Comet 2P/Encke in apparition of 2017: II. Polarization and color

Kiselev, N. N.; Rosenbush, V. K.; Ivanova, Oleksandra; Kolokolova, L.; Петров, Д. В.; Kleshchonok, Valeriy; Afanasiev, V. L.; Shubina, O.

doi:10.1016/j.icarus.2020.113768

Cited by 7 publications

(7 citation statements)

References 40 publications

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“…And at a cometocentric distance of 10,000 km, the gas contributes 1.01 times as much to the brightness of the coma as the dust, which equals to 0.76 mag. Compared to the continuum/emission ratio of 2P/Encke provided in Figure 4 of Kiselev et al (2020), the SED500 filter has a similar central wavelength with the Johnson-Cousins V band presented here, and in both filters the gas contaminations are significant. The continuum/emission ratio of 60P around 10,000 km is much higher than that of 2P/Encke; this is possibly because 2P had a highly active gaseous activity while 60P was comparatively poor in the gas reserves, since it was classified as a depleted comet in A' Hearn et al (1995).…”

Section: Discussionsupporting

confidence: 52%

Monitoring Cometary Activity of 60P/Tsuchinshan During Its 2018–2019 Apparition

Shi

et al. 2023

ApJ

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Comet 60P/Tsuchinshan is a Jupiter family comet. Since the discovery of 60P/Tsuchinshan, little research for cometary activity has been conducted on this comet, though it has returned to perihelion several times. To study the physical properties and activity characteristic of 60P/Tsuchinshan during its 2018–2019 apparition, we observed 60P/Tsuchinshan with broadband B, V, and R filters from 2018 November to 2019 March by using the 80 cm Yaoan High Precision Telescope at Yaoan Station of Purple Mountain Observatory, Chinese Academy of Sciences. Morphological analysis and photometric studies of 60P/Tsuchinshan were performed. The color indices, Af ρ values, and dust production rates of 60P/Tsuchinshan were obtained. Morphological analysis showed that the comet was active and several images showed a spiral structure in the inner coma; this structure is regardless of the enhancement methods and cannot be explained by the rotation of 60P. The Af ρ curve showed that the peak activity of 60P/Tsuchinshan was at about 10 days after perihelion. Compared to other Jupiter family comets at similar heliocentric distances, we found that 60P/Tsuchinshan was a very active comet. Dynamical analysis showed that 60P/Tsuchinshan’s perihelion distance was reduced from 1.77 to 1.62 au due to the close encounter with Jupiter that occurred on 2008 December 20; this may increase its activity in the next apparition.

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Section: Discussionsupporting

confidence: 52%

Monitoring Cometary Activity of 60P/Tsuchinshan During Its 2018–2019 Apparition

Shi

et al. 2023

ApJ

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“…where P obs (ρ) is the observed polarization along the cuts, and P nucl is the polarization of the nucleus. The detailed derivation of this equation is presented by Kiselev et al (2020). We assumed that the polarization of the cometary nucleus is close to the averaged polarization for nuclei of 2P/Encke (Boehnhardt et al 2008) and 133P/Elst-Pizarro (Bagnulo et al 2010); P nucl = -(1.2 ± 0.17)% at the phase angle 10 • .…”

Section: Profiles Of Color and Polarizationmentioning

confidence: 99%

“…We assumed that the polarization of the cometary nucleus is close to the averaged polarization for nuclei of 2P/Encke (Boehnhardt et al 2008) and 133P/Elst-Pizarro (Bagnulo et al 2010); P nucl = -(1.2 ± 0.17)% at the phase angle 10 • . Using the technique described by Kiselev et al (2020), we estimated the uncertainty in the coma polarization after correction for the nucleus contribution; the maximum absolute error is ∆P dust coma ≈ 1%.…”

Section: Profiles Of Color and Polarizationmentioning

confidence: 99%

Observations of distant comet C/2011 KP36 (Spacewatch): photometry, spectroscopy, and polarimetry

