Spectroscopic Monitoring of Comet C/1996 B2 (Hyakutake) with the JCMT and IRAM Radio Telescopes

Biver, Nicolás; Bockelée‐Morvan, Dominique; Crovisier, J.; Davies, John K.; Matthews, H. E.; Wink, J. E.; Rauer, H.; Colom, P.; Dent, W. R. F.; Despois, D.; Moreno, R.; Paubert, G.; Jewitt, David; Senay, M.

doi:10.1086/301033

Cited by 153 publications

(91 citation statements)

References 34 publications

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“…The best-fit temperature variation followed a power law in R h of −2.0 (T rot = T 1AU R h −2.0 ± 0.2 , with T 1AU = (93 ± 3) K representing the fitted value extrapolated to R h = 1 AU; see Figure 3). Although our measurements sample a relatively small range of R h , this power law is consistent with "typical" values for other comets (e.g., see Biver et al 1997Biver et al , 1999.…”

Section: Rotational Temperaturessupporting

confidence: 90%

“…Our best-fit results indicate a rather steep increase in water production with decreasing heliocentric distance (Q H2O = Q 1AU R h −4.7 ± 0.9 , with Q 1AU = (6.66 ± 1.55) × 10 28 s −1 ; Figure 3(B)), which is somewhat steeper than the typical (insolation-limited) value (R h −2 ) often seen in comets (Biver et al 1999). A steeper power law could be related to an increase in outgassing associated with (slow) nucleus rotation during this brief interval.…”

Section: Production Ratesmentioning

confidence: 54%

“…These comets are C/1995 O1 (Hale-Bopp; DiSanti et al 1999DiSanti et al , 2001Bockelée-Morvan et al 2010), C/1996 B2 (Hyakutake; Mumma et al 1996;Biver et al 1999;DiSanti et al 2003), C/1999Mumma et al 2003;Biver et al 2006), C/2001 Q4 (NEAT; Lupu et al 2007), C/2008Ootsubo et al 2012), and C/2009 P1 (Garradd; e.g., Paganini et al 2012b;Feaga et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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C/2013 R1 (Lovejoy) at Ir Wavelengths and the Variability of Co Abundances Among Oort Cloud Comets

Paganini

Mumma

Villanueva

et al. 2014

ApJ

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We report production rates, rotational temperatures, and related parameters for gases in C/2013 R1 (Lovejoy) using the Near InfraRed SPECtrometer at the Keck Observatory, on six UT dates spanning heliocentric distances (R h ) that decreased from 1.35 AU to 1.16 AU (pre-perihelion). We quantified nine gaseous species (H 2 O, OH * , CO, CH 4 , HCN, C 2 H 6 , CH 3 OH, NH 3 , and NH 2 ) and obtained upper limits for two others (C 2 H 2 and H 2 CO). Compared with organics-normal comets, our results reveal highly enriched CO, (at most) slightly enriched CH 3 OH, C 2 H 6 , and HCN, and CH 4 consistent with "normal", yet depleted, NH 3 , C 2 H 2 , and H 2 CO. Rotational temperatures increased from ∼50 K to ∼70 K with decreasing R h , following a power law in R h of −2.0 ± 0.2, while the water production rate increased from 1.0 to 3.9 × 10 28 molecules s −1 , following a power law in R h of −4.7 ± 0.9. The ortho-para ratio for H 2 O was 3.01 ± 0.49, corresponding to spin temperatures (T spin ) 29 K (at the 1σ level). The observed spatial profiles for these emissions showed complex structures, possibly tied to nucleus rotation, although the cadence of our observations limits any definitive conclusions. The retrieved CO abundance in Lovejoy is more than twice the median value for comets in our IR survey, suggesting this comet is enriched in CO. We discuss the enriched value for CO in comet C/2013 R1 in terms of the variability of CO among Oort Cloud comets.

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Section: Rotational Temperaturessupporting

confidence: 90%

Section: Production Ratesmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

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C/2013 R1 (Lovejoy) at Ir Wavelengths and the Variability of Co Abundances Among Oort Cloud Comets

Paganini

Mumma

Villanueva

et al. 2014

ApJ

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“…For T rot = 100 K, the abundance ratio limit is ∼4-6%. Our limit on CO production in GZ is similar to the estimated abundance of CO in the nucleus of Comets 1P/Halley (3.5%, Eberhardt 1998), Bradfield (C/1979 Y1) (3.5%, Feldman et al 1997), and Levy (C/1990 K1) (4.1-8.4%, Feldman et al 1997), and is significantly lower than the estimated CO abundances in comets Hyakutake (C/1996 B2) (∼14%, McPhate et al 1996; ∼20%, Biver et al 1999b;Mumma et al 1996 derived a preliminary value of 7%) and Hale-Bopp (∼10% at r ∼ 1 AU, according to Weaver et al 1999 andDiSanti et al 1999; ∼23% at r ∼ 1 AU, according to Biver et al 1999a). The CO abundance limit for GZ is somewhat larger than the abundance ratio observed in Comet Austin (C/1989 X1) (1.7%, Feldman et al 1997) and the upper limits derived for 103P/Hartley 2 (≤1.2%, Weaver et al 1994) and Shoemaker-Levy (C/1991 T2) (≤1.8%, Feldman et al 1997).…”

