Fig. 55. albedo versus scattering angle measured in 12 comets [150]

Both albedos are related by: AB = Apq. Here, q is the phase integral and is equal to 4 in case of isotropic scattering where AB = 1 and Ap = 0.25. In general q is given as:

Figure 55 shows the albedo versus scattering angle measured in 12 comets [150]. The albedo is derived from measurements made quasi simultaneously at thermal IR and optical wavelengths. The scattering function can be derived when comets are observed over a wide range of phase angles. This is however, only rarely possible. Therefore, often a "standard" phase function is assumed based on [67]. We note, however, that the phase function for individual comets can be quite different to the standard phase curve (e.g., [188]).

8 Outlook

At the beginning of this chapter, we recalled the main motivation for cometary studies: How did comets form and what do we learn from them about the formation of our solar system? Answering this fundamental questions requires knowledge of many different fields of physics, such as gas dynamics, plasma

physics, chemistry, scattering theory, molecular physics, etc., including their applications to the conditions found in comets. In the previous sections, we looked at some of the basic concepts scientists use to address the problems in the different areas of comet research. Of course, students specialize in their field of interest to obtain a much deeper understanding in that area. However, I encourage students to have a broader view on the context of their specialist research fields to be able to see interrelations and avoid misconceptions.

An enormous progress has been made in the past 20 years in our understanding of comets, although important key processes are still far from being understood (e.g., activity). Space missions have been sent to observe comets directly and provide in situ data. Ground-based technology progressed with new detector technologies and telescopes allowing us to observe comets not only in the optical but also at radio and near-IR wavelengths with high sensitivity. In addition, space telescopes provide access to wavelengths regions we can not investigate from the ground. The technical progress resulted in an enlarged volume of high quality data, which stimulated the development of theory to explain what had been observed. Nevertheless, there is still no generally accepted theory on comet formation. We need to proceed and obtain further data and improve our theory in the future. Future investigations need to include

- Direct investigations of nucleus material by landers.

- Sample return of cometary material (nucleus and coma).

- Improved statistical database of cometary gas and dust composition.

- Measurements of gas and dust activity over wide ranges of heliocentric distances.

- Laboratory comet simulation experiments (e.g., outgassing processes, ice formation).

- Numerical models of cometary activity.

- Understanding of the relation to Kuiper belt objects.

Some of these point will be already addressed in the near future by space missions. The Stardust mission has already transported in situ samples of coma dust particles to Earth [37]. ESA's Rosetta [195] mission will follow a comet over a substantial part of its orbit and will drop a lander on its nucleus to investigate the upper surface layers directly. In parallel, ground-based facilities, such as the radio telescope array ALMA [29, 202] will provide a new wealth of data on parent gas molecules. The field of cometary science therefore needs young motivated students educated in cometary science to explore the information to come.

Solving the problem of comet formation is like solving a big puzzle. We have to ask the right questions to find the right puzzle pieces and then find the right places for them to be able to solve "the big picture" of comet and planet formation. Each student works on his/her own small or larger "puzzle piece." It is the combination of all of them that will help us to obtain the whole picture.


1. M. F. A'Hearn, M. J. S. Belton, W. A. Delamere, J. Kissel, K. P. Klaasen, L. A. McFadden, K. J. Meech, H. J. Melosh, P. H. Schultz, J. M. Sunshine, P. C. Thomas, J. Veverka, D. K. Yeomans, M. W. Baca, I. Busko,

C. J. Crockett, S. M. Collins, M. Desnoyer, C. A. Eberhardy, C. M. Ernst, T. L. Farnham, L. Feaga, O. Groussin, D. Hampton, S. I. Ipatov, J.-Y. Li,

D. Lindler, C. M. Lisse, N. Mastrodemos, W. M. Owen, J. E. Richardson, D. D. Wellnitz, and R. L. White. Deep impact: Excavating comet tempel 1. Science, 310:258-264, October 2005.

2. M. F. A'Hearn, R. L. Millis, D. G. Schleicher, D. J. Osip, and P. V. Birch. The ensemble properties of comets: Results from narrowband photometry of 85 comets, 1976-1992. Icarus, 118:223-270, December 1995.

3. M. F. A'Hearn, D. G. Schleicher, and P. D. Feldman. The discovery of S2 in comet IRAS-Araki-Alcock 1983d. ApJL, 274:L99-L103, November 1983.

4. M. F. A'Hearn, D. G. Schleicher, R. L. Millis, P. D. Feldman, and D. T. Thompson. Comet Bowell 1980b. AJ, 89:579-591, April 1984.

5. H. Alfven. On the theory of comet tails. Tellus, 9:92-96, 1957.

6. R. Ali, P. A. Neill, P. Beiersdorfer, C. L. Harris, M. J. Rakovic, J. G. Wang,

D. R. Schultz, and P. C. Stancil. On the significance of the contribution of multiple-electron capture processes to cometary X-Ray emission. ApjL, 629:L125-L128, August 2005.

7. M. Allen, M. Delitsky, W. Huntress, Y. Yung, and W.-H. Ip. Evidence for methane and ammonia in the coma of comet P/Halley. A&A, 187:502-512, November 1987.

8. K. Altwegg, H. Balsiger, J. Geiss, R. Goldstein, W.-H. Ip, A. Meier, M. Neugebauer, H. Rosenbauer, and E. Shelley. The ion population between 1300 KM and 230000 KM in the coma of comet P/Halley. A&A, 279:260-266, November 1993.

9. E. Anders and N. Grevesse. Abundances of the elements - Meteoritic and solar. GCA, 53:197-214, January 1989.

10. C. Arpigny, E. Jehin, J. Manfroid, D. Hutsemekers, R. Schulz, J. A. Stuwe, J.-M. Zucconi, and I. Ilyin. Anomalous Nitrogen Isotope Ratio in Comets. Science, 301:1522-1525, September 2003.

11. C. Arpigny. Physical Chemistry of Comets: Models, Uncertainties, Data Needs. In I. Nenner, editor, AIP Conf. Proc. 312: Molecules and Grains in Space, page 205, 1994.

12. H. Balsiger, K. Altwegg, F. Buhler, J. Geiss, A. G. Ghielmetti, B. E. Goldstein, R. Goldstein, W. T. Huntress, W.-H. Ip, A. J. Lazarus, A. Meier, M. Neugebauer, U. Rettenmund, H. Rosenbauer, R. Schwenn, R. D. Sharp,

E. G. Shelly, E. Ungstrup, and D. T. Young. Ion composition and dynamics at comet Halley. Nature, 321:330-334, May 1986.

13. H. Balsiger, K. Altwegg, and J. Geiss. D/H and O-18/O-16 ratio in the hydro-nium ion and in neutral water from in situ ion measurements in comet Halley. JGR, 100:5827-5834, April 1995.

