The Subsurface Structure and Density of Cometary Nuclei

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• 作者：P. L. Lamy ; A. Herique ; I. Toth
• 关键词：Comets ; nucleus ; Comets ; nucleus surface ; Radar ; comets ; Comets ; individual ; 2P/Encke ; 8P/Tuttle ; 26P/Grigg ; Skjellerup ; 67P/Churyumov ; Gerasimenko ; 103P/Hartley 2 ; C/1983 H1 (IRAS ; Araki ; Alcock) ; C/1983 J1 (Sugano ; Saigusa ; Fujikawa)
• 刊名：Space Science Reviews
• 出版年：2015
• 出版时间：December 2015
• 年：2015
• 卷：197
• 期：1-4
• 页码：85-99
• 全文大小：1,376 KB
• 参考文献：M.F. A’Hearn, Deep impact and the origin and evolution of cometary nuclei. Space Sci. Rev. 138, 237-46 (2008) CrossRef ADS
  W.J. Altenhoff, J.H. Bieging, B. Butler, H.M. Butner, R. Chini et al., Coordinated radio continuum observations of comets Hyakutake and Hale-Bopp from 22 to 860 GHz. Astron. Astrophys. 348, 1020-034 (1999) ADS
  E. Asphaug, W. Benz, Size, density, and structure of Comet Shoemaker-Levy 9 inferred from the physics of tidal breakup. Icarus 121, 225-48 (1996) CrossRef ADS
  M.J.S. Belton, P. Thomas, J. Veverka, P. Schultz, M.F. A’Hearn et al., The internal structure of Jupiter family cometary nuclei from deep impact observations: The “talps-or “layered pile-model. Icarus 187, 332-44 (2007) CrossRef ADS
  H. Boehnhardt, Split comets, in Comets II, ed. by M.C. Festou, H.U. Keller, H.A. Weaver (University of Arizona Press, Tucson, 2004), pp. 301-16
  M.J. Campbell, J. Ulrichs, Electrical properties of rocks and their significance for lunar radar observations. J. Geophys. Res. B, Solid Earth Planets 74, 5867-881 (1969) CrossRef
  D.B. Campbell, J.K. Harmon, A.A. Hine, I.I. Shapiro, B.G. Marsden, G.H. Pettengill, Arecibo radar observations of comets IRAS-Araki-Alcock and Sugano-Saigusa-Fujikawa (Invited). Bull. Am. Astron. Soc. 15, 800 (1983) ADS
  B.J.R. Davidsson, P.J. Gutiérrez, Estimating the nucleus density of Comet 19P/Borrelly. Icarus 168, 392-08 (2004) CrossRef ADS
  B.J.R. Davidsson, P.J. Gutiérrez, Non-gravitational force modeling of Comet 81P/Wild 2. I. A nucleus bulk density estimate. Icarus 180, 224-42 (2006) CrossRef ADS
  B.J.R. Davidsson, P.J. Gutiérrez, H. Rickman, Nucleus properties of Comet 9P/Tempel 1 estimated from non-gravitational force modeling. Icarus 191, 547-61 (2007) CrossRef ADS
  B. Donn, D.W. Hughes, Characteristics and implications of a comet nucleus formed by random grain accretion. Bull. Am. Astron. Soc. 17, 689 (1985) ADS
  T.L. Farnham, A.L. Cochran, A McDonald observatory study of Comet 19P/Borrelly: Placing the deep space 1 observations into a broader context. Icarus 160, 398-18 (2002) CrossRef ADS
  Y.R. Fernández, C.M. Lisse, A. Kundu, M.F. A’Hearn, W.F. Hoffmann, A. Dayal, The nucleus of Comet Hyakutake (C/1996 B2). Bull. Am. Astron. Soc. 28, 1088 (1996) ADS
  R.M. Goldstein, R.F. Jurgens, Z. Sekanina, A radar study of Comet IRAS-Araki-Alcock 1983d. Astron. J. 89, 1745-754 (1984) CrossRef ADS
  T.I. Gombosi, H.L.F. Houpis, An icy-glue model of cometary nuclei. Nature 324, 43-4 (1986) CrossRef ADS
  O. Groussin, P.L. Lamy, L. Jorda, The nucleus of Comet C/1983 H1 IRAS-Araki-Alcock. Planet. Space Sci. 58, 904-12 (2010) CrossRef ADS
  M.T. Hallikainen, F.T. Ulaby, M. Abdelrazik, Dielectric properties of snow in the 3 to 37 GHz range. IEEE Trans. Antennas Propag. AP-4, 1329 (1986) CrossRef ADS
  J.K. Harmon, M.C. Nolan, Radar observations of Comet 2P/Encke during the 2003 apparition. Icarus 176, 175-83 (2005) CrossRef ADS
  J.K. Harmon, D.B. Campbell, A.A. Hine, I.I. Shapiro, B.G. Marsden, Radar observations of Comet IRAS-Araki-Alcock 1983d. Astrophys. J. 338, 1071-093 (1989) CrossRef ADS
  J.K. Harmon, S.J. Ostro, K.D. Rosema, R.F. Jurgens, R. Winkler et al., Radar echoes from Comet Hyakutake (C/1996 B2). Bull. Am. Astron. Soc. 28, 1195 (1996) ADS
  J.K. Harmon, S.J. Ostro, L.A.M. Benner, K.D. Rosema, R.F. Jurgens et al., Radar detection of the nucleus and coma of Comet Hyakutake (C/1996 B2). Science 278, 1921-924 (1997) CrossRef ADS
  J.K. Harmon, M.C. Nolan, S.J. Ostro, D.B. Campbell, Radar studies of comet nuclei and grain comae, in Comets II, ed. by M.C. Festou, H.U. Keller, H.A. Weaver (University of Arizona Press, Tucson, 2004), pp. 265-79
  J.K. Harmon, M.C. Nolan, J.-L. Margot, D.B. Campbell, L.A.M. Benner, J.D. Giorgini, Radar observations of Comet P/2005 JQ5 (Catalina). Icarus 184, 285-88 (2006) CrossRef ADS
  J.K. Harmon, M.C. Nolan, J.D. Giorgini, E.S. Ellen, Radar observations of 8P/Tuttle: A contact-binary comet. Icarus 207, 499-02 (2010) CrossRef ADS
  J.K. Harmon, M.C. Nolan, E.S. Howell, J.D. Giorgini, P.A. Taylor, Radar observations of Comet 103P/Hartley 2. Astrophys. J. Lett. 734, L2, 4 pp. (2011) CrossRef ADS
  E. Heggy, E.M. Palmer, W. Kofman, S.M. Clifford, K. Righter, A. Herique, Radar properties of comets: Parametric dielectric modeling of Comet 67P/Churyumov-Gerasimenko. Icarus 221, 925-39 (2012) CrossRef ADS
  P.G. Kamoun, Radar observations of cometary nuclei. Ph.D. thesis, Massachusetts Institute of Technology (MIT) (1983)
  P.G. Kamoun, D.B. Campbell, S.J. Ostro, G.H. Pettengill, I.I. Shapiro, Comet Encke—Radar detection of nucleus. Science 216, 293-95 (1982a) CrossRef ADS
  P.G. Kamoun, G.H. Pettengill, I.I. Shapiro, Radar detectability of comets, in Comets, ed. by L.L. Wilkening (University of Arizona Press, Tucson, 1982b), pp. 288-96
  P. Kamoun, D. Campbell, G. Pettengill, I. Shapiro, Radar observations of three c
• 作者单位：P. L. Lamy (1)
  A. Herique (2)
  I. Toth (1) (3)
  
