Physical Properties of Cometary Dust from Light Scattering and Thermal Emission

Kolokolova, L.; Hanner, M. S.; Levasseur-Regourd, Anny-Chantal; Gustafson, B. Å. S.

doi:10.2307/j.ctv1v7zdq5.37

Cited by 155 publications

(125 citation statements)

References 140 publications

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“…from Jewitt et al (2016), where p v is the albedo of the comet, assumed to be 0.10, typical for comet dust (Jewitt & Meech 1986;Kolokolova et al 2004). We caution that uncertainties of H abs inferred from Eq.…”

Section: Mass Lossmentioning

confidence: 99%

Characterization of the Nucleus, Morphology and Activity of Interstellar Comet 2I/Borisov by Optical and Near-Infrared GROWTH, Apache Point, IRTF, ZTF and Keck Observations

Bolin,

Lisse,

Kasliwal

et al. 2019

Preprint

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We present visible and near-infrared photometric and spectroscopic observations of interstellar object 2I/Borisov taken from 2019 September 10 to 2019 November 03 using the GROWTH, the APO ARC 3.5 m and the NASA/IRTF 3.0 m combined with post and pre-discovery observations of 2I obtained by ZTF from 2019 March 17 to 2019 May 5. Comparison with imaging of distant Solar System comets shows an object very similar to mildly active Solar System comets with an out-gassing rate of ∼10 27 mol/sec. The photometry, taken in filters spanning the visible and NIR range shows a gradual brightening trend of ∼ 0.03 mags/day since 2019 September 10 UTC for a reddish object becoming neutral in the NIR. The lightcurve from recent and pre-discovery data reveals a brightness trend suggesting the recent onset of significant H 2 O sublimation with the comet being active with super volatiles such as CO at heliocentric distances >6 au consistent with its extended morphology. Using the advanced capability to significantly reduce the scattered light from the coma enabled by highresolution NIR images from Keck adaptive optics taken on 2019 October 04, we estimate a diameter of 2I's nucleus of 3 km, though the true size is likely ∼2-3 times smaller due to the incomplete removal of dust from the measurement. We use the size estimates of 1I/'Oumuamua and 2I/Borisov to roughly estimate the slope of the ISO size-distribution resulting in a slope of -2.9, similar to Solar System comets, though the true slope is likely significantly steeper due to small numbers.

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Section: Mass Lossmentioning

confidence: 99%

Characterization of the Nucleus, Morphology and Activity of Interstellar Comet 2I/Borisov by Optical and Near-Infrared GROWTH, Apache Point, IRTF, ZTF and Keck Observations

Bolin,

Lisse,

Kasliwal

et al. 2019

Preprint

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“…At the moment of observations the comet phase angle was a = 4.6°. We adopted the value of geometric albedo equal to p(k) = 0.05 for all wavelengths (Hanner and Newburn, 1989;Kolokolova et al, 2004) and the phase darkening to U(a) = 0.8255. 5…”

Section: Photometrymentioning

confidence: 99%

Distant Jupiter family Comet P/2011 P1 (McNaught)

Корсун

Ivanova

Afanasiev

et al. 2016

Icarus

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“…We conclude from Figure 3 that the dust composition would be a peripheral factor in explaining the observed interdependences of P excess and F Si /F cont . Moreover, supposing that the scattering cross-section of coma dust is dominated by non-Rayleigh particles (Fulle et al 2000;Kolokolova et al 2004), we would expect a composition-driven dependence of the two metrics to manifest as an anti-correlation rather than the observed positive correlation. That is because more strongly absorbing (carbon-rich) dust would yield a higher P than transparent dust (Zubko et al 2014(Zubko et al , 2016, and suppress silicate features by enhancing the underlying pseudo-continuum, featureless signal (see, e.g., Wooden 2002).…”

Section: Resultsmentioning

confidence: 99%

An Update of the Correlation between Polarimetric and Thermal Properties of Cometary Dust

Kwon,

Kolokolova,

Agarwal

et al. 2021

Preprint

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Context. Comets are conglomerates of ice and dust particles, the latter of which encode information on changes in the radiative and thermal environments to date. Dust displays distinctive scattered and thermal radiation in the visible and mid-infrared (MIR) wavelengths, respectively, based on its inherent characteristics. Aims. We aim to identify a possible correlation between the properties of scattered and thermal radiation from dust and the principal dust characteristics responsible for this relationship, and therefrom to gain insights into comet evolution. Methods. We use the NASA/PDS archival polarimetric data on cometary dust in the Red (0.62-0.73 µm) and K (2.00-2.39 µm) domains to leverage the relative excess of the polarisation degree of a comet to the average trend at the given phase angle (P excess ) as a metric of the dust's scattered light characteristics. The flux excess of silicate emissions to the continuum around 10 µm (F Si /F cont ) is adopted from previous studies as a metric of the dust's MIR feature.Results. The two observables -P excess and F Si /F cont -show a positive correlation when P excess is measured in the K domain (Spearman's rank correlation coefficient ρ = 0.71 +0.10 −0.19 ). No significant correlation was identified in the Red domain (ρ = 0.13 +0.16 −0.15 ). The gas-rich comets have systematically weaker F Si /F cont than the dust-rich ones, yet both groups retain the same overall tendency with different slope values. Conclusions. The observed positive correlation between the two metrics indicates that composition is a peripheral factor in characterising the dust's polarimetric and silicate emission properties. The systematic difference in F Si /F cont for gas-rich versus dust-rich comets would rather correspond with the difference in their dust size distribution. Hence, our results suggest that the current MIR spectral models of cometary dust, which search for a minimum χ 2 fit by considering various dust properties simultaneously, should prioritise the dust size and porosity over the composition. With light scattering being sensitive to different size scales in two wavebands, we expect the K-domain polarimetry to be sensitive to the properties of dust aggregates, such as size and porosity, which might have been influenced by evolutionary processes. On the other hand, the Red-domain polarimetry reflects the characteristics of sub-µm constituents in the aggregate.

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Physical Properties of Cometary Dust from Light Scattering and Thermal Emission

Cited by 155 publications

References 140 publications

Characterization of the Nucleus, Morphology and Activity of Interstellar Comet 2I/Borisov by Optical and Near-Infrared GROWTH, Apache Point, IRTF, ZTF and Keck Observations

Characterization of the Nucleus, Morphology and Activity of Interstellar Comet 2I/Borisov by Optical and Near-Infrared GROWTH, Apache Point, IRTF, ZTF and Keck Observations

Distant Jupiter family Comet P/2011 P1 (McNaught)

An Update of the Correlation between Polarimetric and Thermal Properties of Cometary Dust

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