14. H. Balsiger. Measurements of ion species within the coma of comet Halley from Giotto, page 129. Comet Halley: Investigations, Results, Interpretations. Vol. 1: Organization, Plasma, Gas, 1990.

15. A. Bar-Nun and D. Laufer. First experimental studies of large samples of gas-laden amorphous "cometary" ices. Icarus, 161:157-163, January 2003.

16. A. Bar-Nun, D. Prialnik, D. Laufer, and E. Kochavi. Trapping of gases by water ice and implications for icy bodies. Advances in Space Research, 7:45-47, 1987.

17. J. E. Beaver, R. M. Wagner, D. G. Schleicher, and B. L. Lutz. Anomalous molecular abundances and the depletion of NH2 in Comet P/Giacobini-Zinner. Astrophysical Journal, 360:696-701, September 1990.

18. J. Benkhoff and D. C. Boice. Modeling the thermal properties and the gas flux from a porous, ice-dust body in the orbit of P/Wirtanen. Planetary and Space Science, 44:665-673, July 1996.

19. J. Benkhoff and W. F. Huebner. Influence of the vapor flux on temperature, density, and abundance distributions in a multicomponent, porous, icy body. Icarus, 114:348-354, April 1995.

20. J. Benkhoff and W. F. Huebner. Modeling the gas flux from a Jupiter-family comet nucleus. Planetary and Space Science, 44:1005-1013, September 1996.

21. J. Benkhoff. On the flux of water and minor volatiles from the Surface of Comet Nuclei. Space Science Reviews, 90:141-148, 1999.

22. L. Biermann. Kometenschweife und solare Korpuskularstrahlung. Zeitschrift fur Astrophysik, 29:274, 1951.

23. M. K. Bird, P. Janardhan, T. L. Wilson, W. K. Huchtmeier, P. Gensheimer, and C. Lemme. K-band radio observations of comet Hale-Bopp: Detections of ammonia and (possibly) water. Earth Moon and Planets, 78:21-28, 1999.

24. N. Biver, D. Bockelee-Morvan, P. Colom, J. Crovisier, J. K. Davies, W. R. F. Dent, D. Despois, E. Gerard, E. Lellouch, H. Rauer, R. Moreno, and G. Paubert. Evolution of the outgassing of comet Hale-Bopp (C/1995 O1) from radio observations. Science, 275:1915-1918, 1997.

25. N. Biver, D. Bockelee-Morvan, P. Colom, J. Crovisier, B. Germain, E. Lellouch, J. K. Davies, W. R. F. Dent, R. Moreno, G. Paubert, J. Wink, D. Despois, D. C. Lis, D. Mehringer, D. Benford, M. Gardner, T. G. Phillips, M. Gunnarsson, H. Rickman, A. Winnberg, P. Bergman, L. E. B. Johansson, and H. Rauer. Long-term evolution of the outgassing of comet Hale-Bopp from radio observations. Earth Moon and Planets, 78:5-11, 1999.

26. N. Biver, D. Bockelee-Morvan, P. Colom, J. Crovisier, F. Henry, E. Lellouch, A. Winnberg, L. E. B. Johansson, M. Gunnarsson, H. Rickman, F. Rantakyro, J. K. Davies, W. R. F. Dent, G. Paubert, R. Moreno, J. Wink, D. Despois, D. J. Benford, M. Gardner, D. C. Lis, D. Mehringer, T. G. Phillips, and H. Rauer. The 1995 2002 Long-term monitoring of Comet C/1995 O1 (HALE BOPP) at radio wavelength. Earth Moon and Planets, 90:5-14, June 2002.

27. N. Biver, D. Bockelee-Morvan, J. Crovisier, P. Colom, F. Henry, R. Moreno, G. Paubert, D. Despois, and D. C. Lis. Chemical composition diversity among 24 comets observed at radio wavelengths. Earth Moon and Planets, 90: 323-333, March 2002.

28. N. Biver, D. Bockelee-Morvan, J. Crovisier, J. K. Davies, H. E. Matthews, J. E. Wink, H. Rauer, P. Colom, W. R. F. Dent, D. Despois, R. Moreno, G. Paubert, D. Jewitt, and M. Senay. Spectroscopic monitoring of comet C/1996 B2 (Hyakutake) with the JCMT and IRAM Radio Telescopes. AJ, 118:1850-1872, October 1999.

29. N. Biver. Comets with ALMA. In A. Wilson, editor, The Dusty and Molecular-Universe: A Prelude to Herschel and ALMA, pages 151-156, January 2005.

30. D. Bockelee-Morvan, J. Crovisier, P. Colom, and D. Despois. The rotational lines of methanol in comets Austin 1990 V and Levy 1990 XX. A&A, 287: 647-665, July 1994.

31. D. Bockeiee-Morvan, J. Crovisier, and E. Gerard. Retrieving the coma gas expansion velocity in P/Halley, Wilson (1987 VII) and several other comets from the 18-cm OH line shapes. A&A, 238:382-400, November 1990.

32. D. Bockelee-Morvan, J. Crovisier, M. J. Mumma, and H. A. Weaver. Comets II, Chapter The composition of cometary volatiles. University of Arizona Press, 2005.

33. D. Bockelee-Morvan and J. Crovisier. The role of water in the thermal balance of the coma. In E. J. Rolfe and B. Battrick, editors, ESA SP-278: Diversity and Similarity of Comets, pages 235-240, September 1987.

34. D. Bockelee-Morvan, D. Gautier, D. C. Lis, K. Young, J. Keene, T. Phillips, T. Owen, J. Crovisier, P. F. Goldsmith, E. A. Bergin, D. Despois, and A. Wootten. Deuterated water in Comet C/1996 B2 (Hyakutake) and its implications for the origin of comets. Icarus, 133:147-162, May 1998.

35. D. Bockelee-Morvan, J. Wink, D. Despois, P. Colom, N. Biver, J. Crovisier, D. Gautier, E. Gerard, E. Lellouch, R. Moreno, G. Paubert, H. Rauer, J. K. Davies, and W. R. F. Dent. A molecular survey of Comet C/1995 O1 (Hale-Bopp) at the IRAM telescopes. Earth Moon and Planets, 78:67-67, 1999.

36. T. Y. Brooke, A. T. Tokunaga, H. A. Weaver, J. Crovisier, D. Bockelee-Morvan, and D. Crisp. Detection of acetylene in the infrared spectrum of Comet Hyaku-take. Nature, 383:606-608, 1996.

