Light Scattering and Thermal Emission by Primitive Dust Particles in Planetary Systems

Kimura, Hiroshi; Kolokolova, L.; Li, Aigen; Lebreton, J.

doi:10.1007/978-3-662-49538-4_8

Cited by 9 publications

(10 citation statements)

References 156 publications

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“…We model the dust thermal emission of 2I/Borisov in terms of cometary dust paricles-porous aggregates of amorphous silicates and amorphous carbon grains 18 -which are commonly used for modeling the dust-scattered sunlight and dust thermal emission of comets 51,52 . The dust is characterized by (i) size a -the radius of the sphere encompassing the entire aggregate (we assume that all grains are spherical in shape), (ii) porosity P -the fractional volume of vaccum, and (iii) mixing mass ratio m carb /m sil for the amorphous silicate and amorphous carbon constituent grains.…”

Section: Methodsmentioning

confidence: 99%

Compact pebbles and the evolution of volatiles in the interstellar comet 2I/Borisov

Yang

Cordiner

et al. 2021

Nat Astron

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The interstellar traveler, 2I/Borisov, is the first clearly active extrasolar comet, ever detected in our Solar system. We obtained high-resolution interferometric observations of 2I/Borisov with the Atacama Large Millimeter/submillimeter Array (ALMA), and multi-color optical observations with the Very Large Telescope (VLT) to gain a comprehensive understanding of the dust properties of this comet. We found that the dust coma of 2I/Borisov consists of compact "pebbles" of radii exceeding ∼ 1 mm, suggesting that the dust particles have experienced compaction through mutual impacts during the bouncing collision phase in the protoplanetary disk. We derived a dust mass loss rate of > ∼ 200 kg s −1 and a dust-to-gas ratio > ∼ 3. Our long term monitoring of 2I/Borisov with VLT indicates a steady dust mass loss with no significant dust fragmentation and/or sublimation occurring in the coma. We also detected emissions from carbon monoxide gas (CO) with ALMA and derived the gas production rate of Q(CO) = (3.3 ± 0.8) × 10 26 s −1 . We found that the CO/H 2 O mixing ratio of 2I/Borisov changed drastically before and after perihelion, indicating the heterogeneity of the cometary nucleus, with components formed at different locations beyond the volatile snow-line with different chemical abundances. Our observations suggest that 2I/Borisov's home system, much like our own system, experienced efficient radial mixing from the innermost parts of its protoplanetary disk to beyond the frost line of CO.

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Section: Methodsmentioning

confidence: 99%

Compact pebbles and the evolution of volatiles in the interstellar comet 2I/Borisov

Yang

Cordiner

et al. 2021

Nat Astron

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“…Modelling the scattering properties of aggregates can be achieved by utilising numerical methods such as the T-matrix method (TMM, for cluster spheres) or the discrete dipole approximation (DDA, for arbitrary shape particles). These methods need time-consuming computations, and because of this limitation, they have been applied so far only to small aggregates of a few micrometre size at most (Kolokolova et al 2004;Kimura et al 2016). The analysis of the VIRTIS spectra would require considering large aggregates.…”

Section: Modellingmentioning

confidence: 99%

Comet 67P outbursts and quiescent coma at 1.3 au from the Sun: dust properties from Rosetta/VIRTIS-H observations

Bockelée‐Morvan

Rinaldi

Erard

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present 2-5 µm spectroscopic observations of the dust coma of 67P/Churyumov-Gerasimenko obtained with the VIRTIS-H instrument onboard Rosetta during two outbursts that occurred on 2015, 13 September 13.6 h UT and 14 September 18.8 h UT at 1.3 AU from the Sun. Scattering and thermal properties measured before the outburst are in the mean of values measured for moderately active comets. The colour temperature excess (or superheat factor) can be attributed to submicrometresized particles composed of absorbing material or to porous fractal-like aggregates such as those collected by the Rosetta in situ dust instruments. The power law index of the dust size distribution is in the range 2-3. The sudden increase of infrared emission associated to the outbursts is correlated with a large increase of the colour temperature (from 300 K to up to 630 K) and a change of the dust colour at 2-2.5 µm from red to blue colours, revealing the presence of very small grains (≤ 100 nm) in the outburst material. In addition, the measured large bolometric albedos (∼ 0.7) indicate bright grains in the ejecta, which could either be silicatic grains, implying the thermal degradation of the carbonaceous material, or icy grains. The 3-µm absorption band from water ice is not detected in the spectra acquired during the outbursts, whereas signatures of organic compounds near 3.4 µm are observed in emission. The H 2 O 2.7-µm and CO 2 4.3-µm vibrational bands do not show any enhancement during the outbursts.

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“…Wilck & Mann (1996) calculated the β values of dust particles by using a core-mantle spherical particle model composed of silicate and amorphous carbon with different porosities and suggested that cometary dust particles have β max =1-1.8. Transparent materials such as silicates and water ice tend to have small β maximum values (i.e., β max <1), whereas that of absorbing particles such as carbon is β max >1 (see e.g., Kimura et al 2016). The β max value determined in our measurement, 1.6 ± 0.2, is consistent with that in the porous absorbing particles model (Wilck & Mann 1996) and silicate-core, organic-coated grains model for dust aggregates (Kimura et al 2003).…”

Section: Maximum Radiation Pressure Force and Constraint On Dust Physmentioning

confidence: 99%

2014–2015 Multiple Outbursts of 15p/Finlay

Ishiguro

Kuroda

Hanayama

et al. 2016

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-3 -Multiple outbursts of a Jupiter-family comet, 15P/Finlay, occurred from late 2014 to early 2015. We conducted an observation of the comet after the first outburst and subsequently witnessed another outburst on 2015 January 15.6-15.7. The gas, consisting mostly of C 2 and CN, and dust particles expanded at speeds of 1,110 ± 180 m s −1 and 570 ± 40 m s −1 at a heliocentric distance of 1.0 AU. We estimated the maximum ratio of solar radiation pressure with respect to the solar gravity β max = 1.6 ± 0.2, which is consistent with porous dust particles composed of silicates and organics. We found that 10 8 -10 9 kg of dust particles (assumed to be 0.3 µm-1 mm) were ejected through each outburst. Although the total mass is three orders of magnitude smaller than that of the 17P/Holmes event observed in 2007, the kinetic energy per unit mass (10 4 J kg −1 ) is equivalent to the estimated values of 17P/Holmes and 332P/2010 V1 (Ikeya-Murakami), suggesting that the outbursts were caused by a similar physical mechanism. From a survey of cometary outbursts on the basis of voluntary reports, we conjecture that 15P/Finlay-class outbursts occur >1.5 times annually and inject dust particles from Jupiter-family comets and Encke-type comets into interplanetary space at a rate of ∼10 kg s −1 or more.

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Light Scattering and Thermal Emission by Primitive Dust Particles in Planetary Systems

Cited by 9 publications

References 156 publications

Compact pebbles and the evolution of volatiles in the interstellar comet 2I/Borisov

Compact pebbles and the evolution of volatiles in the interstellar comet 2I/Borisov

Comet 67P outbursts and quiescent coma at 1.3 au from the Sun: dust properties from Rosetta/VIRTIS-H observations

2014–2015 Multiple Outbursts of 15p/Finlay

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