6,845 research outputs found

    The cosmic ray spectrum above 10(17) eV

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    The final analysis of the data obtained by the Sydney University Giant Airshower Recorder (SUGAR) is presented. The data has been reanalysed to take into account the effects of afterpulsing in the photomultiplier tubes. Event data was used to produce a spectrum of equivalent vertical muon number and from this a model dependent primary energy spectrum was obtained. These spectra show good evidence for the Ankle: a flattening at 10(19) eV. There is no sign of the cut-off which would be expected from the effects of the universal black body radiation

    HATS-1b: The First Transiting Planet Discovered by the HATSouth Survey

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    We report the discovery of HATS-1b, a transiting extrasolar planet orbiting the moderately bright V=12.05 G dwarf star GSC 6652-00186, and the first planet discovered by HATSouth, a global network of autonomous wide-field telescopes. HATS-1b has a period P~3.4465 d, mass Mp~1.86MJ, and radius Rp~1.30RJ. The host star has a mass of 0.99Msun, and radius of 1.04Rsun. The discovery light curve of HATS-1b has near continuous coverage over several multi-day periods, demonstrating the power of using a global network of telescopes to discover transiting planets.Comment: Submitted to AJ 10 pages, 5 figures, 6 table

    Five New Transits of the Super-Neptune HD 149026

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    We present new photometry of HD 149026 spanning five transits of its "super-Neptune" planet. In combination with previous data, we improve upon the determination of the planet-to-star radius ratio: R_p/R_star = 0.0491^{+0.0018}_{-0.0005}. We find the planetary radius to be 0.71 +/- 0.05 R_Jup, in accordance with previous theoretical models invoking a high metal abundance for the planet. The limiting error is the uncertainty in the stellar radius. Although we find agreement among four different ways of estimating the stellar radius, the uncertainty remains at 7%. We also present a refined transit ephemeris and a constraint on the orbital eccentricity and argument of pericenter, e cos(omega) = -0.0014 +/- 0.0012, based on the measured interval between primary and secondary transits.Comment: To appear in ApJ [19 pages

    Model of real-time automation and control systems for combined sewers

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    CER72-73WB-CBW-GLS41.Includes bibliographical references (page 79).Supported by OWRR grant number 14-31-0001-3410, project no. C-2207 from funds provided by the U.S. Dept. of Interior as authorized under the Water Resources Act of 1964, Public Law 88-379, as amended.Supported by OWRR grant number 14-31-0001-3410, project no. C-2207

    Cytogenetic variability in radiation induced mouse leukaemia.

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    C57BL mice and certain of their hybrids have a high incidence of radiation induced leukaemia. The incidence is greater than 70 % in (C57BL x CBA.T6T6)F1 hybrids aged between 30 and 40 days receiving 4 fractions of 200 rads gamma radiation at 4-day intervals (Ilbery, 1967). The great majority of primary reticular neoplasms arising in irradiated mice show a variation in chromosome number in the range 41 to 45 and distinctive new marker chromosomes are often present (Ford, Hamerton and Mole, 1958). It has been suggested that karyotypic alterations are of primary significance in the onset of neoplasia (Winge, 1930) but more probably there is an association for such changes with tumour progression (Hauschka, 1961). Nevertheless from cytogenetic studies of the thymus in the preleukaemic phase it seems that observable variations in chromosome number and form accompany an early stage of leukaemia induction (Ilbery et al., 1963; Joneja and Stich, 1965). This report is concerned with the cytogenetic results of mice involved in radiation experiments during the last 5 years and who subsequently exhibited macroscopically leukaemia of the thymic type. Thymomas were passaged so that, where for technical reasons examination ofthe primary neoplasm failed, subsequent sampling of the malignant cells could be made in the passage mice. Cytogenetic results of a total of 43 radiation induced leukaemias are recorded of which 26 were sampled from the propositi. A related paper will give the cytogenetic results of mice exposed to the leukaemogenic effects of radiation and in which attempts were made, by the administration of cell supplements, to modify or prevent the onset of leukaemia. MATERIALS AND METHODS Mice of both sexes between 30 and 40 days of age at the time of irradiation were used in the leukaemia induction experiments. The inbred strains employed were C57BL, CBA, DBA and T6T6 all maintained in this laboratory by selective inbreeding during the last 10 years. CBA/H and CBA.T6T6 have been inbred a further 12 and 9 generations respectively in this laboratory since the importation in 1963 of these syngeneic mice from Dr. Mary Lyon of the M.R.C. Radiobiologica

    Confirmation of two extended objects along the line of sight to PKS1830-211 with ESO-VLT adaptive optics imaging

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    We report on new high-resolution near-infrared images of the gravitationally lensed radio source PKS1830-211, a quasar at z=2.507. These adaptive optics observations, taken with the Very Large Telescope (VLT), are further improved through image deconvolution. They confirm the presence of a second object along the line of sight to the quasar, in addition to the previously known spiral galaxy. This additional object is clearly extended in our images. However, its faint luminosity does not allow to infer any photometric redshift. If this galaxy is located in the foreground of PKS1830-211, it complicates the modeling of this system and decreases the interest in using PKS1830-211 as a means to determine H0 via the time delay between the two lensed images of the quasar.Comment: Accepted in A&A Letter

