References of "Weaver, H"
     in
Bookmark and Share    
Full Text
See detailThe evolving chemical composition of C/2012 S1 ISON as it approached the Sun
Dello Russo, N.; Vervack, R.; Weaver, H. et al

in Muinonen, Karri (Ed.) Asteroids, Comets, Meteors 2014 (2014, July 01)

Shortly after its discovery by Vitali Nevski and Artyom Novichonok on September 21, 2012, the orbit of C/2012 S1 ISON was determined, indicating a perihelion passage very close to the Sun (0.012 au) in ... [more ▼]

Shortly after its discovery by Vitali Nevski and Artyom Novichonok on September 21, 2012, the orbit of C/2012 S1 ISON was determined, indicating a perihelion passage very close to the Sun (0.012 au) in late November 2013. Initial observations suggested that ISON could be quite bright with a long period of favorable observing conditions leading up to perihelion, followed by a close post-perihelion approach to the Earth (0.42 au) in December 2013. Comet ISON thus became the first sungrazing comet discovered early enough to be studied for many months prior to perihelion, through its close solar passage, and potentially after perihelion. This spurred a worldwide campaign to coordinate observations of ISON from numerous facilities covering a broad spectral range. We report volatile abundances in comet ISON as determined from high-resolution (R ˜ 25,000) infrared spectroscopy. Our strategy was to use the NIRSPEC spectrometer at the 10-m Keck observatory and the CSHELL spectrometer on the 3-m IRTF telescope. We proposed to use NIRSPEC when the comet was fainter but still available during darktime (October through early November 2013 pre-perihelion, and January 2014 post-perihelion), and CSHELL when the comet was brighter and closer to the Sun, but only available during daytime. Although observations on many dates were lost owing to poor weather, and the disruption of the comet near perihelion prevented any post-perihelion observations, successful observations were obtained with NIRSPEC on October 26 (R_h= 1.12 au, Δ = 1.38 au) and October 28 (R_h = 1.08 au, Δ = 1.32 au), and CSHELL on November 19 (R_h = 0.46 au, Δ = 0.86 au) and November 20 (R_h = 0.43 au, Δ = 0.86 au). All dates are specified in UT. The primary results from these observations are as follows. (1) The overall volatile productivity as measured by the H_2O production rate increased from ˜ 10^{28} molec/s on October 26 and 28 to ˜ 3-4×10^{29} molec/s on November 19/20. (2) The volatile production rate was increasing rapidly as ISON approached perihelion, and we investigate whether statistically significant variations in volatile production rates are seen on November 19 between UT 17:15 to 23:00. (3) The relative abundances of some measured volatiles with respect to water remained constant during this time period (e.g., C_2H_6 and CH_3OH), whereas others increased significantly from late October to November 19/20 (e.g., C_2H_2, NH_2, NH_3). (4) Comparison of the measured spatial distributions within the coma of ISON on November 19 show differences that suggest some species are released from extended sources in the coma as well as ices in the nucleus. (5) C_2H_6, CH_3OH and CH_4 appear slightly depleted relative to H_2O in ISON compared to other comets. C_2H_2, HCN, and OCS abundances appear to be in the typical range on November 19, although C_2H_2 abundances appeared depleted in October. Abundances of H_2CO, NH_2, and NH_3 in November were significantly enhanced compared to other comets, with NH_3 abundances being the highest measured to date in any comet. This contrasts with measured abundances and upper limits for NH_2 and NH_3 in late October, which are closer to the typical values seen in comets. [less ▲]

Detailed reference viewed: 17 (0 ULg)
Full Text
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.

Detailed reference viewed: 10 (0 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 59 (15 ULg)
Full Text
Peer Reviewed
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 ▲]

Detailed reference viewed: 15 (2 ULg)
Full Text
See detailHigh-dispersion Spectroscopic Observations Of 8P/Tuttle With VLT/CRIRES
Kobayashi, Hitomi; Bockelee-Morvan, D.; Dello Russo, N. et al

in Bulletin of the American Astronomical Society (2008, September 01), 40

We present near-infrared observations of organic molecules in comet 8P/Tuttle. Comet 8P/Tuttle is a Halley-type comet and its last perihelion was in early January 2008. Our observations were carried out ... [more ▼]

We present near-infrared observations of organic molecules in comet 8P/Tuttle. Comet 8P/Tuttle is a Halley-type comet and its last perihelion was in early January 2008. Our observations were carried out on January 28 and February 4 using CRIRES (CRyogenic high-resolution InfraRed Echelle Spectrograph) at the Very Large Telescope (VLT). We used a 0.2" slit which provided a spectral resolving power of 80,000. We detected H[SUB]2[/SUB]O, OH, HCN, C[SUB]2[/SUB]H[SUB]2[/SUB] on Jan 28, and H[SUB]2[/SUB]O, OH, CH[SUB]4[/SUB], C[SUB]2[/SUB]H[SUB]6[/SUB], and CH[SUB]3[/SUB]OH on Feb 4. We find that 8P/Tuttle is depleted in HCN, C[SUB]2[/SUB]H[SUB]2[/SUB] and C[SUB]2[/SUB]H[SUB]6[/SUB] relative to H[SUB]2[/SUB]O compared with most other Oort cloud comets studied to date. Perhaps these depletions suggest that 8P/Tuttle formed in a different region from most Oort cloud comets, but it is also possible that the depletions are caused by repeated passages through the inner solar system. [less ▲]

Detailed reference viewed: 72 (6 ULg)
Full Text
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)

Detailed reference viewed: 19 (3 ULg)
Peer Reviewed
See detailHubble Space Telescope far-ultraviolet imaging of Jupiter during the impacts of Comet Shoemaker-Levy 9
Clarke, J. T.; Prange, R.; Ballester, G. E. et al

in Highlights of Astronomy, Vol. 10 (1995)

Detailed reference viewed: 21 (4 ULg)