scholarly journals Significantly high polarization degree of the very low-albedo asteroid (152679) 1998 KU2

2018 ◽  
Vol 611 ◽  
pp. A31 ◽  
Author(s):  
Daisuke Kuroda ◽  
Masateru Ishiguro ◽  
Makoto Watanabe ◽  
Sunao Hasegawa ◽  
Tomohiko Sekiguchi ◽  
...  
Keyword(s):  
Solar System ◽  
Polarization Degree ◽  
Polarimetric Observation ◽  
High Polarization ◽  
Planetary Satellites ◽  
Large Phase ◽  
Solar Phase ◽  
Phase Angles ◽  
Similar Phase ◽  
Geometric Albedo

We present a unique and significant polarimetric result regarding the near-Earth asteroid (152679) 1998 KU2, which has a very low geometric albedo. From our observations, we find that the linear polarization degrees of 1998 KU2are 44.6 ± 0.5% in theRCband and 44.0 ± 0.6% in theVband at a solar phase angle of 81.0°. These values are the highest of any known airless body in the solar system (i.e., high-polarization comets, asteroids, and planetary satellites) at similar phase angles. This polarimetric observation is not only the first for primitive asteroids at large phase angles, but also for low-albedo (<0.1) airless bodies. Based on spectroscopic similarities and polarimetric measurements of materials that have been sorted by size in previous studies, we conjecture that 1998 KU2has a highly microporous regolith structure comprising nano-sized carbon grains on the surface.

scholarly journals Umov effect in asteroid (3200) Phaethon

2018 ◽  
Vol 620 ◽  
pp. A179 ◽  
Author(s):  
Maxim Zheltobryukhov ◽  
Ekaterina Chornaya ◽  
Anton Kochergin ◽  
Gennady Kornienko ◽  
Alexey Matkin ◽  
...  
Keyword(s):  
Linear Polarization ◽  
Lunar Regolith ◽  
Wavelength Dependence ◽  
Parent Body ◽  
Meteor Shower ◽  
Accurate Estimation ◽  
Space Technology ◽  
Large Phase ◽  
Phase Angles ◽  
Geometric Albedo

Context. The near-Earth asteroid (3200) Phaethon occasionally reveals a comet-like activity. It is a parent body to the Geminid meteor shower and considered as a target for the space mission called Demonstration and Experiment of Space Technology for Interplanetary Voyage Phaethon Flyby Dust Science, DESTINY+. Aims. We aim to characterize Phaethon through measurements of the degree of linear polarization P measured on Phaethon at large phase angles on its closest approach to Earth on December 17, 2017. These observations allow a more accurate estimation of the maximum value of the degree of linear polarization Pmax of Phaethon, and therefore, of studying the Umov effect. Methods. We performed polarimetric measurements of Phaethon at large phase angles α and thus constrained its Pmax. We also estimated the geometric albedo a based on the data available in the literature. The obtained Pmax and A were analysed with the Umov effect previously derived for the Moon that establishes an inverse linear correlation between log(Pmax) and log(A) in the lunar regolith. Results. Our polarimetric observations of Phaethon in the visible reveal the degree of linear polarization P ≈ (17.23 ± 2.00)% at α ≈ 57.9° and P ≈ (31.86 ± 2.00)% at α ≈ 73.2°, which demonstrates no significant wavelength dependence within the error bars of our measurements (± 2%). These data, when combined with what has previously been reported in the literature, suggests at least three types of polarimetric response on Phaethon. For two of them, we infer the maximum linear polarization to be Pmax ≈ 57.9%, occurring at αmax = 131° and Pmax ≈ 44.5% occurring at αmax = 127°. We estimate the geometric albedo (adjusted to α = 3°) to be AR = 0.075 ± 0.007 in the R filter, which appears to be consistent with dark F-type asteroids, as which Phaethon was first classified. We examine the Umov diagrams previously inferred for lunar regolith and find that they are hardly applicable to Phaethon and therefore not to other asteroids either.

scholarly journals High polarization degree of the continuum of comet 2P/Encke based on spectropolarimetric signals during its 2017 apparition

