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Mumma, M.J.1
Weissman, P.R.2
Stern, S.A.3
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2
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0003720944
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Univ. of Arizona Press, Tucson, AZ
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W. M. Irvine, F. P. Schloerb, J. Crovisier, B. Fegley, M. J. Mumma, in Protostars and Planets IV (Univ. of Arizona Press, Tucson, AZ, 2000), pp. 1159-1200.
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Irvine, W.M.1
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Fegley, B.4
Mumma, M.J.5
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3
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0343908477
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note
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i < 2. They include Halley-type orbits, long-period comets, and dynamically new comets.
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4
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0342602668
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note
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Temperatures are approximate. They depend on the degree of nebular clearing, the luminosity of the young Sun, and other details (1).
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6
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0343908481
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note
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2 and CN have revealed differences among Jupiter-family comets, and to a much lesser degree among Oort cloud comets (11). The reason for this difference is not fully understood.
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7
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0000835588
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From Stardust to Planetesimals: Review Papers San Francisco, CA
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M. J. Mumma, in From Stardust to Planetesimals: Review Papers (Astronomical Society Pacific Conference Series 122, San Francisco, CA, 1997), pp. 369-396.
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Mumma, M.J.1
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0033578088
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M. A. DiSanti et al., Nature 399, 662 (1999).
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DiSanti, M.A.1
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11
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0041923384
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M. F A'Hearn et al., Icarus 118, 223 (1995).
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Icarus
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A'Hearn, M.F.1
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12
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0343472740
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note
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The International Astronomical Union (IAU) designations of the four comparison comets are: 1P/Halley, C/1996 B2 (Hyakutake), C/1995 O1 (Hale-Bopp), and C/1999 H1 (Lee).
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13
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0029908980
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M. J. Mumma, Nature 383, 581 (1996).
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Mumma, M.J.1
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J. Crovisier et al., Science 275, 1904 (1997).
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Crovisier, J.1
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C. H. Stokes et al., Icarus 148, 21 (2000).
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Stokes, C.H.1
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24
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0343036902
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personal communication
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B. Marsden, personal communication.
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Marsden, B.1
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25
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0029665392
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M. J. Mumma et al., Science 272, 1310 (1996).
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Mumma, M.J.1
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26
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0029663989
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T. Y. Brooke et al., Nature 383, 606 (1996).
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Nature
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Brooke, T.Y.1
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31
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0343472739
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We used the IRTF's CSHELL (32)
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We used the IRTF's CSHELL (32).
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32
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0001538584
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T. P. Greene et al., in Proc. SPIE 1946, 311 (1993).
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(1993)
Proc. SPIE
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Greene, T.P.1
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33
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0343472738
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We used the Keck Observatory's NIRSPEC (34)
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We used the Keck Observatory's NIRSPEC (34).
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34
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85042615396
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Infrared Detector Arrays for Astronomy Bellingham, WA
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I. S. McLean et al., in Infrared Detector Arrays for Astronomy (SPIE Conference Proceedings 3354, Bellingham, WA, 1998), pp. 566-578.
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(1998)
SPIE Conference Proceedings
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McLean, I.S.1
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35
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0343036901
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note
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CSHELL affords a relatively small spectral grasp for each grating setting, so several separate instrument settings are needed to provide adequate spectral coverage for a typical molecular vibrational band. The 1K-by-1K detector array in NIRSPEC provides a larger spectral grasp for each order and the echelle grating is cross-dispersed, permitting multiple spectral orders to be sampled simultaneously. The instantaneous spectral coverage in the organics region (3.4 μm) is thus about 24 times larger for NIRSPEC than for CSHELL.
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36
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0343472737
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note
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The slit was oriented east-west on the sky for all observations reported in this paper. Cometary spectra were acquired using sequences of four scans (switching between the A and B beams in a sequence of ABBA and keeping the comet on-slit for each position) with a total integration time of 4 min on-source per sequence (the K1 setting used 8 min per sequence). With CSHELL, the slit length was 30 arc-sec (150 detector rows) on the sky, and the telescope was nodded 15 arc-sec. We used the 2-arc-sec-wide slit and guided with the internal camera until sunrise. Thereafter, we imaged after each spectral sequence (in the ABBA sequence) to correct tracking and guiding. For NIRSPEC, the slit length was 24 arc-sec (∼125 detector rows) on the sky, and the telescope was nodded 12 arc-sec. During K- and L-band observations with NIRSPEC, guiding was accomplished with the internal camera (SCAM) with the KL filter.
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37
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0343908474
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note
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For each grating setting, spectra of IR standard stars were acquired for absolute flux calibration of the comet spectra. Stellar spectra were acquired with the same slit width used for the comet, and slit losses were estimated by assuming an azimuthally symmetric stellar profile. Appropriate corrections were incorporated into the absolute flux calibrations.
