Umov effect in asteroid (3200) Phaethon

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.

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

Astronomy and Astrophysics ◽

10.1051/0004-6361/201732086 ◽

2018 ◽

Vol 611 ◽

pp. A31 ◽

Cited By ~ 2

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.

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

The Astronomical Journal ◽

10.3847/1538-3881/ac3234 ◽

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.

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Overview and Science of DESTINY+

10.5194/epsc2021-877 ◽

2021 ◽

Author(s):

Tomoko Arai ◽

Keyword(s):

High Speed ◽

High Performance ◽

Interstellar Dust ◽

Parent Body ◽

Meteor Shower ◽

Cosmic Dust ◽

Dust Particles ◽

Current Status ◽

Space Technology ◽

The Earth

DESTINY+ (Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon fLyby and dUst Science) was selected in 2017 as a mission for JAXA/ISAS small class program. It will be launched in 2024 by an Epsilon S rocket and flyby Phaethon in January, 2028. It is a joint mission of technology demonstration and scientific observation. The engineering mission is led by ISAS/JAXA and the science mission is led by PERC, Chiba Inst. of Technology (ChiTech). It will test high performance electric propelled vehicle technology and high-speed flyby of asteroid (3200) Phaethon and possibly asteroid 2005UD, a likely break-up body from Phaethon, as an extended mission. Engineering challenges include an up-close encounter at a distance of 500 km from Phaethon with radio-optical hybrid navigation guidance and control, and autonomous imaging based on optical information for target tracking during a high-speed flyby of about 35km/sec. The science goal is to understand the nature and origin of cosmic dust brought onto the Earth, in the context of exogenous contribution of carbon and organics for possible prebiotic seeds of the terrestrial life. Phaethon is a parent body of Geminid meteor shower, and thus a known source to periodically provide dust to the Earth, via its dust stream. The science objectives are two folded: (1) in-situ analyses of velocity, arrival direction, mass and chemical composition of interplanetary and interstellar dust particles around 1 au, the dust trail, and nearby Phaethon, and (2) flyby imaging of Phaethon to study its geology, for understanding dust ejection mechanism of active asteroid and the surface feature and composition which are affected by extensive solar heating. Science payloads include a panchromatic, telescopic camera with a tracking capability (TCAP), a visible-NIR multi-band camera with four bands of 425, 550, 700, 850 nm (MCAP), and a dust analyzer (DDA), which is an upgrade version of Cassini Cosmic Dust Analyzer (CDA). While the two cameras are developed by PERC/Chitech, DDA is developed by Univ. of Stuttgart, as an international collaboration with DLR. Ground calibration for DDA is being performed with German/Japanese joint efforts. International observation campaign for Phaethon was conducted in December 2017, and that of asteroid 2005 UD in October, 2018. Also, international observation campaign for stellar occultation by Phaethon was performed in 2019. Here, we present the current status and science of DESTINY+ mission.

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Ceres’ opposition effect observed by the Dawn framing camera

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833596 ◽

2018 ◽

Vol 620 ◽

pp. A201 ◽

Cited By ~ 6

Author(s):

Stefan E. Schröder ◽

Jian-Yang Li ◽

Marc D. Rayman ◽

Steven P. Joy ◽

Carol A. Polanskey ◽

...

Keyword(s):

Wavelength Dependence ◽

Phase Curve ◽

Angular Width ◽

Opposition Effect ◽

Physically Based ◽

Phase Angles ◽

Coherent Backscatter ◽

Zero Phase ◽

Geometric Albedo ◽

Framing Camera

Context. The surface reflectance of planetary regoliths may increase dramatically towards zero phase angle, a phenomenon known as the opposition effect (OE). Two physical processes that are thought to be the dominant contributors to the brightness surge are shadow hiding (SH) and coherent backscatter (CB). The occurrence of shadow hiding in planetary regoliths is self-evident, but it has proved difficult to unambiguously demonstrate CB from remote sensing observations. One prediction of CB theory is the wavelength dependence of the OE angular width. Aims. The Dawn spacecraft observed the OE on the surface of dwarf planet Ceres. We aim to characterize the OE over the resolved surface, including the bright Cerealia Facula, and to find evidence for SH and/or CB. It is presently not clear if the latter can contribute substantially to the OE for surfaces as dark as that of Ceres. Methods. We analyze images of the Dawn framing camera by means of photometric modeling of the phase curve. Results. We find that the OE of most of the investigated surface has very similar characteristics, with an enhancement factor of 1.4 and a full width at half maximum of 3° (“broad OE”). A notable exception are the fresh ejecta of the Azacca crater, which display a very narrow brightness enhancement that is restricted to phase angles <0.5° (“narrow OE”); suggestively, this is in the range in which CB is thought to dominate. We do not find a wavelength dependence for the width of the broad OE, and lack the data to investigate the dependence for the narrow OE. The prediction of a wavelength-dependent CB width is rather ambiguous, and we suggest that dedicated modeling of the Dawn observations with a physically based theory is necessary to better understand the Ceres OE. The zero-phase observations allow us to determine Ceres’ visible geometric albedo as pV = 0.094 ± 0.005. A comparison with other asteroids suggests that Ceres’ broad OE is typical for an asteroid of its spectral type, with characteristics that are primarily linked to surface albedo. Conclusions. Our analysis suggests that CB may occur on the dark surface of Ceres in a highly localized fashion. While the results are inconclusive, they provide a piece to the puzzle that is the OE of planetary surfaces.

