

We present observations of eight Galactic bulge microlensing events taken with the 1.0-m Jacobus Kapteyn Telescope (JKT) on La Palma during 2000 June and July. The JKT observing schedule was optimized using a prioritizing algorithm to automatically update the target list. For most of these events we have sampled the light curves at times where no information was available from the OGLE alert team. We assume a point-source point-lens (PSPL) model and perform a maximum likelihood fit to both our data and the OGLE data to constrain the event parameters of the fit. We then refit the data assuming a binary lens and proceed to calculate the probability of detecting planets with mass ratio   q = 10⁻³  . We have seen no clear signatures of planetary deviations on any of the eight events and we quantify constraints on the presence of planetary companions to the lensing stars. For two well-observed events, 2000BUL31 and 2000BUL33, our detection probabilities peak at ∼30 and ∼20 per cent respectively for   q = 10⁻³  and   a ∼ R _E  for a  Δχ²  threshold value of 60.  相似文献   

Effects of in situ target spatial distributions on acoustic density estimates     

Jech  J. Michael; Horne  John K. 《ICES Journal of Marine Science》2001,58(1):123-136

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Quasilongitudinal approximation for whistler-mode waves in the magnetospheric plasma     

S. S. Sazhin

R. B. Horne 《Planetary and Space Science》1990,38(12):1551-1553

The range of applicability of an improved quasilongitudinal approximation for whistler-mode waves in the equatorial magnetosphere (4 L 6.6) is specified based on the direct comparison between numerical solutions of the hot electromagnetic dispersion equation with the corresponding analytical quasilongitudinal solutions. It is pointed out that this approximation can be used at frequencies ω less than but not close to the electron gyrofrequency Ω (ω 0.6 Ω) and wave normal angles θ less than but not close to the resonance cone angle θ_R. At ω = 0.8 Ω the analytical results deviate considerably from numerical ones due to the strong damping of the waves, and so the quasilongitudinal solution becomes no longer valid.  相似文献   

Local Determination of Weak Anisotropy Parameters from Walkaway VSP qP-Wave Data in the Java Sea Region   总被引：1，自引：0，他引：1  

Gomes  E.  Zheng  X.  Pšenčík  I.  Horne  S.  Leaney  S. 《Studia Geophysica et Geodaetica》2004,48(1):215-231

We apply the inversion scheme of Zheng and Peník (2002) to the walkaway VSP data of Horne and Leaney (2000) collected in the Java Sea region. The goal is a local determination of parameters of the medium surrounding the borehole receiver array. The inversion scheme is based on linearized equations expressing qP-wave slowness and polarization vectors in terms of weak anisotropy (WA) parameters. It thus represents an alternative approach to Horne and Leaney (2000), who based their procedure on inversion of the Christoffel equation using a global optimization method. The presented inversion scheme is independent of structural complexities in the overburden and of the orientation of the borehole. The inverson formula is local, and has therefore potential to separate effects of anisotropy from effects of inhomogeneity. The data used are components of the slowness vector along the receiver array and polarization vectors. The inversion is performed without any assumptions concerning the remaining components of the slowness vector. The inversion is made (a) assuming arbitrary anisotropy, i.e., without any assumptions about symmetry of the medium, (b) assuming transverse isotropy with a vertical axis of symmetry and (c) assuming isotropy of the medium. Inverted are the raw data as well as data, in which weighting is used to reduce the effect of outliers. It is found that the WA parameters _z, ₁₅ and ₃₅ are considerably more stable than the parameters _x and _x. The latter two parameters are also found to be strongly correlated. Weaker correlation is also found between the mentioned two parameters and _z. The results of inversion show clearly that the studied medium is not isotropic. They also seem to indicate that the studied medium does not possess the VTI symmetry.  相似文献   

FRACTURE CHARACTERIZATION FROM NEAR-OFFSET VSP INVERSION     

Steve Horne  Colin MacBeth  J. Queen  W. Rizer  & V. Cox 《Geophysical Prospecting》1997,45(1):141-164

A global optimization method incorporating a ray-tracing scheme is used to invert observations of shear-wave splitting from two near-offset VSPs recorded at the Conoco Borehole Test Facility, Kay County, Oklahoma. Inversion results suggest that the seismic anisotropy is due to a non-vertical fracture system. This interpretation is constrained by the VSP acquisition geometry for which two sources are employed along near diametrically opposite azimuths about the well heads. A correlation is noted between the time-delay variations between the fast and slow split shear waves and the sandstone formations.  相似文献   

Turbulent separated flow over and downstream of a two-element airfoil     

D. Adair  W. C. Horne 《Mineralium Deposita》1993,28(4):531-541

Flow characteristics in the vicinity of the flap of a single-slotted airfoil are presented and analysed. The flow remained attached over the model surfaces except in the vicinity of the flap trailing edge where a small region of boundary-layer separation extended over the aft 7% of flap chord. The airfoil configuration was tested at a Mach number of 0.09 and a chord Reynolds number of 1.8 × 10⁶ in the NASA Ames Research Center 7- by 10-Foot Wind Tunnel. The flow was complicated by the presence of a strong, initially inviscid, jet, emanating from the slot between airfoil and flap, and a gradual merging of the main airfoil wake and flap suction-side boundary layer.Research Engineer, NRC Research AssociateAerospace Engineer  相似文献   

Kronos: a satellite for astrotomography     

B. M. Peterson  R. S. Polidan  K. Horne 《Astronomische Nachrichten》2004,325(3):257-257

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Goulden CE,Sitnikova T,Gelhaus J,Boldgiv B (eds): The geology,biodiversity and ecology of Lake Hövsgöl (Mongolia)     

David J. Horne 《Journal of Paleolimnology》2009,42(2):297-298

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Report of an Excursion to the Assynt district of the north-west Highlands: July 3rd to 11th, 1914     

John Horne 《Proceedings of the Geologists' Association. Geologists' Association》1915,26(2):127-IN5

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