37. D. E. Brownlee, G. Flynn, F. Horz, L. Keller, K. McKeegan, S. Sandford, P. Tsou, and M. E. Zolensky. Comet Samples Returned by the Stardust Mission. In S. Mackwell and E. Stansbery, editors, 37th Annual Lunar and Planetary Science Conference, page 2286, March 2006.

38. M. T. Capria, A. Coradini, and M. C. de Sanctis. Modelling of cometary nuclei: Planetary missions preparation. Advances in Space Research, 31: 2543-2553, June 2003.

39. M. T. Capria. Sublimation mechanisms of comet nuclei. Earth Moon and Planets, 89:161-178, 2002.

40. J. W. Chamberlain and D. M. Hunten. Theory of planetary atmospheres: an introduction to their physics and chemistry . Orlando FL Academic Press Inc International Geophysics Series, 36, 1987.

41. A. L. Cochran, E. S. Barker, T. F. Ramseyer, and A. D. Storrs. The McDonald observatory faint comet survey - gas production in 17 comets. Icarus, 98:151162, August 1992.

42. A. L. Cochran and W. D. Cochran. A high spectral resolution Atlas of Comet 122P/de Vico. Icarus, 157:297-308, June 2002.

43. P. Colom, J. Crovisier, D. Bockelee-Morvan, D. Despois, and G. Paubert. Formaldehyde in comets. I - Microwave observations of P/Brorsen-Metcalf (1989 X), Austin (1990 V) and Levy (1990 XX). A&A, 264:270-281, October 1992.

44. P. Colom, E. Gerard, J. Crovisier, D. Bockele-Morvan, N. Biver, and H. Rauer. Observations of the OH Radical in Comet C/1995 O1 (Hale-Bopp) with the Nancay Radio Telescope. Earth Moon and Planets, 78:37-43, 1999.

45. M. Combes, J. Crovisier, T. Encrenaz, V. I. Moroz, and J.-P. Bibring. The 2.5-12 micron spectrum of Comet Halley from the IKS-VEGA Experiment. Icarus, 76:404-436, December 1988.

46. M. R. Combi, M. E. Brown, P. D. Feldman, H. U. Keller, R. R. Meier, and W. H. Smyth. Hubble space telescope ultraviolet imaging and high-resolution spectroscopy of water photodissociation products in comet hyakutake (C/1996 B2). ApJ, 494:816, February 1998.

47. M. R. Combi, W. M. Harris, and W. H. Smyth. Comets II, Chapter Gas dynamics and kinetics in the cometary coma: Theory and observations. University of Arizona Press, 2005.

48. M. R. Combi, A. A. Reinard, J.-L. Bertaux, E. Quemerais, and T. Makinen. SOHO/SWAN observations of the structure and evolution of the hydrogen Lyman-a coma of comet Hale-Bopp (1995 O1). Icarus, 144:191-202, March 2000.

49. M. R. Combi and W. H. Smyth. Monte Carlo particle-trajectory models for neutral cometary gases. I - Models and equations. II - The spatial morphology of the Lyman-alpha coma. ApJ, 327:1026-1059, April 1988.

50. H. Cottin, Y. Benilan, M.-C. Gazeau, and F. Raulin. Origin of cometary extended sources from degradation of refractory organics on grains: poly-oxymethylene as formaldehyde parent molecule. Icarus, 167:397-416, February 2004.

51. G. Cremonese, H. Boehnhardt, J. Crovisier, H. Rauer, A. Fitzsimmons, M. Fulle, J. Licandro, D. Pollacco, G. P. Tozzi, and R. M. West. Neutral sodium from comet Hale-Bopp: A third type of tail. ApJL, 490:L199+, December 1997.

52. J. F. Crifo, M. Fulle, N. I. Komle, and K. Szego. Comets II, Chapter Nucleus-coma structural relationships: Lessons from physical models. University of Arizona Press, 2005.

53. T. Encrenaz, J. Crovisier, Les Cometes. CNRS Editions, 1995.

54. J. Crovisier, D. Bockeleee-Morvan, N. Biver, P. Colom, D. Despois, and D. C. Lis. Ethylene glycol in comet C/1995 O1 (Hale-Bopp). A&A, 418: L35-L38, April 2004.

55. J. Crovisier, D. Bockelee-Morvan, P. Colom, N. Biver, D. Despois, D. C. Lis, and the Team for target-of-opportunity radio observations of comets. The composition of ices in comet C/1995 O1 (Hale-Bopp) from radio spectroscopy. Further results and upper limits on undetected species. A&A, 418:1141-1157, May 2004.

56. J. Crovisier and T. Encrenaz. Infrared fluorescence of molecules in comets -The general synthetic spectrum. A&A, 126:170-182, September 1983.

57. J. Crovisier, K. Leech, D. Bockelee-Morvan, T. Y. Brooke, M. S. Hanner, B. Altieri, H. U. Keller, and E. Lellouch. The spectrum of Comet Hale-Bopp (C/1995 01) observed with the Infrared Space Observatory at 2.9 AU from the Sun. Science, 275:1904-1907, 1997.

58. J. Crovisier and F. P. Schloerb. The study of comets at radio wavelengths. In R. L. Newburn, M. Neugebauer, and J. Rahe, editors, ASSL Vol. 167: IAU Colloq. 116: Comets in the post-Halley era, pages 149-173, 1991.

59. J. Crovisier. Rotational and vibrational synthetic spectra of linear parent molecules in comets. A&AS, 68:223-258, March 1987.

60. J. Crovisier. Molecular Abundances in Comets. In A. Milani, M. di Martino, and A. Cellino, editors, IAU Symp. 160: Asteroids, Comets, Meteors 1993, page 313, 1994.

61. J. Crovisier. Photodestruction rates for cometary parent molecules. JGR, 99:3777-3781, February 1994.

62. A. C. Danks, D. L. Lambert, and C. Arpigny. The C-12/C-13 ratio in comet Kohoutek /1973f/. ApJ, 194:745-751, December 1974.

64. N. dello Russo, M. A. Disanti, M. J. Mumma, K. Magee-Sauer, and T. W. Rettig. Carbonyl sulfide in Comets C/1996 B2 (Hyakutake) and C/1995 O1 (Hale-Bopp): Evidence for an extended source in Hale-Bopp. Icarus, 135: 377-388, October 1998.

65. I. de Pater and J. J. Lissauer. Planetary Sciences. Planetary Sciences, by Imke de Pater and Jack J. Lissauer, Page. 544. ISBN 0521482194. Cambridge, UK: Cambridge University Press, December 2001.

