WATER PRODUCTION IN COMETS C/2011 L4 (PanSTARRS) AND C/2012 F6 (LEMMON) FROM OBSERVATIONS WITH<i>SOHO</i>/SWAN

Combi, M. R.; Bertaux, Jean-Loup; Quémerais, Éric; Ferron, S.; Mäkinen, Jaakko; Aptekar, G.

doi:10.1088/0004-6256/147/6/126

Cited by 10 publications

(14 citation statements)

References 13 publications

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“…This gives Q(H 2 O) = 1.39 ± 0.26 × 10 29 mol/s for February 7 and Q(H 2 O) = 0.79 ± 0.19 × 10 29 mol/s for June 5. Our production rates are lower than those obtained by Paganini et al (2014) and Combi et al (2014). When comparing the water production rates in comets computed from different sources there is usually a discrepancy between the values computed from observations of H, OH, or H 2 O directly at different wavelengths.…”

Section: Compositioncontrasting

confidence: 68%

TRAPPIST monitoring of comet C/2012 F6 (Lemmon)

Opitom

Jehin

Manfroid

et al. 2015

A&A

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We report the results of the long-term narrowband photometry and imaging monitoring of comet C/2012 F6 (Lemmon) with the robotic TRAPPIST telescope (La Silla Observatory). Observations covered 52 nights pre-and post-perihelion between December 11, 2012, and June 11, 2013 (perihelion: 24 March, 2013. We followed the evolution of the OH, NH, CN, C 3 , and C 2 production rates computed with the Haser model as well as the evolution of the A(θ) f ρ parameter as a proxy for the dust production. All five gas species display similar slopes for the heliocentric dependence. An asymmetry about perihelion is observed, the rate of brightening being steeper than the rate of fading. The chemical composition of the comet's coma changes slightly along the orbit: the relative abundance of C 2 to CN increases with the heliocentric distance (r) below −1.4 au and decreases with r beyond 1.4 au while the C 3 -to-CN ratio is constant during our observations. The behavior of the dust is different from that of the gas, the slope of the heliocentric dependence becoming steeper in early February, correlated to a change in the visual lightcurve slope. However, the dust color does not vary during the observations. The application of several enhancement techniques on the images revealed structures in the CN, C 3 , and C 2 images. These features imply the existence of one or several active zone(s) on the comet nucleus. The shape of the structures is similar in these three filters and changes from a roughly hourglass shape in December and January to a corkscrew shape in February and March. The structures in the continuum filters (sampling the dust) are not correlated to those observed for the gas. During several full nights in February, we observed changes in the CN and C 2 structures that repeated periodically because of the nucleus rotation, our derived rotational period being of 9.52 ± 0.05 h.

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Section: Compositioncontrasting

confidence: 68%

TRAPPIST monitoring of comet C/2012 F6 (Lemmon)

Opitom

Jehin

Manfroid

et al. 2015

A&A

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“…(b) For comet Lemmon, Combi et al (2014) provide Q H 2 O values in the range 7−12 × 10 29 molec s −1 during this period. Contemporaneous SWAN measurements are slightly lower than quoted here, but they were not time-deconvolved and the average values measured by SWAN a few days later are within 10% of those given here.…”

Section: Notesmentioning

confidence: 98%

“…For other periods and for comet Lemmon, the observations of the OH radical could not be used to derive an accurate water production rate owing to significant uncertainties in the quenching of the maser inversion. We either used the water production rates reported elsewhere (Combi et al 2014;Paganini et al 2014) or made an interpolation from the Odin observations of comet Lovejoy at perihelion. Based on Nançay and Odin observations, we adopt a mean Q H 2 O = 5, 5.5, 6, and 7 × 10 29 molec s −1 for the 13−16 January, 13-25 January, 23−25 January, and 26 January-3 February 2015 time intervals, respectively, with a ±20% time variation possible within each time interval.…”

Section: Reference Water Production Ratesmentioning

confidence: 99%

Isotopic ratios of H, C, N, O, and S in comets C/2012 F6 (Lemmon) and C/2014 Q2 (Lovejoy)

Biver

Moreno

Bockelée‐Morvan

et al. 2016

A&A

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The apparition of bright comets C/2012 F6 (Lemmon) and C/2014 Q2 (Lovejoy) in March-April 2013 and January 2015, combined with the improved observational capabilities of submillimeter facilities, offered an opportunity to carry out sensitive compositional and isotopic studies of the volatiles in their coma. We observed comet Lovejoy with the IRAM 30 m telescope between 13 and 26 January 2015, and with the Odin submillimeter space observatory on 29 January-3 February 2015. We detected 22 molecules and several isotopologues. The H (Lovejoy), we report the first D/H ratio in an Oort Cloud comet that is not larger than the terrestrial value. On the other hand, the observation of the same HDO line in the other Oort-cloud comet, C/2012 F6 (Lemmon), suggests a D/H value four times higher. Given the previous measurements of D/H in cometary water, this illustrates that a diversity in the D/H ratio and in the chemical composition, is present even within the same dynamical group of comets, suggesting that current dynamical groups contain comets formed at very different places or times in the early solar system.

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“…Comets Lemmon and Lovejoy became unexpectedly bright naked-eye comets, reaching visual magnitudes of 4.5 and 4.8, and displayed high water production rates near perihelion of 1×10 30 and 1.5×10 29 molec. s −1 (Combi et al 2014;Crovisier et al, priv. comm.…”

Section: Introductionmentioning

confidence: 99%

Complex organic molecules in comets C/2012 F6 (Lemmon) and C/2013 R1 (Lovejoy): detection of ethylene glycol and formamide

Biver

Bockelée‐Morvan

Debout

et al. 2014

A&A

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A spectral survey in the 1 mm wavelength range was undertaken in the long-period comets C/2012 F6 (Lemmon) and C/2013 R1 (Lovejoy) using the 30 m telescope of the Ins titut de radioastronomie millimétrique (IRAM) in April and November−December 2013. We report the detection of ethylene glycol (CH 2 OH) 2 (aGg' conformer) and formamide (NH 2 CHO) in the two comets. The abundances relative to water of ethylene glycol and formamide are 0.2-0.3% and 0.02% in the two comets, similar to the values measured in comet C/1995 O1 (Hale-Bopp). We also report the detection of HCOOH and CH 3 CHO in comet C/2013 R1 (Lovejoy), and a search for other complex species (methyl formate, glycolaldehyde).

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WATER PRODUCTION IN COMETS C/2011 L4 (PanSTARRS) AND C/2012 F6 (LEMMON) FROM OBSERVATIONS WITHSOHO/SWAN

Abstract: The maximum water production rates were ∼1 × 10 30 molecules s −1 for both comets. The activities of both comets were asymmetric about perihelion. C/2011 L4 (PanSTARRS) was more active before perihelion than after, but C/2012 F6 (Lemmon) was more active after perihelion than before.

Cited by 10 publications

References 13 publications

TRAPPIST monitoring of comet C/2012 F6 (Lemmon)

TRAPPIST monitoring of comet C/2012 F6 (Lemmon)

Isotopic ratios of H, C, N, O, and S in comets C/2012 F6 (Lemmon) and C/2014 Q2 (Lovejoy)

Complex organic molecules in comets C/2012 F6 (Lemmon) and C/2013 R1 (Lovejoy): detection of ethylene glycol and formamide

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