Search Results - (Author, Cooperation:B. Altieri)

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  1. 1
    Latest Papers from Table of Contents or Articles in Press
  2. 2
    Latest Papers from Table of Contents or Articles in Press
  3. 3
  4. 4
    Staff View
    Publication Date:
    2013-05-24
    Publisher:
    Nature Publishing Group (NPG)
    Print ISSN:
    0028-0836
    Electronic ISSN:
    1476-4687
    Topics:
    Biology
    Chemistry and Pharmacology
    Medicine
    Natural Sciences in General
    Physics
    Published by:
    Latest Papers from Table of Contents or Articles in Press
  5. 5
    Staff View
    ISSN:
    1573-0794
    Keywords:
    C/1995 O1 Hale-Bopp ; comets ; infrared spectroscopy ; ISO
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Geosciences
    Physics
    Notes:
    Abstract Spectra of comet C/1995 O1 (Hale-Bopp) were obtained with the Infrared Space Observatory (ISO) at medium resolution with the grating spectrometer in the photometer (PHT-S) and/or at high resolution with the short wavelength spectrometer (SWS) and long wavelength spectrometer (LWS) in April 1996 (Crovisier et al., 1996), September–October 1996 (Crovisier et al., 1997a, b) and December 1997, at distances from the Sun of 4.6, 2.9 and 3.9 AU, respectively. For the first time, high-resolution spectra of a comet covering the entire 2.4 to 200 μm spectral range were obtained. The vibrational bands of H2O, CO2 and CO are detected in emission with PHT-S. Relative production rates of 100:22:70 are derived for H2O:CO2:CO at 3 AU pre-perihelion. H2O is observed at high spectral resolution in the ν3 group of bands around 2.7 μm and the ν2 group around 6 μm with SWS, and in several rotational lines in the 100–180 μm region with LWS. The high signal-to-noise ratio of the ν3 band observed on September–October 1996 allows accurate determinations of the water rotational temperature (28 K) and of its ortho-to-para ratio(2.45 ± 0.10, which significantly differs from the high temperature limit and corresponds to a spin temperature of 25 K). Longward of 6 μm the spectrum is dominated by dust thermal continuum emission, upon which broad emission features are superimposed. The wavelengths of the emission peaks correspond to those of Mg-rich crystalline olivine (forsterite). In the September–October 1996 spectra, emission features at 45 and 65 μm and possible absorption at 2.9–3.2 μm suggest that grains of water ice were present at 3 AU from the Sun. The observations made post-perihelion in late December 1997 led to the detections of H2O, CO2 and CO at 3.9 AU from the Sun (Figures 1 and 2). The production rates were ≈3.0 × 1028,3.5 × 1028 and ≈1.5 × 1029 s-1, respectively. This corresponds to H2O:CO2:CO = 100:110:500 and confirms that at such distances from the Sun, cometary activity is dominated by sublimation of CO and CO2 rather than by H2O.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  6. 6
    Staff View
    ISSN:
    1572-9508
    Keywords:
    infrared: general ; instrumentation: detectors ; techniques: photometric
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Physics
    Notes:
    Abstract An overview is given of the absolute flux calibration of the ISOCAMdetectors. The flux calibration is based on observations of standard stars selected from the Ground Based Preparatory Programme, for which Kurucz stellar models are available. No dependencies of the responsivity on different configurations of thecamera were found. No trend of changing responsivity is found throughout the mission for the SW and LW detectors. There exists a decreasing responsivity of about 5% for LW during the orbit.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses
  7. 7
    Staff View
    ISSN:
    1572-9508
    Source:
    Springer Online Journal Archives 1860-2000
    Topics:
    Physics
    Notes:
    Abstract We discuss the instrumental factors which constrain the sensitivity limits of the mid-infrared camera (ISOCAM) of ESA's Infrared Space Observatory (ISO). The observing strategy judged to be best suited to faint-source detection is described. A data analysis technique adapted to the extraction of the faintest point-sources is discussed. We report the application of these techniques to an extremely deep mid-IR observation of high redshift gravitationally lensed objects, in two filters, looking through a lensing galaxy cluster.
    Type of Medium:
    Electronic Resource
    URL:
    Articles: DFG German National Licenses