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See detailExtremely Organic-rich Coma of Comet C/2010 G2 (Hill) during its Outburst in 201
Kawakita, H; Dello Russo; Vervack, R et al

in Astrophysical Journal (2014)

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See detailComet C/2012 S1 (Ison)
Dello Russo, N.; Vervack, R. J.; Kawakita, H. et al

in Central Bureau Electronic Telegrams (2013), 3686

CBET 3686 available at Central Bureau for Astronomical Telegrams.

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See detailHyper-volatiles in Comet C/2010 G2 (Hill)
Kawakita, Hideyo; Dello Russo, N.; Vervack, R. J. J. et al

in Bulletin of the American Astronomical Society (2013, October 01), 45

We performed high-dispersion near-infrared spectroscopic observations of comet C/2010 G2 (Hill) at 2.5 AU from the Sun using NIRSPEC (R ~ 2.5x10^4) at the Keck II telescope on UT 2012 Jan 9 and 10. The ... [more ▼]

We performed high-dispersion near-infrared spectroscopic observations of comet C/2010 G2 (Hill) at 2.5 AU from the Sun using NIRSPEC (R ~ 2.5x10^4) at the Keck II telescope on UT 2012 Jan 9 and 10. The comet had been in outburst. Over the two nights of our observations, prominent emission lines of CH4 and C2H6 along with weaker emission lines of H2O, HCN, CH3OH and CO were detected. The gas production rate of CO was comparable to that of H2O. The mixing ratios of CO, HCN, CH4, C2H6, and CH3OH with respect to H2O are higher than those for normal comets by a factor of five or more. Hyper-volatile species such as CO and CH4 were enriched in the coma of comet Hill suggesting that the sublimation of these hyper-volatiles could sustain the outburst of the comet. Based on a comparison with optical observations, some fraction of water in the inner coma existed as icy grains. Those icy ice grains were likely ejected from nucleus by the sublimation of hyper-volatiles. [less ▲]

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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 detailOPRs of Ammonia versus 14N/15N Ratios in CN in 15 Comets
Shinnaka, Yoshiharu; Kawakita, H.; Kobayashi, H. et al

in Bulletin of the American Astronomical Society (2010, October 01), 42

The solar system was formed from interstellar matter 4.6 Gyrs ago and comets are considered as remnants of icy planetesimals formed in the early solar system. One of interesting primordial characters of ... [more ▼]

The solar system was formed from interstellar matter 4.6 Gyrs ago and comets are considered as remnants of icy planetesimals formed in the early solar system. One of interesting primordial characters of cometary ice is an ortho-to-para abundance ratio (OPR) of molecules such as H2O, NH3, etc. The OPR probably indicates the molecular formation temperatures in the solar nebula or in the pre-solar molecular cloud. We determined the OPRs of ammonia by using the high dispersion optical spectra of NH2 in 15 comets: C/1995 O1 (Hale-Bopp), C/1999 S4 (LINEAR), C/2001 A2 (LINEAR), C/2000 WM1 (LINEAR), 153P/Ikeya-Zhang, C/2002 V1 (NEAT), C/2002 X5 (Kudo-Fujikawa), C/2002 Y1 (Juels-Holvorcem), C/2001 Q4 (NEAT), C/2002 T7 (LINEAR), C/2003 K4 (LINEAR), 8P/Tuttle, 88P/Howell, 9P/Tempel 1, and 73P-B and -C/Schwassmann-Wachmann 3. The observations were mainly carried out by the Ultraviolet and Visual Echelle Spectrograph (UVES) mounted on the Very Large Telescope (VLT) in Chile. Other telescopes/instruments were also used in some cases. The OPRs of ammonia are determined from OPRs of NH2 (0,9,0) ro-vibronic band around 600 nm. Although absorption lines (by the telluric atmosphere) and cometary C2 emission lines blended affected to NH2 emission lines in this region, we removed them in our analysis. The determined OPRs of ammonia clustered around 30K but not in the cases of 73P-B and -C. This situation is very similar to that of 14N/15N ratios in CN (i.e., 73P-B and -C are quite peculiar relative to other comets). We discuss about the relationship between the OPRs of ammonia and 14N/15N ratios in CN in these 15 comets. Our results indicate the formation of materials at relatively higher temperatures for 73P-B and -C than other comets. [less ▲]

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See detailHigh-dispersion infrared spectroscopic observations of comet 8P/Tuttle with VLT/CRIRES
Kobayashi, H.; Bockelée-Morvan, D.; Kawakita, H. et al

in Astronomy and Astrophysics (2010), 509

We report on the composition of the Halley-family comet (HFC) 8P/Tuttle investigated with high-dispersion near-infrared spectroscopic observations. The observations were carried out at the ESO VLT (Very ... [more ▼]

