Observations of the 18-cm OH lines of Comet 103P/Hartley 2 at Nançay in support to the EPOXI and Herschel missions

Crovisier, J.; Colom, P.; Biver, Nicolás; Bockelée‐Morvan, Dominique; Boissier, J.

doi:10.1016/j.icarus.2012.03.033

Cited by 13 publications

(15 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The large dust velocities measured by the radar measurements favor models leading to dust production rates higher than the range of values 830-2700 kg given by models 1 and 2. These values are larger than the CO 2 and H 2 O production rates of 160 kg s −1 and ∼ 300 kg s −1 , respectively, measured in the period of the Plateau de Bure observations (A'Hearn et al, 2011;Dello Russo et al, 2011;Crovisier et al, 2013). They imply a dust-to-gas production rate ratio in the range 2-6, suggesting that 103P/Hartley 2 was highly dust productive.…”

Section: Dust Production Ratesmentioning

confidence: 81%

“…The total cross-section of methanol-water collisions was taken equal to σ c = 5 × 10 −14 cm 2 (Biver et al, 1999). The H 2 O production rate was assumed to be 1.0 × 10 28 s −1 , i.e., within the range (0.5 − 1.5) × 10 28 s −1 of values measured during the observing period (A'Hearn et al, 2011;Combi et al, 2011;Dello Russo et al, 2011;Mumma et al, 2011;Crovisier et al, 2013). We considered outflow at a constant velocity of 0.7 km s −1 , which corresponds to the half width at half maximum of the HCN J(1-0) line observed in On-Off mode, and is consistent with other determinations (Crovisier et al, 2013;Biver et al, 2011).…”

Section: Coma Temperaturementioning

confidence: 99%

“…The H 2 O production rate was assumed to be 1.0 × 10 28 s −1 , i.e., within the range (0.5 − 1.5) × 10 28 s −1 of values measured during the observing period (A'Hearn et al, 2011;Combi et al, 2011;Dello Russo et al, 2011;Mumma et al, 2011;Crovisier et al, 2013). We considered outflow at a constant velocity of 0.7 km s −1 , which corresponds to the half width at half maximum of the HCN J(1-0) line observed in On-Off mode, and is consistent with other determinations (Crovisier et al, 2013;Biver et al, 2011). The brightness distribution of the lines was then computed using the radiative transfer code of Boissier et al (2007), which includes both self-absorption and stimulated emission (see Biver 1997 for detailed explanations).…”

Section: Coma Temperaturementioning

confidence: 99%

See 2 more Smart Citations

Gas and dust productions of Comet 103P/Hartley 2 from millimetre observations: Interpreting rotation-induced time variations

Boissier¹,

Bockelée‐Morvan²,

Biver³

et al. 2014

Icarus

Self Cite

View full text Add to dashboard Cite

Comet 103P/Hartley 2 made a close approach to the Earth in October 2010. It was the target of an extensive observing campaign including ground-and orbit-based observatories and was visited by the Deep Impact spacecraft in the framework of its mission extension EPOXI. We present observations of HCN and CH 3 OH emission lines conducted with the IRAM Plateau de Bure interferometer on 22-23, 28 October and 4, 5 November 2010 at 1.1, 1.9 and 3.4 mm wavelengths. The thermal emission from the dust coma and nucleus is detected simultaneously. Interferometric images with unprecedented spatial resolution of ∼100 to ∼500 km are obtained. A sine-wave like variation of the thermal continuum is observed in the 23 October data, that we associate with the nucleus thermal light curve. The nucleus contributes up to 30-55 % of the observed continuum emission. The dust thermal emission is used to measure the dust production rate. The inferred large dust-to-gas ratio (in the range 2-6) can be explained by the unusual activity of the comet for its size, which allows decimeter size particles and large boulders to be entrained by the gas due to the small nucleus gravity. The rotational temperature of CH 3 OH is measured with beam radii from ∼150 km to ∼1500 km. We attribute the increase from ∼35 K to ∼46 K with increasing beam size to radiative processes. The HCN production rate displays strong rotation-induced temporal variations, varying from ∼0.3×10 25 s −1 to ∼2.0×10 25 s −1 in the 4-5 November period. The HCN production curve, as well as the CO 2 and H 2 O production curves measured by EPOXI, are interpreted with a geometric model which takes into account the complex rotational state of 103P/Hartley 2 and its shape. The HCN and H 2 O production curves are in phase, showing that these molecules have common sources. The ∼ 1.7 h delay, in average, of the HCN and H 2 O production curves with respect to the CO 2 production curve suggests that HCN and H 2 O are mainly produced by subliming icy grains. The scale length of production of HCN is determined to be on the order of 500-1000 km, implying a mean velocity of 100-200 m s −1 for the icy grains producing HCN. From the time evolution of the insolation of the nucleus, we show that the CO 2 production is modulated by the insolation of the small lobe of the nucleus. The three-cycle pattern of the production curves reported earlier is best explained by an overactivity of the small lobe in the longitude range 0-180• . The good correlation between the insolation of the small lobe and CO 2 production is consistent with CO 2 being produced from small depths below the surface. The time evolution of the velocity offset of the HCN lines, as well as the displacement of the HCN photocenter in the interferometric maps, are overall consistent with this interpretation. Other localized sources of gas on the nucleus surface are also suggested.