2018 ◽  
Vol 620 ◽  
pp. A161
Author(s):  
Y. G. Kwon ◽  
M. Ishiguro ◽  
Y. Shinnaka ◽  
T. Nakaoka ◽  
D. Kuroda ◽  
...  
Keyword(s):  
Phase Angle ◽  
Near Infrared ◽  
Scattered Light ◽  
Infrared Camera ◽  
Polarization Vector ◽  
Dust Particles ◽  
Polarization Degree ◽  
High Polarization ◽  
Solar Phase ◽  
The Continuum

Context. Spectropolarimetry is a powerful technique for investigating the physical properties of gas and solid materials in cometary comae without mutual contamination, but only a few spectropolarimetric studies have been conducted to extract each component. Aims. We attempt to derive the continuum (i.e., scattered light from dust coma) polarization degree of comet 2P/Encke, free of the influence of molecular emissions. The target is unique in that its orbit is dynamically decoupled from Jupiter, like the main-belt asteroids, but it ejects gas and dust like ordinary comets. Methods. We observed the comet using the Hiroshima Optical and Near-Infrared Camera attached to the Cassegrain focus of the 150 cm Kanata telescope on UT 2017 February 21 when the comet was at the solar phase angle of α = 75°.7. Results. We find that the continuum polarization degree with respect to the scattering plane is Pcont, r = 33.8 ± 2.7% at the effective wavelength of 0.82 μm, which is significantly higher than those of cometary dust in a high-Pmax group at similar phase angles. Assuming that an ensemble polarimetric response of the dust of 2P/Encke as a function of phase angle is morphologically similar with those of other comets, its maximum polarization degree is estimated to Pmax ≳ 40% at αmax ≈ 100°. In addition, we obtain the polarization degrees of the C2 swan bands (0.51–0.56 μm), the NH2 α bands (0.62–0.69 μm), and the CN-red system (0.78–0.94 μm) in a range of 3–19%, which depend on the molecular species and rotational quantum numbers of each branch. The polarization vector is aligned nearly perpendicularly to the scattering plane with an average of 0°.4 over a wavelength range of 0.50–0.97 μm. Conclusions. From the observational evidence, we conjecture that the high polarization degree of 2P/Encke might be attributable to a dominance of large dust particles around the nucleus, which have remained after frequent perihelion passages near the Sun.

Photometry and polarimetry of Jupiter at large phase angles

Icarus ◽  
1984 ◽  
Vol 58 (1) ◽  
pp. 35-73 ◽  
Author(s):  
Peter H. Smith ◽  
Martin G. Tomasko
Keyword(s):  
Large Phase ◽  
Phase Angles

scholarly journals Tunable valleytronics with symmetry-retaining high polarization degree in SnSxSe1−x model system

2020 ◽  
Vol 116 (6) ◽  
pp. 061105 ◽  
Author(s):  
Shuren Lin ◽  
Zixuan Fang ◽  
Tingzheng Hou ◽  
Ting Wan Hsu ◽  
Chi H. So ◽  
...  
Keyword(s):  
Model System ◽  
Polarization Degree ◽  
High Polarization

scholarly journals Organic matter in the Solar System: From colors to spectral bands

2008 ◽  
Vol 4 (S251) ◽  
pp. 285-292 ◽  
Author(s):  
Dale P. Cruikshank
Keyword(s):  
Organic Matter ◽  
Solar System ◽  
Kuiper Belt ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Outer Solar System ◽  
Spectral Bands ◽  
Organic Complexes ◽  
Planetary Satellites ◽  
Spectral Models

AbstractThe reflected spectral energy distribution of low-albedo, red-colored, airless bodies in the outer Solar System (planetary satellites, Centaur objects, Kuiper Belt objects, bare comet nuclei) can be modeled with spectral models that incorporate the optical properties of refractory complex organic materials synthesized in the laboratory and called tholins. These materials are strongly colored and impart their color properties to the models. The colors of the bodies cannot be matched with plausible minerals, ices, or metals. Iapetus, a satellite of Saturn, is one such red-colored body that is well matched with tholin-rich models. Detection of aromatic and aliphatic hydrocarbons on Iapetus by the Cassini spacecraft, and the presence of these hydrocarbons in the tholins, is taken as evidence for the widespread presence of solid organic complexes aromatic and aliphatic units on many bodies in the outer Solar System. These organic complexes may be compositionally similar to the insoluble organic matter in some classes of the carbonaceous meteorites, and thus may ultimately derive from the organic matter in the interstellar medium.