    The central image of a gravitationally lensed quasar

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    A galaxy can act as a gravitational lens, producing multiple images of a background object. Theory predicts there should be an odd number of images but, paradoxically, almost all observed lenses have 2 or 4 images. The missing image should be faint and appear near the galaxy's center. These ``central images'' have long been sought as probes of galactic cores too distant to resolve with ordinary observations. There are five candidates, but in one case the third image is not necessarily a central image, and in the others, the central component might be a foreground source rather than a lensed image. Here we report the most secure identification of a central image, based on radio observations of PMN J1632-0033, one of the latter candidates. Lens models incorporating the central image show that the mass of the lens galaxy's central black hole is less than 2 x 10^8 M_sun, and the galaxy's surface density at the location of the central image is more than 20,000 M_sun per square parsec, in agreement with expectations based on observations of galaxies hundreds of times closer to the Earth.Comment: Nature, in press [7 pp, 2 figs]. Standard media embargo applies before publicatio

    Observation of the full 12-hour-long transit of the exoplanet HD80606b. Warm-Spitzer photometry and SOPHIE spectroscopy

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    We present new observations of a transit of the 111-day-period exoplanet HD80606b. Using the Spitzer Space Telescope and its IRAC camera on the post-cryogenic mission, we performed a 19-hour-long photometric observation of HD80606 that covers the full transit of 13-14 January 2010. We complement this photometric data by new spectroscopic observations that we simultaneously performed with SOPHIE at Haute-Provence Observatory. This provides radial velocity measurements of the first half of the transit that was previously uncovered with spectroscopy. This new data set allows the parameters of this singular planetary system to be significantly refined. We obtained a planet-to-star radius ratio R_p/R_* = 0.1001 +/- 0.0006 that is slightly lower than the one measured from previous ground observations. We detected a feature in the Spitzer light curve that could be due to a stellar spot. We also found a transit timing about 20 minutes earlier than the ephemeris prediction; this could be caused by actual TTVs due to an additional body in the system or by underestimated systematic uncertainties. The sky-projected angle between the spin-axis of HD80606 and the normal to the planetary orbital plane is found to be lambda = 42 +/- 8 degrees thanks to the fit of the Rossiter-McLaughlin anomaly. This allows scenarios with aligned spin-orbit to be definitively rejected. Over the twenty planetary systems with measured spin-orbit angles, a few of them are misaligned; this is probably the signature of two different evolution scenarios for misaligned and aligned systems, depending if they experienced or not gravitational interaction with a third body. As in the case of HD80606b, most of the planetary systems including a massive planet are tilted; this could be the signature of a separate evolution scenario for massive planets in comparison with Jupiter-mass planets.Comment: 14 pages, 9 figures, 2 tables, accepted for publication in A&

    Searching for Star-Planet interactions within the magnetosphere of HD 189733

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    HD 189733 is a K2 dwarf, orbited by a giant planet at 8.8 stellar radii. In order to study magnetospheric interactions between the star and the planet, we explore the large-scale magnetic field and activity of the host star. We collected spectra using the ESPaDOnS and the NARVAL spectropolarimeters, installed at the 3.6-m Canada-France-Hawaii telescope and the 2-m Telescope Bernard Lyot at Pic du Midi, during two monitoring campaigns (June 2007 and July 2008). HD 189733 has a mainly toroidal surface magnetic field, having a strength that reaches up to 40 G. The star is differentially rotating, with latitudinal angular velocity shear of domega = 0.146 +- 0.049 rad/d, corresponding to equatorial and polar periods of 11.94 +- 0.16 d and 16.53 +- 2.43 d respectively. The study of the stellar activity shows that it is modulated mainly by the stellar rotation (rather than by the orbital period or the beat period between the stellar rotation and the orbital periods). We report no clear evidence of magnetospheric interactions between the star and the planet. We also extrapolated the field in the stellar corona and calculated the planetary radio emission expected for HD 189733b given the reconstructed field topology. The radio flux we predict in the framework of this model is time variable and potentially detectable with LOFAR

    Interferometric Phase Calibration Sources in the Declination Range 0deg to -30deg

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    We present a catalog of 321 compact radio sources in the declination range 0deg > delta > -30deg. The positions of these sources have been measured with a two-dimensional rms accuracy of 35 milliarcseconds using the NRAO Very Large Array. Each source has a peak flux density >50 mJy at 8.4 GHz. We intend for this catalog to be used mainly for selection of phase calibration sources for radio interferometers, although compact radio sources have other scientific uses.Comment: 9 pages. To appear in ApJS. Catalog (Table 3) is abbreviated in printed version. Complete catalog available at ftp://ftp.aoc.nrao.edu/pub/staff/jwrobel/WPW2003_ApJS.tx
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