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38
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0342602666
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note
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Initial data processing included removal of high dark current pixels and cosmic ray hits using median- and sigma-filtering, and registration of spectral frames. The raw spatial-spectral frames are usually anamorphic in both spectral and spatial directions. We resampled the frames, straightening the A and B beams independently within each order so that the spectral dimension fell along a row and the spatial dimension was orthogonal to this. This process also adjusts the spectral dispersion to a common value, row by row. Spectra were then extracted by summing seven rows about the center of each beam position, and those spectra were combined.
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39
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0343472732
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note
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Atmospheric transmittance models were calculated with the Spectrum Synthesis Program (SSP), which accesses the HITRAN-1992 Molecular Data Base. SSP models were used to assign wavelength scales to the spectra and to establish absolute column burdens for relevant absorbing species in the terrestrial atmosphere. The transmittance model was binned to the instrumental sampling interval, convolved to the resolution of the comet spectrum, and normalized to the cometary continuum. For additional details on our data processing techniques, see (9, 28).
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40
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0343472731
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note
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6 in comet Lee agree quite well, which may reflect control of rotational populations by electron collisions in the inner coma (41, 42). We therefore adopt a common temperature (50 K) for all species in C/LINEAR.
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43
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17344388472
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N. D. Biver et al., Astron. J. 118, 1850 (1999).
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Astron. J.
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Biver, N.D.1
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45
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0343472730
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in preparation
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N. Dello Russo et al., in preparation.
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Dello Russo, N.1
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47
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0343908470
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note
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3OH, and OH) (Table 2).
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48
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0343908471
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note
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2O creates OH fragments in rotationally and vibrationally excited states (49-57). The newly formed OH promptly radiates a vibrational quantum (within a few milliseconds) and the rotational distribution then cools to ambient temperatures through collisions; hence, subsequent fluorescent or collisional excitation of the observed lines is negligible (52). The excitation efficiency (g factor) for OH prompt emission is determined by the solar UV flux (mainly Lyman-alpha) responsible for dissociative excitation of water and by the quantum structure of the water molecule. The relative line intensities within each OH quadruplet depend only on the dissociative quantum states of water itself, and so they are independent of the water production rate. They are also independent of the rotational temperature for water, to first order. Such high-J lines cannot be excited by fluorescent pumping (either UV or IR) of thermalized OH in the coma.
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53
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0343908473
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note
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3OH production rate.
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57
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0343908472
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note
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We tailored our ethane fluorescence model (45) to 50 K rotational temperature.
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58
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0035907107
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T. L. Farnham et al. Science 292, 1348 (2001).
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(2001)
Science
, vol.292
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Farnham, T.L.1
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59
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0035906907
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H. A. Weaver et al. Science 292, 1329 (2001).
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(2001)
Science
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Weaver, H.A.1
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61
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0343036892
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note
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The water production rate reported by (59) may need downward revision, if OH electronic prompt emission is significant (62). HST fluxes show a continual decrease from July 6.74 to July 6.87, so the peak production apparently occurred before July 6.74 (59).
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65
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0343036893
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note
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2O = 0.31 ± 0.1% (10).
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67
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0031071224
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G. Notesco et al., Icarus 125, 471 (1997).
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(1997)
Icarus
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, pp. 471
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Notesco, G.1
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69
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0342602662
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note
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2/OH line intensities (Fig. 2D).
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74
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0000724793
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A. Drouart et al., Icarus 140, 129 (1999).
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(1999)
Icarus
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Drouart, A.1
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75
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0001818449
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O. Mousis et al., Icarus 148, 513 (2000).
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(2000)
Icarus
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Mousis, O.1
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76
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0034691588
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J. Nuth et al., Nature 406, 275 (2000).
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(2000)
Nature
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Nuth, J.1
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78
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0342602661
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note
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2O in Hale-Bopp (80).
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80
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0343908467
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note
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i < 3; they formed over a much wider range of heliocentric distance (from the Kuiper belt inward) and only later entered their present orbits.
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82
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0000720915
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A. Delsemme, Icarus 146, 313 (2000).
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(2000)
Icarus
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Delsemme, A.1
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83
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0342602660
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note
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Supported by the NASA Planetary Astronomy Program (grants RTOP 344-32-30-07 to M.J.M. and NAG5-7905 to M.A.D.), by the NASA Planetary Atmospheres Program (grant NAC5-7753 to N.D.R.), and by NSF (grant AST-9619461 to K.M.S.). The NASA IRTF is operated by the University of Hawaii under contract to NASA. The Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation; it is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. We thank the staff of IRTF and Keck for their expert assistance and H. Levison for valuable discussions. M.J.M. thanks S. T. Mumma and S. E. Selonick, without whose support this research would not have been possible.
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