Section: Cosupporting

confidence: 76%

“…f C 2 H 6 /CH 3 OH: using Q CH 3 OH from Bockelée-Morvan et al (1995), except for Hyakutake (Biver et al 1999b), Hale-Bopp (Biver et al 1999a), and GZ (this work); for GZ, C 2 H 6 /H 2 O ≤ 0.05-0.08% and C 2 H 6 /CH 3 OH ≤ 5.9% from our high resolution data (see Table II). …”

Section: Hmentioning

confidence: 68%

An Infrared Investigation of Volatiles in Comet 21P/Giacobini–Zinner

Weaver¹,

Chin

Bockelée‐Morvan

et al. 1999

Icarus

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We obtained high resolution (λ/δλ ∼ 10,000-20,000) infrared (IR) spectra of Comet 21P/Giacobini-Zinner (GZ) at five different wavelengths between 1.9 and 5.0 µm during 25-29 October 1998 using CSHELL at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea. We also obtained a moderate resolution (λ/δλ ∼ 680) spectrum covering the wavelength range from 3.082 to 3.720 µm on 29 October 1998 using CGS4 at the United Kingdom Infrared Telescope (UKIRT) on Mauna Kea. Five rovibrational lines in three different vibrational bands of H 2 O were detected in the CSHELL spectra. Assuming that the rotational temperature was ∼50 K, we derive a H 2 O production rate of ∼2-3 × 10 28 molecules s −1 , which is ∼2 times smaller than the value derived from nearly simultaneous radio observations of OH. After continuum subtraction, the CGS4 spectrum displays significant excess flux that we attribute mainly to CH 3 OH fluorescence, and we derive that the CH 3 OH production rate was ∼2.7 × 10 26 molecules s −1 . The corresponding CH 3 OH/H 2 O relative abundance is ∼0.9-1.4%, which falls within the range of values observed in other comets, albeit at the low end. The CGS4 spectrum also has significant excess flux near 3.43 µm that is not explained by our CH 3 OH fluorescence model; a similar feature has been observed in several other comets, but its origin remains a mystery. We did not detect any excess emission near 3.28 µm, where some comets show a feature that may be associated with polycyclic aromatic hydrocarbons. We also searched for emissions from C 2 H 6 , CO, HCN, C 2 H 2 , and H 2 CO but did not detect any of these molecules. The 3σ upper limits for the abundances relative to H 2 O are 0.05-0.08% for C 2 H 6 , 2-3% for CO, 0.2-0.3% for HCN, 0.3-0.4% for C 2 H 2 , and 0.5-0.8% for H 2 CO, assuming that all species are parent molecules and that their rotational temperature in the coma is 50 K. C 2 H 6 is depleted by a factor of ∼15 or more compared to its relative abundance in Comets Hale-Bopp VOLATILES IN COMET 21P/GZ 483 (C/1995 O1) and Hyakutake (C/1996 B2); this depletion is similar to that observed for C 2 and C 3 from optical observations of GZ (A'Hearn et al. 1995) and suggests that the formation of volatile carbon-chain molecules was inhibited in GZ. We are unable to find any clear correlation between the C 2 H 6 and the C 2 and C 3 abundances in a sample of nine other comets, assuming that the residual emission near 3.35 µm in moderate resolution spectra of seven of the comets provides an accurate indicator of the C 2 H 6 abundance. However, this latter assumption is questionable and highlights the need to obtain high spectral resolution data in order to make accurate abundance measurements of C 2 H 6 .

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The precipitation of keV energetic oxygen ions at Mars and their effects during the comet Siding Spring approach

Gronoff

Rahmati

Wedlund

et al. 2014

Geophysical Research Letters

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Comet Siding Spring C/2013 A1 will pass Mars on 19 October 2014, entailing particle and dust precipitation in the Martian upper atmosphere and a potential dust hazard for orbiters. An estimate of the flux of energetic O + ions picked up by the solar wind from the cometary coma is shown, with an increase of the O + flux above 50 keV by 2 orders of magnitude. While the ionization of Mars' upper atmosphere by precipitating O + ions is expected to be negligible compared to solar EUV-XUV ionization, it is of the same order of magnitude at 110 km altitude during the cometary passage, leading to detectable increases in ionospheric densities. Cometary O + pickup ion precipitation is expected to be the major nightside ionization source, creating a temporary ionosphere and a global airglow. These effects are dependent on the solar and cometary activities at the time of the encounter.

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Spectroscopic Monitoring of Comet C/1996 B2 (Hyakutake) with the JCMT and IRAM Radio Telescopes

Cited by 153 publications

References 34 publications

C/2013 R1 (Lovejoy) at Ir Wavelengths and the Variability of Co Abundances Among Oort Cloud Comets

C/2013 R1 (Lovejoy) at Ir Wavelengths and the Variability of Co Abundances Among Oort Cloud Comets

An Infrared Investigation of Volatiles in Comet 21P/Giacobini–Zinner

The precipitation of keV energetic oxygen ions at Mars and their effects during the comet Siding Spring approach

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