<i>Spitzer</i>
                    Observations of the Dust Coma and Nucleus of 29P/Schwassmann‐Wachmann 1

Stansberry, J.; Cleve, J. Van; Reach, W. T.; Cruikshank, D. P.; Emery, J. P.; Fernández, Y. R.; Meadows, Victoria; Su, K. Y. L.; Misselt, K. A.; Rieke, G. H.; Young, E. T.; Werner, M. W.; Engelbracht, C. W.; Gordon, K. D.; Hines, Dean C.; Kelly, Douglas; Morrison, J. E.; Muzerolle, James

doi:10.1086/422473

Cited by 89 publications

(100 citation statements)

References 19 publications

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“…An enhancement in dust density in this direction has been seen in the infrared using the Spitzer telescope (Stansberry et al 2004) in observations between the two HERA observations. This may hint at a connection between the dust coma and the possible CO source, but the confinement of such a source in a limited region is not easily explained.…”

Section: The "Excessive" Regionmentioning

confidence: 71%

Mapping the carbon monoxide coma of comet 29P/Schwassmann-Wachmann 1

Gunnarsson

Bockelée‐Morvan²,

Biver³

et al. 2008

A&A

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Context. CO is assumed to be the main driver behind the activity of comet 29P/Schwassmann-Wachmann 1, which resides in a nearcircular orbit at 6 AU from the Sun. Several properties of the outgassing of CO can be deduced from its millimetre-wave emission. Earlier studies have indicated CO production from the nucleus as well as an extended source. Aims. We have sought to further investigate the nature of the CO production in comet 29P/Schwassmann-Wachmann 1, through the use of newly available instrumentation. Methods. We used the HERA receiver array on the 30-m IRAM telescope to map the 230 GHz CO(J = 2−1) line in the comet with an unprecedented sensitivity and spatial coverage, and a high spectral resolution (20 Results. The CO emission line has a characteristic asymmetric profile. Our analysis is based on a coma model, where the outgassing pattern is derived from the shape of this line at the central position of the map. When comparing to the observations, both maps show a line intensity at offset positions that is 2−3 times stronger than the model prediction. Different explanations for this are evaluated, and it is found that for the global coma character, an extremely low gas temperature in the inner coma reproduces the observed radial profile. A cold inner coma depletes the population of the CO J = 2 rotational level in the region closest to the nucleus, making spectra observed at offset positions relatively stronger. From the global appearance of the maps, the coma was found to be largely axisymmetric, and the presence of a strong extended source of CO, as indicated from earlier observations using the SEST telescope, was not seen. When examining the maps in more detail, a possible exception to this was seen in an area ∼30 south of the comet, where an excess in emission is present in both maps. Model fits to the spectra based on the cold inner coma that we find, with an intital kinetic temperature T kin = 4 K, give a measure of Q CO , the CO production rate. Q CO was found to be (3.9 ± 0.2) × 10 28 mol s −1 in June 2003, and (3.7 ± 0.2) × 10 28 mol s −1 in January 2004. These values are a factor ∼1.5 higher than that derived using only the information available from non-mapped data, and this adjustment applies also to previously published production rates.

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Section: The "Excessive" Regionmentioning

confidence: 71%

Mapping the carbon monoxide coma of comet 29P/Schwassmann-Wachmann 1

Gunnarsson

Bockelée‐Morvan²,

Biver³

et al. 2008

A&A

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“…Most comets are not active at heliocentric distances beyond ∼ 3 au, where the temperature is too low for the water ice to sublimate efficiently (e.g., (Duffard et al 2014b, Ruprecht et al 2015, Sicardy et al 2016, and there are reports of Echeclus (as described earlier in this section) and 29P both having a secondary source of dust emission (and a second small CO outgassing region for 29P), possibly emitting from a chunk or fragment in the coma (Stansberry et al 2004, Gunnarsson et al 2008, Womack et al 2017. In order to test physical and chemical models of Centaurs (and hence by extension models of KBOs and JFCs), it is important to determine whether gaseous activity is common amongst Centaurs.…”

Section: Introductionmentioning

confidence: 89%

Carbon Monoxide in the Distantly Active Centaur (60558) 174P/Echeclus at 6 au

Wierzchoś

Womack

Sarid

2017

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“…Other comets show activity at large distances beyond 3 AU (cf. Stansberry et al 2004;Lisse et al 2004;Meech et al 2009). Thus such behavior is not unprecedented.…”

Section: Co 2 Activitymentioning

confidence: 99%

WISE/NEOWISE PRELIMINARY ANALYSIS AND HIGHLIGHTS OF THE 67P/CHURYUMOV-GERASIMENKO NEAR NUCLEUS ENVIRONS

Bauer

Kramer

Stevenson

et al. 2012

ApJ

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On 2010 January 18-19 and June 28-29, the Wide-field Infrared Survey Explorer (WISE) spacecraft imaged the Rosetta mission target, comet 67P/Churyumov-Gerasimenko. We present a preliminary analysis of the images, which provide a characterization of the dust environment at heliocentric distances similar to those planned for the initial spacecraft encounter, but on the outbound leg of its orbit rather than the inbound. Broadband photometry yields low levels of CO 2 production at a comet heliocentric distance of 3.32 AU and no detectable production at 4.18 AU. We find that at these heliocentric distances, large dust grains with mean grain diameters on the order of a millimeter or greater dominate the coma and evolve to populate the tail. This is further supported by broadband photometry centered on the nucleus, which yield an estimated differential dust particle size distribution with a power-law relation that is considerably shallower than average. We set a 3σ upper limit constraint on the albedo of the large-grain dust at 0.12. Our best estimate of the nucleus radius (1.82 ± 0.20 km) and albedo (0.04 ± 0.01) are in agreement with measurements previously reported in the literature.

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Spitzer Observations of the Dust Coma and Nucleus of 29P/Schwassmann‐Wachmann 1

Cited by 89 publications

References 19 publications

Mapping the carbon monoxide coma of comet 29P/Schwassmann-Wachmann 1

Mapping the carbon monoxide coma of comet 29P/Schwassmann-Wachmann 1

Carbon Monoxide in the Distantly Active Centaur (60558) 174P/Echeclus at 6 au

WISE/NEOWISE PRELIMINARY ANALYSIS AND HIGHLIGHTS OF THE 67P/CHURYUMOV-GERASIMENKO NEAR NUCLEUS ENVIRONS

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