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See detailA study of the distant activity of comet C/2006 W3 (Christensen) with Herschel and ground-based radio telescopes
Bockelée-Morvan, D.; Hartogh, P.; Crovisier, J. et al

in Astronomy and Astrophysics (2010), 518(Letters), 1491-6

Comet C/2006 W3 (Christensen) was observed in November 2009 at 3.3 AU from the Sun with Herschel.The PACS instrument acquired images of the dust coma in 70-μm and 160-μm filters and spectra covering ... [more ▼]

Comet C/2006 W3 (Christensen) was observed in November 2009 at 3.3 AU from the Sun with Herschel.The PACS instrument acquired images of the dust coma in 70-μm and 160-μm filters and spectra covering several H[SUB]2[/SUB]O rotational lines. Spectra in the range 450-1550 GHz were acquired with SPIRE. The comet emission continuum from 70 to 672 μm was measured, but no lines were detected. The spectral energy distribution indicates thermal emission from large particles and provides a measure of the size distribution index and dust production rate. The upper limit to the water production rate is compared to the production rates of other species (CO, CH[SUB]3[/SUB]OH, HCN, H[SUB]2[/SUB]S, OH) measured with the IRAM 30-m and Nançay telescopes. The coma is found to be strongly enriched in species more volatile than water, in comparison to comets observed closer to the Sun. The CO to H[SUB]2[/SUB]O production rate ratio exceeds 220%. The dust-to-gas production rate ratio is on the order of 1. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Figures 2, 5, 6 are only available in electronic form at <A href="http://www.aanda.org">http://www.aanda.org</A> [less ▲]

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See detailFirst results of Herschel-PACS observations of Neptune
Lellouch, E.; Hartogh, P.; Feuchtgruber, H. et al

in Astronomy and Astrophysics (2010), 518

We report on the initial analysis of a Herschel-PACS full range spectrum of Neptune, covering the 51-220 μm range with a mean resolving power of ~3000, and complemented by a dedicated observation of CH ... [more ▼]

We report on the initial analysis of a Herschel-PACS full range spectrum of Neptune, covering the 51-220 μm range with a mean resolving power of ~3000, and complemented by a dedicated observation of CH[SUB]4[/SUB] at 120 μm. Numerous spectral features due to HD (R(0) and R(1)), H[SUB]2[/SUB]O, CH[SUB]4[/SUB], and CO are present, but so far no new species have been found. Our results indicate that (i) Neptune's mean thermal profile is warmer by ~3 K than inferred from the Voyager radio-occultation; (ii) the D/H mixing ratio is (4.5 ± 1) × 10[SUP]-5[/SUP], confirming the enrichment of Neptune in deuterium over the protosolar value (~2.1 × 10[SUP]-5[/SUP]); (iii) the CH[SUB]4[/SUB] mixing ratio in the mid stratosphere is (1.5 ± 0.2) × 10[SUP]-3[/SUP], and CH[SUB]4[/SUB] appears to decrease in the lower stratosphere at a rate consistent with local saturation, in agreement with the scenario of CH[SUB]4[/SUB] stratospheric injection from Neptune's warm south polar region; (iv) the H[SUB]2[/SUB]O stratospheric column is (2.1 ± 0.5) × 10[SUP]14[/SUP] cm[SUP]-2[/SUP] but its vertical distribution is still to be determined, so the H[SUB]2[/SUB]O external flux remains uncertain by over an order of magnitude; and (v) the CO stratospheric abundance is about twice the tropospheric value, confirming the dual origin of CO suspected from ground-based millimeter/submillimeter observations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. [less ▲]

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See detailThe Herschel-SPIRE submillimetre spectrum of Mars
Swinyard, B. M.; Hartogh, P.; Sidher, S. et al

in Astronomy and Astrophysics (2010), 518

We have obtained the first continuous disk averaged spectrum of Mars from 450 to 1550 Ghz using the Herschel-SPIRE Fourier-transform spectrometer. The spectrum was obtained at a constant resolution of 1.4 ... [more ▼]

We have obtained the first continuous disk averaged spectrum of Mars from 450 to 1550 Ghz using the Herschel-SPIRE Fourier-transform spectrometer. The spectrum was obtained at a constant resolution of 1.4 GHz across the whole band. The flux from the planet is such that the instrument was operated in “bright source” mode to prevent saturation of the detectors. This was the first successful use of this mode and in this work we describe the method used for observing Mars together with a detailed discussion of the data reduction techniques required to calibrate the spectrum. We discuss the calibration accuracy obtained and describe the first comparison with surface and atmospheric models. In addition to a direct photometric measurement of the planet the spectrum contains the characteristic transitions of [SUP]12[/SUP]CO from J 5-4 to J 13-12 as well as numerous H[SUB]2[/SUB]O transitions. Together these allow the comparison to global atmospheric models allowing the mean mixing ratios of water and [SUP]12[/SUP]CO to be investigated. We find that it is possible to match the observed depth of the absorption features in the spectrum with a fixed water mixing ratio of 1×10[SUP]-4[/SUP] and a [SUP]12[/SUP]CO mixing ratio of 9×10[SUP]-4[/SUP]. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. [less ▲]

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See detailA study of the distant activity of comet C/2006 W3 (Christensen) using Herschel and ground-based radio telescopes
Bockelée-Morvan, D.; Hartogh, P.; Crovisier, J. et al

Poster (2010)

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