Sublimating components in the coma of comet C/2000 WM<sub>1</sub>(LINEAR)

Tozzi, G. P.; Lara, L. M.; Kolokolova, L.; Boehnhardt, H.; Licandro, J.; Schulz, R.

doi:10.1051/0004-6361:20035893

Cited by 29 publications

(23 citation statements)

References 17 publications

(16 reference statements)

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“…Since the cold component contributes to about half of the mass, as shown in Table 7, it implies that crystalline species are mostly located in the deeper layers/outer region of the disk. This result does not fit into the classical picture where thermal annealing of amorphous silicates takes place by means of heating to high temperatures very close to the central star (at about 800 K, corresponding to 10 −1 ∼ 10 −3 AU in the case of brown dwarfs, Gail 1998;Hallenbeck et al 2000;Kessler-Silacci et al 2007) and resulting in a higher crystallinity closer to the star than in the outer parts of the disks (van Boekel et al 2004). In the following sections we discuss our results in the context of tree scenarios that may be responsible for the production of crystalline silicate grains in protoplanetary disks: (1) annealing in the very early stages of the accretion disk formation; (2) annealing in the hot inner regions of the disk followed by large-scale outward radial transport; (3) local annealing in the outer cold regions produced by energetic events such as flares or shocks.…”

Section: Crystallization Of Silicatesmentioning

confidence: 59%

Structural and compositional properties of brown dwarf disks: the case of 2MASS J04442713+2512164

Bouy¹,

Huélamo

Pinte

et al. 2008

A&A

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Aims. To improve our understanding of substellar formation, we have performed a compositional and structural study of a brown dwarf disk. Methods. We present the results of photometric, spectroscopic, and imaging observations of 2MASS J04442713+2512164, a young brown dwarf (M 7.25) member of the Taurus association. Our dataset, combined with results from the literature, provides a complete coverage of the spectral energy distribution from the optical range to the millimeter, including the first photometric measurement of a brown dwarf disk at 3.7 mm, and allows us to perform a detailed analysis of the disk properties. Results. The target was known to have a disk. High-resolution optical spectroscopy shows that it is accreting intensely, and powers both a jet and an outflow. The disk structure is similar to what is observed for more massive TTauri stars. Spectral decomposition models of Spitzer/IRS spectra suggest that the mid-infrared emission from the optically thin disk layers is dominated by grains with intermediate sizes (1.5 μm). Crystalline silicates are significantly more abundant in the outer part and/or deeper layers of the disk, implying very efficient mixing and/or additional annealing processes. Submillimeter and millimeter data indicate that most of the disk mass is in large grains (>1 mm).

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Section: Crystallization Of Silicatesmentioning

confidence: 59%

Structural and compositional properties of brown dwarf disks: the case of 2MASS J04442713+2512164

Bouy¹,

Huélamo

Pinte

et al. 2008

A&A

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“…In the past, such anomalous enhancements were observed in other comets and interpreted by the presence of organic grains that sublimated in the coma with a certain lifetime τ while moving away from the nucleus (Tozzi et al 2004(Tozzi et al , 2007. If this is the case, the lifetime (and the scalelength) should decrease when the comet approaches the Sun.…”

Section: Discussionmentioning

confidence: 89%

Evolution of the dust coma in comet 67P/Churyumov-Gerasimenko before the 2009 perihelion

Tozzi

Patriarchi

Boehnhardt

et al. 2011

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Context. Comet 67P/Churyumov-Gerasimenko is the main target of ESA's Rosetta mission and will be encountered in May 2014. Because the spacecraft will orbit the comet nucleus before and after release of the lander Philae, it is necessary to know the conditions in the coma. Aims. We study the dust environment, including the dust production rate and its variations along the comet's pre-perihelion orbit. Methods. The comet was observed during its approach to the Sun on four epochs between early-June 2008 and mid-January 2009 over a large range of heliocentric distances that will be covered by the mission in 2014.Results. An anomalous enhancement of the coma dust density was measured toward the comet nucleus. The scale length of this enhancement increased with decreasing heliocentric distance of the comet. We interpret this as a result of an unusually slow expansion of the dust coma. Assuming a spherically symmetric coma, we derive the average amount of dust as well as its ejection velocity. The latter increases exponentially with decreasing heliocentric distance (r h ), ranging from about 1 m/s at 3 AU to about 25-35 m/s at 1.4 AU. Based on these results we describe the dust environment at those nucleocentric distances at which the spacecraft will presumably be in orbit.