Ivanova

Rosenbush

Lukyanyk

et al. 2021

A&A

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Aims. The main objective of our study is to obtain new observational results for the active long-period comet C/2011 KP36 (Spacewatch). This comet has unusual orbital properties and moves at distances larger than 5 au from the Sun. Methods. We carried out extensive observations of comet C/2011 KP36 (Spacewatch) at the 6-m BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences with the focal reducer SCORPIO-2. We obtained quasi-simultaneous long-slit spectra in the visible, as well as photometric and linear polarimetric images with the g-sdss and r-sdss filters on November 25, 2016 when the heliocentric and geocentric distances of the comet were 5.06 au and 4.47 au, respectively. We modeled the behavior of the color and polarization in the coma, considering the dust as an ensemble of polydisperse nonspherical particles. Results. Two strong jet-like structures in solar and antisolar directions and two short and narrow jet features in the perpendicular direction were revealed in the coma. Our simulations showed that the latter two jets originated from the same active area. We determined the orientation of the rotation axis of the nucleus and the position of three active areas. High activity of the comet was characterized by Afρ values of 1065 ± 11 cm in the g-sdss filter and 1264 ± 17 cm in the r-sdss filter. The comet was found to be rich in CO+, while there was no clear detection of CN, C3, C2, and N2+. The dust color g–r varies over the coma from about 0.2m to 0.7m, and the linear polarization degree from about −1% to −6% at the phase angle 9.6°. The color of the nucleus of comet C/2011 KP36 (Spacewatch) is ultrared, B – R = 1.9m ± 0.3m. Conclusions. The high variability of the observed characteristics over the coma of comet C/2011 KP36 (Spacewatch) indicates significant and variable activity of the nucleus with, probably, numerous small active areas. Together with the three identified large active areas, they are characterized by different combinations of water ice, CO2 ice, and refractory dust and sizes of their particles, which are in the micron-size range.

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“…The relatively featureless inner coma color and polarization maps of C/2017 K2 stands in contrast to those of C/1995 O1 (Hale-Bopp), which showed prominent reddened and positively polarized (near +2%) jets superimposed on a strongly negatively polarized (near −5%) halo at a similar α = 6 • .9, but at a closer r = 4.1 au (Hadamcik & Levasseur-Regourd 2003a). Similarly negatively polarized halos appear around a number of periodic comets (Hadamcik & Levasseur-Regourd 2003b;Hadamcik et al 2016), although some of these halos may instead be recording the polarization of the nucleus (Kiselev et al 2020). It remains unclear how many of observed differences are due to true physical differences between the physical properties of these comets, or if similar features will develop on C/2017 K2 as it approaches the Sun.…”

Section: Comparison With Other Distant Cometsmentioning

confidence: 89%

Dust Evolution in the Coma of Distant, Inbound Comet C/2017 K2 (PANSTARRS)

Zhang,

Kolokolova,

et al. 2022

Preprint

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C/2017 K2 (PANSTARRS) is an Oort cloud comet previously observed to be active at heliocentric distances r > 20 au on what is likely its first passage through the inner solar system. We observed the comet on 2021 March 19-20 at r = 6.82 au pre-perihelion and 8 • .35 phase angle with the Hubble Space Telescope (HST), and obtained high spatial resolution photometry and polarimetry mapping the properties of dust over the coma prior to the onset of water ice sublimation activity on the nucleus. We found clear radial gradients in the color and polarization of the coma: the F475W-F775W (g − i ) reflectance slope increased from ∼4.5% per 100 nm within ∼10,000 km of the nucleus up to ∼7% per 100 nm by ∼50,000 km, while the negative polarization in F775W (i ) strengthened from about −2% to −3.5% over the same range. The radial intensity profiles moreover strongly deviate from profiles simulated for stable dust grains. Near-infrared imagery obtained with the Palomar Hale Telescope on 2021 May 18 at r = 6.34 au revealed a continued absence of micron-sized grains in the tail, but showed no clear spatial gradient in JHK s colors. The observed patterns collectively appear consistent with the inner coma being optically dominated by sublimating, micron-sized water ice grains, unlike the tail of more stable, millimeter-sized grains. Finally, we evaluated these results alongside other Oort cloud comets, and found in a reanalysis of HST observations of C/2012 S1 (ISON) that the near-nucleus polarimetric halo reported for that comet is likely an observational artifact.

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Comet 2P/Encke in apparition of 2017: II. Polarization and color

Cited by 7 publications

References 40 publications

Monitoring Cometary Activity of 60P/Tsuchinshan During Its 2018–2019 Apparition

Monitoring Cometary Activity of 60P/Tsuchinshan During Its 2018–2019 Apparition

Observations of distant comet C/2011 KP36 (Spacewatch): photometry, spectroscopy, and polarimetry

Dust Evolution in the Coma of Distant, Inbound Comet C/2017 K2 (PANSTARRS)

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