66. M. A. Disanti, M. J. Mumma, N. Dello Russo, and K. Magee-Sauer. Carbon monoxide production and excitation in Comet C/1995 O1 (Hale-Bopp): Isolation of native and Distributed CO sources. Icarus, 153:361-390, October 2001.

67. N. Divine. A Simple Radiation Model of the Cometary Dust for P/Halley. ESA-SP 174, 1981.

68. P. Eberhardt, D. Krankowsky, W. Schulte, U. Dolder, P. Lammerzahl, J. J. Berthelier, J. Woweries, U. Stubbemann, R. R. Hodges, J. H. Hoffman, and J. M. Illiano. To CO and N2 abundance in Comet P/Halley. A&A, 187:481, November 1987.

69. P. Eberhardt, M. Reber, D. Krankowsky, and R. R. Hodges. The D/H and 18O/16O ratios in water from comet P/Halley. A&A, 302:301, October 1995.

70. P. Eberhardt. Comet Halley's gas composition and extended sources: Results from the neutral mass spectrometer on Giotto. Space Science Reviews, 90: 45-52, 1999.

71. K. E. Edgeworth. The evolution of our planetary system. Journal of the British Astronomical Association, 53:181-188, 1943.

72. A. Enzian, H. Cabot, and J. Klinger. A 2 1/2 D thermodynamic model of cometary nuclei. I. Application to the activity of comet 29P/Schwassmann-Wachmann 1. A&A, 319:995-1006, March 1997.

73. A. Enzian, H. Cabot, and J. Klinger. Simulation of the water and carbon monoxide production rates of comet Hale-Bopp using a quasi 3-D nucleus model. Planetary and Space Science, 46:851-858, August 1998.

74. A. Enzian. On the prediction of CO outgassing from comets Hale-Bopp and Wirtanen. Space Science Reviews, 90:131-139, 1999.

75. P. D. Feldman, A. L. Cochran, and M. R. Combi. Comets II, Chapter Spec-troscopic investigations of fragment species in the coma. University of Arizona Press, 2005.

76. P. D. Feldman, M. F. A'Hearn, and R. L. Millis. Temporal and spatial behavior of the ultraviolet emissions of comet IRAS-Araki-Alcock 1983d. ApJ, 282: 799-802, July 1984.

77. P. D. Feldman, M. C. Festou, G. P. Tozzi, and H. A. Weaver. The CO2/CO abundance ratio in 1P/Halley and several other comets observed by IUE and HST. ApJ, 475:829, February 1997.

78. P. D. Feldman, K. B. Fournier, V. P. Grinin, and A. M. Zvereva. The abundance of ammonia in Comet P/Halley derived from ultraviolet spectrophotometry of NH by ASTRON and IUE. ApJ, 404:348-355, February 1993.

79. J. A. Fernandez. Comets; Nature, Dynamics, Origin and their Cosmogonical Relevance. Springer, 2005.

80. Keller H. U. Weaver H. A. Festou, M., editor. Comets II. University of Arizona Press, 2005.

81. M. C. Festou. The density distribution of neutral compounds in cometary atmospheres. I - Models and equations. A&A, 95:69-79, February 1981.

82. U. Fink and M. D. Hicks. A survey of 39 comets using CCD spectroscopy. Astrophysical Journal, 459:729-743, March 1996.

83. M. L. Finson and R. F. Probstein. A theory of dust comets. I. Model and equations. ApJ, 154:353-380, October 1968.

84. N. Fray, Y. Benilan, H. Cottin, M.-C. Gazeau, and J. Crovisier. The origin of the CN radical in comets: A review from observations and models. PSS, 53:1243-1262, October 2005.

85. N. Fray, Y. Benilan, H. Cottin, M.-C. Gazeau, R. D. Minard, and F. Raulin. Experimental study of the degradation of polymers: Application to the origin of extended sources in cometary atmospheres. Meteoritics and Planetary Science, 39:581-587, April 2004.

86. N. Fray, Y. Benilan, H. Cottin, and M.-C. Gazeau. New experimental results on the degradation of polyoxymethylene: Application to the origin of the formaldehyde extended source in comets. Journal of Geophysical Research (Planets), 109:7, June 2004.

87. M. Fulle. A dust-tail model based on Maxwellian velocity distribution. A&A, 265:817-824, November 1992.

88. M. Fulle. Comets II, Chapter Motion of cometary dust. University of Arizona Press, 2005.

89. J. Geiss, K. Altwegg, E. Anders, H. Balsiger, A. Meier, E. G. Shelley, W.-H. Ip, H. Rosenbauer, and M. Neugebauer. Interpretation of the ion mass spectra in the mass per charge range 25-35 amu/e obtained in the inner coma of Halley's comet by the HIS-sensor of the Giotto IMS experiment. A&A, 247:226-234, July 1991.

90. E. Gerard, J. Crovisier, P. Colom, N. Biver, D. Bockelee-Morvan, and H. Rauer. Observations of the OH radical in comet C/1996 B2 (Hyakutake) with the Nancay radio telescope. PSS, 46:569-577, May 1998.

91. E. Gerard. The discrepancy between OH production rates deduced from radio and ultraviolet observations of comets. I - A comparative study of OH radio and UV observations of P/Halley 1986 III in late November and early December 1985. A&A, 230:489-503, April 1990.

92. J. L. Greenstein. High-resolution spectra of Comet MRKOS (1957d). ApJ, 128:106-106, July 1958.

93. S. F. Green, N. McBride, M. T. S. H. Colwell, J. A. M. McDonnell, A. J. Tuzzolino, T. E. Economou, B. C. Clark, Z. Sekanina, P. Tsou, and D. E. Brownlee. Stardust wild 2 dust measurements. LPI Contributions, 1280:59, September 2005.

94. E. Gruen and E. Jessberger. Physics and chemistry of comets, chapter Dust, page 113. Springer-Verlag.

95. R. M. Haberli, K. Altwegg, H. Balsiger, and J. Geiss. Heating of the thermal electrons in the coma of comet P/Halley. JGR, 101:15579-15590, July 1996.

96. R. M. Haberli, T. I. Gombosi, D. L. DeZeeuw, M. R. Combi, and K. G. Powell. Modeling of cometary X-rays caused by solar wind minor ions. Science, 276:939-942, May 1997.

97. R. M. Haberli. The temperature of the thermal electrons in the coma of comet P/Halley. Advances in Space Research, 18:215-215, 1996.

98. R. M. Haberli, K. Altwegg, H. Balsiger, and J. Geiss. Physics and chemistry of ions in the pile-up region of comet P/Halley. A&A, 297:881, May 1995.

