A survey of volatile species in Oort cloud comets C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR) at millimeter wavelengths
| Autor: | C. Jarchow, Dominique Bockelée-Morvan, Paul Hartogh, M. Küppers, M. de Val-Borro, Geronimo L. Villanueva, Ladislav Rezac, Jacques Crovisier, Nicolas Biver |
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| Přispěvatelé: | Max-Planck-Institut für Sonnensystemforschung (MPS), Max-Planck-Gesellschaft, Operations Department (ESAC), European Space Astronomy Centre (ESAC), European Space Agency (ESA)-European Space Agency (ESA), Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), NASA Goddard Space Flight Center (GSFC), Max-Planck-Institut für Sonnensystemforschung = Max Planck Institute for Solar System Research (MPS), Agence Spatiale Européenne = European Space Agency (ESA)-Agence Spatiale Européenne = European Space Agency (ESA) |
| Jazyk: | angličtina |
| Rok vydání: | 2013 |
| Předmět: |
Physics
Earth and Planetary Astrophysics (astro-ph.EP) [PHYS]Physics [physics] Solar System 010504 meteorology & atmospheric sciences Comet FOS: Physical sciences Astronomy and Astrophysics Rotational temperature Astrophysics 01 natural sciences Wavelength 13. Climate action Space and Planetary Science 0103 physical sciences Mixing ratio Millimeter Spectroscopy [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph] 010303 astronomy & astrophysics ComputingMilieux_MISCELLANEOUS 0105 earth and related environmental sciences Line (formation) Astrophysics - Earth and Planetary Astrophysics |
| Zdroj: | Astronomy and Astrophysics-A&A Astronomy and Astrophysics-A&A, EDP Sciences, 2013, 559, pp.A48. ⟨10.1051/0004-6361/201322284⟩ Astronomy and Astrophysics-A&A, 2013, 559, pp.A48. ⟨10.1051/0004-6361/201322284⟩ |
| ISSN: | 0004-6361 |
| Popis: | The line emission in the coma was measured in the comets C/2001 Q4 (NEAT) and C/2002 T7 (LINEAR), that were observed on five consecutive nights, 7-11 May 2004, at heliocentric distances of 1.0 and 0.7 AU, respectively, by means of high-resolution spectroscopy using the 10-m Submillimeter Telescope (SMT). We present a search for six parent- and product-volatile species (HCN, H2CO, CO, CS, CH3OH, and HNC) in both comets. Multiline observations of the CH3OH J = 5-4 series allow us to estimate the rotational temperature using the rotation diagram technique. We derive rotational temperatures of 54(9) K for C/2001 Q4 (NEAT) and 119(34) K for C/2002 T7 (LINEAR) that are roughly consistent with observations of other comets at similar distances from the Sun. The gas production rates of material are computed using a spherically symmetric molecular excitation code that includes collisions between neutrals and electrons. We find an HCN production rate of 2.96(5)e26 molec.s-1 for comet C/2001 Q4 (NEAT), corresponding to a mixing ratio with respect to H2O of 1.12(2)e-3. The mean HCN production rate during the observing period is 4.54(10)e26 molec.s-1 for comet C/2002 T7 (LINEAR), which gives a Q_HCN/Q_H2O mixing ratio of 1.51(3)e-3. With systematically lower mixing ratios in comet C/2001 Q4 (NEAT), production rate ratios of the observed species with respect to H2O lie within the typical ranges of dynamically new comets in both objects. We find a relative low abundance of CO in C/2001 Q4 (NEAT) compared to the observed range in other comets based on millimeter/submillimeter observations, and a significant upper limit on the CO production in C/2002 T7 (LINEAR) is derived. Depletion of CO suggests partial evaporation from the surface layers during previous visits to the outer Solar System and agrees with previous measurements of dynamically new comets. 20 pages, 18 figures. Minor changes to match the published version |
| Databáze: | OpenAIRE |
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