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Dust Science with the DESTINY+ Dust Analyzer

10.5194/epsc2021-871 ◽

2021 ◽

Author(s):

Harald Krüger ◽

Keyword(s):

Impact Ionization ◽

Interplanetary Space ◽

Parent Body ◽

Meteor Shower ◽

Dust Particles ◽

Space Technology ◽

Space Agency ◽

Essential Questions ◽

Type Object ◽

Small Asteroid

The DESTINY+ spacecraft (Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon fLyby and dUst Science) will be launched to the active asteroid (3200) Phaethon by the Japanese Space Agency JAXA in 2024. The main mission target will be Phaethon with a close flyby in 2028. Together with two cameras, the DESTINY+ Dust Analyzer (DDA) on board will perform close observations of this rockcomet type object to solve essential questions related to the evolution of our inner Solar System, especially the heating processes of small bodies. Phaethon is believed to be the parent body of the Geminids meteor shower and is considered to be a comet-asteroid transition object. Such objects likely play a major role to better understand the nature and origin of mass accreted on to Earth. The DDA dust analyzer is an upgrade of the Cassini Cosmic Dust Analyzer (CDA) which very successfully investigated the dust environment of the Saturnian system. The DDA instrument is an impact ionization time-of-flight mass spectrometer with integrated trajectory sensor, which will analyse sub-micrometer and micrometer sized dust particles. The instrument will measure the particle composition (mass resolution m/&#916;m &#8776; 100-150), mass, electrical charge, impact velocity (about 10% accuracy), and impact direction (about 10&#176; accuracy). In addition to dust analysis in the vicinity of Phaethon during the close flyby at this small asteroid, DDA will continuously measure dust in interplanetary space in the spatial region between 0.9 and 1.1 AU during the approximately four years spanning cruise phase from Earth to Phaethon. We give a progress report of the instrument development together with an update on the preparation of the scientific measurements planned during the DESTINY+ mission.

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Photometry and polarimetry of Jupiter at large phase angles

Icarus ◽

10.1016/0019-1035(84)90097-6 ◽

1984 ◽

Vol 58 (1) ◽

pp. 35-73 ◽

Cited By ~ 61

Author(s):

Peter H. Smith ◽

Martin G. Tomasko

Keyword(s):

Large Phase ◽

Phase Angles

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The resonance Raman spectra and excitation profiles of some 4-sulfamylazobenzenes

Canadian Journal of Chemistry ◽

10.1139/v77-203 ◽

1977 ◽

Vol 55 (9) ◽

pp. 1444-1453 ◽

Cited By ~ 28

Author(s):

Kamal Kumar ◽

P. R. Carey

Keyword(s):

Raman Spectrum ◽

Raman Spectra ◽

Resonance Raman ◽

Valence Bond ◽

Wavelength Dependence ◽

Accurate Estimation ◽

Intensity Changes ◽

Stretching Vibration ◽

Resonance Raman Spectra ◽

Frequency Changes

The resonance Raman spectra of three pharmacologically important sulfonamides, 4-sulfamyl-4′-dimethylaminoazobenzene (1), 4-sulfamyl-4′-hydroxyazobenzene (2), and 4-sulfamyl-4′-aminoazobenzene (3), are compared with those of analogues lacking the sulfonamide group. The —SO2NH2 moiety does not directly contribute intense or moderately intense bands to the resonance Raman spectra of 1, 2, and 3. However, —SO2NH2 ionization is reflected by frequency changes in a band near 1140 cm−1 and intensity changes in the 1420 cm−1 region. The normal Raman spectrum of 2 confirms that the intensity changes reflect —SO2NH2 ionization rather than unrelated changes in vibronic coupling. The effect of —OH ionization on the resonance Raman spectrum of 2 emphasizes that caution must be exercised when relating spectral perturbations to changes in contributions from valence bond type structures. Resonance Raman excitation profiles for the 1138, 1387, and 1416 cm−1 bands of 2 show that these bands gain intensity by coupling with the electronic transitions in the 240 to 450 nm region and that, more than 1000 cm−1 to the red of λmax, the wavelength dependence can be closely reproduced by the FB type terms of Albrecht and Hutley. The excitation profile for each band shows evidence for structure in the 470 nm region, although lack of sufficient excitation wavelengths prevents accurate estimation of the spacing. Under conditions of rigorous resonance the intense Raman lines all occur in the 1400 cm−1 region, i.e. they are 'bunched' in the region known to contain the —N=N— stretching vibration.