We report on the composition of the Halley-family comet (HFC) 8P/Tuttle investigated with high-dispersion near-infrared spectroscopic observations. The observations were carried out at the ESO VLT (Very Large Telescope) with the CRIRES instrument as part of a multi-wavelength observation campaign of 8P/Tuttle performed in late January and early February 2008. Radar observations suggested that 8P/Tuttle is a contact binary, and it was proposed that these components might be heterogeneous in chemistry. We determined mixing ratios of organic volatiles with respect to H[SUB]2[/SUB]O and found that mixing ratios were consistent with previous near infrared spectroscopic observations obtained in late December 2007 and in late January 2008. It has been suggested that because 8P/Tuttle is a contact binary, it might be chemically heterogeneous. However, we find no evidence for chemical heterogeneity within the nucleus of 8P/Tuttle. We also compared the mixing ratios of organic molecules in 8P/Tuttle with those of both other HFCs and long period comets (LPCs) and found that HCN, C[SUB]2[/SUB]H[SUB]2[/SUB], and C[SUB]2[/SUB]H[SUB]6[/SUB] are depleted whereas CH[SUB]4[/SUB] and CH[SUB]3[/SUB]OH have normal abundances. This may indicate that 8P/Tuttle was formed in a different region of the early solar nebula than other HFCs and LPCs. We estimated the conversion efficiency from C[SUB]2[/SUB]H[SUB]2[/SUB] to C[SUB]2[/SUB]H[SUB]6[/SUB] by hydrogen addition reactions on cold grains by employing the C[SUB]2[/SUB]H[SUB]6[/SUB]/(C[SUB]2[/SUB]H[SUB]6[/SUB]+C[SUB]2[/SUB]H[SUB]2[/SUB]) ratio. The C[SUB]2[/SUB]H[SUB]6[/SUB]/(C[SUB]2[/SUB]H[SUB]6[/SUB]+C[SUB]2[/SUB]H[SUB]2[/SUB]) ratio in 8P/Tuttle is consistent with the ratios found in other HFCs and LPCs within the error bars. We also discuss the source of C[SUB]2[/SUB] and CN based on our observations and conclude that the abundances of C[SUB]2[/SUB]H[SUB]2[/SUB] and C[SUB]2[/SUB]H[SUB]6[/SUB] are insufficient to explain the C[SUB]2[/SUB] abundances in comet 8P/Tuttle and that the abundance of HCN is insufficient to explain the CN abundances in the comet, so at least one additional parent is needed for each species, as pointed out in previous study. Based on observations collected at the European Southern Observatory, Paranal, Chile (ESO Prog. 080.C-0615 and 280.C-5053).We regret to note the death of Dr. J. -M. Zucconi in 2009 May. [less ▲]

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See detailRevisit to Nuclear Spin Temperature of Ammonia in Comets
Shinnaka, Yoshiharu; Jehin, Emmanuel ULg; Manfroid, Jean ULg et al

in Bulletin of the American Astronomical Society (2009, September 01), 41

Comets had formed from dust and icy materials in the solar nebula 4.6 Gyrs ago. The cometary materials are considered as the most pristine in the solar system and both dust grains and icy materials in ... [more ▼]

Comets had formed from dust and icy materials in the solar nebula 4.6 Gyrs ago. The cometary materials are considered as the most pristine in the solar system and both dust grains and icy materials in comets have been used to investigate the formation conditions of the solar system. One of interesting primordial characters is a nuclear spin temperature (related to an ortho-to-para ratio; OPR) of cometary molecules such as H2O, NH3, etc. The nuclear spin temperatures probably reflect the molecular formation temperatures in the solar nebula (or in the presolar molecular cloud). In this work, we analyzed high dispersion optical spectra of C/2001 Q4 (NEAT), C/2000 WM1 (LINEAR), 88P/Howell, fragments B and C of 73P/Schwassmann-Wachmann 3 and 8P/Tuttle. Our observations were performed by the Ultraviolet and Visual Echelle Spectrograph (UVES) mounted on the Very Large Telescope (VLT) in Chile and the High Dispersion Spectrograph (HDS) mounted on the Subaru telescope in Hawaii. We determined nuclear spin temperatures of NH3 in five comets based on optical spectra of NH2. The nuclear spin temperatures of NH3 can be obtained from OPRs of NH2. We used the (0,9,0) ro-vibronic band at 610nm in this work. Absorption lines (by the telluric atmosphere) and cometary C2 emission lines blended with NH2 emission lines were also taken into account in our analysis. These lines have never been considered in previous studies. The origin of icy materials in the five comets will be discussed based on these results. [less ▲]

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See detailA Multi-Wavelength Simultaneous Study of the Composition of the Halley Family Comet 8P/Tuttle
Jehin, Emmanuel ULg; Bockelée-Morvan, Dominique; Dello Russo, N. et al

in Earth, Moon, and Planets (2009), 105

We report on simultaneous optical and infrared observations of the Halley Family comet 8P/Tuttle performed with the ESO Very Large Telescope. Such multi-wavelength and coordinated observations are a good ... [more ▼]

We report on simultaneous optical and infrared observations of the Halley Family comet 8P/Tuttle performed with the ESO Very Large Telescope. Such multi-wavelength and coordinated observations are a good example of what can be done to support space missions. From high resolution optical spectroscopy of the CN (0,0) 388 nm and NH[SUB]2[/SUB] (0,9,0) 610 nm bands using UVES at UT2 we determined [SUP]12[/SUP]C/[SUP]13[/SUP]C = 90 ± 10 and [SUP]14[/SUP]N/[SUP]15[/SUP]N = 150 ± 20 in CN and we derived a nuclear spin temperature of NH[SUB]3[/SUB] of 29 ± 1 K. These values are similar to those found in Oort-Cloud and Jupiter Family comets. From low resolution long slit spectroscopy with FORS1 at UT2 we determined the CN, C[SUB]3[/SUB] and C[SUB]2[/SUB] production rates and the parent and daughter scale lengths up to 5.2 10[SUP]5[/SUP] km tailward. From high resolution IR spectroscopy with CRIRES at UT1 we measured simultaneously the production rates and mixing ratios of H[SUB]2[/SUB]O, HCN, C[SUB]2[/SUB]H[SUB]2[/SUB], CH[SUB]4[/SUB], C[SUB]2[/SUB]H[SUB]6[/SUB], and CH[SUB]3[/SUB]OH. [less ▲]

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See detailA Multi-Wavelength Simultaneous Study of the Composition of the Halley-Family Comet 8P/Tuttle at the VLT
Bockelée-Morvan, Dominique; Dello Russo, N.; Jehin, Emmanuel ULg et al

in LPI contribution 1405 (2008)

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