Photometry and polarimetry of Jupiter at large phase angles

Icarus ◽  
1978 ◽  
Vol 33 (3) ◽  
pp. 558-592 ◽  
Author(s):  
M.G. Tomasko ◽  
R.A. West ◽  
N.D. Castillo
Keyword(s):  
Large Phase ◽  
Phase Angles

scholarly journals Terrestrial Planet Optical Phase Curves. I. Direct Measurements of the Earth

2021 ◽  
Vol 163 (1) ◽  
pp. 5
Author(s):  
Roderick De Cock ◽  
Timothy A. Livengood ◽  
Daphne M. Stam ◽  
Carey M. Lisse ◽  
Tilak Hewagama ◽  
...  
Keyword(s):  
Phase Angle ◽  
Terrestrial Planet ◽  
Wavelength Dependence ◽  
Deep Impact ◽  
Spectral Filters ◽  
Optical Phase ◽  
The Earth ◽  
Direct Measurements ◽  
Phase Angles ◽  
Geometric Albedo

Abstract NASA’s EPOXI mission used the Deep Impact spacecraft to observe the disk-integrated Earth as an analog to terrestial exoplanets’ appearance. The mission took five 24 hr observations in 2008–2009 at various phase angles (57.°7–86.°4) and ranges (0.11–0.34 au), of which three equatorial (E1, E4, E5) and two polar (P1, North and P2, South). The visible data taken by the HRIV instrument ranges from 0.3 to 1.0 μm, taken trough seven spectral filters that have spectral widths of about 100 nm, and which are centered about 100 nm apart, from 350 to 950 nm. The disk-integrated, 24 hr averaged signal is used in a phase angle analysis. A Lambertian-reflecting, spherical planet model is used to estimate geometric albedo for every observation and wavelength. The geometric albedos range from 0.143 (E1, 950 nm) to 0.353 (P2, 350 nm) and show wavelength dependence. The equatorial observations have similar values, while the polar observations have higher values due to the ice in view. Therefore, equatorial observations can be predicted for other phase angles, but (Earth-like) polar views (with ice) would be underestimated.

scholarly journals Spectroscopic Observations of Solar System Objects: Pushing the Limits

1995 ◽  
Vol 167 ◽  
pp. 251-261
Author(s):  
Anita L. Cochran
Keyword(s):  
Solar System ◽  
Minor Planets ◽  
Spectroscopic Observations ◽  
Planetary Satellites ◽  
Solar System Objects ◽  
Spatially Extended

Targets within the solar system generally fall into one of two types: a) major planets (except Pluto) and our Moon; b) minor planets, comets, Pluto and planetary satellites. The first group is noteworthy for being reasonably bright. Most are also spatially extended. The inner planets never achieve large solar elongation. The second group comprises bodies which are generally faint. Comets are spatially extended. The minor planets and comets may be in orbits which are highly inclined or viewed at small solar elongations. Comets may even be in retrograde orbits. Planetary satellites may be bright or faint but suffer from being in the glare of the parent planet.

scholarly journals Organic chemistry in planetary satellites of gas giants and implications for habitability

2015 ◽  
Vol 11 (A29B) ◽  
pp. 421-425
Author(s):  
Athena Coustenis
Keyword(s):  
Organic Chemistry ◽  
Solar System ◽  
Outer Solar System ◽  
Icy Moons ◽  
Planetary Satellites

AbstractWe look at the icy moons in our outer solar system in which we find organics and the possibility for habitabile conditions therein.

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