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See detailHerschel observations of gas and dust in comet C/2006 W3 (Christensen) at 5 AU from the Sun
de Val-Borro, M; Bockelée-Morvan, D; Jehin, Emmanuel ULg et al

in Astronomy and Astrophysics (2014)

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See detailEPOXI: Comet 103P/Hartley 2 Observations from a Worldwide Campaign
Meech, K. J.; A'Hearn, M. F.; Adams, J. A. et al

in Astrophysical Journal (2011), 734(Letters), 11-9

Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible ... [more ▼]

Earth- and space-based observations provide synergistic information for space mission encounters by providing data over longer timescales, at different wavelengths and using techniques that are impossible with an in situ flyby. We report here such observations in support of the EPOXI spacecraft flyby of comet 103P/Hartley 2. The nucleus is small and dark, and exhibited a very rapidly changing rotation period. Prior to the onset of activity, the period was ~16.4 hr. Starting in 2010 August the period changed from 16.6 hr to near 19 hr in December. With respect to dust composition, most volatiles and carbon and nitrogen isotope ratios, the comet is similar to other Jupiter-family comets. What is unusual is the dominance of CO[SUB]2[/SUB]-driven activity near perihelion, which likely persists out to aphelion. Near perihelion the comet nucleus was surrounded by a large halo of water-ice grains that contributed significantly to the total water production. [less ▲]

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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 detailObservations of Comet 73P/SW3 close to its closest approach to the Earth.
Tozzi, G. P.; Bagnulo, S.; Boehnhardt, H. et al

in European Planetary Science Congress 2006 (2006)

In May 2006 comet 73P/SW3 passed at less than 0.1 AU from Earth providing us an unique opportunity for high spatial resolution study of its coma. This event was expected to be particularly interesting ... [more ▼]

In May 2006 comet 73P/SW3 passed at less than 0.1 AU from Earth providing us an unique opportunity for high spatial resolution study of its coma. This event was expected to be particularly interesting because the comet had broken apart in 3-4 fragments in 1996. The 2006 apparition has been even more interesting because the fragments produced in 1996, when approaching the Sun, were continuously breaking apart. This process resulted in many small sub-fragments and in the injection in the coma of fresh material, coming from the interior of the nuclei, giving the possibility to study this uncontaminated material. The breaking fragments have been observed at ESO in the visible and near-IR with the aim of analyzing this fresh solid component of the coma in search of possible presence of organic solids. In the presentation we will report preliminary results of this campaign. [less ▲]

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See detailComet C/2001 Q4 (NEAT) at its closest approach to the Earth
Tozzi, G. P.; Boehnhardt, H.; Del Bo, M. et al

in American Astronomical Society, DPS meeting #36 (2004, November 01)

Comet C/2001 Q4 (NEAT) was observed at ESO (La Silla) for three consecutive nights at the beginning of May, 2004 at its closest approach to Earth. The observations consisted of quasi-simultaneous multi ... [more ▼]

Comet C/2001 Q4 (NEAT) was observed at ESO (La Silla) for three consecutive nights at the beginning of May, 2004 at its closest approach to Earth. The observations consisted of quasi-simultaneous multi-wavelength exposures in the visible, near-IR and thermal-IR in order to study different properties of the solid component that are responsible for the scattering and emission of radiation in different spectral ranges. The comet was observed with the 3.6m telescope, equipped with TIMMI2 for the thermal-IR region, the NTT, equipped with EMMI and SOFI for the visible and near-IR regions. Narrow band images and long slit spectra were recorded for each spectral region. In the near-IR range, polarimetric observations were also performed during the last night. The aim of the observations was the characterization of the solid component at small scalelength to search for possible short lifetime organic components, as those found in the comet C/2000 WM1 (Tozzi et al., 2004, A&A, 424, 235), dust fragmentation etc.. Here we report preliminary results of the analysis of these observations. [less ▲]

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