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Polarization Measurements of Some Herbig Ae/Be Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900190369 ◽

1990 ◽

Vol 140 ◽

pp. 323-324

Author(s):

S. K. Jain ◽

H.C. Bhatt ◽

Ram Sagar

Keyword(s):

Linear Polarization ◽

Wavelength Dependence ◽

Be Stars ◽

Polarization Measurements

We have measured the linear polarization of 8 bright Herbig Ae/Be stars in UBVRI bands. No unique wavelength dependence of polarization magnitude as well as direction is found in these measurements.

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Waiting to make an impact: a probable excess of near-Earth asteroids in 2018 LA-like orbits

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834313 ◽

2019 ◽

Vol 621 ◽

pp. A137

Author(s):

C. de la Fuente Marcos ◽

R. de la Fuente Marcos

Keyword(s):

Outer Space ◽

Statistical Significance ◽

Randomization Test ◽

Orbital Evolution ◽

Parent Body ◽

Meteor Shower ◽

Physical Relationship ◽

Common Precursor ◽

Near Earth Asteroids ◽

Orbit Model

Context. The discovery and tracking of 2018 LA marks only the third instance in history that the parent body of a fireball has been identified before its eventual disintegration in our atmosphere. The subsequent recovery of meteorites from 2018 LA was only the second time materials from outer space that reached the ground could be linked with certitude to a particular minor body. However, meteoroids like 2018 LA and its forerunners, 2008 TC3 and 2014 AA, are perhaps fragments of larger members of the near-Earth object (NEO) population. As the processes leading to the production of such fragments are unlikely to spawn just one meteoroid per event, it is important to identify putative siblings and plausible candidates from which the observed meteoroids might have originated. Aims. Here, we study the pre-impact orbital evolution of 2018 LA to place this meteoroid within the dynamical context of other NEOs that follow similar trajectories. Methods. Our statistical analyses are based on the results of direct N-body calculations that use the latest orbit determinations and include perturbations by the eight major planets, the Moon, the barycentre of the Pluto–Charon system, and the three largest asteroids. A state-of-the-art NEO orbit model was used to interpret our findings and a randomization test was applied to estimate their statistical significance. Results. We find a statistically significant excess of NEOs in 2018 LA-like orbits; among these objects, we find one impactor, 2018 LA, and the fourth closest known passer-by, 2018 UA. A possible connection with the χ-Scorpiids meteor shower is also discussed. The largest known NEO with an orbit similar to that of 2018 LA is the potentially hazardous asteroid (454100) 2013 BO73 and we speculate that they both originate from a common precursor via a collisional cascade. Conclusions. Future spectroscopic observations of 454100 and other NEOs in similar orbits may confirm or deny a possible physical relationship with 2018 LA.

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Scattering Properties of Cometary Dust Based on Polarimetric Data

International Astronomical Union Colloquium ◽

10.1017/s0252921100066884 ◽

1991 ◽

Vol 126 ◽

pp. 249-252

Author(s):

Sonoyo Mukai ◽

Tadashi Mukai ◽

Sen Kikuchi

Keyword(s):

Linear Polarization ◽

Phase Function ◽

Mie Scattering ◽

Mixing Ratio ◽

Small Particles ◽

Cometary Dust ◽

Maximum Polarization ◽

Large Particles ◽

Lower Maximum ◽

Phase Angles

AbstractReferring to the dust model in Mukai and Mukai(1990), where the scattering by large rough particles and Mie scattering by small particles are taken into account, a phase function of linear polarization of several comets is examined, especially in a region of phase angles α near a maximum polarization. A lower maximum polarization observed in comet Austin(1989c1) than those in comets West(1975n) and P/Halley leads a speculation that a mixing ratio of rough scattering to Mie scattering in comet Austin increases from a sun-comet distance r of 0.6 AU to 1.2 AU. This implies that a shortage of large particles in comet Austin occured in r <1 AU.

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