99. S. A. Haider, A. Bhardwaj, and R. P. Singhal. Role of auroral and photo-electrons on the abundances of methane and ammonia in the coma of Comet Halley. Icarus, 101:234-243, February 1993.

100. M. S. Hanner, R. H. Giese, K. Weiss, and R. Zerull. On the definition of albedo and application to irregular particles. A&A, 104:42-46, December 1981.

101. M. S. Hanner. Thermal emission from cometary dust. Advances in Space Research, 2:157-157, 1982.

102. M. Hanner and J. P. Bradley. Comets II, Chapter Composition and mineralogy of cometary dust. University of Arizona Press, 2005.

103. L. Haser. Distribution d'intensite dans la tete d'une comete. Bulletin de la Societe Royale des Sciences de Liege, 43:740-750, 1957.

104. Probstein R. F. Hayes, W. D. Hypersonic flow theory. Academic Press, New York, USA, 1959.

105. J. Helbert, H. Rauer, D. C. Boice, and W. F. Huebner. The chemistry of C2 and C3 in the coma of Comet C/1995 O1 (Hale-Bopp) at heliocentric distances rh > 2.9 AU. A&A, 442:1107-1120, November 2005.

106. G. Herzberg. Molecular Spectra and Molecular Structure II. Infrared and Raman Spectra of Polyatomic Molecules. Van Nordstrand Reinhold Company, 1945.

107. G. Herzberg. Molecular Spectra and Molecular Structure I. Spectra ofDiatomic Molecules. Van Nordstrand Reinhold Company, 1950.

108. G. Herzberg. Molecular Spectra and Molecular Structure III. Electric Spectra of Polyatomic Molecules. Van Nordstrand Reinhold Company, 1966.

109. M. D. Hicks and U. Fink. Spectrophotometry and the Development of Emissions for C/1996 B2 (Comet Hyakutake). Icarus, 127:307-318, June 1997.

110. W. F. Huebner, D. C. Boice, H. U. Schmidt, and R. Wegmann. Comets in the Post-Halley Era, Chapter Structure of the coma: Chemistry and solar wind interaction, pages 907-936. Kluwer, Dordrecht, 1991.

111. W. F. Huebner, D. C. Boice, and C. M. Sharp. Polyoxymethylene in Comet Halley. ApJL, 320:L149-L152, September 1987.

112. W. F. Huebner, J. J. Keady, and S. P. Lyon. Solar photo rates for planetary atmospheres and atmospheric pollutants. ApSS, 195:1-289, September 1992.

113. W. F. Huebner. First polymer in space identified in Comet Halley. Science, 237:628-630, August 1987.

114. W. F. Huebner. Composition of comets: Observations and models. Earth Moon and Planets, 89:179-195, 2002.

115. van de Hulst. Light Scattering by Small Particles. New York: John Wiley and Sons, 1957.

116. D. Hutsemekers, J. Manfroid, E. Jehin, C. Arpigny, A. Cochran, R. Schulz, J. A. Stuwe, and J.-M. Zucconi. Isotopic abundances of carbon and nitrogen in Jupiter-family and Oort Cloud comets. A&A, 440:L21-L24, September 2005.

117. W. M. Irvine, E. A. Bergin, J. E. Dickens, D. Jewitt, A. J. Lovell, H. E. Matthews, F. P. Schloerb, and M. Senay. Chemical processing in the coma as the source of cometary HNC. Nature, 393:547, 1998.

118. W. M. Irvine, J. E. Dickens, A. J. Lovell, F. P. Schloerb, M. Senay, E. A. Bergin, D. Jewitt, and H. E. Matthews. The HNC/HCN ratio in comets. Earth Moon and Planets, 78:29-35, 1999.

119. W. M. Irvine. Spectroscopic evidence for interstellar ices in Comet Hyakutake. Nature, 383:418-420, 1996.

120. W. M. Jackson. Laboratory studies of photochemical and spectroscopic phenomena related to comets. In L. L. Wilkening, editor, IAU Colloq. 61: Comet Discoveries, Statistics, and Observational Selection, pages 480-495, 1982.

121. E. Jehin, J. Manfroid, A. L. Cochran, C. Arpigny, J.-M. Zucconi, D. Hutsemekers, W. D. Cochran, M. Endl, and R. Schulz. The Anomalous 14N/15 N ratio in comets 122P/1995 S1 (de Vico) and 153P/2002 C1 (Ikeya-Zhang). ApJL, 613:L161-L164, October 2004.

122. E. Jehin, J. Manfroid, D. Hutsemekers, A. L. Cochran, C. Arpigny, W. M. Jackson, H. Rauer, R. Schulz, and J.-M. Zucconi. Deep Impact: High-resolution optical spectroscopy with the ESO VLT and the Keck I Telescope. ApJL, 641:L145-L148, April 2006.

123. E. K. Jessberger, A. Christoforidis, and J. Kissel. Aspects of the major element composition of Halley's dust. Nature, 332:691-695, April 1988.

124. E. K. Jessberger and J. Kissel. Chemical properties of cometary dust and a note on carbon isotopes. In R. L. Newburn, M. Neugebauer, and J. Rahe, editors, ASSL Vol. 167: IAU Colloq. 116: Comets in the Post-Halley Era, pages 1075-1092, 1991.

125. D. Jewitt. Kuiper Belt and Comets: An Observational Perspective. In K. Altwegg, W. Benz and N. Thomas, editors, Trans-Neptuninan Objects and Comets, Vol. 35, pages 1-78, 2008.

126. D. Jewitt, H. E. Matthews, T. Owen, and R. Meier. The 12C/13C, 14N/15N and 32S/ 34S Isotope ratios in comet Hale-Bopp (C/1995 O1). Science, 278:9093, October 1997.

127. L. Jorda. Atmospheres Cometaires: Interpretation des Observations dans le visible et Comparasion avec les Observations Radio. PhD thesis, Observatoire de Paris Meudon, 1995.

128. H. Kawakita, J.-I. Watanabe, D. Kinoshita, S. Abe, R. Furusho, H. Izumiura, K. Yanagisawa, and S. Masuda. High-dispersion spectra of NH2 in the Comet C/1999S4 (LINEAR): Excitation mechanism of the NH2 molecule. PAS J, 53:L5-L8, February 2001.

129. H. Kawakita and J.-I. Watanabe. Revised fluorescence efficiencies of cometary NH2: Ammonia abundance in comets. ApJL, 572:L177-L180, June 2002.