  1. Laboratoire d’Astrophysique de Marseille, UMR 7326, CNRS & Aix Marseille Université, Marseille, France
  2. UJF-Grenoble 1 & CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble UMR 5274, Grenoble, France
  3. Konkoly Observatory, MTA CSFK CSI, Budapest, Hungary
  
• 刊物类别：Physics and Astronomy
• 刊物主题：Physics
  Astronomy
  Extraterrestrial Physics and Space Sciences
  Astrophysics
  Planetology
  
• 出版者：Springer Netherlands
• ISSN：1572-9672

文摘

Little is known about the internal structure and density of cometary nuclei. Indirect evidences available so far are not compelling and these questions essentially remain a matter of speculation. It is therefore important to fully exploit the potential sources of information and this is particularly the case of radar observations which have the capability to probe the first few meters of cometary nuclei when they come sufficiently close to Earth. We review the available results and find that proper data are available for eight nuclei yielding their geometric radar albedo and the dielectric permittivity of their subsurface assuming that the scattering of the radar beam is predominantly specular. The range of permittivity is quite broad, extending from 1.7 to 3.1 although a more realistic interval is probably 2 to 3.1 implying pronounced diversity in the subsurface properties of cometary nuclei. A novel interpretation of these results is performed based on the calculation of the dielectric permittivity of various samples of three-phase mixtures of ice, dust and vacuum using two mixing formulas and on the introduction of ternary diagrams where the three axes correspond to the volumetric fraction of the three phases. The derived values of the permittivity supplemented by a general constraint on the dust-to-ice mass ratio define restricted regions in the ternary diagrams broadly imposing that the ice fraction lies in the range 0.1 to 0.2, the dust fraction in the range 0.2 to 0.5, and the porosity in the range 35 % to 75 %. The density of the subsurface of the considered eight nuclei is only constrained to the broad range 500 to 2000 kg?m? due to the poorly known density of the dust phase. However, the results unambiguously reveal considerable variation among cometary nuclei of the structure and properties of their subsurface layers. Keywords Comets: nucleus Comets: nucleus surface Radar: comets Comets: individual: 2P/Encke, 8P/Tuttle, 26P/Grigg-Skjellerup, 67P/Churyumov-Gerasimenko, 103P/Hartley 2, C/1983 H1 (IRAS-Araki-Alcock), C/1983 J1 (Sugano-Saigusa-Fujikawa)