show abstract

Section: Dust Production Ratesmentioning

confidence: 81%

Section: Coma Temperaturementioning

confidence: 99%

Section: Coma Temperaturementioning

confidence: 99%

See 1 more Smart Citation

Gas and dust productions of Comet 103P/Hartley 2 from millimetre observations: Interpreting rotation-induced time variations

Boissier¹,

Bockelée‐Morvan²,

Biver³

et al. 2014

Icarus

Self Cite

View full text Add to dashboard Cite

show abstract

“…There are two lines (1.665 and 1.667 GHz) that are regularly observed in comets, especially using the Nançay array (Crovisier et al 2013). The (at the time) largest single dish telescope in the world, the 300 m Arecibo radio telescope, has also targeted comets at 18 cm (Lovell et al 2002), but even using these facilities only the brightest comets are detectable, with the most sensitive detection again coming from the close approach of 103P to Earth in 2010.…”

Section: Infrared and Sub-mm/radio Emission Featuresmentioning

confidence: 99%

The Main Belt Comets and ice in the Solar System

Snodgrass

Agarwal

Combi

et al. 2017

Astron Astrophys Rev

View full text Add to dashboard Cite

We review the evidence for buried ice in the asteroid belt; specifically the questions around the so-called Main Belt Comets (MBCs). We summarise the evidence for water throughout the Solar System, and describe the various methods for detecting it, including remote sensing from ultraviolet to radio wavelengths. We review progress in the first decade of study of MBCs, including observations, modelling of ice survival, and discussion on their origins. We then look at which methods will likely be most effective for further progress, including the key challenge of direct detection of (escaping) water in these bodies.

show abstract

“…Earth-based observations over multiple orbits revealed a secular decrease in activity since 1991 and a strong asymmetry in production rates around perihelion (Combi et al 2011;Knight & Schleicher 2013). Many larger-scale properties at or near the time of the flyby were constrained from Earth, including an Earth ocean-like D/H ratio (Hartogh et al 2011), activity levels and relative abundances of various gas species (e.g., Dello Mumma et al 2011;Weaver et al 2011;Crovisier et al 2013;McKay et al 2013;Boissier et al 2014), and coma morphology (e.g., Lara et al 2011;Samarasinha et al 2011;Waniak et al 2012;Mueller et al 2013). A number of measurements of the apparent period were determined and are discussed in detail below.…”

Section: Introductionmentioning

confidence: 99%

A Further Investigation of Apparent Periodicities and the Rotational State of Comet 103p/Hartley 2 From Combined Coma Morphology and Light Curve Data Sets

Knight

Mueller

Samarasinha

et al. 2015

View full text Add to dashboard Cite

We present an analysis of Kitt Peak National Observatory and Lowell Observatory observations of comet 103P/ Hartley 2 obtained from 2010 August through December. The results are then compared with contemporaneous observations made by the EPOXI spacecraft. Each ground-based data set has previously been investigated individually; the combined data set has complementary coverage that reduces the time between observing runs and allows us to determine additional apparent periods at intermediate times. We compare CN coma morphology between ground-based data sets, making nine new measurements of apparent periods. The first five are consistent with the roughly linearly increasing apparent period during the apparition found by previous authors. The final four suggest that the change in apparent period slowed or stopped by late November. We also measure an inner coma light curve in both CN and R-band ground-based images, finding a single-peaked light curve which repeats in phase with the coma morphology. The apparent period from the light curve had significantly larger uncertainties than from the coma morphology, but varied over the apparition in a similar manner. Our ground-based light curve aligns with the published EPOXI light curve, indicating that the light curve represents changing activity rather than viewing geometry of structures in the coma. The EPOXI light curve can best be phased by a triple-peaked period near 54-55 hr that increases from October to November. This phasing reveals that the spacing between maxima is not constant, and that the overall light curve shape evolves from one triple-peaked cycle to the next. These behaviors suggest that much of the scatter in apparent periods derived from ground-based data sets acquired at similar epochs are likely due to limited sampling of the data.

show abstract

Observations of the 18-cm OH lines of Comet 103P/Hartley 2 at Nançay in support to the EPOXI and Herschel missions

Cited by 13 publications

References 20 publications

Gas and dust productions of Comet 103P/Hartley 2 from millimetre observations: Interpreting rotation-induced time variations

Gas and dust productions of Comet 103P/Hartley 2 from millimetre observations: Interpreting rotation-induced time variations

The Main Belt Comets and ice in the Solar System

A Further Investigation of Apparent Periodicities and the Rotational State of Comet 103p/Hartley 2 From Combined Coma Morphology and Light Curve Data Sets

Contact Info

Product

Resources

About