130. H. Kawakita and J.-I. Watanabe. Revised Fluorescence Efficiencies of Cometary NH2: Ammonia Abundance in Comets, page 32. Annual Report of the National Astronomical Observatory of Japan, Volume 5, Fiscal 2002. Editors: Kiyotaka Tanikawa, Masatoshi Imanishi, Makoto Miyoshi, Toshiya Mu-ramatsu, Takashi Sekii, Mitsuru Soma, Akitoshi Ueda, Yoshiko Yamashita, Naoki Yasuda, National Astronomical Observatory of Japan, Osawa, Mitaka-shi, Tokyo, Japan. ISSN 1346-1192, 2004, page 32, 2004.

131. M. Kleine, S. Wyckoff, P. A. Wehinger, and B. A. Peterson. The carbon isotope abundance ratio in comet Halley. ApJ, 439:1021-1033, February 1995.

132. J. Knollenberg. Modellrechnungen zur Staubverteilung in der inneren Koma von Kometen unter spezieller Bercksichtigung der HMC Daten der Giotto-Mission. PhD thesis, University Gttingen, 1994.

133. L. Kolokolova, M. S. Hanner, A.-Ch. Levasseur-Regourd, and B. A. S. Gustafson Comets II, Chapter Global solar wind interaction and ionospheric dynamics. University of Arizona Press, 2005.

134. Eberhardt P. Krankowsky, D. Comet Halley, Chapter Evidence for the composition of ices in the nucleus of comet Halley, page 273. Ellis Horwood, 1990.

135. V. A. Krasnopolsky, M. J. Mumma, M. Abbott, B. C. Flynn, K. J. Meech, D. K. Yeomans, P. D. Feldman, and C. B. Cosmovici. Detection of Soft X-rays and a Sensitive Search for Noble Gases in Comet Hale-Bopp (C/1995 O1). Science, 277:1488-1491, September 1997.

136. V. A. Krasnopolsky. On the nature of soft X-Ray radiation in comets. Icarus, 128:368-385, August 1997.

137. G. P. Kuiper. O the Origin of the Solar System. In J. A. Hynek, editor, Proceedings of a Topical Symposium, Commemorating the 50th Anniversary of the Yerkes Observatory and Half a Century of Progress in Astrophysics. New York: McGraw-Hill, page 357, 1951.

138. C. Laffont, D. C. Boice, G. Moreels, J. Clairemidi, P. Rousselot, and

H. Andernach. Tentative identification of S2 in the IUE spectra of Comet Hyakutake (C/1996 B2). GRL, 25:2749-2752, July 1998.

139. P. Lammerzahl, D. Krankowsky, R. R. Hodges, U. Stubbemann, J. Woweries,

I. Herrwerth, J. J. Berthelier, J. M. Illiano, P. Eberhardt, U. Dolder, W. Shulte, and J. H. Hoffman. Expansion Velocity and Temperatures of Gas and Ions Measured in the Coma of Comet p/ Halley. A&A, 187:169, November 1987.

140. Y. Langevin, J. Kissel, J.-L. Bertaux, and E. Chassefiere. First statistical analysis of 5000 mass spectra of cometary grains obtained by PUMA 1 (Vega 1) and PIA (Giotto) impact ionization mass spectrometers in the compressed modes. A&A, 187:761-766, November 1987.

141. H. P. Larson, M. J. Mumma, and H. A. Weaver. Kinematic properties of the neutral gas outflow from comet P/Halley. A&A, 187:391-397, November 1987.

142. C. M. Lisse, D. J. Christian, K. Dennerl, K. J. Meech, R. Petre, H. A. Weaver, and S. J. Wolk. Charge Exchange-Induced X-Ray Emission from Comet C/1999 S4 (LINEAR). Science, 292:1343-1348, May 2001.

143. C. M. Lisse, T. E. Cravens, and K. Dennerl. X-ray and extreme ultraviolet emission from comets. Comets II, pages 631-643, 2005.

144. C. M. Lisse, K. Dennerl, J. Englhauser, M. Harden, F. E. Marshall, M. J. Mumma, R. Petre, J. P. Pye, M. J. Ricketts, J. Schmitt, J. Trumper, and R. G. West. Discovery of X-ray and extreme ultraviolet emission from comet C/Hyakutake 1996 B2. Science, 274:205-209, October 1996.

145. D. C. Lis, J. Keene, K. Young, T. G. Phillips, D. Bockelee-Morvan, J. Crovisier, P. Schilke, P. F. Goldsmith, and E. A. Bergin. Spectroscopic observations of Comet C/1996 B2 (Hyakutake) with the Caltech submillimeter observatory. Icarus, 130:355-372, December 1997.

146. D. C. Lis, D. M. Mehringer, D. Benford, M. Gardner, T. G. Phillips, D. Bockelee-Morvan, N. Biver, P. Colom, J. Crovisier, D. Despois, and H. Rauer. New molecular species in comet C/1995 O1 (Hale-Bopp) observed with the Caltech Submillimeter observatory. Earth Moon and Planets, 78: 13-20, 1999.

147. A. J. Lovell, F. P. Schloerb, E. A. Bergin, J. E. Dickens, C. H. De Vries, M. C. Senay, and W. M. Irvine. HCO+ in the coma of comet Hale-Bopp. Earth Moon and Planets, 77:253-258, 1999.

148. A. J. Lovell, F. P. Schloerb, J. E. Dickens, C. H. De Vries, M. C. Senay, and W. M. Irvine. HCO + Imaging of Comet C/Hale-Bopp 1995 O1. ApJL, 497:L117-L121, April 1998.

149. J. Manfroid, E. Jehin, D. Hutsemekers, A. Cochran, J.-M. Zucconi, C. Arpigny, R. Schulz, and J. A. Stuwe. Isotopic abundance of nitrogen and carbon in distant comets. A&A, 432:L5-L8, March 2005.

150. C. G. Mason, R. D. Gehrz, T. J. Jones, C. E. Woodward, M. S. Hanner, and D. M. Williams. Observations of unusually small dust grains in the coma of comet Hale-Bopp C/1995 O1. ApJ, 549:635-646, March 2001.

151. J. W. (ed.) Mason. Comet Halley. Ellis Horwood, 1990.

152. D. J. McComas, J. T. Gosling, S. J. Bame, J. A. Slavin, E. J. Smith, and J. L. Steinberg. The Giacobini-Zinner magnetotail - Tail configuration and current sheet. JGR, 92:1139-1152, February 1987.

153. J. A. M. McDonnell, P.L. Lamy, and G.S: Pankiewicz. Physical properties of cometary dust. In R. L. Newburn, M. Neugebauer, and J. Rahe, editors, ASSL Vol. 167: IAU Colloq. 116: Comets in the Post-Halley Era, pages 1043-1074, 1991.

