The effect of porosity of dust particles on polarization and color with special reference to comets

Sen, A. K.; Botet, Robert; Vilaplana, R.; Choudhury, Naznin R.; Gupta, Ranjan

doi:10.1016/j.jqsrt.2017.05.009

Cited by 14 publications

(6 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Let us add yet another possibility that can enhance Phaethon’s polarization degree: Large surface porosity. It has been numerically confirmed that large porosity significantly increases polarization of material surface 48 , 49 . We also know that this trend holds true regardless of wavelength of incident light 50 , 51 , although its theoretical understanding is not yet completely established, particularly when the wavelength is shorter than the characteristic size of light scatterers on the object surface.…”

Section: Discussionmentioning

confidence: 82%

Extremely strong polarization of an active asteroid (3200) Phaethon

et al. 2018

View full text Add to dashboard Cite

The near-Earth asteroid (3200) Phaethon is the parent body of the Geminid meteor stream. Phaethon is also an active asteroid with a very blue spectrum. We conducted polarimetric observations of this asteroid over a wide range of solar phase angles α during its close approach to the Earth in autumn 2016. Our observation revealed that Phaethon exhibits extremely large linear polarization: P = 50.0 ± 1.1% at α = 106.5°, and its maximum is even larger. The strong polarization implies that Phaethon’s geometric albedo is lower than the current estimate obtained through radiometric observation. This possibility stems from the potential uncertainty in Phaethon’s absolute magnitude. An alternative possibility is that relatively large grains (~300 μm in diameter, presumably due to extensive heating near its perihelion) dominate this asteroid’s surface. In addition, the asteroid’s surface porosity, if it is substantially large, can also be an effective cause of this polarization.

show abstract

Section: Discussionmentioning

confidence: 82%

Extremely strong polarization of an active asteroid (3200) Phaethon

et al. 2018

View full text Add to dashboard Cite

show abstract

“…In laboratory experiments with analog fluffy aggregates, polarizations in the 50%−100% range were measured (Volten et al 2007). In a very recent study, Sen et al (2017) concluded that, over the range in porosity of 0%−50%, p max varies nonmonotonically and can reach or exceed 60%. For a spatially unresolved source, the scattered light can contribute significantly to the total integrated light and associated distance estimates.…”

Section: Introductionmentioning

confidence: 99%

Mapping Circumstellar Matter with Polarized Light: The Case of Supernova 2014J in M82

Yang

Wang

Baade

et al. 2018

ApJ

View full text Add to dashboard Cite

Optical polarimetry is an effective way of probing the environment of supernova for dust. We acquired linear HST ACS/WFC polarimetry in bands F 475W , F 606W , and F 775W of the supernova (SN) 2014J in M82 at six epochs from ∼277 days to ∼1181 days after the B-band maximum. The polarization measured at day 277 shows conspicuous deviations from other epochs. These differences can be attributed to at least ∼ 10 −6 M ⊙ of circumstellar dust located at a distance of ∼ 5 × 10 17 cm from the SN. The scattering dust grains revealed by these observations seem to be aligned with the dust in the interstellar medium that is -2responsible for the large reddening towards the supernova. The presence of this circumstellar dust sets strong constraints on the progenitor system that led to the explosion of SN 2014J; however, it cannot discriminate between single-and double-degenerate models.

show abstract

“…It was shown theoretically and through numerical simulations by Sen et al (2017), that a decrease in the colour index is indicative of the increasing presence of finer dust particles while such decrease is not related to change in the particle porosity. Considering a typical size-distribution of the dust particles in the form of an inverse power-law (that is: ∼ 1/a s with the particle radius a), a decrease in the colour index may then be the sign of a larger exponent s. From another point of view, it seems then unlikely to use colourindex data to obtain precise information on the shape and structure (fluffy or compact) of the dust particles.…”

Section: Colour Index and Dust Properties In The Different Coma Regiomentioning

confidence: 99%

Photometry and colour index of Comet 67P/Churyumov-Gerasimenko on 2015 December 12

Sen

Hadamcik

Botet

et al. 2019

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

Comet 67P/Churyumov-Gerasimenko (hereafter, 67P) was observed on 12 December 2015, from 2 m Himalayan Chandra Telescope in India in photometry to study its dust properties, using Bessell R and I filters. We study the photometric images to highlight coma structures and jets. The radial decrease in intensity in the different coma structures are compared to the azimuthally integrated intensities. The observations of the slopes show a quasi-steady-state coma to an optocentric distance of about 20 000 km. The change in the slopes in the structures indicates changing properties of the dust particles and/or change in their local size distributions. Comparison of the radial decrease in the two wavelengths suggests a change in the local colour-index. Based on the absolute photometry carried out in the present work, we calculate the reddening of the comet dust which helps to characterize variations in the size and the materials of the particles. The colour-index is calculated for different apertures and regions in the coma (0.40 ± 0.07 mag) for a 22000 diameter aperture. A colour map is constructed showing the variation of the colour-index through the coma. Changes appear at the transition between the coma and the tail with a low colour-index (< 0.3 mag) close to the optocentre and further away increasing up in the tail direction (about 0.45 mag at 10 000 km). We interpret these changes in terms of dust properties and we compare our results to other remote observations of 67P including in situ Rosetta observations.

show abstract

The effect of porosity of dust particles on polarization and color with special reference to comets

Cited by 14 publications

References 59 publications

Extremely strong polarization of an active asteroid (3200) Phaethon

Extremely strong polarization of an active asteroid (3200) Phaethon

Mapping Circumstellar Matter with Polarized Light: The Case of Supernova 2014J in M82

Photometry and colour index of Comet 67P/Churyumov-Gerasimenko on 2015 December 12

Contact Info

Product

Resources

About