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“…Similar trends of A f ρ vs. ρ, including the steep increase at small ρ with a comparable scale length, were already observed in several other comets at various heliocentric distances. We cite the data regarding comets C/1999 S4 (LINEAR) by Bonev et al (2002) and Tozzi & Licandro (2002), C/2000 WM1 (LINEAR) by Lara et al (2004) and Tozzi et al (2004), 9P/Tempel 1 by Tozzi et al (2007), C/2007 N3 (Lulin) by Woodward et al (2011), and 67P/Churyumov-Gerasimenko by Tozzi et al (2011). An intriguing explanation for the steepness of the A f ρ profiles, or equivalently of those of its derived parameter ΣA f (Tozzi & Licandro 2002), close to the nucleus was proposed by Tozzi et al (2004) for comet C/2000 WM1 (LINEAR).…”

Section: Af ρmentioning

confidence: 99%

Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage

Bertini

Barbieri

et al. 2012

A&A

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Context. The Jupiter-family comet 81P/Wild 2, target of the NASA Stardust mission, is very important in the context of the studies of pristine objects in the solar system. First, it was only recently deflected into the present orbit, having spent at least 300 yr at higher heliocentric distance prior to the orbital change in 1974. It is therefore likely that the comet experienced a recent activation with consequent low alteration of its original material. Second, it is the only comet whose coma material was brought back to Earth for laboratory analysis. We observed the object between 2010 February 9 and September 9 for a total of 11 nights during the 2010 perihelion passage. Aims. The goals of the campaign were the characterization of the comet's dust activity and the comparison with previous apparitions to derive hints on the secular behavior of the object. Methods. Broadband R-and I-images were acquired using three instruments: ALFOSC, CAMELOT, and TCP. The first one is mounted at the Nordic Optical Telescope on La Palma, while the second and the third are mounted at the Instituto de Astrofisica de Canarias 0.82-m telescope on Tenerife. We analyzed the presence and variability of dust structures in the coma with image-enhancing techniques, the radial profile of the dust brightness, and we measured the dust production rate and the dust reddening. Results. We found evidence of a long-lasting sunward fan and anti-solar tail activity throughout all our observations up to a heliocentric distance of 2.42 AU. A f ρ measurements suggest a pre-perihelion peak of the activity, caused by a seasonal effect, plus two post-perihelion outbursts. Both spatial and A f ρ radial profiles indicate a steady-state coma at nucleocentric distances greater than ∼1000-2000 km. The color analysis reveals a moderately reddened dust with a 6-9%/1000 Å reddening, consistent with the current picture of cometary dust. The second outburst emitted dust with lower reddening. Conclusions. The comparison with previous perihelion passages points toward a recurrent main activity always driven by the same areas on the nucleus, producing dust with similar characteristics and in similar coma structures in different years. Our A f ρ measurement at the longest heliocentric distance suggests the comet was less dust-productive in 2010, pointing toward a possible secular aging of the object and its activity. The change of dust colors during the unusual second outburst suggests that an internal part of the nucleus has different physical properties compared with those that produce the recurrent main activity, pointing toward a heterogeneous comet.

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Sublimating components in the coma of comet C/2000 WM₁(LINEAR)

Cited by 29 publications

References 17 publications

Structural and compositional properties of brown dwarf disks: the case of 2MASS J04442713+2512164

Structural and compositional properties of brown dwarf disks: the case of 2MASS J04442713+2512164

Evolution of the dust coma in comet 67P/Churyumov-Gerasimenko before the 2009 perihelion

Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage

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Sublimating components in the coma of comet C/2000 WM1(LINEAR)

Cited by 29 publications

References 17 publications

Structural and compositional properties of brown dwarf disks: the case of 2MASS J04442713+2512164

Structural and compositional properties of brown dwarf disks: the case of 2MASS J04442713+2512164

Evolution of the dust coma in comet 67P/Churyumov-Gerasimenko before the 2009 perihelion

Photometric observations of comet 81P/Wild 2 during the 2010 perihelion passage

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Sublimating components in the coma of comet C/2000 WM₁(LINEAR)