154. K. J. Meech and J. Dvoren. Comets II, Chapter Physical and chemical evolution of cometary nuclei. University of Arizona Press, 2005.

155. R. Meier, P. Eberhardt, D. Krankowsky, and R. R. Hodges. The extended formaldehyde source in comet P/Halley. A&A, 277:677, October 1993.

156. R. Meier, P. Eberhardt, D. Krankowsky, and R. R. Hodges. Ammonia in comet P/Halley. A&A, 287:268-278, July 1994.

157. R. Meier, T. C. Owen, D. C. Jewitt, H. E. Matthews, M. Senay, N. Biver, D. Bockeleee-Morvan, J. Crovisier, and D. Gautier. Deuterium in Comet C/1995 O1 (Hale-Bopp): Detection of DCN. Science, 279:1707, March 1998.

159. M. Min, J. W. Hovenier, A. de Koter, L. B. F. M. Waters, and C. Dominik. The composition and size distribution of the dust in the coma of Comet Hale Bopp. Icarus, 179:158-173, December 2005.

160. A. Morbidelli. Comets and their Reservoirs: Current Dynamics and Primordial Evolution. In K. Altwegg, W. Benz and N. Thomas, editors, Trans-Neptunian Objects and Comets, Vol. 35, pages 79-164, 2008.

161. M. Muller, S. F. Green, and N. McBride. An easy-to-use Model for the Optical Thickness and Ambient Illumination within Cometary Dust Comae. Earth Moon and Planets, 90:99-108, March 2002.

162. M. J. Mumma, M. A. Disanti, N. dello Russo, M. Fomenkova, K. Magee-Sauer, C. D. Kaminski, and D. X. Xie. Detection of Abundant Ethane and Methane, Along with Carbon Monoxide and Water, in Comet C/1996 B2 Hyakutake: Evidence for Interstellar Origin. Science, 272:1310-1314, May 1996.

163. M. J. Mumma, M. A. Disanti, N. dello Russo, K. Magee-Sauer, E. Gibb, and R. Novak. Remote infrared observations of parent volatiles in comets: A window on the early solar system. Advances in Space Research, 31:2563-2575, June 2003.

164. M. J. Mumma, H. A. Weaver, H. P. Larson, M. Williams, and D. S. Davis. Detection of water vapor in Halley's comet. Science, 232:1523-1528, June 1986.

165. F. M. Neubauer. Giotto magnetic-field results on the boundaries of the pile-up region and the magnetic cavity. A&A, 187:73-79, November 1987.

166. H. F. Newall. The spectrum of the daylight comet 1910a. MNRAS, 70:459, March 1910.

167. R. L. Newburn and H. Spinrad. Spectrophotometry of 25 comets - Post-Halley updates for 17 comets plus new observations for eight additional comets. AJ, 97:552-569, February 1989.

168. M. B. Niedner and J. C. Brandt. Interplanetary gas. XXII - Plasma tail disconnection events in comets - Evidence for magnetic field line reconnection at interplanetary sector boundaries. ApJ, 223:655-670, July 1978.

169. G. Notesco, A. Bar-Nun, and T. Owen. Gas trapping in water ice at very low deposition rates and implications for comets. Icarus, 162:183-189, March 2003.

170. G. Notesco and A. Bar-Nun. Enrichment of CO over N2 by Their Trapping in Amorphous Ice and Implications to Comet P/Halley. Icarus, 122:118-121, July 1996.

171. J. H. Oort. The structure of the cloud of comets surrounding the Solar System and a hypothesis concerning its origin. Bull. Astron. Inst. Neth., 11:91-110, January 1950.

172. T. Owen. The isotope ratio 12C/13C in comet Tago-Sato (1969g). ApJ, 184:3344, August 1973.

173. E.N. Parker. Interplanetary Dynamical Processes. New York: Interscience Publishers, 1963.

174. D. Prialnik, J. Benkhoff, and M. Podolak. Comets II, Chapter Modelling the structure and activity of comet nuclei. University of Arizona Press, 2005.

175. D. Prialnik. A Model for the Distant Activity of Comet Hale-Bopp. ApJL, 478:L107-L110, April 1997.

176. J. Rahe, C. W. McCracken, and B. D. Donn. Monochromatic and white-light observations of Comet Bennett 1969i /1970II/. A&AS, 23:13-35, January 1976.

177. H. Rauer, C. Arpigny, H. Boehnhardt, F. Colas, J. Crovisier, L. Jorda, M. Kueppers, J. Manfroid, K. Rembor, and N. Thomas. Optical observations of comet Hale-Bopp (C/1995 O1) at large heliocentric distances before perihelion. Science, 275:1909-1912, 1997.

178. H. Rauer, J. Helbert, C. Arpigny, J. Benkhoff, D. Bockelee-Morvan, H. Boehnhardt, F. Colas, J. Crovisier, O. Hainaut, L. Jorda, M. Kueppers, J. Manfroid, and N. Thomas. Long-term optical spectrophotometric monitoring of comet C/1995 O1 (Hale-Bopp). A&A, 397:1109-1122, January 2003.

179. H. Rauer, R. Wegmann, H. U. Schmidt, and K. Jockers. 3-D MHD simulations of the effect of comoving discontinuities in the solar wind on cometary plasma tails. A&A, 295:529-550, March 1995.

180. Weiler M. Hainaut O. Jehin E. Sterken C. Rauer, H. A&A, submitted, 2006.

181. C. Reyle and D. C. Boice. An S2 Fluorescence Model for Interpreting HighResolution Cometary Spectra. I. Model Description and Initial Results. ApJ, 587:464-471, April 2003.

182. K. Richter, M. R. Combi, H. U. Keller, and R. R. Meier. Multiple scattering of hydrogen Lya radiation in the coma of comet Hyakutake (C/1996 B2). ApJ, 531:599-611, March 2000.

183. S. D. Rodgers, H. M. Butner, S. B. Charnley, and P. Ehrenfreund. The HNC/HCN ratio in comets: Observations of C/2002 C1 (Ikeya-Zhang). Advances in Space Research, 31:2577-2582, June 2003.

184. S. D. Rodgers, S. B. Charnley, W. F. Huebner, and D. C. Boice. Comets II, Chapter Physical processes and chemical reactions in cometary comae. University of Arizona Press, 2005.

185. S. D. Rodgers and S. B. Charnley. HNC and HCN in Comets. ApJL, 501: L227-L230, July 1998.

186. S. D. Rodgers and S. B. Charnley. On the origin of HNC in Comet Lee. MNRAS, 323:84-92, May 2001.

187. D. G. Schleicher, S. M. Lederer, R. L. Millis, and T. L. Farnham. Photometric behavior of Comet Hale-Bopp (C/1995 O1) before perihelion. Science, 275:1913-1915, 1997.

