44 research outputs found

    A close look into the carbon disk at the core of the planetary nebula CPD-568032

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    We present high spatial resolution observations of the dusty core of the Planetary Nebula with Wolf-Rayet central star CPD-568032. These observations were taken with the mid-infrared interferometer VLTI/MIDI in imaging mode providing a typical 300 mas resolution and in interferometric mode using UT2-UT3 47m baseline providing a typical spatial resolution of 20 mas. The visible HST images exhibit a complex multilobal geometry dominated by faint lobes. The farthest structures are located at 7" from the star. The mid-IR environment of CPD-568032 is dominated by a compact source, barely resolved by a single UT telescope in a 8.7 micron filter. The infrared core is almost fully resolved with the three 40-45m projected baselines ranging from -5 to 51 degree but smooth oscillating fringes at low level have been detected in spectrally dispersed visibilities. This clear signal is interpreted in terms of a ring structure which would define the bright inner rim of the equatorial disk. Geometric models allowed us to derive the main geometrical parameters of the disk. For instance, a reasonably good fit is reached with an achromatic and elliptical truncated Gaussian with a radius of 97+/-11 AU, an inclination of 28+/-7 degree and a PA for the major axis at 345+/-7 degree. Furthermore, we performed some radiative transfer modeling aimed at further constraining the geometry and mass content of the disk, by taking into account the MIDI dispersed visibilities, spectra, and the large aperture SED of the source. These models show that the disk is mostly optically thin in the N band and highly flared.Comment: Paper accepted in A&

    Characterisation of Long Baseline Calibrators at 2.3 GHz

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    We present a detailed multi-epoch analysis of 31 potential southern hemisphere radio calibrators that were originally observed as part of a program to maintain the International Celestial Reference Frame (ICRF). At radio wavelengths, the primary calibrators are Active Galactic Nuclei (AGN), powerful radio emitters which exist at the centre of most galaxies. These are known to vary at all wavelengths at which they have been observed. By determining the amount of radio source structure and variability of these AGN, we determine their suitability as phase calibrators for long baseline radio interferometry at 2.3 GHz. For this purpose, we have used a set of complementary metrics to classify these 31 southern sources into five categories pertaining to their suitability as VLBI calibrators. We find that all of the sources in our sample would be good interferometric calibrators and almost ninety per cent would be very good calibrators.Comment: 9 pages, 7 Figures, accepted MNRA

    When "IVS Live" meets "e-RemoteCtrl" real-time data ...

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    VLBI2010 imaging and structure corrections

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    The Bordeaux VLBI Image Database

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    Proceedings of the 11th European VLBI Network Symposium & Users Meeting, 9-12 October 2012, Bordeaux - France

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    International audienceThe conference highlighted the latest scientific results and technical developments from VLBI, space VLBI and e-VLBI. All fields of astrophysics were concerned - stellar, galactic and extragalactic - as well as astrometry and planetary science. Presentations addressing synergy between (e-)VLBI and other new or planned radio facilities (ALMA, LOFAR, e-MERLIN,...) or instruments at other wavelengths (Fermi, CTA, Gaia,...) were also an integral part of the program. The scientific program was organized in 11 sessions including 71 oral presentations, with an additional 43 posters available for viewing during the entire length of the conference. An EVN Users Meeting was also held during one of the evening to foster interaction between the EVN users and the EVN organization. The symposium was attended by a total of 122 delegates originating from 47 institutes world-wide, sharing new VLBI science and innovations while also building links with other communities

    A Programmable VLBI Image Model-Fitting Pipeline

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