188. D. G. Schleicher, R. L. Millis, and P. V. Birch. Narrowband photometry of Comet P/Halley: Variation with heliocentric distance, season, and solar phase angle. Icarus, 132:397-417, April 1998.

189. F. P. Schloerb, M. J. Claussen, and L. Tacconi-Garman. OH Radio Observations of Comet p/ Halley. A&A, 187:469, November 1987.

190. F. P. Schloerb, C. H. De Vries, A. J. Lovell, W. M. Irvine, M. Senay, and H. A. Wootten. Collisional quenching of OH radio emission from comet Hale-Bopp. Earth Moon and Planets, 78:45-51, 1999.

191. F. P. Schloerb and W. Ge. Submillimeter molecular line observations of cometary Levy (1990c). In A. W. Harris and E. Bowell, editors, Asteroids, Comets, Meteors 1991, pages 533-536, December 1992.

192. F. P. Schloerb, W. M. Kinzel, D. A. Swade, and W. M. Irvine. Observations of HCN in comet P/Halley. A&A, 187:475-480, November 1987.

193. M. Schmidt-Voigt. Time-dependent MHD simulations for cometary plasmas. A&A, 210:433-454, February 1989.

194. H.-U. Schmidt, R. Wegmann, W. F. Huebner, and D. C. Boice. Cometary gas and plasma flow with detailed chemistry. Comparative Physical Communication, 49:17-59, 1988.

195. G. Schwehm and P. Murdin. Rosetta. Encyclopedia of Astronomy and Astrophysics, November 2000.

196. Z. Sekanina, D. E. Brownlee, T. E. Economou, A. J. Tuzzolino, and S. F. Green. Modeling the nucleus and jets of Comet 81P/Wild 2 based on the stardust encounter data. Science, 304:1769-1774, June 2004.

197. L. E. Snyder, P. Palmer, and I. de Pater. VLA Observations of Formaldehyde Emission from Comets Halley and Machholz 1988J. PASP, 101:882, October 1989.

198. L. A. Soderblom, D. C. Boice, D. T. Britt, R. H. Brown, B. J. Buratti, R. L. Kirk, M. Lee, R. M. Nelson, J. Oberst, B. R. Sandel, S. A. Stern, N. Thomas, and R. V. Yelle. Imaging Borrelly. Icarus, 167:4-15, January 2004.

199. A. Stawikowski and J. L. Greenstein. The Isotope Ratio 12C/13C in a Comet. ApJ, 140:1280, October 1964.

200. K. S. Swamy. Physics of Comets. Worlds Scientific, 1997.

201. P. Swings. Complex structure of cometary bands tentatively ascribed to the contour of the solar spectrum. Lick Observatory Bulletin, 19:131-136, 1941.

202. M. Tarenghi and T. L. Wilson. The ALMA Project. In L. I. Gurvits, S. Frey, and S. Rawlings, editors, EAS Publications Series, pages 423-430, 2005.

203. N. Thomas and H. U. Keller. Fine dust structures in the emission of comet P/Halley observed by the Halley Multicolour Camera on board Giotto. A&A, 187:843-846, November 1987.

204. A. J. Tuzzolino, T. E. Economou, B. C. Clark, P. Tsou, D. E. Brownlee, S. F. Green, J. A. M. McDonnell, N. McBride, and M. T. S. H. Colwell. Dust measurements in the coma of comet 81P/Wild 2 by the dust flux monitor instrument. Science, 304:1776-1780, June 2004.

205. V. Vanysek. Carbon isotope ratio in comets and interstellar matter. In A. H. Delsemme, editor, IA U Colloq. 39: Comets, Asteroids, Meteorites: Interrelations, Evolution and Origins, pages 499-503, 1977.

206. V. Vanysek. Isotopic ratios in comets. In R. L. Newburn, M. Neugebauer, and J. Rahe, editors, ASSL Vol. 167: IAU Colloq. 116: Comets in the Post-Halley Era, pages 879-895, 1991.

207. H. A. Weaver, T. Y. Brooke, G. Chin, S. J. Kim, D. BockeMe-Morvan, and J. K. Davies. Infrared Spectroscopy of Comet Hale-Bopp. Earth Moon and Planets, 78:71-80, 1999.

208. H. A. Weaver, P. D. Feldman, J. B. McPhate, M. F. A'Hearn, C. Arpigny, and T. E. Smith. Detection of CO Cameron band emission in comet P/Hartley 2 (1991 XV) with the Hubble Space Telescope. ApJ, 422:374-380, February 1994.

209. H. A. Weaver, M. J. Mumma, H. P. Larson, and D. S. Davis. Post-perihelion observations of water in comet Halley. Nature, 324:441-444, December 1986.

210. R. Wegmann, H. U. Schmidt, W. F. Huebner, and D. C. Boice. Cometary MHD and chemistry. A&A, 187:339-350, November 1987.

211. R. Wegmann. Large-scale disturbance of the solar wind by a comet. A&A, 389:1039-1046, July 2002.

212. M. Weiler, H. Rauer, J. Knollenberg, L. Jorda, and J. Helbert. The dust activity of comet C/1995 O1 (Hale-Bopp) between 3 AU and 13 AU from the Sun. A&A, 403:313-322, May 2003.

213. M. Womack, A. Homich, M. C. Festou, J. Mangum, W. T. Uhl, and S. A. Stern. Maps of HCO+ Emission in c/1995 O1 (Hale-Bopp). Earth Moon and Planets, 77:259-264, 1999.

214. L. M. Woodney, J. McMullin, and M. F. A'Hearn. Detection of OCS in comet Hyakutake (c/1996 B2). PSS, 45:717-719, June 1997.

215. M. C. H. Wright, I. de Pater, J. R. Forster, P. Palmer, L. E. Snyder, J. M. Veal, M. F. A'Hearn, L. M. Woodney, W. M. Jackson, Y.-J. Kuan, and A. J. Lovell. Mosaicked images and spectra of J = 1 -> 0 HCN and HCO+ emission from Comet Hale-Bopp (1995 O1). AJ, 116:3018-3028, December 1998.

216. S. Wyckoff, S. C. Tegler, and L. Engel. Ammonia abundances in four comets. ApJ, 368:279-286, February 1991.

217. L. M. Ziurys, C. Savage, M. A. Brewster, A. J. Apponi, T. C. Pesch, and S. Wyckoff. Cyanide chemistry in comet Hale-Bopp (C/1995 O1). ApJL, 527:L67-L71, December 1999.

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